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Fig. 4 Other compounds
with potent antidiabetic
property
Y. A. T. Ngandjui et al.
Fig. 5 Some alkaloids with
anticardiovascular property
their efciency against CVDs. These compounds have
been classied in several classes including alkaloids, phenolic compounds, terpenoids, and steroids.
2.2.1 Alkaloids
Among the groups of secondary metabolites, we have alkaloids, found in nature and which have in their structure basic
nitrogen atoms. Alkaloids can be found in the Acanthaceae,
Apocynaceae, Papaveraceae, and Solanaceae families. Some
alkaloids were shown to be effective against cardiovascular
diseases or to have cardioprotective effect [64] such as tet-
randrine (72) [65], berberine (1) [66, 67], sophocarpine (73)
[68, 69], sinomenine (74) [70], stachydrine (75) [71–73],
sanguiranine (76) [74], leonurine (77) [75–77] (Fig.5).
2.2.2 Phenolic Compounds
Phenolic compounds are one of the largest clusters of
phytochemicals. They were reported to show good activities against various diseases including cardiovascular diseases. Some phenolic compounds belonging to phenolic
acids, stilbenes, avonoids, and guaiacols were reported
to exhibit good anticardiovascular activity including cur-
Chemical Characterization ofPhytoconstituents forLifestyle Diseases
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Fig. 6 Some phenolic
compounds with
anticardiovascular property
65
cumin (78) [78, 79], caffeic acid (79) [80], resveratrol
(80) [81, 82], quercetin (81) [83–87], apigenin (82) [88–
90], luteolin (83) [91–93], naringenin (84) [89, 94, 95],
epigallocatechin- 3- gallate (28) [96], kaempferol (85)
[97], genistein (86) [98], 6-gingerol (87) [99], thymoquinone (88) [100], plumbagin (89) [101, 102], emodin (90)
[103, 104], cryptotanshinone (91) [105, 106], and shinkonin (92) [107] (Fig.6).
2.2.3 Terpenoids andSteroids
Terpenoids are sorted into structural types which are
monoterpenoids, sesquiterpenoids, diterpenoids, triterpenoids, and carotenoid tetraterpenes [108]. Some phytoterpenoids were reported in the literature to possess
cardiovascular properties including daucuside (93), daucusol (94) [109], triptolide (95) [110, 111], artemisinin (96)
[112, 113], paeoniorin (97) [114, 115], picroside II (98)
[116], ginsenoside Re (99) [117, 118], diosgenin (100)
[119], ginkgolide C (101) [120], sesamin (102) [121], germacranolide (103), heliangolide (104), eudesmane (105),
𝛼-spinasterol (106), β-amyrin (107) [122], alisol A (108),
alisol B 23-acetate (109), cucurbitacin E (110) [123], rubiarbonol C (111) [124], rubiarbonone C (112) [125],
β-sitosterol glycoside (113), asiatic acid (114) [126], stigmasterol (115), campesterol (116) [127, 128], betulinic
acid (117) [129], boswellic acid (118) [130], celastrol
(119) [131] (Fig.7).
2.2.4 Miscellaneous
Other natural products not belonging to the above-mentioned
classes were also reported compounds were reported to be
used for the prevention of the CVDs like glucoraphanin
(120), allicin, and diallyl disulde (121) [132, 133] (Fig.8).
2.3 Cancer
It is a large class of illnesses which is characterized by the
unregulated and uncontrolled development of the body’s
cells that generally attack and as a rule destroy normal
cells. Cancer can start in almost any tissue or organ of the
body when abnormal cells grow uncontrollably, go beyond
their habitual limits to occupy adjoining parts of the body
and/or spread to other organs. Metastasizing is the latest
process of cancer progression and is generally a major
cause of death. Compounds isolated from natural sources
have regularly had an important part in treating and preventing human illnesses since olden times including cancer
[134]. Among natural products, alkaloids, phenolic compounds, and terpenoids were reported to possess antiproliferative activity.
2.3.1 Alkaloids
Alkaloids compounds isolated from plants were established
to play a signicant role in the suppression of cancer cells
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Fig. 7 Some terpenoids with
anticardiovascular property
Y. A. T. Ngandjui et al.
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Fig. 8 Other compounds
with anti-cardiovascular
property
Fig. 9 Some alkaloids with
anticancer activity
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[135, 136]. Some secondary metabolites obtained from
plants as isostrychnopentamine (122) [137], montamine
(123) [138], antone (124) [139], gramichunosin (125),
4-(2-formyl-5-(methoxymethyl)-1H-pyrrole-1-yl)butanoic
acid (126) [6], piperine (127) [140], jatrorrhizine (11),
8-methoxydihydrosanguinarine (128) [141], tabernaelegantine B and D (129–130) [142], 6-nor-antirhine-N1-methyl
(131), razyamide (132) [143], vincosamide-N-oxide (133),
and isodihydroamino cadambine (134) [144] were reported
to exhibit anticancer activity (Fig.9).
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Fig. 10 Some phenolic
compounds with anticancer
activity
Y. A. T. Ngandjui et al.
2.3.2 Phenolic Compounds
Phenolic compounds are mostly found in fruits, red wine,
coffee, cocoa, and seeds [30]. Some phenolic compounds
were reported to display anticancer effects counting resveratrol (80) [145], curcumin (78) [146], quercetin (81) [52], apigenin (82), epigallocathechin-3-gallate (28) [147], liquiritin
(135) [148], luteolin (112), setin (136), and myricetin (137)
[149–151] (Fig.10).
2.3.3 Terpenoids andSteroids
These classes of compounds account for the main class of
secondary metabolites made by plants and were broadly considered as active agents counting anticancer agent [152].
Terpenoids which displayed anti-cancer activities are alisol A
(108), alisol B 23-acetate (109) [153], euscaphic acids G
(138), hederagenin (139), triregeloic acid (140) [154],
hydroxylindestrenolide (141), lindestrenolide (142) [155],
3-epicyclomusalenol (143), cyclosadol (144) [156, 157], cauloside A (145), α-hederin (146), sapindoside B (147) [158],
isoartemisolide (148) [159], α-cadinol (149) [160], linderolide G (150) [155], syreiteate A (151), syreiteate B (152)
[161], 10-O-acetylmacrophyllide (153) [162], β-pinene (154)
[163], withaferin A (155), and celastrol (119) [164] (Fig.11).
2.4 Chronic Respiratory Diseases
Chronic respiratory diseases (CRDs) are chronic illnesses of
the airways and other parts of the lung such as asthma,
chronic and obstructive pulmonary diseases, cystic brosis,
occupational lung diseases, pneumoconiosis, pulmonary
sarcoidosis, and sleep apnea. CRDs affect seniors, adults,
teens, and all ages-children, and pose major health care and
economic strain across the world [165]. There are two most
important risk factors for chronic respiratory illnesses which
are outdoor and indoor air quality and tobacco smoke. Plants
can be used against CRDs and they contain compounds
which are able to show benecial activity against CRDs. It
is reported that secondary metabolites such as alkaloids,
phenolic compounds, and triterpenes can produce desirable
effects against chronic respiratory ailments.
2.4.1 Alkaloids
Alkaloids can be categorized into several subclasses depending on their structure, viz. indole, pyridines, pyrrolidines,
pyrrolizidines, isoquinolines, quinolines, steroids, terpenoids
and tropanes. Some alkaloids were reported to exhibit activities against respiratory chronic diseases such as picrine
(156), 19-epischolaricine (157) [166], berberine (1) [167],
evodiamine (158) [168], and antidesmone (159) [160]
(Fig.12).
2.4.2 Phenolic Compounds
Phenols are plant secondary metabolites commonly present
in human diet [169]. Phenols represent ideal therapeutic
agents for the management of respiratory diseases due to
their potent anti-inammatory and anti-oxidant activities
[170, 171]. Resveratrol [172, 173], curcumin [174, 175],
quercetin [176, 177], epigallocatechin-3-gallate (EGCG)
[178, 179], apocynin (160), paeonol (161), zingerone (162)
[180], ellargic acid (163) [181], protocatechuic acid (164)
[182], tricetin (165), luteolin, apigenin-7-glucoside (166),
baicalein (167), baicalin (168), hyperoside (169), quercitrin
(170), morin (171), tectogenin (172), and eriodictyol (173)
[183–185] were reported to display notable properties
against CRDs (Fig.13).
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Fig. 11 Some terpenoids and
steroids with anticancer
activity
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Fig. 12 Some alkaloids with
anti-CRD property
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Fig. 13 Some phenolic
compounds with anti-CRD
property
Y. A. T. Ngandjui et al.
Fig. 14 Some terpenoids and
steroids anti-CRD property
2.4.3 Terpenoids andSteroids
Several terpenoids were reported in the literature to play a
signicant role against some respiratory chronic diseases
including limonene (174) [186], shikonin (175) [187, 188],
linalool (176), asperuloside (177), cannabidiol (178), eriodictyol [189, 190], taraxasterol (179) [191], and triptolide
(180) [192] (Fig.14).
3 Characterization oftheMain Groups
ofCompounds Involve
intheManagement ofLifestyle
Diseases
The complete characterization of phytoconstituents obtained
from natural products requires the determination of sample
purity and physical properties, elementary composition,
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71
empirical formula, functional groups, and elucidation of
structural formula and spatial relationships. It is obvious that
the known molecule identication will include a lesser
amount of advanced investigations. The criteria and procedural steps which will be chosen frequently depends on the
availability of special equipment. Chemists and biologists
make use of both qualitative and quantitative techniques for
the characterization of phytoconstituents from plants including those involved in the management of lifestyle diseases.
In this section, we will describe the main techniques used in
the characterization of classes of compounds mostly involve
in the management of these diseases.
3.1 Qualitative Estimation ofSecondary
Metabolites
Many interesting methods are used on plants’ extracts to
assess the existence of many groups of secondary metabolites. In order to show the presence of these compounds, different qualitative tests can be realized.
3.1.1 Some Qualitative Tests forAlkaloids
3.1.1.1 Test ofMayer
The reagent of Mayer is prepared from mercury and potassium iodide to form a solution of dipotassium tetraiodomercura (II) (K2HgI4). To perform the alkaloids identication,
1mL of plant extract is mixed with 1mL of potassium mercuric iodide solution (Mayer’s reagent) in the test tube. After
shaking to ensure complete mixing, the formation of a precipitate with cream color in the test tube indicates a positive
result. The absence of this precipitate indicates a negative
result that is the absence of alkaloids [193].
are added. The presence of avonoids is indicated by effervescence and a deep pink (purplish) color [193].
3.1.2.2 Test ofFerric Chloride
This test is used to assess the existence of phenols and polyphenols in a plant extract. To an alcoholic solution of the
sample, few drops of FeCl3 are added and the change of
color from yellow to purple designates the existence of phenols [194].
3.1.2.3 Test ofGelatin Hydrolysis
This test assesses the existence of phenolic compounds in a
sample. It consists of the formation of a white precipitate due
to the addition of 10% NaCl and 1% gelatin on dried extract
dissolved in water [195].
3.1.3 Qualitative Identication ofKetone:
2,4-Dinitrophenyl Hydrazine Test
About 0.5g of 2,4-dinitrophenyl hydrazine is dissolved in
2.5mL aqueous solution of concentrated H2SO4 to give solu-
tion A.The sample is dissolved in a lowest quantity of 75%
EtOH to give solution B.The appearance of a yellow/orange/
red precipitate when solution A is added drop wise to solution B indicates the presence of aldehyde or ketone functional groups.
3.1.4 Qualitative Identication
ofAnthraquinones: Bornträger Test
A small amount of the sample (~0.5mg) is dissolved in 5mL
of a solvent that is immiscible with water (chloroform, ether,
methylene chloride, carbon tetrachloride). The formation of
a red coloration in the aqueous phase when 10% of an aqueous alkaline solution is added (NH4OH, NaOH or KOH)
indicates the presence of anthraquinones [196].
3.1.1.2 Test ofDragendor
After adding 1mL of the reagent of Dragendorff to 2mL of
extract, the presence of alkaloids can be indicated by the formation of an orange red precipitate observed [193].
3.1.1.3 Test ofHager
To perform the Hager’s test, few drops of Hager’s reagent
are added to two 2mL of extract. We observe the formation
of a yellow precipitate which reveals the presence of alkaloids [193].
3.1.2 Some Qualitative Tests forPhenolic
Compounds andTannins
3.1.2.1 Test ofSchinoda
To an alcoholic solution of the sample, few drops of concentrated hydrogen chloride and a pinch of magnesium shavings
3.1.5 Some Qualitative Tests forTerpenoids
andSteroids
3.1.5.1 Test ofLiebermann–Burchard
To a CHCl3 solution of the sample to be analyzed, we add a
few drops of acetic anhydride and concentrated H2SO4. The
presence of triterpenes and steroids is indicated by a change
of color to brick red for terpenoids and purple (or blue that
rapidly changes to green) for steroids.
3.1.5.2 Test ofHorizon
When 2mL of trichloroacetic acid is added to 1mL of an
extract or organic sample, the existence of terpenoids is
observed by the appearance of a red precipitate [193].
3.1.5.3 Test ofSalkowski
The organic sample is shaken alongside with chloroform
and concentrated solution of sulfuric acid (H2SO4), and
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Y. A. T. Ngandjui et al.
added along the walls of the test tube. After some minutes,
the red color which is observed indicates the presence of
steroids [193].
3.1.6 Qualitative Test forthePresence
ofSaponins
In this qualitative test, few drops of a solution of sodium carbonate (Na2CO3) is added to 5mL of extract in the test tube.
The formation of foam after vigorous shaking indicates the
presence of saponins [193].
3.1.7 Some Qualitative Tests forCarbohydrates
3.1.7.1 Test ofBenedict
Eight to ten drops of the extract is added to 5 mL of
Benedict’s reagent, followed by heating for 5min. The formation of dark red precipitate indicates the existence of carbohydrates [193].
3.1.7.2 Test ofMolish
The sample to be analyzed is introduced into a test tube and
dissolved in a solution of 1% ethanol in α-naphtol. A few
drops of concentrated H2SO4 are added by letting it ow
down the side of the tube. The appearance of a purple-red
ring at the interface between the liquids indicates the presence of a sugar or sugars.
3.2 General Characterization Techniques
ofPhytoconstituents
After determining the nature of the organic sample by means
of qualitative analyses, the complete characterization is generally done using spectroscopic methods such as UV, IR,
mass, and NMR spectroscopy, and sometimes X-ray analysis. When necessary, synthesis can also be used [197].
3.2.1 Mass Spectrometry
This is a powerful analytical technique for the identication
of known and unknown phytochemicals. Mass spectrometry
consists of an ionization chamber in which the molecules
being examined enter the gas phase and acquire electrical
charge. In mass spectrometry, the symbol z characterizes the
number of charges on the molecule and the symbol m means
the molar mass of a molecule of analyte in grams per mole.
The spectrum is a histogram of the relative amount of each
type of analyte that has a particular mass-to-charge ratio
which the symbol is m/z. Some ionization methods commonly used are chemical ionization (CI), fast atom bombardment (FAB), and eld desorption (FD). Chemical ionization
spectra can be recorded from both positive and negative ions
[198]. In mass spectrometry, the relative molecular mass can
be determined with high accuracy and an exact molecular formula can be determined with a knowledge of places where
the molecule have been fragmented [199]. Moreover, the
HPLC and MS combination facilitates rapid and accurate
identication of chemical compounds in medicinal plants
[200–203].
3.2.2 UV-Visible Spectroscopy
Spectrophotometry or UV-Vis Spectroscopy is a tool used
to measure how much a chemical substance absorbs light.
The experience consists of determining the intensity of
light that passes through a sample with regard to the intensity of light through a reference sample or blank. This
method can be utilized for numerous sample types counting
glass, thin- lms, solids, and liquids. The absorption of UV
light or visible light by organic compounds is the principle
of UV-Visible Spectroscopy which results in the production
of distinct spectra. Spectroscopy is based on the interaction
between matter and light. When the matter retains the light,
it experiences excitation and de-excitation, coming about
within the generation of a spectrum. This technique can be
used for qualitative analysis and for the identication of
certain groups of compounds which have chromophores in
their structures [204]. For instance, phenolic compounds
such as anthocyanins, phenols, polymer dyes, and tannins
form complexes with iron that are detected by UV-visible
spectroscopy [205, 206]. This technique does not take
much time and is less expensive than other techniques
[207].
3.2.3 Infrared Spectroscopy
Infrared (IR) spectroscopy through the absorption of infrared light is a very important technique for detecting the
characteristic bonds of several functional groups. If infrared
light is shone on a molecule, it is possible that the molecule
will absorb the energy of the light. The energy absorbed can
cause a bend or bond to stretch. That is called a bending or
stretching vibration. These vibrations which correspond to
the frequency of infrared light only occur at specic frequencies. The infrared light is absorbed when the frequency
of IR light corresponds to the frequency of a particular
vibrational mode. You can then know which frequencies are
being absorbed by looking at your infrared spectrum. The
different types of bonds vibrate at different frequencies and
therefore absorb different frequencies of infrared light,
which makes it possible to determine the functional groups
present. The characteristic vibrational frequencies are
known for the majority of commonly occurring chemicals
[208]. Infrared spectra can be sorted into two principal
regions:
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73
– Diagnostic region—generally provides the clearest infor-
mation and has fewer peaks. This region includes all signals from all bonds in a molecule. This region has the
wavenumbers with value higher than 1500cm−1;
– Fingerprint region—contains signals resulting from the
vibrational excitation of most single bonds (bending and
stretching). Values of wavenumbers in this region are less
than 1500cm−1.
Infrared spectroscopy is used for the identication of different vibrational frequencies of single, double, and triple
bonds present in an organic molecule [205, 207].
3.2.4 Nuclear Magnetic Resonance
Spectroscopy
This technique is commonly known as NMR which gives
chemical, physical, and biological properties of compounds.
Chemists generally use one-dimensional and twodimensional techniques to determine the structure of molecules [205]. The technique is linked to the magnetic
properties of certain atomic nuclei of proton and carbon. For
instance, 13C-NMR and 1H-NMR are used for the identication of different types of carbon and hydrogen present in
natural products [204, 205].
the alkaloid is a simple derivative of a known alkaloid that can
be recognized by comparing MS and UV data.
3.3.1 UV andIR Characteristics ofAlkaloids
UV is the oldest and still an important tool for the identication of alkaloids, especially indole and isoquinoline alkaloids which have a large number of different characteristic
chromophores, providing information on the aromatic part of
the molecule [211]. Identication of alkaloids by UV spectrophotometer was achieved by dissolving the isolates with
solvent (chloroform for example) and measuring its absorbance at a wavelength of 200–400nm.
IR is particularly useful for conrming the structure of
known alkaloids. It can be useful for the identication of certain functional groups such as carbonyl groups but also for
the determination of stereochemistry. For instance, in heteroyohimbine alkaloids, the appearance of Bohlman bands at
about 2900cm−1 is indicative of the stereochemistry of the C
and D rings [212].
Identication of alkaloids using FTIR can be achieved by
mixing isolates with potassium bromide using a mixing
vibrator, then printing pellets and inserting then into the
FTIR.The absorbance is then measured at a frequency of
4000–5000cm−1.
3.2.5 X-Ray Crystallography
X-ray crystallography is a commonly used technique to
determine the structure of an organometallic or organic molecule where the spatial arrangement of atoms around a chiral
center is more readily determined. The X-ray crystallography technique can give a structure at a resolution of 0.083
Angstrom. A single crystal of a pure substance is an orderly
range of molecules [209]. The underlying principle is that
the crystalline atoms cause a beam of X-rays to diffract into
many specic directions. A crystallographer can produce a
three-dimensional picture of the density of electrons within
the crystal by measuring the angles and intensities of these
diffracted beams.
3.3 Characterization Techniques
ofAlkaloids
The identication of alkaloids depends on their classication.
Known alkaloids can be identied by high performance liquid
chromatography coupled and gas chromatography coupled to
mass spectrometry (LC-MS and GC-MS). Known alkaloids
can also be detected in complex mixtures by 1H- NMR and 13CNMR which are more suitable because of the wide range of
shifts [210]. In addition, 2D-NMR especially 2D-COSY
seems very suitable because of their good sensitivity. For
unknown alkaloids, the identication can be easily achieved if
3.3.2 Mass Spectrometry (MS)
The mass spectroscopy of alkaloids has been widely reviewed
in regard of the importance of the technique and its utility in
the determination of the mass of the compounds [213, 214].
The direct coupling of mass spectroscopy with gas chromatography (GC) or high-pressure liquid chromatography
(HPLC) turns these techniques into very powerful tools in
the identication of alkaloids. GC-MS has the advantage that
mass spectra also showing fragmentation, either by electron
impact (EI) or chemical ionization (CI), are more easily
obtained. In most of the interfaces available for LC-MS, no
fragmentation spectra can be obtained; only the protonated
molecule (M+ 1) can be observed in the positive ion mode.
However, because of their great variety of structure, we have
not given the general mass of alkaloids.
3.3.3 Nuclear Magnetic Resonance (NMR)
Many reviews on the NMR data of alkaloids have been published [215]. The 1H-NMR spectrum gives an indication by
showing features already known for other alkaloids, including the pattern of aromatic signals in indole alkaloids which
can be used to obtain information on the type of indole alkaloid involved [210].
The fact that the signals of different protons overlap can
complicate the interpretation of the 1H-NMR spectra. The
use of shifting reagents allows overlapping signals to be
resolved. Triuoroacetic acid has been shown to be a useful
shifting reagent for alkaloids [216]. In CDCl3 solution it
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