Chemical Constituents and Pharmacological
Activities of Garlic (Allium sativum L.): A Review
Gaber El-Saber Batiha 1, 2, *,†, Amany Magdy Beshbishy 1, †, Lamiaa G. Wasef 2,
Yaser H. A. Elewa 3,4, Ahmed A. Al-Sagan 5, Mohamed E. Abd El-Hack 6, Ayman E. Taha 7,
Yasmina M. Abd-Elhakim 8and Hari Prasad Devkota 9
1National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary
Medicine, Nishi 2-13, Inada-cho, Obihiro, Hokkaido 080-8555, Japan; firstname.lastname@example.org
2Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University,
Damanhour 22511, AlBeheira, Egypt; email@example.com
3Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine,
Hokkaido University, Sapporo, Hokkaido 060-0818, Japan; firstname.lastname@example.org
4Department of Histology and Cytology, Faculty of Veterinary Medicine, Zagazig University,
Zagazig 44511, Egypt
5King Abdulaziz City for Science and Technology, P.O. Box 6086, Riyadh 11442, Saudi Arabia;
6Department of Poultry, Faculty of Agriculture, Zagazig University, Zagazig 44511, Egypt;
7Department of Animal Husbandry and Animal Wealth Development, Faculty of Veterinary Medicine,
Alexandria University, Edﬁna 22578, Egypt; Ayman.Taha@alexu.edu.eg
8Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Zagazig University,
Zagazig 44511, Egypt; email@example.com
9Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku,
Kumamoto City, Kumamoto, 862-0973, Japan; firstname.lastname@example.org
*Correspondence: email@example.com; Tel.: +20-45-271-6024; Fax: +20-45-271-6024
†These two authors share the ﬁrst authorship.
Received: 27 February 2020; Accepted: 12 March 2020; Published: 24 March 2020
Medicinal plants have been used from ancient times for human healthcare as in the form of
traditional medicines, spices, and other food components. Garlic (Allium sativum L.) is an aromatic
herbaceous plant that is consumed worldwide as food and traditional remedy for various diseases.
It has been reported to possess several biological properties including anticarcinogenic, antioxidant,
antidiabetic, renoprotective, anti-atherosclerotic, antibacterial, antifungal, and antihypertensive
activities in traditional medicines. A. sativum is rich in several sulfur-containing phytoconstituents
such as alliin, allicin, ajoenes, vinyldithiins, and ﬂavonoids such as quercetin. Extracts and isolated
compounds of A. sativum have been evaluated for various biological activities including antibacterial,
antiviral, antifungal, antiprotozoal, antioxidant, anti-inﬂammatory, and anticancer activities among
others. This review examines the phytochemical composition, pharmacokinetics, and pharmacological
activities of A. sativum extracts as well as its main active constituent, allicin.
Garlic; Allium sativum; pharmacological activities; phytoconstituents; allicin;
Medicinal plants have been a good source of new pharmacologically active molecules.
natural products could be a potential alternative for controlling the pathogen associated with diseases [
]. Recently, antibiotics and most drugs on the market have shown unwanted symptoms and the
Nutrients 2020,12, 872; doi:10.3390/nu12030872 www.mdpi.com/journal/nutrients
Nutrients 2020,12, 872 2 of 21
emergence of resistant pathogenic microorganisms, toxic eﬀects related to these drugs, and withdrawal
issues restricting their use in many countries [
], therefore, much attention has been paid to the
herbal extracts and pharmacologically active molecules extracted from diﬀerent plant species that are
used previously in the traditional medicine [
]. Many plant species have been reported to exert
pharmacological properties due to their phytoconstituents such as glycosides, alkaloids, saponins,
steroids, ﬂavonoids, tannins, and terpenoids (e.g., monoterpenes, diterpenes, and sesquiterpenes).
Nowadays, eighty percent of the world’s populations depend on traditional medicines as an essential
source of their primary health care [
]. Medicinal plant extracts and their constituents also possess
various biological activities including virucidal, bactericidal, fungicidal, anti-inﬂammatory, analgesic,
sedative, spasmolytic, and local anesthetic activities among others [14,15].
Garlic (Allium sativum L.; Family: Amaryllidaceae) is an aromatic herbaceous annual spice and
one of the oldest authenticated and most important herbs that have been used from ancient times
as traditional medicine [
]. It is considered the second broadly used Allium species with onion
(Allium cepa L.), which is used as a remedy against several common diseases such are cold, inﬂuenza,
snake bites, and hypertension [
]. Allium species and their active components are reported to reduce
the risk of diabetes and cardiovascular diseases, protect against infections by activating the immune
system and have antimicrobial, antifungal, anti-aging as well as anti-cancer properties which conﬁrmed
by epidemiological data from human clinical studies [
]. Garlic has been used for cooking purposes
as a spice that can ﬂavor foods during the cooking process. As well, it possesses therapeutic purposes
including the treatment of lung disorders, whooping cough, stomach disorders, cold, earache, and
assists in preventing cardiovascular disease [
]. While aged garlic extract (AGE), prepared from aged
garlic is a folk herbal remedy that has been shown to enhance the immune system and thus inhibit
cancer and heart disorders. Raw garlic and its transformed products have been reported to contain
various sulfur compounds that have been included in several types of preparations [
quercetin, the major ﬂavonoid isolated from garlic, was found to interact with some medications such
as vitamin E and C [
] and modify the
as well as the
transferases and cytochrome
P450 isozymes activity, however, the
studies revealed that garlic oil and its three allyl sulﬁde
components increase the CYP3A1, 2B1, and 1A1 expression in the hepatic detoxiﬁcation system .
Allicin [S-(2-propenyl)-2-propene-1-sulﬁnothioate], the most biologically active sulfur-containing
compound of garlic, is responsible for its smell and taste [
]. Alliin (S-allyl-L-cysteine sulfoxide) is
the main precursor of allicin, which represents about 70% of total thiosulﬁnates existing in the crushed
]. Allyl mercaptan is the odorant molecule responsible for the garlic breath and results
from the interaction of allicin or diallyl disulﬁde with cysteine in the presence of S-ally-mercapto
]. Allicin is a lipid-soluble sulfur compound, which can be easily damaged by cooking
and has the ability to provoke intolerance, allergic reactions, and gastrointestinal disorders [
Various pharmacological activities have also been reported for the extracts and isolated compounds
from garlic. The main aim of this article is to critically review the available scientiﬁc information about
the traditional uses, chemical constituents, pharmacokinetics, and pharmacological activities of garlic.
2. Chemical Constituents of Garlic
Bulbs of A. sativum are reported to contain hundreds of phytochemicals including sulfur-containing
compounds (Table 1) such as ajoenes (E-ajoene, Z-ajoene), thiosulﬁnates (allicin), vinyldithiins
(2-vinyl-(4H) -1,3-dithiin, 3-vinyl-(4H)-1,2-dithiin), sulﬁdes (diallyl disulﬁde (DADS), diallyl trisulﬁde
(DATS)) and others that accounted 82% of the overall garlic sulfur content [
]. Alliin, the main cysteine
sulfoxide is transformed to allicin by allinase enzyme after cutting oﬀthe garlic and breaking down the
]. S-propyl-cysteine-sulfoxide (PCSO), allicin and S-methyl cysteine-sulfoxide (MCSO)
are the main odoriferous molecules of freshly milled garlic homogenates [
]. PCSO can produce
more than ﬁfty metabolites depend on water content and temperature as well as allinase enzyme that
can act on the mixture of MCSO, PCSO, and alliin to produce other molecules, such as allyl methane
Nutrients 2020,12, 872 3 of 21
thiosulﬁnates, methyl methanethiosulfonate, and further corresponding thiosulﬁnates (R-S-S-R
which R and R0are allyl, propyl, and methyls groups .
List and structures of some of the sulfur-containing compounds isolated from Allium sativum.
Compounds Molecular formula Structure
Diallyl sulﬁde (DAS) C6H10S
Diallyl disulﬁde (DADS) C6H10S2
Diallyl trisulﬁde (DATS) C6H10S3
Allyl methyl sulﬁde (AMS) C4H8S
S-alk(en)yl-l-cysteine sulfoxides are the secondary metabolites obtained from cysteine which
accumulate in the plants of Allium genus [
]. Garlic formulations consist of several organosulfur
compounds, N-acetylcysteine (NAC), S-allyl-cysteine (SAC) [
], and S-ally-mercapto cysteine (SAMC),
which are derived from alliin [
]. Notably, SAC has antioxidant, anti-inﬂammation, regulated redox,
pro energetic, antiapoptotic, and signaling capacities [
], while SAMC shows an anticancer activity
through preventing the cancer cells multiplication .
Allicin (allyl thiosulﬁnate), is a sulfenic acid thioester and its pharmacological eﬀect is attributed
to its antioxidant activity as well as its interaction with thiol-containing proteins [
]. In the
allicin biosynthesis, cysteine is transformed to alliin that is hydrolyzed by the allinase enzyme [
This enzyme composed of pyridoxal phosphate (PLP) which splits alliin and produces ammonium,
pyruvate, and allyl sulfenic acid that are highly reactive and unstable at room temperature, where two
molecules were combined to form allicin [37,39].
3. Pharmacokinetics and Stability of Garlic Components
De Rooij et al. [
] reported the existence of N-acetyl-S-allyl cysteine (NASAC) in human urine
after garlic ingestion that is created by converting SAC into the N-acetylated metabolite by N-acetyl
transferase enzyme. Previous reports revealed the existence of diallyl disulﬁde (DADS), allyl methyl
sulﬁde (AMS), diallyl sulﬁde (DAS), allyl methyl disulﬁde (AMDS), dimethyl sulﬁde, acetone and
diallyl trisulﬁde (DATS) in tested participants breath after administration of 38 g of raw garlic. It
was reported that DADS, DAS, DATS, and AMDS achieved the maximum concentrations within 2
to 3 h. Freeman and Kodera [
] examined allicin stability in simulated gastric ﬂuid (SGF), blood,
stimulated intestinal ﬂuid (SIF) and various solvents such as; methanol, water, ethyl acetate at pH 1.2
and 7.5 and they observed that allicin aﬀected the SGF and SIF at pH 1.2 and 7.5, respectively. These
Nutrients 2020,12, 872 4 of 21
results suggest that allicin degraded at room temperature and was more stable in methanol than in
ethyl acetate. Furthermore, about 90% of the allicin stayed in the SIF (pH 7.5) and SGF (pH 1.2) after
incubation at 37
C for 5 h, while only a small amount could be detected after 5 min in the blood.
About 62% and 80% of allicin remained one day after Allium administration without increasing the
concentration of allicin decomposition products such as DADS [
]. The pharmacokinetic examination
in rats using 35 S-labeled alliin, vinyl dithiins, and allicin, revealed that the alliin peak time (T
lower than 10 min and was eliminated after 6 h from the blood, whereas the allicin peak time (T
was 30–60 min and the mean total fecal and urinary excretion was 85.5% after 72 h.
Allicin, a bright yellow oily liquid that possesses a distinctive garlic odor and it is very unstable,
therefore it can be easily decomposed even at room temperature [
]. Previous studies reported
that allicin can easily degrade under the inﬂuence of temperature to form ajoenes ((E)- and (Z)-4, 5,
9-trithiadodeca-1, 6, 11-triene-9-oxides) and vinyldithiins which are more stable than allicin [
degradation products are commonly isolated from oil, aqueous and chloroform garlic extracts and are
present as (E) and (Z) isomers, where (E)-ajoene is usually found in double amounts .
4. Pharmacological Activities of Garlic and Its Related Compounds
4.1. Traditional Uses of Garlic
Garlic is one of the most important bulb vegetables that has a pungent ﬂavor and widely used all
over the world as a spice and ﬂavoring agent. The organosulfur compounds like allicin and DADS
are the main compounds responsible for its pungency eﬀects and spicy aroma. Garlic is well-known
to be used in food preparation, especially dried foods for storage and some types of soup and it can
be utilized in both fresh and dehydrated states [
]. Traditionally, garlic and its related compounds
have been stated to have several biological activities including anticarcinogenic, antioxidant [
antidiabetic, renoprotective, anti-atherosclerotic, antibacterial, antifungal [
], and antihypertensive
]. Moreover, garlic has been used in traditional medicine to treat indigestion, respiratory
and urinary tract infections and cardiac disorders and it showed carminative, antipyretic, sedative,
aphrodisiac, and diuretic eﬀects .
4.2. Activities Related to Infectious Diseases
4.2.1. Antibacterial Activity
The antimicrobial activity of garlic is attributed to allicin activity that was reported toward a wide
variety of microorganisms including antibiotic-resistant, Gram-positive and Gram-negative bacteria
such as Shigella, Escherichia coli [
], Staphylococcus aureus,Pseudomonas aeruginosa [
mutans,S. faecalis,S. pyogenes,Salmonella enterica, Klebsiella aerogenes [
vulgaris, and Enterococcus faecalis [
]. Various garlic extracts (aqueous, chloroform, methanolic, and
ethanolic extracts) were reported to inhibit the growth of several pathogenic bacteria with varying
degrees of susceptibility. For instance, a study revealed that ethanolic garlic extract showed higher
inhibitory eﬀect against E. coli and Sal. typhi than the aqueous extract that showed little or no
inhibition eﬀect [
]. Meriga et al. [
] reported that aqueous garlic extract showed antibacterial activity
toward Gram-negative (Kl. pneumoniae and E. coli) as well as Gram-positive (e.g., Bacillus subtilis and
S. aureus) strains, whereas methanolic garlic extract showed antimicrobial activity against all tested
strains except S. aureus. However, hexane, ethyl acetate, and chloroform extracts did not show any
antibacterial eﬀect. Moreover, garlic extracts prevented the growth of enterotoxigenic E. coli strains
and other pathogenic intestinal bacteria, which are the main cause of diarrhea in humans and animals.
Besides the antibacterial activity of garlic, it was reported to prevent the toxins produced by bacterial
]. Allicin also showed eﬀectiveness toward methicillin-resistant S. aureus (MRSA) [
Allicin’s antimicrobial activity is due to its chemical interaction with enzymes containing thiol e.g.,
thioredoxin reductase, RNA polymerase, and alcohol dehydrogenase [
] by oxidizing protein cysteine
Nutrients 2020,12, 872 5 of 21
or glutathione residues under physiological conditions. Allicin is a dose-related biocide that can
inﬂuence essential metabolism of cysteine proteinase, and thus, kill all eukaryotic cells due to the
presence of thiol groups in all living cells.
4.2.2. Antifungal Activity
Garlic extracts showed a broad spectrum fungicidal eﬀect against a wide range of fungi
including Candida, Torulopsis, Trichophyton, Cryptococcus, Aspergillus,Trichosporon, and Rhodotorula
species. Recently, garlic extract was found to inhibit the Meyerozyma guilliermondii and Rhodotorula
mucilaginosa germination and growth [
]. Another study reported the antifungal activity of various
A. sativum extracts namely aqueous, ethanolic, methanolic, and petroleum ether against human
pathogenic fungi such are Trichophyton verrucosum,T. mentagrophytes,T. rubrum,Botrytis cinerea,Candida
species, Epidermophyton ﬂoccosum,Aspergillus niger,A. ﬂavus,Rhizopus stolonifera, Microsporum gypseum,
M. audouinii,Alternaria alternate, Neofabraea alba, and Penicillium expansum [
]. The garlic extract acted
by aﬀecting the fungal cell wall and causing irreversible ultrastructural changes in the fungal cells,
which lead to loss of structural integrity and aﬀected the germination ability. These changes in the
cytoplasmic content lead to nucleus and cell organelles damage that ultimately leads to cell death.
Moreover, allicin and garlic oil showed potent antifungal eﬀects against Candida albicans, Ascosphaera
apisin, and A. niger [
] and they acted by penetrating the cellular membrane as well as organelles
membranes like the mitochondria and leading to organelles destruction and cell death [
and DATS separated from garlic essential oil showed antifungal activity against a number of fungi
(C. albicans,C. tropicalis, and Blastoschizomyces capitatus). In addition to that, saponins extracted from
A. sativum exhibited antifungal activity against Botrytis cinerea and Trichoderma harzianum .
4.2.3. Anti-Protozoal Activity
Various studies reported the anti-protozoal activity of garlic extracts and its phytochemicals
against several protozoan parasites. For instance, an
study revealed that the aqueous,
ethanolic, and dichloromethane A. sativum extracts exhibited anthelmintic activity against Haemonchus
contortus and the ethanolic extract was the most eﬀective one, while aqueous garlic extract showed
potent activity against Trichuris muris and Angiostrongylus cantonensis [
]. Garlic was also examined
against Taenia taeniaeformis,Hymenolepis microstoma,H. diminuta,Echinostoma
caproni, and Fasciola hepatica [
]. Abdel-Hafeez et al. [
] showed that garlic extract inhibited the
growth of Blastocystis spp.
and this activity attributed to that garlic extracts contains several
phytochemicals e.g., thiosulﬁnates are one of the bioactive compounds that possess antibacterial
activity that is related to thiol enzymes inhibition which presents in several microorganisms. Allicin
also acts by preventing the parasite’s RNA as well as DNA and protein synthesis. Moreover, allicin
and DATS, phytochemicals isolated from garlic extract, showed antiparasitic activity against Entamoeba
histolytica, Plasmodium falciparum, Babesia, Theleria, Trypanosoma brucei, and Giardia lamblia [
also exhibited antiparasitic activity by inhibiting the human glutathione reductase and T. cruzi
trypanothione reductase [
]. Hazaa et al. [
] reported the activity of garlic oil toward broad-spectrum
microorganisms such are Cochlospermum planchonii, Plasmodium, Giardia,Leishmania, and Trypanosoma.
4.2.4. Antiviral Activity
The antiviral activity of garlic extracts has been evaluated against inﬂuenza B, human rhinovirus
type 2, human cytomegalovirus (HCMV), Parainﬂuenza virus type 3, herpes simplex type 1 and 2,
vaccinia virus, and vesicular stomatitis virus [
experiment exhibited the
antiviral activity of garlic extract and they reported that garlic showed protective activity against
inﬂuenza viruses by improving the production of neutralizing antibodies when given to mice and
this activity was based on the presence of several phytochemicals namely, ajoene, allicin, allyl methyl
thiosulﬁnate, and methyl allyl thiosulﬁnate [
]. Allicin acts by preventing several thiol enzymes, while
ajoene’s antiviral activity was due to the prevention of adhesive interaction and fusion of leukocytes.
Nutrients 2020,12, 872 6 of 21
Moreover, DATS was eﬀective against the HCMV replication and viral immediate-early gene expression
and it acts by enhancing natural killer-cell (NK-cell) activity that destroys virus-infected cells .
4.3. Antioxidant and Anti-inﬂammatory Activities
4.3.1. Antioxidant Activity
Asdaq and Inamdar [
] reported that the frequent garlic intake promotes internal antioxidant
activities and reduces oxidative adverse eﬀects either by increasing the endogenous antioxidant
synthesis or reducing the production of oxidizers such as oxygen-free radical species (ORS). Gentamycin
is an antibiotic that has been used to treat several types of bacterial infections and was reported to
promote hepatic damage through raising aspartate transaminase and alanine aminotransferase enzymes
in addition to lowering the plasma albumin level. It is demonstrated that garlic protects against
gentamycin- as well as acetaminophen-induced hepatotoxicity by improving antioxidant status, and
regulating oxidative stress [
]. As ROS seems to be at the core of many ailments, it is justiﬁed to assume
that the antioxidant eﬀect of garlic might be through modulation of ROS, increasing glutathione and
cellular antioxidant enzymes [
]. Moreover, garlic extract was found to increase the activities of some
antioxidant enzymes (e.g., superoxide dismutase (SOD)) and decrease glutathione peroxidase (GSH-Px)
in hepatic tissues of rats. Notably, several reports indicated that AGE rich in ﬂavonoid, phenol, and
diﬀerent sulfur compounds e.g., SAC shows high radical scavenging activity [
]. Additionally, AGE
acted by stimulating the expression of diﬀerent antioxidant enzymes, namely glutamate-cysteine ligase
modiﬁer (GCLM) and heme oxygenase-1 (HO-1) subunit by the nuclear factor erythrobia-2 related
factor 2 (Nrf2)-antioxidant response element (ARE) pathway that is responsible for human endothelial
cells protection against oxidative stress [
]. Alliin, the major compound isolated from AGE, showing
wide-spectrum antioxidant activities by controlling ROS generation and preventing mitogen-activated
protein kinase (MAPK). Moreover, it was reported to prevent ROS production by inhibiting NADPH
oxidase 1, and thus, inhibiting the osteoclast fusion caused by receptor activator of nuclear factor-kappa
B ligand (RANKL) [
]. Allicin, DADS, and DATS are the main antioxidative compounds that showed
an antioxidant eﬀect in lower doses at the physiological level [
]. Saponins extracted from garlic
were reported to scavenge intracellular ROS and protect mouse-derived C2C12 myoblasts towards
growth inhibition and H
-induced DNA damage [
Abdel-Daim et al. 
that DAS exhibited potent antioxidant and cytoprotective activities and these activities may be due to
suppressing the enzymatic activity of cytochrome P450-2E1 and thereby reducing the generation of
reactive oxygen and nitrogen species or by inducing the mRNA expression of Nrf2 and heme-oxygenase
4.3.2. Anti-Inﬂammatory Activity
Garlic extracts and its related phytochemicals have been reported to possess anti-inﬂammatory
activity. A study reported that the garlic extracts remarkably impaired the liver inﬂammation and
damage caused by Eimeria papillate infections [
]. Hobauer et al. [
], as well as Gu et al. [
that the anti-inﬂammatory activity of garlic is caused by inhibiting the emigration of neutrophilic
granulocytes into epithelia. Aged black garlic (ABG) exhibited potent antioxidant activities and these
activities may be responsible for its anti-inﬂammatory activity. The ABG chloroform extract acts by
B activation in human umbilical vein endothelial cells caused by tumor necrosis factor-
). Moreover, ABG methanolic extract was reported to prevent the cyclooxygenase-2 (COX-2)
and prostaglandin E
) production by NF-
B inactivation [
]. You et al. [
] investigated the
anti-inﬂammatory eﬀect of ABG and they reported that this activity may be attributed to the direct
suppression of toll-like receptor 4 (TLR4) signaling cascade activation in macrophages, reducing
B level and improving the NF-
B and I
B cytosolic levels in LPS-activated RAW264.7
cells. Additionally, they revealed that ABG extract may act by another mechanism of action by
inhibiting the iNOS and COX-2 expression, and thus, prevented the NO, interleukin-6 (IL-6) and
Nutrients 2020,12, 872 7 of 21
formation of in LPS-activated RAW264.7 cells and TPA-mediated dermatitis in mice. Allicin
demonstrated a defensive mechanism against pathogens by its ability to enhance the activity of
immune cells and inﬂuence signaling pathways associated with these immune cells. Moreover,
allicin works on T-cell lymphocytes by inhibiting the SDF1
chemokine which is associated with
the weakness of the dynamic structure of the actin cytoskeleton [
], in addition to this, it leads to
inhibit the Transendothelial migration of neutrophils. Notably, Abdel-Daim et al. [
] reported that
the anti-inﬂammatory activity of DAS induced by diminishing the expression of the inﬂammatory
cytokines (e.g., NF-
, and TNF-
), and the ROS generation by suppressing CYP-2E1 hepatic
enzyme. Another report indicated that thiacremonone (a sulfur compound isolated from garlic)
prevents neuroinﬂammation and amyloidogenesis by blocking the NF-
B activity, and therefore can be
used to treat neurodegenerative disorders (e.g., Alzheimer’s disease) related to inﬂammation .
4.4. Anticancer Activity
Raw garlic extract was found to be the most eﬀective and highly speciﬁc anticancer drug
when compared with 33 raw vegetable extracts against diﬀerent cancer cells without aﬀecting the
non-cancerous cells [
]. Shang et al. [
] reported that the anticancer mechanisms of garlic extracts
were attributed to the inhibition of cell growth and proliferation, regulation of carcinogen metabolism,
stimulation of apoptosis, prevention of angiogenesis, invasion, and migration and thus reducing the
anticancer agent’s negative eﬀects. Interestingly, in 1960, tumor cells were reported to be killed when
incubated in an allicin solution [
]. Allicin isolated from garlic was reported to suppress colorectal
cancer metastasis through enhancing the immune function and preventing the formation of tumor
vessels as well as survivin gene expression to enhance the cancer cell’s apoptosis. It also can enhance the
treatment of pancreatic cancer thereby invert gene silencing and restrain cancer cell proliferation [
Furthermore, Zhang et al. [
] revealed that allicin can prevent gastrointestinal cancer cells MGC 803
proliferation and induce apoptosis, which can be accomplished through enhancing p38 expression and
cleaved caspase 3. Allicin-derived polysulfanes have been reported to target microtubules, which lead
to interruption of the cell-cycle and ﬁnally to apoptosis. Several studies reported the activity of allicin in
preventing cell proliferation [
] by targeting tubulin that shapes the mitotic spindle and thus inhibits
cell division [
]. Iciek et al. [
] have reported the anti-tumor properties of organo-sulfur compounds
(OSC) including allicin, DADS, alliin, DAS, allyl mercaptan (AM), and S-allyl cysteine (SAC), isolated
from garlic. In addition, garlic powders inhibited the DNA damage caused by N-nitrosodimethylamine
in the liver when administered to rats by 35% and this eﬀect was due to the high concentration of alliin
up to 60% in the samples [
]. Notably, Fleischauer and Arab [
] reported that continuous garlic
intake could decrease diﬀerent kinds of cancer propagation such as lung, colon, stomach, breast, and
prostate. Piscitelli et al. [
] reported that garlic reduced the plasma concentrations of saquinavir by
about 50% in healthy participants, after 3-week of a garlic supplement uptake, in addition to this,
many researchers evaluated the antitumor and cytotoxic actions of garlic and its related constituents
. Moreover, Z-ajoene has shown anti-proliferative activities against diﬀerent types
of cancers and it inhibits the growth of human breast cancer cells and glioblastoma multiforme cancer
stem cells (GBM CSC) [
]. It was found to stimulate apoptosis in human leukemic cells by promoting
the peroxide production, caspase-3-like and caspase-8 activities .
4.5. Anti-Alzheimer’s Disease Activity
Alzheimer’s disease (AD) is the main cause of dementia in the elderly with neurodegenerative
and cerebrovascular disorders [
]. Acetylcholinesterase (AChE) is the main enzyme that converts the
acetylcholine (ACh) in the nervous system to acetate and choline [
]. ACh depletion in the central
nervous system has been involved in the pathophysiology noticed in AD [
], therefore, donepezil
(AChE inhibitor) was eﬀective in the management/prevention of AD. Surprisingly, oil from garlic bulbs
suppressed AChE activity of cerebral cortex synaptosome and exhibits antioxidant properties, thus,
inhibiting AChE activity
] as well as their ability to scavenge diphenyl-1-picrylhydrazyl
Nutrients 2020,12, 872 8 of 21
(DPPH) free radical that are used to evaluate the compound’s ability to act as hydrogen donors or free
radical scavengers and to assess the antioxidant activity of food [
] and reduce Fe
suggested as the possible mechanism of action for their neuroprotective potential .
Noteworthy, the inclusion of garlic in cholesterol-fed rats’ diet remarkably reduced the total
glycosaminoglycans (GAGs) concentration in heart and aorta. This may be due to the enhanced
GAGs degrading enzyme activity such as hyaluronidase,
-N-acetylhexosaminidase arylsulfatase and
]. Sulfated GAGs are involved in lipid aggregation in the lesion development due
to their ability to bind to plasma lipoproteins, mainly LDL. Moreover, sulfated GAGs stimulated the
neurotoxic activities of various amyloidogenic peptides such as A in AD [
]. Borek [
the neuroprotective eﬀect of AGE using an animal model and they showed that AGE protected the
brain from neurodegenerative diseases by preventing brain injury following ischemia, saving neurons
toward apoptosis, and inhibiting oxidative death caused by
]. Moreover, Mbyirukira
and Gwebu [
] reported that AGE or SAC inhibits the brain’s frontal lobe degeneration, promotes
memory and learning retention, and prolongs the lifespan.
Based on the amyloid hypothesis, aggregated
) accumulation in the brain is believed
to be the pathological factors that drive the onset of AD. It has been suggested that the formation
of the neuroﬁbrillary tangles contain
-protein and synaptic degradation caused by the imbalance
consequences between A
clearance and A
production. Haider et al. [
] reported that the prolonged
garlic uptake is related to promoting the memory function by aﬀecting the levels of the neurotransmitter,
consumption of A. sativum extracts have shown that it improves memory by
eliminating free radicals that cause oxidative damage and inhibit AChE enzyme [
]. It was noted
that allicin inhibits AChE and butyrylcholinesterase (BuChE) enzymes (enzymes that break down
neurotransmitter choline) which successively increased ACh concentration in the brain. Thus, delayed
cognitive decline and dementia .
Garlic is also investigated to have immunomodulatory, anti-inﬂammatory, and antioxidant eﬀects
and this focused on the question of whether the known eﬀect of processed garlic and its related
compounds mainly allicin in inhibiting AChE and BuChE enzymes [
]. Combination therapy of
allicin with cholinesterase inhibitors (ChEIs) including; rivastigmine, galantamine, and donepezil
are now the most commonly used for the treatment of AD [
] as they have the ability to correct the
cholinergic deﬁciency seen with AD. Antioxidants such as tocopherol, selegiline, and ascorbic acid
(vitamin C) were examined as a possible preventive therapy for AD, and they show delayed functional
deterioration in AD patients [
]. Anti-inﬂammatory drugs such as NSAIDs have been used as a
potential treatment in AD because of their capacity to bind to and stimulate the nuclear receptor
peroxisome proliferator-activated receptor (PPAR)-
as well as their direct eﬀects on the amyloid
It should be noted that AChE inhibitors could be part of any combination therapy against AD [
For instance, Millard et al. [
] reported that AChE incubated with allicin produced rapid inactivation
that was concentration and time-dependent. Many results showed concentration-dependent inhibition
of bovine AChE by allicin complementing the previous ﬁnding. However, diﬀerent cholinesterase
inhibitors such as donepezil, rivastigmine, and tacrine are used to treat AD, and their side eﬀects are
becoming increasingly remarkable [
]. Therefore, the search for new derivatives extracted from
the natural product with a dual function and lower side eﬀects could be useful for patients with AD.
Allicin is a small lipophilic molecule that can suppress BuChE and AChE, and therefore, enhances
ACh concentration, which is decreased remarkably in AD patient’s brains [
]. Recently, allicin
has been shown to have a protective eﬀect on ischemic or traumatic neuronal damage controlled by
apoptosis and oxidative stress pathways .
Nutrients 2020,12, 872 9 of 21
4.6. Activities Related to Metabolic Diseases
4.6.1. Eﬀect on Dyslipidemia
Dyslipidemia is known to be the main cause of myocardial infarction and cardiovascular diseases
and it is deﬁned by high levels of triglyceride (TG), LDL, total cholesterol (TC), and low HDL level [
Interestingly, various evidence encourages the signiﬁcant and crucial role of garlic preparations and its
phytochemicals in treating hypercholesterolemia by preventing the cholesterol biosynthesis in the liver
as well as inhibiting low-density lipoproteins (LDL and HDL) oxidation. Moreover, garlic reduces
the cholesterol level either by stimulating the acidic and neutral steroids excretion or by reducing
the cholesterogenic and lipogenic eﬀects of fatty acid synthase, 3-hydroxy-3-methyl-glutaryl-CoA
reductase, malic, and glucose-6 phosphate dehydrogenase in hepatocytes [
]. Garlic was found to
have an important eﬀect on dyslipidemia by signiﬁcantly decreased serum TC, TG, and LDL levels and
moderately elevated HDL cholesterol [
]. Various experimental and clinical trials were performed in
animals and humans using various garlic preparations and they exhibited disputable results. They
claimed that these variable results were attributed to the diﬀerences in garlic preparation composition,
amount of active sulfur compounds exist in each preparation and the mechanism by which they act.
For instance, Iweala et al. [
] reported that ethanolic garlic extract uptake to albino rabbits resulting in
decreased their cholesterol level and body weight. Campbell et al. [
] reported that AGE signiﬁcantly
prevented the development of thickened, lipid-ﬁlled lesions in the preformed neointima generated
from balloon-catheter harm of the right carotid artery in rabbits fed with cholesterol. In clinical trials
in patients, Sobenin et al. [
] revealed that garlic administration at a dose of 300 and 60 mg/day
for 12 months and 12 weeks, respectively decreased TC, TG, and LDL while increased HDL. Moreover,
Ashraf et al. [
] garlic tablets administration at a dose of 600 mg/day for 12 weeks in diabetic patients
with dyslipidemia results in high HDL and low LDL and TC levels.
4.6.2. Eﬀect on Diabetes Mellitus
Ethanolic garlic extracts exhibited an antidiabetic eﬀect against streptozotocin- and alloxan-induced
diabetic mice and rabbits by activating the insulin secretion from parietal cells of the pancreas [
Another clinical study examined the antidiabetic eﬀect of garlic pills administration at 900 mg/day
in patients with type II diabetes and hyperlipidemia and they reported that garlic pills decrease the
cholesterol, serum lipids, and fasting blood sugar [
]. Moreover, allyl propyl disulﬁde, allicin,
cysteine sulfoxide, and S-allyl cysteine sulfoxide decreased the blood glucose level by preventing the
insulin activation caused by liver, enhancing the secretion of insulin from pancreatic beta cells, isolation
of insulin from the bonded forms, and increasing the cell sensitivity to insulin [
]. Zhai et al. [
reported that the activity of alliin in reducing diabetes mellitus in rats was similar to that demonstrated
by glibenclamide and insulin. Garlic oil also was reported to decrease the serum amylase, serum
aspartate and alanine transferases, and serum alkaline and acidic phosphatase in diabetic rats.
4.6.3. Eﬀect on Obesity
Obesity is the most common health problems that may lead to many ailments like hypertension,
dyslipidemia, cardiovascular disorders, and metabolic syndrome. Garlic extracts have been reported
for their activity in reducing body weight, adipose tissue mass and improved plasma lipid proﬁles in
mice with high-fat diet-induced obesity and these eﬀects mediated by the downregulation of multiple
genes expression that is included in adipogenesis along with upregulation of the mitochondrial inner
membrane proteins expression [
]. Moreover, Lee et al. [
] revealed that the antiobesity eﬀect of
garlic extracts attributed to stimulation of AMP-activated protein kinase (AMPK) as well as increased
thermogenesis and decreased multiple genes expression that is included in adipogenesis. Ajoene
isolated from garlic extracts was found to stimulate apoptosis, decrease the fat accumulation in 3T3-L1
adipocytes and dramatically decrease the body weight gain in mice without aﬀecting the amount
of food intake [
]. 1,2-vinyldithiin also has been reported to prevent the human preadipocytes
Nutrients 2020,12, 872 10 of 21
diﬀerentiation and decrease lipid accumulation by decreasing the C/EBP
2, and LPL expression
and the PPARγeﬀect in human adipocytes .
4.6.4. Antihypertensive Activity
Varshney and Budoﬀ[
] reported the essential function of garlic in the control of cardiovascular
risk factors as it is known to signiﬁcantly decrease systolic as well as diastolic blood pressure.
Garlic formulations have been broadly used to inhibit and relieve cardiovascular disorders such
as hypertension, arrhythmia, thrombosis, hyperlipidemia, and atherosclerosis [
experimental and human studies reported the antihypertensive eﬀect of garlic extracts and its derived
bioactive molecules. For example, Sobenin et al. [
] showed the plasma ﬁbrinolytic activity of garlic
extracts and they found that it increased ﬁbrinolytic activity in both healthy and acute myocardial
infarction participants. Moreover,
experiment exhibited the antihypertensive eﬀect of aqueous
garlic extract in ‘2 kidney 1-clip’ model of hypertension in rat by reducing thromboxane B2 and
prostaglandin E2 level and thereby reduced hypertension in tested rats [
]. Garlic administration
at a dose of 100 mg/kg for 5 days resulted in complete prevention of acute hypoxic pulmonary
vasoconstriction caused by endothelin-1 in isolated rat pulmonary arteries and they found that garlic
acts by reducing endothelin 1 and angiotensin II production [
]. The mechanism of antihypertensive
eﬀect of garlic extracts is that garlic contains many active sulfur molecules that have been shown to
stimulate endothelium-constricting and -relaxing factors leading to lower blood pressure. Garlic has
also been shown to stimulate the production of both nitric oxide (NO) and hydrogen sulphide (H
that ﬁnally leads to vasodilation. Therefore, garlic is used as a medicinal plant for controlling blood
pressure worldwide [
]. Furthermore, garlic exhibited a signiﬁcant role in inhibiting thrombosis
as well as platelet adhesion or aggregation in humans. The AGE was reported to prevent both
ADP-activated platelets binding to immobilized ﬁbrinogen and platelet aggregation by inhibiting
GPIIb/IIIa receptor and increasing cAMP [
]. Furthermore, garlic has been reported to reduce the
risk of plasma viscosity, unstable angina, and peripheral arterial occlusive disorders and increase the
elasticity of the blood vessels and perfusion of capillaries [
]. The gamma-glutamylcysteine isolated
from garlic was reported to decrease the blood pressure by inhibiting the angiotensin-converting
enzyme (ACE). Dubey et al. [
] revealed that allicin shows remarkable activity in reversing systolic
blood pressure caused by dexamethasone and enhances body weight and food intake in hypertension
caused by dexamethasone in rats.
Few pharmacological eﬀects of garlic and its related bioactive compounds are shown in Table 2.
Some of the mechanisms of action related to these activities are shown in Figure 1.
Schematic representation of diﬀerent pharmacological activities of garlic (Allium sativum) and
Nutrients 2020,12, 872 11 of 21
Table 2. The pharmacological activity of garlic (Allium sativum) and its related compounds.
Activities Bioactive Compound Mechanism of Action References
Antibacterial Allicin Chemical interaction with enzymes containing thiol 
Irreversible ultrastructural changes in the fungal cells, loss of structural integrity and aﬀected
the germination ability 
Antiviral Allicin Chemical interaction with enzymes containing thiol 
DATS Enhancing Natural killer-cell (NK-cell) activity that destroys virus-infected cells
Allicin Preventing the parasite’s RNA, DNA and protein synthesis. 
Ajoene Inhibiting the human glutathione reductase and T. cruzi trypanothione reductase 
Allicin, DADS, and DATS Modulation of ROS, increasing glutathione and cellular antioxidant enzymes 
Alliin Controlling ROS generation and preventing mitogen-activated protein kinase (MAPK) 
DAS Suppressing the enzymatic activity of cytochrome P450-2E1, reducing the generation of
reactive oxygen and nitrogen species 
Enhancing the immune cell activity f, inhibiting the SDF1
chemokine and Transendothelial
migration of neutrophils 
DAS Diminishing the expression of the inﬂammatory cytokines (e.g., NF- κB, IL-1β, and TNF-α),
and ROS generation by suppressing CYP-2E1 hepatic enzyme 
Thiacremonone Blocking the NF-κB activity 
Allicin, alliin, DADS, DAS Enhancing p38 expression and cleaved caspase 3. 
Z-Ajoene Stimulating apoptosis in human leukemic cells, promoting the peroxide production,
caspase-3-like, and caspase-8 activities 
Immunomodulatory Allicin Suppressing BuChE and AChE 
Ajoene Decreasing the fat accumulation in 3T3-L1 adipocytes and dramatically decreases the body
weight gain 
1,2-Vinyldithiin Decreasing the C/EBPα, PPARγ2, and LPL expression and the PPARγeﬀect in human
Antidiabetic Allyl propyl disulﬁde, allicin, cysteine sulfoxide,
and S-allyl cysteine sulfoxide, alliin
Decreasing the insulin secretion from pancreatic cells, increasing liver metabolism, and thus
enhancing the short-acting insulin production [114,115]
hypocholesterolaemic Diﬀerent garlic preparations Decreasing serum TC, TG, and LDL levels and moderately elevating HDL cholesterol 
antithrombotic Diﬀerent garlic preparations Preventing ADP-activated platelets binding to immobilized ﬁbrinogen and platelet
aggregation, inhibiting GPIIb/IIIa receptor and increasing cAMP 
Antihypertensive Gamma-glutamylcysteine Inhibiting the angiotensin-converting enzyme 
Nutrients 2020,12, 872 12 of 21
4.7. Recommended Dose and Toxic Side Eﬀects of Garlic
4.7.1. Recommended Dose
The generally recommended doses of the daily garlic uptake for the elderly are 4 g of raw garlic
or 7.2 g of AGE or one dried garlic powder tablet twice to thrice per day [
]. Rana et al. [
that oral or intraperitoneal administration 50 mg/kg of garlic to rats did not show any eﬀect on liver
and lung tissue, while intake garlic at 250, 500, and 1000 mg/kg per day led to acute deformities
in the rat’s liver and lung tissue, suggesting the dose-related toxicity. While garlic intake at a dose
of 500 and 1000 mg/kg/day remarkably decreased the auto-antioxidants without changing the lipid
peroxidation level, whereas the daily intake of 1000 mg/kg resulted in morphological deformities in the
liver under light microscopy and ultrastructural levels. Moreover, histological examination revealed
nonspeciﬁc focal injury to the hepatocytes. In addition to this, Mikaili et al. [
] reported that garlic
bulb extracts ingestion to male and female rats at 300 and 600 mg for 21 days, led to delayed growth and
aﬀects the biological and histological parameters. In particular, Asdaq and Inamdar. [
that the combination therapy of 250 mg/kg of garlic with hydrochlorothiazide shows synergistic
antihypertensive and cardioprotective activities against toxicity caused by fructose and isoproterenol.
While the combination therapy of 250 mg/kg of garlic with propranolol revealed a remarkable elevation
in the antioxidant enzymes activities throughout ischemic injury .
4.7.2. Adverse Eﬀects and Toxicity
Although the US Food and Drug Administration (FDA) considers garlic safe for humans, it can
induce gastric agitation especially if ingested in high doses by sensitive people. To assess the safety
of garlic, randomized controlled trials were performed, side eﬀects such as insomnia, vomiting,
heartburn, dizziness, diarrhea, tachycardia, nausea, bloating, ﬂushing, headache, mild orthostatic
hypotension, sweating, oﬀensive body odor, and ﬂatulence were observed [
]. Ingestion of raw
garlic in high doses on an empty stomach can induce changes in the intestinal ﬂora, ﬂatulence and
gastrointestinal upset [
]. Moreover, blisters dermatitis and burns were observed from raw garlic
local applications [
]. Garlic does not seem to aﬀect the drug metabolism, although recent reports on
healthy participants show inconsistent results regarding the garlic eﬀect in the pharmacokinetics of
protease inhibitors, as well as anticoagulants due to its antithrombotic properties [
]. Many surgeons
recommended stopping garlic administration in high doses up to 7 to 10 days prior to operation due to
its eﬀect to prolong the bleeding time that was observed in one patient with epidural spontaneous
experiments revealed that prolonged feeding of raw garlic in high doses led to
weight loss and anemia due to red blood cells (RBCs) lysis, while administration of 5 mL/kg of raw garlic
juice resulted in stomach injury that led ﬁnally to death [
]. Additionally, the chronic administration
of 50 mg garlic powder per day led to anti-androgenic eﬀects by inhibiting spermatogenesis in rats,
leading to decrease sialic acid concentration in the seminal vesicles, testes, and epididymis with reduced
Leydig cell function [
]. Oxidative hemolysis is the main toxicological mechanism of Allium-derived
sulfur compounds and it is distinguished by methemoglobinemia development and Heinz body
formation in the RBCs [
]. Initially, several clinical symptoms were observed including depression,
vomiting, loss of appetite, abdominal pain, diarrhea, as well as anemia associated with pale mucous
membrane, jaundice, rapid heart and respiratory rates, weakness, and hemoglobinuria [
poisoning symptoms may appear after one day or several days of its ingestion based on the amounts
Previous reports have reported the cardiovascular eﬀects of garlic including potentially irreversible
antiplatelet activity, anticoagulant, ﬁbrinolytic activity, a remarkable decrease in platelet accumulation
and mixed activity on ﬁbrinolytic eﬀectiveness [
]. Chen et al. [
] revealed that dehydrated
raw garlic powder when administered orally resulted in acute injury to the gastric mucosa, whilst
Yuncu et al. [
] reported that AGE, the sulfur-free compound, protects the intestinal mucosa of
Nutrients 2020,12, 872 13 of 21
experimental animals. Clinical studies reported that low doses of garlic are safe, whereas therapeutic
doses might cause mild gastrointestinal disorders, while high doses have been reported to cause liver
Allicin is a membrane-permeable compound that can enter cells easily and interact with cellular
thiols such as glutathione or cysteine residues in proteins [
] as well as enzymes containing
reactive cysteine and this may be the potential interpretation of allicin’s toxicity [
Rana et al. [
] revealed that garlic powder or allicin at a concentration of 200 mg/mL can cause
signiﬁcant cell damages in the isolated rat liver.
5. Combination Therapy with Other Drugs
Recently, Mohammadi et al. [
] revealed the potent activity of garlic and ezetimibe combined
treatment in reducing plasma LDL-C and TC, and thus, inhibiting the absorption of intestinal cholesterol
and reducing the cardiovascular disorders risk factors. Asdaq and Inamdar [
] reported the combined
eﬀect of garlic homogenate and propanol in attenuating the isopropanol-mediated cardiac
excessive stimulation, myocardial hypoperfusion, electrolyte imbalance, glycogen depletion, free radical
injury, thermogenesis, lipid peroxidation, lipid accumulation, and electrocardiographic disturbances.
They indicated that garlic homogenate is a good combination therapy as it reduces the dose and toxic
side eﬀects of propanol, which may assist in decreasing repeated higher doses of propanol. Mikaili et
] reported the combined eﬀect of allicin with polymyxin B against various yeasts and ﬁlamentous
fungi and this combination therapy was found to increase the permeability of plasma membrane in
Saccharo cerevisiae. Moreover, the combination treatments of garlic with captopril showed a higher
synergistic eﬀect regarding ACE inhibition [
]. Notably, the combination treatment of AGE with
methotrexate showed improved activity against the signiﬁcant increase in liver function enzymes,
proinﬂammatory cytokines and antioxidants [
]. Recent researches reported that the fresh garlic
extracts and antibiotics combination therapy resulted in high antibacterial activity. For instance, Ismail
et al. [
] revealed that aqueous garlic extract-ampicillin combined treatment exhibited a potent
synergetic eﬀect towards Kl. pneumoniae,Sal. typhi,E. coli, and P. aeruginosa. Moreover, Vathsala and
] revealed the potent immunomodulatory and anti-plasmodial eﬀect of garlic–artemether
combination treatment. They reported that this combined therapy may have a potential role in reducing
organ injury and protecting against Plasmodium species by aﬀecting NO production, suggesting novel
treatment options against malaria [138,139].
This review focused on the chemical constituents and pharmacological activities of A. sativum.
Sulfur-containing compounds such as alliin, allicin, ajoenes, vinyldithiins, and sulﬁdes, are the main
constituents isolated from A. sativum extracts. Extracts and isolated compounds from A. sativum
reported to possess several biological properties including anticarcinogenic, antioxidant, antidiabetic,
renoprotective, anti-atherosclerotic, antibacterial, antifungal, antiprotozoal, and antihypertensive
activities. Garlic is also well-known to have immunomodulatory and anti-inﬂammatory activities.
Allicin, the active substance of the garlic, can induce gastric agitation especially if administered in high
doses. In addition to that, A. sativum has been reported to aﬀect the pharmacokinetics of antiretroviral
drugs, as well as anticoagulants. Thus, proper consideration should be taken when using garlic as a
medicine for the treatment of diﬀerent diseases.
Author Contributions: A.M.B., G.E.-S.B., L.G.W., Y.H.A.E., A.A.A.-S., M.E.A.E.-H., A.E.T., Y.M.A.-E., and H.P.D.
wrote the paper. A.M.B. and G.E.-S.B. revised the paper. All authors have read and agreed to the published
version of the manuscript.
Funding: This research received no external funding.
Authors extend their thanks to the King Abdulaziz City for Science and Technology, Saudi
Arabia for supporting this work.
Nutrients 2020,12, 872 14 of 21
Conﬂicts of Interest: The authors declare no conﬂict of interest.
AGE aged garlic extract
PCSO S-propyl cysteine-sulfoxide
MCSO S-methyl cysteine-sulfoxide
SAMC S-ally-mercapto cysteine
PLP pyridoxal phosphate
DAS Diallyl sulﬁde
DADS Diallyl disulﬁde
DATS Diallyl trisulﬁde
AMS Allyl methyl sulﬁde
AMDS allyl methyl disulﬁde
SGF simulated gastric ﬂuid
SIF stimulated intestinal ﬂuid
HCMV Human Cytomegalovirus
NK-cell Natural killer-cell
ORS oxygen-free radical species
SOD superoxide dismutase
GSH-Px glutathione peroxidase
GCLM glutamate-cysteine ligase modiﬁer
HO-1 heme oxygenase-1 subunit
Nrf2 nuclear factor erythrobia-2 related factor 2
ARE antioxidant response element
MAPK mitogen-activated protein kinase
RANKL receptor activator of nuclear factor-kappa B ligand
ABG Aged black garlic
TNF-αtumor necrosis factor-α
TLR4 toll-like receptor 4
GBM CSC Glioblastoma multiforme cancer stem cells
AD Alzheimer’s disease
TC total cholesterol
UCP mitochondrial inner membrane proteins
AMPK AMP-activated protein kinase
NO nitric oxide; H2S: hydrogen sulphide
FDA Food and Drug Administration
RBCs red blood cells
ACE Angiotensin-converting enzyme
IUPAC International Union of Pure and Applied Chemistry
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