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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5440_Библиотеки_им_академика_М_И_Перельмана.pdf
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- •Computational Methods for Rational Drug Design
- •Contents
- •1.1.2.2 GROMACS
- •1.1.2.3 Amber
- •1.1.2.4 CHARMM
- •1.1.2.5 AutoDock
- •1.1.2.6 VMD
- •1.1.2.7 PyMOL
- •1.1.2.8 Open Babel
- •List of Contributors
- •Preface
- •1. Molecular Modeling and Drug Design
- •1.1 Introduction
- •1.1.1 What Is Molecular Modeling?
- •1.1.2 Software Used for Molecular Modeling
- •1.1.2.1 Schrodinger
- •1.1.2.9 Avogadro
- •1.1.2.10 Discovery Studio
- •1.1.3 Molecular Mechanics
- •1.1.3.1 Prediction of Binding Affinity
- •1.1.3.2 Conformational Analysis
- •1.1.3.3 Virtual Screening
- •1.1.3.4 Lead Discovery
- •1.1.3.5 Mechanism of Action
- •1.2 Types of Molecular Models
- •1.2.1 Ball-and-Spoke Model
- •1.2.1.1 Future Directions
- •1.2.2 Space-filling Models
- •1.2.2.1 Future Directions
- •1.2.3 Crystal Lattice Models
- •1.2.3.1 Future Directions
- •1.3 Computational Methods in Drug Discovery
- •1.3.1 What Is Drug Discovery?
- •1.3.2 Computational Platforms for Drug Discovery
- •1.3.2.1 NCBI
- •1.3.2.2 Chemical Databases
- •1.3.2.3 PDB
- •1.3.2.5 UniProt
- •1.3.2.6 QSAR
- •1.3.2.8 Desmond
- •1.3.2.9 OpenBabel
- •1.3.2.10 DeepChem and Cheminformatics for Python (RDKit)
- •1.3.2.11 SBML
- •1.3.2.12 Virtual Screening
- •1.3.3 Applications of Computer-Based Methods in Steps of Drug Discovery
- •1.4 Potential Use and Application of AI in Drug Designing
- •1.4.1 Target Identification and Validation
- •1.4.2 Drug Screening and Lead Optimization
- •1.4.3 De Novo Drug Design
- •1.4.4 Predictive Toxicology and ADMET
- •1.4.5 Clinical Trial Optimization
- •1.4.6 Drug Repurposing
- •1.4.7 Concept of Personalized Medicine
- •1.4.8 Drug Combination Optimization
- •1.5 Limitations of Current Methods
- •1.5.1 Data Restrictions
- •1.5.2 Interpretability
- •1.5.3 Generalization
- •1.5.4 Resources and Computation
- •1.5.5 Ethical Considerations
- •1.5.6 Validation and Experimentation
- •1.5.7 Regulatory Obstacles
- •1.6 Case Studies
- •1.7 Molecular Docking
- •1.7.1 What Is Molecular Docking?
- •1.7.1.1 Procedure
- •1.7.1.2 Biophysical Laws
- •1.7.1.3 Rigid and Flexible Docking
- •1.7.1.4 Types of Docking
- •1.7.1.5 Challenges and Future Perspectives
- •1.7.2 Applications of Molecular Docking in Drug Designing
- •1.7.3 Success of Molecular Docking Cases in Drug Designing
- •1.8 Conclusion and Future Works
- •References
- •2. Bioactive Small Molecules and Drug Discovery
- •2.1 Introduction
- •2.1.1 Introduction to Drug Design and Discovery
- •2.1.2 Brief History of Small-Molecule Drug Discovery
- •2.1.3 Importance of Bioactive Small Molecules in Drug Discovery
- •2.2.1 Structure-Based Methods
- •2.2.2 Ligand-Based Methods
- •2.2.3 Network-Based Methods
- •2.3 Natural Products in Bioactive Small-Molecule Discovery
- •2.3.1 Plant Primary and Secondary Molecules as Bioactive Molecules
- •2.3.2 Anticancer Agents as Bioactive Molecules
- •2.3.3 Antiviral Agents as Bioactive Molecules
- •2.3.4 Antimalarial Agents as Bioactive Molecules
- •2.6.6 Toxicity and Side Effects
- •2.6.7 Cost-Effectiveness, Synthetic Feasibility, and Scalability
- •2.6.8 Structural Diversity and Novelty
- •2.6.9 Patentability and Intellectual Property
- •2.3.5 Marine Bioactive Products
- •2.4.1 Importance of DFT in Small-Molecule Drug Discovery
- •2.5 Application of DFT to Bioactive Small Molecules
- •2.5.1 HOMO–LUMO Calculation
- •2.5.1.1 Molecular Electrostatic Potential (MEP) Map
- •2.5.1.3 Natural Bond Orbital (NBO) Analysis
- •2.5.1.4 Implementations and Tools
- •2.6.1 Target Identification and Validation
- •2.6.2 Target Specificity
- •2.6.3 Bioavailability and Pharmacokinetics
- •2.6.4 Chemical Structure and Drug-likeness
- •2.6.5 Safety and Toxicity
- •2.7 Conclusion
- •References
- •3. Novel Drug Targets for Small Molecule-based Drug Discovery
- •3.1 Introduction
- •3.2 Drug Target Identification
- •3.3 Classification of Novel Drug Targets
- •3.3.1 Transcription Factors
- •3.3.2 Cytokines
- •3.3.3 Chaperones
- •3.3.4 Viral Targets
- •3.3.5 G Protein-coupled Receptors
- •3.3.6 Transporters
- •3.3.7 Enzymes
- •3.3.8 RNA Targets
- •3.4 Small Molecules as Drugs
- •3.5 Conclusion
- •References
- •4.1 Introduction
- •4.2 Structure-Based Drug Discovery Concept
- •4.2.1 Structure Generation of the Target
- •4.2.1.1 The Detailed Description of Each Tool
- •4.2.2 Active Binding Site Within the Target
- •4.2.2.1 The Detailed Description of Each Tool
- •4.2.2.2 Molecular Docking Analysis
- •4.2.2.3 The Detailed Description of Each Tool
- •4.2.3 Molecular Dynamic Simulations
- •4.2.3.1 The Detailed Description of Each Tool
- •4.3 Ligand-Based Drug Discovery Concept
- •4.3.1.1 The Detailed Description of Each Tool
- •4.4 Structure- and Ligand-Based Assisted Studies
- •4.4.1 The Detailed Description of Each Tool
- •4.4.2 The Detailed Description of Each Tool
- •4.5 Advancement and Challenges in SBDD and LBDD
- •4.6 Conclusion
- •References
- •5. Virtual Screening and Lead Discovery
- •5.1 Introduction to Virtual Screening and Lead Discovery
- •5.1.1 Overview of Drug Discovery Process
- •5.1.2 Role of Virtual Screening
- •5.1.3 Importance of Lead Discovery
- •5.2 Molecular Targets and Biomolecular Structures
- •5.3 Virtual Screening Approaches
- •5.3.1 Structure-based Virtual Screening
- •5.3.2 Ligand-based Virtual Screening
- •5.3.3 Hybrid Approaches
- •5.4 Databases and Compound Collections
- •5.4.1 Overview of Chemical Databases
- •5.4.2 Compound Filtering and Preparation
- •5.4.3 Diversity and Size of Compound Collections
- •5.5 Molecular Docking
- •5.5.1 Principles of Molecular Docking
- •5.5.2 Docking Algorithms and Scoring Functions
- •5.5.3 Validation of Docking Results
- •5.6 Pharmacophore Modeling
- •5.6.1 Concept of Pharmacophores
- •5.6.2 Generating Pharmacophore Models
- •5.6.3 Applications in Lead Discovery
- •5.7 Quantitative Structure–Activity Relationship (QSAR)
- •5.7.1 Basics of QSAR
- •5.7.2 Model Development and Validation
- •5.7.3 QSAR in Virtual Screening
- •5.8 Machine Learning and AI in Virtual Screening
- •5.8.1 Introduction to Machine Learning and AI
- •5.8.2 Feature Selection and Model Training
- •5.8.3 Applications in Virtual Screening
- •5.9 Hit-to-Lead Optimization
- •5.9.1 Prioritizing Hits from Virtual Screening
- •5.9.2 SAR Analysis and Iterative Design
- •5.9.2.1 SAR Analysis (Structure–Activity Relationship)
- •5.9.2.2 Iterative Design
- •5.9.3 ADME/Tox Considerations
- •5.9.3.1 ADME (Absorption, Distribution, Metabolism, Excretion)
- •5.9.3.2 Toxicity Considerations
- •5.10 Case Studies and Examples
- •5.10.1 Exploration Protocol for Mutant-targeted PI3K Inhibitors
- •5.11 Challenges and Future Directions
- •5.11.1 Limitations of Virtual Screening
- •5.11.2 Emerging Technologies and Trends
- •5.11.3 Integration with High-throughput Experimentation
- •5.12 Ethical and Regulatory Considerations
- •5.12.1 Intellectual Property and Patents
- •5.12.2 Ethical Use of Computational Tools
- •5.12.3 Regulatory Approval Process
- •5.13 Conclusion
- •5.13.1 Future Prospects in Virtual Screening and Lead Discovery
- •5.13.2 Summary of Key Points
- •References
- •6. ADMET and Physicochemical Assessments in Drug Design
- •6.1 ADMET
- •6.1.1 Absorption
- •6.1.1.1 Solubility and Dissolution
- •6.1.1.2 Lipophilicity
- •6.1.1.3 Permeability
- •6.1.2 Distribution
- •6.1.3 Metabolism
- •6.1.4 Excretion
- •6.1.5 Toxicity
- •6.2 Physicochemical Assessments
- •6.2.1 Partition Coefficient
- •6.2.2 Log D: Ionizable Compound Lipophilicity
- •6.2.2.1 Methods for Calculating Lipophilicity
- •6.2.2.2 Direct Experimental Determination of Lipophilicity
- •6.2.2.3 Indirect Experimental Determination of Lipophilicity
- •6.2.3 Acid–Base Properties and Ionization
- •6.2.4 Solubility
- •6.2.5 Polymorphism
- •6.2.6 Molecular Weight
- •6.2.7 Number of Hydrogen Bond Donors (HDB) and Acceptors (HDA)
- •References
- •7. In Silico Modeling and Drug Design
- •7.1 Introduction
- •7.2 Target Identification
- •7.2.1 Experimental Approaches
- •7.2.2 Computational Target Identification
- •7.2.3 Target Validation
- •7.3 Computer-Aided Drug Design
- •7.3.1 Ligand-based CADD
- •7.3.2 Structure-Based CADD
- •7.4 ADMET Assessment
- •7.5 Conclusion
- •References
- •8. Pharmacophore Modeling in Drug Design
- •8.1 Introduction
- •8.1.1 The Role of Pharmacophore Modeling in Drug Design
- •8.1.2 Historical Perspective and Evolution of Pharmacophore Concepts
- •8.2 Essential Concepts in Pharmacophore Hypothesis Generation
- •8.2.1.1 Partitioning Initial Data into Distinctive Datasets
- •8.3 Diverse Approaches to Pharmacophore Modeling
- •8.3.1 Ligand-Based Pharmacophore Modeling
- •8.3.2 Structure-Based Pharmacophore Modeling
- •8.4 Application of Pharmacophore Modeling
- •8.4.1 Applications of Pharmacophore-Based Virtual Screening
- •8.4.1.1 Drug Discovery
- •8.4.2 Applications in Drug Target Fishing
- •8.4.3 Applications in Ligand Profiling
- •8.4.4 Applications in Docking
- •8.4.5 Applications in ADMET
- •8.4.6 Modulation of the Immune System
- •8.5 Emerging Trends in Pharmacophore Model Development
- •8.5.1 Involvement of Machine Learning
- •8.5.2 Prediction of Pharmacokinetic Properties
- •8.5.3 Structural Biology and Protein Functionality Studies
- •8.5.4 Integration with MDs Simulations
- •8.6 Case Studies
- •8.6.1 Case 1
- •8.6.2 Case 2
- •8.7 Challenges in Pharmacophore Modeling
- •8.8 Conclusion
- •Acknowledgments
- •References
- •9. Scaffold Hopping and De Novo Drug Design
- •9.1 Introduction
- •9.2 Scaffold Hopping
- •9.2.1 Classification of Scaffold Hopping
- •9.2.1.1 1° Hop: Heterocycle Replacement
- •9.2.1.2 2° Hop: Ring Opening and Closure: Pseudo Ring Structures
- •9.2.1.3 3° Hop: Pseudopeptides and Peptidomimetics
- •9.2.1.4 4° Hop: Topology/Shape-Based Scaffold Hopping
- •9.2.2 Advantages of Scaffold Hopping
- •9.2.3 Disadvantages of Scaffold Hopping
- •9.2.4 Reasons for Scaffold Hopping
- •9.2.5 Properties and Key Methods of Scaffold Hopping
- •9.3 De Novo Drug Design
- •9.3.1 Classification of De Novo Drug Design
- •9.3.1.1 Structure-based Drug Design
- •9.3.1.2 Ligand-based Drug Design
- •9.3.1.3 De Novo Design Strategies
- •9.3.1.4 Artificial Intelligence (AI) and Machine Learning-based Design
- •9.3.1.5 Hybrid Approaches
- •9.3.2 Basic Principle of De Novo Drug Design
- •9.3.3 Application of De Novo Drug Design
- •9.3.4 Historical Overview of Scaffold Hoping and De Novo Drug Design
- •9.3.5 Methodological Approaches in De Novo Drug Design
- •9.3.5.1 Structure-based De Novo Drug Design
- •9.3.5.2 Ligand-based De Novo Drug Design
- •9.3.5.3 Generation of Drug-Like Molecular Fragments
- •9.3.5.4 Similarity Searching
- •9.3.5.5 Selection of Target Reference Structure
- •9.3.5.6 Similarity Analysis of De Novo-generated Compounds
- •9.3.5.7 Evaluation of Scaffold Diversity
- •9.4 Results and Discussion
- •9.4.1 Generation of Drug-Like Molecular Fragments
- •9.4.2 De Novo Design with a Single Reference Structure
- •9.4.3 De Novo Design with a Focused Set of Five Similar Templates
- •9.4.4 De Novo Design with a Diverse Set of Five Templates
- •9.6 Case Study
- •9.6.1 De Novo Drug Design
- •9.6.2 Scaffold Hopping
- •9.7 Conclusion
- •References
- •10. Fragment-based Drug Design and Drug Discovery
- •10.1 Introduction
- •10.2 The Process of Finding Fragments
- •10.3 FBDD Strategies
- •10.4 Case Studies
- •10.5 Conclusion and Future Perspectives
- •References
- •11. AI/ML Approaches in Drug Design
- •11.1 Introduction
- •11.2 Traditional Drug Design Methods
- •11.2.1 The Rise of Computational Methods
- •11.2.2 The Importance of AI/ML in Modern Drug Design
- •11.3 AI/ML Landscape in Drug Design
- •11.3.1 AI/ML Algorithms and Methods
- •11.3.1.1 Machine Learning Models
- •11.3.1.2 Neural Networks
- •11.3.2 Applications in Drug Design
- •11.3.2.1 Peptide Synthesis
- •11.3.2.2 Molecular Design
- •11.3.2.3 Virtual Screening (VS)
- •11.3.2.4 Quantitative Structure–Activity Relationship Models
- •11.3.2.5 Drug Repurposing
- •11.3.3 Challenges and Failures
- •11.4 Ethics, Reliability, and Regulatory Issues
- •11.5 Future Directions
- •11.6 Conclusion
- •References
- •12. Network-based Methods in Drug Discovery
- •12.1 Introduction
- •12.1.1 Background of Drug Discovery Future Challenges
- •12.1.2 Single Target Approach Limitations
- •12.1.3 Emergence of Network Biology and Polypharmacology
- •12.2 Network Pharmacology: Practical Guide
- •12.2.1 Common Network Pharmacology Databases
- •12.2.1.1 Network Pharmacology-Related Databases and Data Analysis Tools
- •12.2.1.2 Exploring IMPPAT Network Pharmacology Databases
- •12.2.1.3 Target Genes of Phytoconstituents
- •12.2.2 Network Analysis and Visualization
- •12.2.3 Applications of Network Pharmacology in Drug Discovery
- •12.3 Ayurveda and Traditional Indian Medicine
- •12.3.1 Overview of Ayurveda and Its Complex Formulations
- •12.3.2 Diversity of Ingredients and Bioactive Compounds in Ayurvedic Medicines
- •12.4 Network Pharmacology in Herbal Remedies
- •12.4.1 Application of Network Pharmacology in Herbal Drug Discovery
- •12.4.1.1 Cancer
- •12.4.1.2 Cardiovascular Diseases (CVDs)
- •12.4.1.3 Diabetes Mellitus (DM)
- •12.4.2 Screening Pharmacological Efficacy of Herbal Remedies
- •12.4.3 Utilizing Network Pharmacology to Understand Complex Diseases
- •12.5 Conclusion and Future Prospects
- •References
- •13. Rational Design of Natural Products for Drug Discovery
- •13.1 Introduction
- •13.2 Natural Products for the Development of New Drugs
- •13.3 Criteria for Selecting Natural Products for Drug Design
- •13.4 Importance of Biodiversity in Sourcing Natural Products
- •13.5 Structural Elucidation of Natural Products
- •13.6.3 High-Throughput Screening Methods for Efficient Compound Selection
- •13.6.4 Molecular Dynamics Simulations for Predicting Solubility and Stability
- •13.6.5 ADMET Attributes Predicted In Silico
- •13.7 Formulation Challenges with Natural Products
- •13.8 Quality by Design (QbD) Approaches
- •13.8.1 Use of Computational Models for Formulation Optimization
- •13.9 Conclusion
- •References
- •14. Design of Enzyme Inhibitors in Drug Discovery
- •14.1 Introduction
- •14.3 Classification of Enzyme Inhibitors
- •14.3.1 Reversible Inhibitors
- •14.3.2 Irreversible Inhibitors
- •14.3.3 Competitive Inhibitors
- •14.3.4 Noncompetitive Inhibitors
- •14.3.5 Allosteric Modulators
- •14.4.1 Structure-Based Design
- •14.4.2 Computer-Aided Design
- •14.4.3 Fragment-Based Design
- •14.4.4 Virtual Screening Method
- •14.4.4.1 Ligand Based
- •14.4.4.2 Receptor Based
- •14.4.5 Natural Product-Based Discovery
- •14.4.6 Using Iterative Protein Crystallographic Analysis
- •14.4.7 Utilization of Covalent Inhibitors
- •14.4.8 Encapsulation Techniques
- •14.4.9 Based on Active-Site Specificity
- •14.4.10 Machine Learning Inhibitor Design
- •14.4.11 Enzyme-Templated Dynamic Combinatorial Chemistry
- •14.5 Limitations and Challenges
- •14.6 Future Directions
- •14.7 Conclusion
- •References
- •15.1 Introduction
- •15.2 Peptides as Therapeutics
- •15.2.1 Peptide Antibiotics
- •15.2.1.1 Peptides in Bone Diseases
- •15.2.1.2 Peptides in Cancer
- •15.2.1.3 Peptides in Metabolic Diseases
- •15.2.1.4 Peptides in Gastrointestinal Diseases
- •15.2.2 Advantages and Limitations of Peptide Therapeutics
- •15.2.3 FDA-Approved Peptide Therapeutics
- •15.2.4 Peptide-Based Entities in Clinical Trials
- •15.2.5 Peptide Synthesis and Diversification
- •15.2.5.1 Chemical Synthesis of Peptides
- •15.2.5.2 Chemical Modification of Peptide and Peptidomimetics
- •15.2.5.3 Backbone Modification of Peptides
- •15.2.5.4 Side-Chain Modification of Peptides
- •15.2.5.5 Peptide Cyclization
- •15.2.5.6 Peptide Mimicking of α-Helices and Stabilization
- •15.2.5.7 Peptide Mimicking of β-Strands and β-Sheets
- •15.2.5.8 Peptide Production by Recombinant Technology
- •15.2.5.9 Peptides Modification by Genetic Code Expansion
- •15.2.5.10 PEGylation of Peptides and Proteins
- •15.3 New Technologies for Peptide-Based Drug Discovery
- •15.3.1 Phage Display
- •15.3.2 mRNA Display
- •15.3.3 DNA-Encoded Libraries
- •15.3.4 Cell-Penetrating Peptides
- •15.3.5 Macrocyclic Peptides
- •15.4 Computational Approaches in Peptide Drug Discovery
- •15.5 Conclusion
- •References
- •16. Rational Design of Drugs for Neurodegenerative Disorders
- •16.1 Introduction
- •16.2 Common Mechanism of Neurodegeneration
- •16.3 Brief Overview of Computational Methods in Drug Design
- •16.4 Parkinson’s Disease as Prevalent Neurodegenerative Disorder
- •16.4.1 Epidemiology of Parkinson’s Disease
- •16.4.2 Pathogenesis of PD
- •1) Accumulation of Lewy bodies in substantia nigra
- •2) Mitochondrial dysfunction
- •3) Genetic factors
- •4) Neuroinflammation
- •5) Impaired protein handling
- •6) Oxidative stress
- •7) Environmental toxins
- •16.4.3 Signaling Pathway of Parkinson’s Disease
- •1) DA signaling
- •2) MAPK/ERK pathway
- •3) PI3K/Akt/mTOR pathway
- •4) Wnt/β-catenin pathway
- •5) NF-κB (nuclear factor-κB) pathway
- •6) Autophagy-lysosomal pathway
- •7) JNK (c-Jun N-terminal kinase) pathway
- •8) AMPK (AMP-activated protein kinase) pathway
- •9) Nrf2 (nuclear factor erythroid 2-related factor 2) pathway
- •16.4.4 Enzymatic Targets in Parkinson’s Disease
- •1) MAO-B (monoamine oxidase B)
- •2) COMT (catechol-O-methyltransferase)
- •3) LRRK2
- •4) GCase (glucocerebrosidase)
- •5) PARP-1 [poly(ADP-ribose) polymerase-1]
- •6) PINK1
- •7) DJ-1 (Parkinson protein 7)
- •8) Nrf2
- •16.4.5 Current Therapeutic Approaches to Treat PD
- •1) Drugs to treat motor symptoms of PD
- •2) Drugs to treat non-motor symptoms of PD
- •3) Disease-modifying therapies to treat PD
- •16.4.6 Current Therapeutic Challenges to Treat Parkinson’s disease
- •1) Symptomatic relief only
- •2) Motor fluctuations and dyskinesias
- •3) Limited efficacy in nonmotor symptoms
- •4) Disease progression
- •5) Side effects
- •6) Limited treatment options for advanced PD
- •7) Individual variability
- •16.4.7 Unmet Needs in Parkinson’s Disease Therapeutics
- •16.4.8 Significance of Computational Approaches in Parkinson’s Disease
- •16.4.9 Use of Computational Tools in Identifying Biomarkers
- •16.4.10 Neuroprotective Strategies Through Computational Insights
- •16.4.10.1 Computational Models for Neuroprotection
- •1) Target identification and validation
- •2) Drug repurposing
- •3) Alpha-synuclein aggregation inhibitors
- •4) Deep learning in biomarker discovery
- •5) Personalized medicine
- •6) Drug-induced neuroprotection
- •7) Optimizing clinical trials
- •1) ML and AI-based diagnostics
- •2) Wearable technology integration
- •3) Multimodal data fusion
- •4) Predictive modeling of disease progression
- •5) Network analysis of brain connectivity
- •6) Personalized treatment optimization
- •7) Data sharing and collaboration platforms
- •16.5 Conclusion
- •References
- •17. Rational Design of Anti-inflammatory Therapeutics
- •17.1 Introduction
- •17.2 Navigating Inflammation and its Microenvironment
- •17.2.1 Inflammatory Cell Infiltration and Vascular Permeability
- •17.2.2 Acidosis
- •17.2.3 Increased Oxidative Stress in Tissues
- •17.3 The Demand for Advanced Anti-inflammatory Medications
- •17.5 Rational Design of Anti-inflammatory Agents
- •17.5.2 New Anti-inflammatory Agent with Indoyl-imidazole Hybrids
- •17.5.3 Rational Design of Novel Aminopiperidinyl Amide
- •17.5.4 Lipid Nanoparticles (LNPs) as Anti-inflammatory Agents
- •17.6 Conclusion and Future Perspectives
- •Authors’ Contribution
- •References
- •18.1 Introduction
- •18.2 Treatment
- •18.3 Antibacterial Resistance
- •18.3.1 Mutation
- •18.3.2 Horizontal Gene Transfer (HGT)
- •18.3.3 Enzymatic Modification or Degradation
- •18.3.4 Target Site Modification
- •18.3.5 Decreased Permeability
- •18.3.6 Efflux Pumps
- •18.3.7 Plasmids
- •18.3.8 Transposons
- •18.3.9 Gene Amplification
- •18.3.10 Formation of Biofilms
- •18.3.11 Modified Metabolic Pathways
- •18.3.12 Adaptive Evolution
- •18.4.1 Structure- Based Drug Design
- •18.4.2 Modification of Existing Antibiotics
- •18.4.3 Bioisosterism
- •18.4.4 Prodrug Strategies
- •18.4.5 Similar Bacterial Components Target
- •18.4.6 Combine or Combination Therapy
- •18.4.7 Drug Repurposing
- •18.4.8 Resistant Mechanism Blocking
- •18.4.9 Improving Drug Delivery by Nanotechnology
- •18.4.10 Phage Intervention
- •18.4.11 Host Targeting
- •18.4.12 CRISPR-Cas Technique
- •18.4.13 Peptides as Antibacterials
- •18.4.14 Immunizations and Immunotherapy
- •18.4.15 Natural Product Derivatives
- •18.4.16 Fragment- Based Drug Discovery (FBDD)
- •18.4.17 Metabolomics and Genetics
- •18.4.18 Cheminformatics
- •18.5 Summary and Conclusion
- •References
- •19. Rational Design of Antiviral Therapeutics
- •19.1 Introduction to Antiviral Therapeutics
- •19.1.1 Overview
- •19.1.2 Blueprints for Antiviral Drug Interventions
- •19.1.2.1 Protein Folding and Binding Sites
- •19.1.2.2 Conformational Changes
- •19.1.2.3 Protein–Protein Interactions (PPIs)
- •19.1.2.4 Capsid and Envelope Structures
- •19.1.2.5 Structural Vulnerabilities
- •19.1.2.6 Enzymatic Activities
- •19.1.2.7 Viral Attachment
- •19.1.2.8 Viral Assembly and Replication Machinery
- •19.1.2.9 The Host’s Immune Response
- •19.2 Targets for Antiviral Therapeutics and Inhibition Strategies
- •19.2.1 Enzyme Inhibitors
- •19.2.2 Antiviral Peptides
- •19.2.3 Antiviral Antibodies
- •19.2.4 Lipid-Mimicking Compounds
- •19.2.5 Vaccines
- •19.2.6 Immunomodulation
- •19.3 Rational Strategies for Antiviral Therapeutics
- •19.3.1 CADD and QSAR (Quantitative Structure–Activity Relationship)
- •19.3.2 AI and ML
- •19.3.3 Systems Biology and Network Pharmacology
- •19.3.4 CRISPR Systems
- •19.3.5 Nanotechnology-Based Design and Delivery Systems
- •19.3.6 Reverse Vaccinology
- •19.4 Conclusion
- •References
- •20. Rational Design of Anticancer Therapeutics
- •20.1 Introduction
- •20.2 Rational Design of Nanomedicine for Cancer Treatment
- •20.4.1 Particle Size
- •20.4.2 Shape
- •20.4.3 Surface Modification
- •20.6 Artificial Intelligence’s Progress in Anticancer Drug Development
- •20.6.1 Identification of Anticancer Drug Targets Using Artificial Intelligence
- •20.6.3 Artificial Intelligence-Based De Novo Anticancer Drug Design
- •20.6.4 Artificial Intelligence for Repurposing Anticancer Drugs
- •20.7 Conclusion
- •References
- •21. PROTAC and ProTide Strategies in Drug Design
- •21.1 Introduction
- •21.2 Drug Design: Past to Present
- •21.3 PROTAC Strategy in Drug Design
- •21.3.1 Ubiquitin Proteasome System and PROTACs
- •21.3.2 Chemical Formulations of PROTACs
- •21.3.3 Advent of PROTACs as Antiviral
- •21.3.4 NS3/4A-Targeting PROTACs Against HCV
- •21.3.4.1 Neuraminidase-Targeting PROTACs
- •21.4 Emergence of ProTide Technology in Drug Design
- •21.5 Approaches of ProTides in Drug Development
- •21.6 Implementation of ProTides as Nucleoside Analogs
- •21.6.1 Antiviral Applications of ProTides
- •21.7 Conclusion
- •References

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25
2.1 Introduction
2.1.1 Introduction to Drug Design and Discovery
The process of finding possible new therapeutic entities through the application of computational,
experimental, translational, and clinical models is known as drug discovery. Despite improve-
ments in biotechnology and our understanding of biological systems, the process of finding new
therapeutics is still exceedingly time-consuming, expensive, challenging, and inefficient [1]. The
entire process of creating a new medication, from conception to market release, can take 12–15
years and exceed one billion dollars. Based on the knowledge of a biological target, the inventive
process of finding new medications is known as drug design [2]. Preclinical research on animal
and cell models as well as human clinical trials is all part of the process of developing and discover-
ing new drugs [3]. Afterward, the drug must receive regulatory approval before being put on the
market. Identification of screening hits, medicinal chemistry, and optimization of those hits to
boost their affinity, selectivity (to lower the risk of adverse effects), efficacy/potency, metabolic
stability (to lengthen the half-life), and oral bioavailability are all important components of mod-
ern drug research. Following the discovery of a chemical meeting each of these criteria, the process
of developing a medicine will start before any clinical trials are conducted [4].
Drug design, in its most basic form, is the design of molecules that complement the molecu-
lar target that they interact and bind to in terms of charge and shape. In the big data era,
bioinformatics methods and computer modeling techniques are often, but not always, used in
drug design. Apart from small molecules, biopharmaceuticals, particularly therapeutic
antibodies, are becoming a significant class of medications. Significant progress has also been
made in computational methods for enhancing the stability, selectivity, and affinity of these
protein-based treatments [5].
2
Bioactive Small Molecules and Drug Discovery
Ashish Shah
1
, Vaishali Patel
2
, Sathiaseelan Perumal
3
, Riddhi Dave
4
,
5
, Ghanshyam Parmar
1
, and Jay Mukesh Chudasama
1
1
2
3
4
5

26
2.1.2 Brief History of Small-Molecule Drug Discovery
Numerous small-molecule medications have enhanced patient outcomes and advanced medicine
throughout history. While some of these pioneering medications remain on the market today, oth-
ers have vanished from use but played a significant role in opening the door for more effective
therapies within their particular use. For almost a century, small molecules have been crucial in
producing medical advancements for human ailments. The quick development of biopharmaceu-
tical research and technology creates opportunities for fresh, imaginative methods of creating
small-molecule medications [6].
For almost a century, small-molecule medications have served as the foundation of the pharma-
ceutical business. Small-molecule medications, which are defined as any organic substance with a
low molecular weight, offer several unique therapeutic benefits. The majority are oral medications
that can cross cell membranes and reach intracellular targets [7]. Because of these qualities, small-
molecule medicines are becoming more popular in the pharmaceutical industry and are excellent
candidates for therapeutic development. Because of their inadequate efficacy or severe side effects,
the medications now employed in clinical practice are insufficient, even with the developments in
molecular genetics and the creation of new, efficient drug discovery techniques. For this reason,
creating novel, effective medications is crucial to the prevention and treatment of disease [8].
2.1.3 Importance of Bioactive Small Molecules in Drug Discovery
Their inherent qualities, such as their capacity to pass through biological barriers and affect vari-
ous distinct biological targets, have played a significant role in their effectiveness as medications.
Majority of small-molecule medications have oral bioavailability, which allows for conventional
oral administration as a tablet [9]. When compared to biologics, this convenience factor is a signifi-
cant benefit, even though the pharmacological impact size may be comparable. For example,
recombinant biologic erythropoietin (EPO) can be treated for renal anemia with small-molecule
inhibitors (HIF-PH), which can be taken as a pill instead of an injection or infusion. The modular
structure and chemical synthesis accessibility of tiny molecules are further essential features [10].
Because of this, their chemical structures may be quickly varied, and their attributes can be
improved in a systematic way. The unaltered tiny molecule is the primary component of the major-
ity of pharmaceutical preparations. The unaltered small molecule is typically the active ingredient
in drug formulations. Prodrugs, or appropriate reversible chemical changes, can be created to com-
pensate for possible drawbacks such as low water solubility. Targeted activation or transport of a
pharmaceutical component toward a target tissue can also be accomplished using a comparable
method. Lastly, most medication formulations and administration routes are compatible with
small molecules, and they often have a high shelf life [11]. For a more comprehensive overview of
small-molecule properties, see Table 1.
2.2 Importance of Computational Methods in Bioactive
Small-Molecules Discovery
Computational techniques play a crucial role in the search for bioactive small molecules, making
them a powerful and efficient strategy for drug development. Molecular docking, synthetic
screening, molecular dynamics (MD) models, and quantitative structure–activity relationship
(QSAR) models are all components of these methodologies. The ability of computational

27
methods to predict potential bioactive compounds and their interactions with target proteins,
thereby decreasing the number of candidates that need to be experimentally validated, is a sig-
nificant advantage in the process of drug discovery [12]. The intricate molecular mechanisms
underlying drug–target interactions can be comprehended more effectively through the utiliza-
tion of these approaches, thereby facilitating the rational development of novel compounds pos-
sessing enhanced pharmacological attributes [13]. Computer programs also assist in the search
for novel chemical entities with favorable therapeutic characteristics by enabling the identifica-
tion of structurally diverse molecules. Integrating computational methodologies provides an effi-
cient and cost-effective method for identifying potential therapeutic candidates, as traditional
drug development can be resource-intensive and time-consuming. Computational methodolo-
gies are essential in the detection of bioactive small molecules since they enhance the velocity,
efficacy, and cost-efficiency of pharmaceutical research and development. Consequently, this
enables us to tackle medical demands that have not been fulfilled and enhance the results for
patients [14].
2.2.1 Structure-Based Methods
Computational techniques for the discovery of small bioactive compounds rely heavily on structure-
based methods. To aid in the development of pharmaceuticals, these techniques make use of the
three-dimensional structures of biological macromolecules, such as proteins or nucleic acids. One
of the most well-known methods in this area is molecular docking, which uses computational
methodologies to model the binding geometry of small molecules (ligands) with target proteins in
order to anticipate how these two would interact [15]. To aid in the selection of potential medica-
tion candidates, this method makes it easier to identify potential binding sites and evaluate the
binding strength of ligands [16, 17]. In order to find compounds that can bind to a certain target
protein, structure-based virtual screening methodically searches through large compound librar-
ies [18, 19]. This approach helps reduce the time and resources needed for hit identification by
prioritizing compounds for experimental testing. By showing how biomolecular complexes behave
dynamically over time, MD simulations improve structure-based methods and provide a better
understanding of ligand binding and stability [14]. Also, structure-based methods are useful for
developing fragment-based drugs or designing novel small compounds through de novo ligand
design. In de novo ligand design, new compounds with desired properties are generated computa-
tionally, whereas in fragment-based approaches, smaller molecular fragments are found and opti-
mized to form a ligand with high binding affinity. Finding bioactive tiny compounds relies heavily
on structure-based approaches. By utilizing these tools, we may make informed predictions about
ligand–target interactions, virtually screen compound libraries, analyze molecules’ dynamic
behaviors, and rationally create new therapeutic candidates [20]. The use of these computational
techniques considerably improves the efficacy and efficiency of medication development
(Table 2.1).
2.2.2 Ligand-Based Methods
In order to infer information about possible medication candidates, ligand-based approaches to
bioactive small-molecule discovery examine the features and qualities of already-known bioactive
molecules. An alternative to using target protein structures, these strategies make use of ligand-derived
data [21]. The process of discovering new drugs often makes use of a few essential ligand-based
methods enlisted in Table 2.2.

28
QSAR models are used to create mathematical relationships between the chemical struc-
tures of ligands and their observed biological activities. QSAR models evaluate datasets of
known bioactive chemicals and predict the activity of new molecules to aid in the design of
more potent drugs or those with fewer adverse effects. Pharmacophore models are extremely
useful for determining the essential structural and spatial components involved in ligand
binding to a target [22]. These models guide medicinal chemists in constructing compounds
that imitate the required interactions, thereby facilitating the design of new molecules by
emphasizing crucial characteristics. Molecular fingerprints enable the comparison of ligand
structures by converting molecular information into a binary format. Comparable finger-
prints facilitate the virtual screening of potential drug candidates and the search for similar
Table 2.1 Structure-based methods for drug discovery.
Structure-based
methods Description
Docking process Uses simulated binding geometry to predict how a tiny chemical (ligand) will
interact with a target protein. A useful tool for determining binding affinity and
locating possible binding locations
Structure-based
virtual screening
Systematically screens large compound libraries to identify molecules with the
potential to bind to a specific target protein. Prioritizes compounds for
experimental testing, saving time and resources
Molecular dynamics
simulations
Provides insights into the dynamic behavior of biomolecular complexes over
time. Enhances understanding of ligand binding and stability, contributing to a
more comprehensive analysis
De novo ligand design Generates new molecules computationally with desired properties. Facilitates
the design of novel small molecules for specific targets
Fragment-based drug
discovery
Identifies and optimizes smaller molecular fragments that can be combined to
form a high-affinity ligand. A strategic approach to drug design
Table 2.2 Essential ligand-based methods for drug discovery.
Ligand-based
methods Description
QSAR Statistical approaches are employed to establish a relationship between the chemical
structure and biological activity of a set of ligands. By analyzing the structural
properties of novel compounds, QSAR models can predict their activity
Pharmacophore
modeling
Discovers shared spatial or structural characteristics needed for ligand–target
interactions. New compounds with comparable pharmacological characteristics can
be designed using this three-dimensional arrangement of features as a template
Molecular
fingerprints
Creates a binary fingerprint using molecular characteristics like substructures or
chemical patterns. To help with ligand similarity searches and virtual screening,
fingerprints that are structurally similar are useful
Machine learning
approaches
Uses various machine learning algorithms to draw conclusions about ligand
bioactivity from data, including neural networks and random forests. These
techniques improve predicting abilities by handling complicated interactions among
massive datasets

29
ligands by highlighting structural similarities. Neural networks and random forests are two
machine learning methods that analyze large amounts of ligand data to identify patterns that
can provide insights about the behavior of chemicals in the body. Ligand-based approaches
offer valuable tools for the discovery of bioactive small molecules by utilizing data from
known ligands to forecast the activities and characteristics of novel compounds [23, 24].
These methodologies are highly effective in forecasting the pharmacological characteristics
of novel drugs and in identifying intricate patterns and correlations in intricate datasets.
When there is an absence or inadequate amount of structural data available for the target
protein, numerous strategies seem to be effective [25].
2.2.3 Network-Based Methods
Network-based approaches utilize network theory and analysis to comprehend and forecast
the interactions among biological entities, such as proteins, genes, or tiny molecules. These
methods are especially effective for investigating the intricacy of biological systems and
revealing correlations that contribute to the identification of drugs [26]. Various essential
network-based methodologies are employed in the investigation of bioactive small mole-
cules (Table 2.3).
Protein–protein interactions (PPIs) are illustrated in PPI networks, providing a comprehensive
view of biological activity at a systems level. These networks are useful in drug development as
they help identify core proteins or hubs that could serve as therapeutic targets or play significant
roles in disease pathways. Drug–target interaction networks refer to networks that illustrate the
connections between drugs and the proteins they specifically operate upon. Through the explora-
tion of drug–target interaction networks, researchers can get insights into the polypharmacology
of medications, enabling them to comprehend the mechanisms of therapeutic action by detect-
ing potential off-target effects. Chemical similarity networks were created to facilitate the identi-
fication of compounds that share similar structures. These networks were built using the
chemical similarity of small molecules. Chemical similarity networks facilitate the discovery of
novel drug concepts and the identification of alternative applications for existing ones. A net-
work that displays the interconnectedness among different biological processes is referred to as a
Table 2.3 Network-based methods for bioactive small molecules.
Network-based methods Description
Protein–protein
interaction (PPI)
networks
Represent interactions between proteins in a network format. Analyzing PPI
networks helps identify key proteins or hubs that play crucial roles in cellular
processes, aiding in the identification of potential drug targets
Drug–target
interaction networks
Model the interactions between drugs and their target proteins. Analyzing these
networks provides insights into the polypharmacology of drugs, helping
understand their multiple interactions and potential side effects
Chemical similarity
networks
Constructed based on the similarity of chemical structures between small
molecules. These networks assist in identifying structurally related compounds,
guiding the exploration of chemical space for drug discovery
Biological pathway
networks
Depict the relationships between biological pathways, illustrating how different
pathways interact. Analyzing these networks aids in understanding the broader
context of a target’s involvement in cellular processes

30
biological pathway network. Analyzing these networks allows researchers to get a more compre-
hensive foundation for drug discovery projects by better understanding the potential involve-
ment of a single target in several pathways. Hence, considering the many interconnections
among biological systems, network-based techniques offer a comprehensive methodology for
identifying bioactive small compounds. These methods provide insights into chemical similari-
ties, biological pathways, PPIs, drug–target links, and drug–target linkages, enabling a better
understanding of potential drug candidates and their effects on cellular processes [27–30].
2.3 Natural Products in Bioactive Small-Molecule Discovery
Since ancient times, natural products (NPs) have been the main source of treatment. Traditional medi-
cines like Ayurveda, Chinese medicine, Siddha, and Unani all use NPs as a source of medicine. The key
component of these NPs is bioactive small molecules. Bioactive small molecules are soluble molecules
that can interact and moderate the activity of a cell. Many of these bioactive molecules are derived from
primary and secondary metabolites of plants. They are also obtained from marine sources. These bioac-
tive molecules are mainly used as anticancer, antiviral, and antimalarial agents [31].
2.3.1 Plant Primary and Secondary Molecules as Bioactive Molecules
Chemicals that are fundamental for activities such as respiration, photosynthesis, and transloca-
tion are known as primary metabolites. Although they are not directly engaged, plants may need
secondary metabolites for growth and development [32].
Primary metabolites include amino acids, nucleosides, and carbohydrates. Branched chain
amino acids like valine, leucine, and isoleucine have been found to enhance muscle health. The
consumption of glycine improved the quality of sleep compared to chemical substances like ben-
zodiazepines. Supplementation of cysteine and theanine improved the overall immunity by
antigen-specific antibody production after encountering an antigen. Plants also contain a wide
range of vitamins, which are essential for metabolism. Several vitamins originating from plants,
including pro-vitamins A, B complex, C, E, and K1, have antioxidant properties. Supplements con-
taining these vitamins are available [33].
Secondary metabolites include phenolics, terpenes, steroids, alkaloids, and flavonoids. Phenolics
have antioxidant and anti-inflammatory properties that can moderate inflammatory signaling path-
ways and can serve as bioactive small molecules for anti-inflammatory drugs used in the treatment
of various diseases like cancer. Phenolics also serves as antimicrobial and anticancer compounds.
Flavonoids have antioxidative, anti-inflammatory, antitumoral, and cardioprotective activities.
These are mainly found in plants like cabbage, cauliflower, berries onion, apples, and pears [34].
Terpenes contain many bioactive small molecules like eugenol (from Syzygium aromaticum),
Germacrone (from Eryngium maritimum), and Santalol (from Santalum album), which acts as antivi-
ral drugs against influenza infections. They also serve as anti-inflammatory compounds by inducing
the release of pro-inflammatory cytokines and leukotrienes [35]. Steroids have a great affinity toward
nuclear receptors. This led to the development of drugs derived from steroids for receptor-mediated
diseases. Several anticancer molecules and antihormonal drugs have been synthesized from steroids.
Alkaloids are a major part of Chinese herbal medicine. Alkaloids are majorly found in higher plants,
especially in dicots. Berberine obtained from Coptidis rhizoma acts as an antibacterial and anticancer
drug. Matrine from Sophora flavescens acts as an anti-inflammatory, anti-arrhythmic, and antifibrotic

31
drug. Piperine from Piper nigrum has antioxidant, anti-asthmatic, anticarcinogenic, anti-inflammatory,
anti-ulcer, and anti-amoebic properties. Rhyncophylline obtained from Uncaria rhynchophylla can be
used as a substitute for amphetamine to treat psychological disorders [36] (Table 2.4).
2.3.2 Anticancer Agents as Bioactive Molecules
Developing less toxic anticancer medications is crucial because cancer is one of the top causes of
mortality in the modern era. Bioactive compounds with anticancer properties regulate metabolic
and signaling pathways, thereby limiting and preventing the growth and division of aberrant
Table 2.4 Pharmacological effects of bioactive compounds.
Bioactive
compound Source Effect Reference
Preussiafuran
Cissetin
Asterric acid
Preussia sp. Antimalarial [37]
Piliformic acid Xylaria sp. Antimalarial [37]
Fumoquinone
Pseurotin
Aspergillus sp. Antimalarial [37]
Bostrycin
Nigrosporin B
Fusarubin
Fusarium sp. Antimalarial [37]
Gallic acid Vitis vinifera and
Camellia sinensis
Antioxidant, antimicrobial, anti-inflammatory,
and antitumoral
[38]
Luteolin Brassica oleracea and
Apium graveolens
Antioxidant, anti-inflammatory, and
antitumoral
[38]
Anthocyanins Vitis vinifera and Daucus
carota
Antimicrobial, anti-inflammatory, antioxidant,
and anti-proliferative
[38]
Curcumin Curcuma longa Anti-inflammatory [39]
Paclitaxel Taxus brevifolia Antimitotic agent – various cancers [39]
Artemisinin Artemisia annua Malignant cerebral malaria
Tomatine Solanum lycopersicum Anticancer, immune effects, and antifungal [39]
Oblongolide Phomopsis sp. Antiviral [39]
Illudin S Omphalotus illudens Antiviral [39]
Fucoidans Fucus vesiculosus and
Lonicera japonica
Antioxidative [40]
Fucoidans Fucus vesiculosus Antithrombin, anti-inflammatory [41]
Nisin A Lactococcus lactis Cancers of the head and neck, breast, liver,
and blood cells (acute T cell leukemia)
[41]
Pediocin Pediococcus acidilactici Colon adenocarcinoma [42]
N-butanol fraction Acacia arabica Anti-HIV activity [43]
Methanolic
extract
Ocimum basilicum Inhibition of viral replication [43]
Aqueous extra Olea europaea Inhibition of cell-to-cell transmission of HIV [43]

32
cancer cells. Untailored natural materials or their synthetic versions constituted 47.1% of the 155
anticancer medications that were clinically authorized between 1961 and 2006. Majority of the
bioactive compounds with anticancer properties originate from microbes and plants. The presence
of bioactive molecules like anthraquinones, polysaccharides, and chromones in Aloe vera makes it
an anticancer and antiproliferative drug [44]. Luteolin, a flavonoid acts as an anticancer agent by
inhibiting the histone acetyltransferase (HAT) pathway of cancer cells. HAT is an enzyme that
causes acetylation of chromatin to isomers of histone. In most cases of cancer, elevated levels of
HAT are observed. Vinblastine, Vincristine (from Catharanthus roseus), and Colchicine (from
Colchium autumnale) are alkaloids that inhibit cancer cell migration and metastasis by binding to
microtubulins. Microtubules are cytoskeletal structures that are involved in various processes like
cell migration, maintaining the cell shape, and cell division [45]. Podophyllotoxin is a lignan (sec-
ondary metabolite) derived from Podophyllum peltatum L. It prevents the growth of tumor cells by
preventing polymerization of tubulin thereby arresting mitosis. Etoposide, teniposide, and
etopophos are semisynthetic derivatives of Podophyllotoxin [46].
Certain antibiotics like Actinomycin D, Bleomycin, Doxorubicin, and Mitomycin C are used to
treat cancers like sarcomas, leukemia, and carcinomas. They are derived from Actinomycetes such
as Streptomyces antibioticus, Streptomyces verticillus, Streptomyces peucetius, and Streptomyces
caespitosus, respectively. Actinomycin D treats tumors by inducing p53-independent apoptosis.
Bleomycin cleaves the DNA and causes DNA damage. Doxorubicin blocks replication and tran-
scription process and causes oxidative damage to the cell components. Mitomycin C crosslinks the
DNA strands [42, 47].
2.3.3 Antiviral Agents as Bioactive Molecules
Antiviral drugs are important for treating clinically significant viruses like HIV (human immuno-
deficiency virus), HSV (herpes simplex virus) influenza, and hepatitis C. Most of the existing viral
drugs like zidovudine, acyclovir, and ribavirin have serious adverse effects on the body. Therefore,
development of antiviral drugs with the least side effects is necessary for which natural bioactive
molecules are a great choice. Methanol extracts from various plants like Alchornea laxiflora, Panax
notoginseng, and Senecio scandens have inhibitory effects on HIV integrase. Ethanol extracts from
Justicia gendarussa and Bauhinia variegata and hexane extracts from Aerva lanata, Acorus cala-
mus, and Rhinacanthus nasutus had inhibitory effects on HIV reverse transcriptase [48]. Anti-HSV
activity was shown by ethanol, methanol, and chloroform extracted from plants like Aglaia odor-
ata, Pistacia vera, and Quercus brantii. They halted viral growth by inhibiting viral replication, viral
DNA synthesis, and virus entry. Dichloromethane and methanol obtained from plants like
Mussaenda elmeri and Baccaurea angulata in 1:1 ratio inhibited hemagglutination due to influ-
enza infection [20]. An anti-influenza drug, oseltamivir synthesized from shikimic acid and qui-
nine acid was found to decrease the mortality rate in COVID-19-infected patients [49].
Several bioactive compounds from fungi are also known to have antiviral properties. Ganodeeric
acid in Ganoderma lucidum and adenosine in Cordyceps militaris show inhibitory effects on HIV
protease. Beta glucan protein of Agaricus subrufescens limits the replication of HSV [50].
2.3.4 Antimalarial Agents as Bioactive Molecules
Antimalarial bioactive molecules help combat the malarial infection caused by various Plasmodium
species. Malaria caused by Plasmodium falciparum is considered the most fatal one due to its
nature of causing cerebral infections. The most successful antimalarial drugs, quinine and
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