GARLIC
Source:Allium sativumL. (Family Amaryl-
lidaceae or Liliaceae).
Common/vernacular names:Common garlic,
allium.
GENERAL DESCRIPTION
A strong scented perennial herb with long, flat,
and firm leaves, 0.5–1.5 cm wide; flowering
stem up to 1.2 m high; bulbs with several
bulblets (cloves), all enclosed in membranous
skins; origin unclear; a variable cultigen
(found only in cultivation), garlic’s wild pro-
genitor,Allium longicuspis, is thought to have
originated in the high plains of west-central
Asia perhaps in the Kirgiz Desert; spread east
and west with nomadic tribes; known to be
cultivated in the Middle East more than 5000
years ago; naturalized in North America; cul-
tivated worldwide. Part used is the fresh or
dehydrated bulb. Garlic oil is obtained by
steam distillation of the crushed fresh bulbs;
powdered garlic is derived from the dried
bulbs.
CHEMICAL COMPOSITION
Contains 0.1–0.36% (usually ca. 0.2%)
volatile oil, alliin (S-allyl-L-cysteine sulfox-
ide),S-methyl-L-cysteine sulfoxide, enzymes
(e.g., alliinase, peroxidase, and myrosinase),
ajoenes (E,Z-ajoene,E,Z-methylajoene, and
dimethylajoene), protein (16.8%, dry weight
basis), minerals, vitamins (thiamine, ribofla-
vin, niacin, etc.), lipids, amino acids, and
others (JIANGSU;KARRER;LIST AND HO€RHAMMER;
MARSH;MARTINDALE).1–3
The volatile oil contains allicin (diallyldi-
sulfide-S-oxide; diallyl thiosulfinate), allyl-
propyl disulfide, diallyl disulfide, and diallyl
trisulfide as the major components, with
lesser amounts of dimethyl sulfide, dime-
thyl disulfide; dimethyl trisulfide, allylmethyl
sulfide, 2,3,4-trithiapentane, bis-2-propenyl
tri-, tetra-, and pentasulfides, and other related
sulfur compounds.2,4Boiled garlic also con-
tains sodium 2-propenyl thiosulfate.^5 Most
published data since 1892 have indicated dia-
llyl disulfide to be the main compound in
garlic oil (60%). However, one study indicated
that diallyl trisulfide dominated in freshly
distilled oils.^6 Other volatile compounds pres-
ent include citral, geraniol, linalool, anda-
andb-phellandrene (JIANGSU;KARRER;LIST AND
HO€RHAMMER).^7
Prostaglandins A 2 and Flawere isolated
from a homogenized garlic extract.^3 High-
molecular weight fructans and agglutinins
(homo- and heterodimeric mannose-binding
lectins) were also isolated from garlic.8–11
Allicin is the major odor principle that is
produced by the enzymatic action of alliinase
on alliin; it is decomposed by heat and alkali
but is unaffected by dilute acids in solution
(JIANGSU;MERCK).
Composition of garlic products depends on
productform.Thiosulfinates(e.g.,allicin)were
found to be released only from garlic cloves
and garlic powder products; vinyl dithiins and
ajoeneswerefoundonlyinproductscontaining
garlicmaceratedinvegetableoil;diallyl,meth-
ylallyl,anddimethylsulfideseriescomponents
wereexclusive toproductscontaining the oil of
steam distilled garlic.^12PHARMACOLOGY AND BIOLOGICAL
ACTIVITIESGarlic and garlic oil have been reported to
exhibit numerous pharmacological proper-
ties.13–17The ones most frequently reported
include (i) hypolipidemic/lowering of serum
cholesterol (or lipids) in rabbits and humans
(including lowering triglycerides and total
low-density lipoprotein cholesterol), while
raising levels of high-density lipoprotein cho-
lesterol;18–28 (ii) cardiovascular enhancing
and hypotensive properties in humans and
animals (MARTINDALE). Possible mechanisms
include sodium pump modulation and/or beta-
receptor blockade;28–35(iii) antibacterial, an-
tifungal, and ativiral properties (in vitroand308 Garlic