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TABLE 4.2 Botanical sources, parts used, active constituents with their dose range, pharmacokinetics, and mechanism of action, essential formula-
tions, and clinical trials of various herbal drugs.dcont’d
Botanical
sources
Part
used
Active
constituents
Dose range and
route
Pharmacokinetics
parameter
Possible
mechanism of
action Properties
Essential
formulation Clinical trials References
Ferula
asafoetida
Rhizome
and root
Umbelliferone 0.034 mmol/g in
diet for 5 weeks
for
anticarcinogenic
activity
Volatile oil in the
gum is eliminated
through the lungs,
making this an
excellent treatment
for asthma
Ability to inhibit
the generation of
ROS
Oleo gum
resin (highly
soluble in
ethanol)
Solid lipid
nanoparticle
Inhibit the release of
proinflammatory
mediators via the NF-
kB signaling pathway
[39]
Larrea
tridentata
Leaf and
flower
Nordihydro-
guaiaretic
acid
417 mg/kg Bioavailability 1.75
or 3.50 mmol/L at
60 min.
Reduction of
genotoxic damage
induced by
ethynodiol
diacetate
Soluble in
hot water
and organic
solvent
(natural
lignan)
Microemulsion Doses of NDGA in
sister chromatic
exchanges of number
of abnormal cells
[40]
Nicotiana
tobbacum
Root and
leaves
Nicotine Smoked dosage -
0.3e0.8 mg
Oral dosage - 0.5
e2mg
Intranasal
dosage - 0.3
e1mg
Onset-5e60 sec.
Duration - 10
e30 min. (smoked
dosage)
Onset - 2e15 min.
Duration - 1e2hrs.
(oral dosage)
Onset - 20e90sec.
Duration - 10
e30 min (intranasal
dosage)
Rise in plasma FFA
could be prevented
by administration
of nicotinic acid
Alkaloids Lipid emulsion Atrial, atrio-ventricular
nodal and ventricular
conduction times and
refractoriness, and
sinus node function
were studied by his
bundle electrography
combined with
programmed electrical
stimulation
[41]
Olea
europaea
Seed Olive oil (oleic
acid)
10 mL/kg orally Plasma levels
monitored over
12 h by using non-
compartment
model.
Fast and extensive
uptake of the
molecule by the
organs and tissues
investigated, with
a preferential renal
uptake
Vegetable
oil
Lipid emulsion Show appreciable
toxicity up to 2 g/kg
body weight
[42]
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TABLE 4.3 Various lipids based delivery systems.
SN Delivery system
Size/Composition/Feature/
Characteristics
Common preparation
techniques
Advantages/
Disadvantages References
I. Lipid based emulsion system
1. Lipid emulsion Lipid globules 1e100 nm,
lipid, hydrophilic liquid
and surfactant
O/W, W/O, W/O/W
and W/O/O
For delivering lipid-soluble
drugs
Water soluble compound
cannot be loaded
[50]
2. Oily suspension Diameter of 20 mmor
smaller, suspending agent,
a wax, and a dispersing
agent
“Bottom up
technology” and “top
down technologies”
Increased bioavailability of
an active ingredient
Scale up is not easy due to
mill size and heavy oily
nanosuspensions
contaminated with
materials eroded from balls
may be problematic when it
is used for long therapy
[51]
3. Lipid micelles Surfactant molecules
dispersed in a liquid
colloid
Emulsion
polymerization
Allows the absorption of
complicated lipids, phase
behavior of many lipids
according to their
polymorphism
[52]
II. Lipid based vesicular system
1. Liposome 25 nme100 mm
membranous bilayer,
natural and synthetic
polymer
Mechanical dispersion,
solvent dispersion
method
Flexibility to couple with
site-specific ligands to
achieve active targeting
Production cost is high,
less stability
[53]
2. Pharmacosomes Colloid dispersion which
exists as ultrafine vesicular,
micellar, or hexagonal
aggregates depending on
the chemical structure of
the drug-lipid complex
Self-dispersion through
moderate mixing and
sonication, hand
shaking, and ether
injection method
More bioavailable drug
delivery systems with low
interfacial tension between
the system and the GI fluid
Loss of drug by hydrolysis
is possible
[54]
3. Multivesicular
liposomes
The internal chambers of
the particles meet at
phospholipid bilayer
junctions that are filled
with bulk triglyceride
molecules, which impart
the unique multivesicular
structure.
Water-in-oil-in-water
double emulsification
method
Enhanced stability during
encapsulation as well as an
improved release kinetic
pattern of therapeutic
protein IFN a
[55]
4. Phytosome It’s component is herbal
extract and
phosphatidylcholine
Solvent evaporation
method, mechanical
dispersion method
Can effectively deliver the
product by topical and oral
route, highly beneficial for
hydrophilic drugs
[56]
5. Ethosomes Phospholipid containing
elastic nanovesicles with a
high proportion of ethanol
(20%e45%).
Hot/Cold method,
classic mechanical
dispersion method
Effective delivery of
product by transdermal
and oral route
[57]
(Continued)
1. Introduction 89
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TABLE 4.3 Various lipids based delivery systems.dcont’d
SN Delivery system
Size/Composition/Feature/
Characteristics
Common preparation
techniques
Advantages/
Disadvantages References
6. Transferosomes Elastic or deformable
vesicle by soya
phosphatidyl choline with
sodium cholate and a small
concentration of ethanol
Thin film hydration
technique, modified
hand shaking, lipid film
hydration technique
This ultraflexible vesicle
could deliver the product
through skin
[58]
III. Lipid based particulate system
1. Lipid
microtubules/
microcylinders
Diameter 0.5 mm and length
ranging 25e45 mm, natural
and synthetic lipids with
suitable surfactant
Self-emulsification
method
Sustained release of
proteins and nucleic acids
for biomedical applications
Methodologies that
produce high aspect ratio
and lipid tubules often
degrade the aspect ratios
and/or cause the lipid
tubules to “clumps or
weld”
[59]
2. Solid lipid
nanoparticles
(SLNs)
50e1000nm/submicron
colloidal carrier, monolayer
of phospholipids and fats of
natural or synthetic origin
High-pressure
homogenization,
microemulsion
formation,
precipitation, and as
lipid nanopellets
Biodegradable and bio-
acceptable nature of SLNs
make them less toxic as
compared to polymeric
nanoparticles
It cannot be employed to
incorporate hydrophilic
active ingredients/drugs
[60]
3. Lipospheres or
lipid microsphere
Dispersible solid
microparticles with a
particle size between 0.2
and 100 mm in diameter
composed of a solid
hydrophobic fat core
stabilized by a monolayer
of phospholipid molecules
embedded in a
microparticle surface
a) Melt dispersion
b) Solvent evaporation
Melt technique produced
particles with smooth
surface and loading of
20%w/v as compared to
other with 2%w/v only.
[61,62]
4. Lipid nanoparticle Size ranges typically from
50 to 1000 nm lipid core is
in the solid state and matrix
consists of solid lipids or
mixtures of lipids
surfactants or polymers
and natural lecithin
High pressure
homogenization, Hot
and cold
homogenization
followed by sonication
technique
Increased drug loading,
improved drug
incorporation and
suspensions of higher solid
content can be produced
(e.g., 30%e50% solid)
[63]
5. Lipid
nanocapsules
Synthetic lipoprotein
100 nm with a narrow
distribution consists of a
solid-lipid core which is
often stabilized by an
external monolayer of steric
or charged surfactant
Solvent-free phase
inversion method
The exact knowledge
especially on the in vitro
drug release is still lacking,
Due to their very small size
their capacity to
encapsulate lipophilic and
hydrophilic drugs is limited
[64]
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2. Issues related to the extraction of herbs and their safety
Before the discussion on lipid-based systems, we intend to provide a brief overview on the
various methodologies adopted to prepare the plant extracts and major safety issues associ-
ated with them. Herbal medicines are herbal preparations including complex mixes of one or
more plants that contain active ingredients in the raw or processed form of one or more
plants. Medicinal components from plant sources are obtained by various methods of extrac-
tion. Some of the novel techniques are discussed below.
2.1 Novel techniques for extraction of herbs
Compared to conventional methods of extraction, novel techniques proved to be highly
beneficial. It was mainly becau se extracts obtained are of improved quality and purity
with significance of a particular compound, which can act as a marker for future application
of herb [65]. Extraction can be achieved by use of the minimum quantity of solvent and en-
ergy resources, within less time-period, and thus proved to be cost-effective.
Different techniques of extraction are supercritical fluid extraction methods (SFE),
microwave-assisted extraction (MAE), solid-phase extraction (SPE), ultrasonication-assisted
extraction (UAE), hollow fiber extraction (HFE), and phytonics process enzyme assisted
extraction, pressurized liquid extraction (PLE), pulsed-electric field extraction [66,67].
2.1.1 Supercritical fluid extraction methods
SFE is widely used in the industry for extraction of the biologically important constituents
of high potency from the medicinal and aromatic plants. It helps in isolation of specific phy-
toconstituents, which are util ized for production of herbal medicines, nutraceuticals, and cos-
meceuticals of a specific property [68,69].
2.1.2 Microwave-assisted extraction
MAE technology is used for cost-benefit purpose. It helps in extraction of significant phy-
toconstituent from natural sources and from biomass. Extracting carotenoids, taxanes, essen-
tial fatty acids from microalgae, phytosterols from medicinal plants, polyphenols from green
tea, and essential oils from diverse sources have been done using MAE [70e72].
2.1.3 Solid-phase extraction
To isolate analytes from a liquid matrix and herbal extract purification, the SPE technique
is employed. This technique has been proven advantageous because, it can extract the analy-
tes of wide polarity range. Among the 13 pesticides that can be identified with this technol-
ogy are benzene hexachloride (BHC), and alpha-benzene hexachloride (ABH). Analysis of
aristolochic acid I and II in herbal medicines can be done using a solid phase extraction pro-
cedure [72e74].
2.1.4 Ultrasonication-assisted extraction
UAE is a cheap, easy, and proficient alternative, which involves the use of ultrasound
waves using frequencies greater than 20 kHz. Ultrasound in extraction breaks down
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cell walls, making it easier for components to be released. Ultrasound decreases the operating
temperature permitting the extraction of thermolabile compounds. It can be used with any
solvent for extracting a broad variety of natural compounds [75,76].
2.1.5 Hollow fiber extraction
This technique is used for the determination of natural constituent in medicinal plant sam-
ples. It has some advantageous features, such as reduced risk of cross-contamination and
carry-over problems, single-use fibers, recovery of analyte s from single extract. This method
shows good line arity, repeatability, low limits of detection, and excellent enrichment [77,78].
2.1.6 Phytonics process
This process is mainly used for extraction in biotechnology, in the herbal drug industry, in
the food, essential oil and flavor industries, and in the production of other pharmacologically
active products. Hydrofluorocarbon-134a, a nonflammable, nontoxic, and ozone-depleting
solvent, is utilized in the phytonics process. This solvent has a boiling point of 25
C. The
products are never damaged by acid hydrolysis or oxidation because the process is carried
out at a neutral pH and without oxygen. Using this method, you can set operating conditions
that allow you to produce a variety of items [79].
2.1.7 Enzyme-assisted extraction (EAE)
Specificity and high efficiency are two of enzymes’ most notable characteristics. The mod-
erate extraction conditions and minimal impact on nature and the environment make EAE a
specially promising extraction approach for plant actives [80]. Activated bioactive chemicals
are released during enzyme degradation of plant cell walls and degradation of composition.
EAE extensively employs pectinase, cellulase, hemicellulose, and b-glucosidase. These en-
zymes could be obtained from fungi, bacteria, fruit and vegetable extracts, or animal organs
[80,81]. Plant antioxidants such as phenolics, flavonoids, anthocyanins, and carotenoids,
which are extracted using EAE procedures, have been found to benefit from increased extrac-
tion efficiency [82,83]. Pectinex, celluclast, and novoferm were used in EAE to extract the
phenolic compounds from grape waste, and it was found that novoferm had the strongest
effect on phenolic release from grape waste [84].
2.1.8 Pressurized liquid extraction (PLE)
Pressured liquid extraction (PLE), often referred to as a pressurized fluid extraction (PFE),
high-pressure solvent extraction (HSPE), or enhanced-solvent-extraction (ESE), was initially
described in 1996 by Richter et al. [85]. For chemicals that stay solvent liquid beyond their
boiling point, the extraction process is facilitated by the use of high pressure, which is the
PLE principle. Because of the shorter extraction times and fewer solvents used, PLE-based ap-
proaches have seen rapid growth in recent years. Due to the combination of high pressure
and temperature, PLE requires only a modest number of solvents. For the isolation of polar
chemicals, PLE is now being regarded as an alternative to supercritical fluid extraction [86].
There’s also the fact that the use of modest amounts of organic solvents makes PLE an excel-
lent green extraction method [ 87 ]. Bioactive chemicals can be extracted from a variety of plant
sources using PLE. Gallocatechin (GCT), catechin, epicatechin gallate (EGCG), caffeic acid,
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chlorogenic acid, and myricetin were recovered from Anatolia propolis using PLE at optimal
conditions (40 C, 1500 Psi for 15 min) [88]. The total phenolic content was also recovered.
The effects of PLE on the recovery of phenolic components (anthocyanins, bifurcates) from
Brazilian pepper fruits [89] was studied by Feuereisen and coworkers.
2.1.9 Pulsed electric field extraction (PEFE)
The pulsed electric field extraction (PEFE) technique is a useful tool for improving the
extraction, pressing, drying, and diffusion processes. PEFE works by rupturing the cell mem-
brane in order to increase extraction. When a live cell is suspended in an electric field, an elec-
tric potential travels across its membrane, separating the molecules based on the dipole
nature of the membrane and the charge they carry. In weak sections of the membrane, holes
occur due to repulsion between charge-carrying molecules when the transmembrane poten-
tial exceeds the critica l value (about 1 V). In order to speed up extraction and reduce extrac-
tion time, PEFE is capable of rupturing the plant material’s membrane structure. By
enhancing the permeability of cell membranes, PEFE has also been used to promote intracel-
lular bioactive release from plant tissue [90]. Polyphenols from Pinus abies(L.) Karst bark was
successfully isolated usi ng PEFE. By exposing the exposed plant components to PEFE treat-
ment, the total phenolic content extraction and antioxidant activity were increased by more
than eight times [91].
2.2 Herbal extracts: issues of efficacy and safety
The general thought that herbal medicines are harmless and without side effects is wrong.
Plants have many constituents some of which are very toxic. However, the side effect of herb-
al medicine is less as compared to synthetic medicine, but clinical trials have now inveterate
that such effects are really present. Harmonization and development in the processes of regu-
lation is essential. The changes in the cultivation, collection, production, processing, and he-
reditary improvement of medicinal plants will offer great advantages over the use of plants
harvested naturally to get consistent and high-quality crude drugs that are fundamental to
the efficacy and safety of herbal medicines [92]. There are four kinds of herbal medications
based on its origin, evolution, and present use. Indigenous herbal medicines; systemic herbal
medicines; modified herbal medicines; and imported items have a herbal medicine base. Spe-
cific safety assessments are needed for these categories. Classification of herbal medicines and
their safety assessments are specified in Table 4.4.
2.2.1 Guidelines for herbal medicine standardization as per WHO guidelines
The World Health Organization (WHO) supports and promotes the use of traditional herb-
al treatments in national healthcare programs. The WHO uses contemporary procedures and
appropriate criteria to ensure the quality of therapeutic plant products [93]. Toxicological in-
vestigations and experience-based documentation of safety are emphasized in the WHO rec-
ommendations for quality control of crude pharmaceuticals and plant preparations, as well
as finished products [92]. Ethnomedical information and biological activity evaluations are
used for efficacy assessment.
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The standardization of crude drug materials includes the following steps.
1. The identity of the drug: botanical evaluation, sensory characters, foreign organic mat-
ter, microscopical, histological characteristics, and histochemical evaluation and quanti-
tative measurements.
2. The physicochemical character of the drug: physical and chemical identity, chromato-
graphic fingerprints, ash values, extractive values, moisture content, volatile oil, alka-
loidal assays.
3. The pharmacological parameters: biological activity profiles, bitterness values, hemolytic
index, swelling factor, foaming index, astringency, etc.
4. Toxicity details: pesticide residues, heavy metals, microbial contamination like total
viable count of pathogens.
5. Microbial contamination: observing the growth in nutrient media of collected parts.
6. Radioactive contamination.
TABLE 4.4 Classification and safety assessment of herbal medicine.
Category Classification Characteristics Safety consideration
1. Indigenous
herbal
medicines/Folk
medicine
Historically used for long time by local
population in terms of its composition,
treatment, and dosage.
Safety category 1: Safety data are not
needed.
Safety category 2: Meet the usual
requirements for safety of herbal medicines.
Safety category 3: Herbal medicines of
uncertain safety will be identical to that of
any new substance.
2. Herbal
medicines in
system
Medicines in this category have been used
for a long time and are documented with
their special theories and concepts, and
accepted by the countries. For example,
ayurveda, unani, and siddha.
Safety categories 1/2: Safety data would not
be needed.
Safety category 3: Requirements for safety
of “herbal medicines of uncertain safety.”
3. Modified herbal
medicines
Herbal medicines as described above in
categories 1 and 2, except that they have
been modified by either shape or form
including dose, dosage form, mode of
administration, herbal medicinal
ingredients, methods of preparation, and
medical indications
The medicines have to meet the
requirements of safety of herbal medicines
or requirements for the safety of “herbal
medicines of uncertain safety,” depending
on the modification.
4. Imported
products with a
herbal medicine
This category covers all imported herbal
medicines including raw materials and
products registered and marketed in the
countries of origin.
Safety and efficacy data have to be
submitted to the national authority of the
importing country and need to meet the
requirements of safety and efficacy of
regulation of herbal medicines in the
recipient country.
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In addition to dealing with the normal Western bias against Ayurveda (Indian traditional
medicine system), correct identification, and quality assurance of the beginning material,
markers play an important role in drug discovery, development, and therapies [65]. Herbal
medicine’s safety and effectiveness are enhanced by the use of markers, which are a necessary
prerequisite for ensuring reproducible quality. Genetic markers (DNA) and chemical markers
(chemical) are the two types of markers. In general, DNA markers are a dependable source
since the genetic composition of each species remains unchanged by physiological or environ-
mental variables. Fresh or dried plant material can be used to extract DNA. In order to
undertake molecular taxonomic investiga tions and give definitive means of authentication,
DNA bar coding is used. Chemomarkers are biological substances, such as primary and
secondary metabolites, macromolecules, and micro-molecules that are used to track disease
progression. The safety of isolated plant extracts after extraction usi ng diverse procedures
must also be strictly regulated [94].
Plant actives and extracts have enormous therapeutic potential, but their ultimate value is
restricted by the inability to transfer the active concentration to the site of action. Polymers
and lipids have been used as delivery strategies in order to remove these stumbling blocks.
There are numerous toxicity concerns with polymer systems, which make lipid systems more
appealing.
3. Lipid-based systems
Lipid-based delivery systems have been utilized for the oral, parenteral, and topical deliv-
ery of poorly water-soluble, lipophilic drugs to improve bioavailability, stability, solubility,
and therapeutic efficacy [48,49]. Lipid-based systems benefit from the integration of lipophilic
substances into their matrix, which provides a more regulated structure for the drug ’s incor-
poration and rele ase. In spite of more than 40 years of ongoing research only the insignificant
fraction of the polymeric- based systems developed are available in the pharmaceutical mar-
ket. Reasons for this could include a lack of regulatory acceptance for cost-effective produc-
tion processes and an unaccepted status for excipients currently in use. The lipid-based
system does not have this problem (Pharmacosol’s pathfinder technology). Several benefits of
lipid-based system have been acknowledged with respect to plant extracts including
enhancement of chemical stability, film formation, controlled occlusion, skin hydration,
enhanced bioavailability and physical stability for topical formulations [95].
Similar to topical, it has a wide range of benefits when administered in various ways. Since
lipid-based carriers have been demonstrated to be safe and effective for pharmaceutical for-
mulations, as we ll as vaccines, diagnostics, and nutraceuticals, they are a viable option. For
delivery of diverse plant extracts and actives, there are numerous lipid-based delivery
methods that may be created as the wiser carriers (Fig. 4.2 and Table 4.3).
There are several parameters, which are to be considered while selecting appropriate lipid
constructs for the delivery of bioactive compounds. Firstly, phase transition temperature,
which is essential to change the physical state of the lipid used. Secondly, the stability of
drug-lipid constructs used in the formulation. Since the biological membranes are negatively
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charged, charge of the lipid formulation also affects the drug delivery into cells. Third param-
eter is the source of lipids, which can be either synthetic or tissue derived. Tissue-derived
lipids pose many threats of viral and protein contamination. Therefore, synthetic or semi-
synthetic lipids are mainly used for drug delivery [96].
3.1 Lipid emulsion system
In recent years, the pharmaceutical industries have shown drastic inclination toward natu-
rally derived new compounds particularly from plant sources as plant actives and extracts.
Approximately 90% of these chemical entities from plant constituents contain hydrophobic
FIGURE 4.2 Types of lipid-based systems.
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substituent that result in the poor aqueous solubility. Lipid-based emulsion drug delivery
systems can be tailored to meet the specific needs of the disease with respect to stability,
toxicity, and efficacy via diverse routes of administration because these components are lipo-
philic [97]. These systems are mostly used for entrapping lipophilic bioactive and herbal com-
ponents in the pharmaceutical industry [98].
Kumar and group developed clove oil nanoemulsions for delivery of curcumin and resver-
atrol and examined their synergistic effect against breast cancer cells and harmful bacteria.
The formulation exhibited a good therapeutic potential against MDA-MB 231 and Hep G2
breast cancer cells [ 99 ].
In another work Ghazy and team developed nanoemulsion of anise seed extract by cold
solvent extraction method and compared its efficacy with the bulk extract against pathogenic
bacteria. The antimicrobial potential of the developed nanoemulsion was tested against food-
borne pathogenic bacterial species. They reported that the nanoemulsion exhibited better
antimicrobial efficacy than bulk extract against tested foodborne pathogenic bacteria [100].
In this regard Lima et al. also developed Cineole-enriched nanoemulsion by spontaneous
emulsification method and reported potential antimicrobial potential of developed nanoe-
mulsion against Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pyogenes [101].
Basically, in these systems, lipophilic herbal and bioactive components are entrapped in
the oil phase followed by homogenization in the aqueous phase containing a water-soluble
emulsifier or surfactant. The size of the globules obtained depends on the composition of
the lipid and the method used. It is advantageous in terms of ease of preparation, drug sol-
ubilization, reduced toxicity, and long shelf life [102].
Vincristine is another lipophilic agent, which is not stable in water, but lipid microemulsion
has shown to be more suitable for long circulating delivery of vincristine [5]. Lipid microemul-
sions are thermodynamically stable and remain physically stable during the 1-year storage
period at 7e8
C in the dark. Silymarin lipid nanoemulsion formulations have shown increased
solubility and bioavailability of silymarin with rapid onset and increased absorption after oral
administration of silymarin due to the lipid constituents in formulations [103]. Thus, lipid mi-
cro- or nanoemulsions have shown improved oral bioavailability of poorly water-soluble drug
compounds with rapid onset of action, reduced intersubject variability in terms of gastrointes-
tinal fluid volume, longer shelf life [104,105], toxicological safety, and enhanced entrapment of
lipophilic drugs due to the high content of the lipid phase.
3.2 Lipid vesicular system
Lipid vesicular systems are microscopic vesi cles consisting of membranelike phospholipid
bilayers surrounding an aqueous medium. These lipid droplets with elastic bilayers are
responsible for the penetration through the stratum corneum via intracellular or transcellular
routes which have beneficial applications in cosmetics and drug delivery (Table 4.3). A lipid
vesicular system is susceptible to oxidation leading to breakdown of the layer of vesicular
structure [106]. Vesicular systems, like liposomes are the most exploited, popular systems
serving as a good candidate for the delivery of phytoconstituents, vitamins, and other
molecules to regenerate the epidermis by facilitating the continuous release of
constituents into the targeted area for a prolonged time. Several active ingredients,
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