showed strong antibacterial activity against gram-positive and gram-negative bacteria (Dervendži and Karanfilov 1992). Another compound called alliin, with
needle-shaped crystals without smell was isolated. Alliin has no antibacterial action
but by adding the enzyme alliinase from fresh garlic, allicin having strong
antibacterial action is produced (Petrovska and Cekovska 2010). The wide spectrum
of pharmacological effects of A. sativum has been reported with the minimum
toxicity. It is also used as a spice and food additive Health benefits of garlic are well
known and studied to cure ailments caused by infections. The active constituents of
garlic showed potential antimicrobial activity due to sulfur compound present
in their chemical structure that has been proved against some microorganisms
such as Escherichia, Helicobacter, Klebsiella, Mycobacterium, Porphyromonas,
Pseudomonas, Salmonella, Streptococcus species (Cellini et al. 1996; Uchida et al.
1975), Candida, Cryptococcus, and Rhodotorula, etc. (Yousuf et al. 2011). Some
fungal infections caused by fungi such as Trichophyton and Aspergillus have also
been cured by the use of garlic constituents (Saif et al. 2020). Calcium hydroxide
show less antibacterial activity compared to garlic. There is also a report that is
utilized for the management of the parasite infection and in diarrhea.
12.3.1 Phytochemistry of Garlic
The bulbs of garlic are known to contain hundreds of phytoconstituents including
0.1 to 0.36% volatile oil and these are generally responsible for their pharmacological effects. Garlic includes as ammonium of 33 sulfur compounds, for instance,
alliin, allicin (thiosulfinates), ajoenes (E-ajoene and Z-ajoene), allyl propyl, diallyl
disulfide, diallyl trisulphide), sallylcysteine, and vinyldithiines, etc. (Motteshard
2008). After the chopping of the garlic bulb and breaking down the parenchyma,
the cysteine sulfoxide, i.e., alliin in the presence of alliinase enzyme produces
allicin, the chief odoriferous organosulfur compounds are alliin, S-allyl cysteine,
S-ethylcysteine, and S-methylcysteine (Al-Snafi 2013; El-Saber Batiha et al. 2020;
Zeng et al. 2017). During the storage of garlic bulbs at cool temperatures, alliin
accumulates naturally. Allicin can be transformed into stable lipid-soluble allylsulfides such as ajoene. Ajoene from garlic is obtained by the conversion of alliin
into allicin by the alliinase-induced cleavage and then in the presence of a polar
solvent such as water or alcohol, allicin forms ajoene. Ajoene is chemically more
stable than allicin (Viswanathan et al. 2014). Garlic bulbs upon steam distillation
yield oil dimethyl mono to hexasulfides (6% of oil), allyl methyl sulfides (37% of
oil), and diallylsulphides (57% of oil), which are reported for excellent antibacterial
properties (Abubakar 2009; Tripathi 2009). On average, a garlic bulb contains up to
0.9%—glutamylcysteines and up to 1.8% alliin. The pungent offensive odor and its
health benefits are generally due to the presence of sulfur compounds. Chemical
structures of chief constituents are illustrated in Fig. 12.3. Besides these compounds, garlic also contains 17 amino acids such as leucine, methionine,
S-propyl-L-cysteine, S-propenyl-L-cysteine, S-allyl cysteine sulphoxide (alliin),
12 Antimicrobial Application Potential …
415
needle-shaped crystals without smell was isolated. Alliin has no antibacterial action
but by adding the enzyme alliinase from fresh garlic, allicin having strong
antibacterial action is produced (Petrovska and Cekovska 2010). The wide spectrum
of pharmacological effects of A. sativum has been reported with the minimum
toxicity. It is also used as a spice and food additive Health benefits of garlic are well
known and studied to cure ailments caused by infections. The active constituents of
garlic showed potential antimicrobial activity due to sulfur compound present
in their chemical structure that has been proved against some microorganisms
such as Escherichia, Helicobacter, Klebsiella, Mycobacterium, Porphyromonas,
Pseudomonas, Salmonella, Streptococcus species (Cellini et al. 1996; Uchida et al.
1975), Candida, Cryptococcus, and Rhodotorula, etc. (Yousuf et al. 2011). Some
fungal infections caused by fungi such as Trichophyton and Aspergillus have also
been cured by the use of garlic constituents (Saif et al. 2020). Calcium hydroxide
show less antibacterial activity compared to garlic. There is also a report that is
utilized for the management of the parasite infection and in diarrhea.
12.3.1 Phytochemistry of Garlic
The bulbs of garlic are known to contain hundreds of phytoconstituents including
0.1 to 0.36% volatile oil and these are generally responsible for their pharmacological effects. Garlic includes as ammonium of 33 sulfur compounds, for instance,
alliin, allicin (thiosulfinates), ajoenes (E-ajoene and Z-ajoene), allyl propyl, diallyl
disulfide, diallyl trisulphide), sallylcysteine, and vinyldithiines, etc. (Motteshard
2008). After the chopping of the garlic bulb and breaking down the parenchyma,
the cysteine sulfoxide, i.e., alliin in the presence of alliinase enzyme produces
allicin, the chief odoriferous organosulfur compounds are alliin, S-allyl cysteine,
S-ethylcysteine, and S-methylcysteine (Al-Snafi 2013; El-Saber Batiha et al. 2020;
Zeng et al. 2017). During the storage of garlic bulbs at cool temperatures, alliin
accumulates naturally. Allicin can be transformed into stable lipid-soluble allylsulfides such as ajoene. Ajoene from garlic is obtained by the conversion of alliin
into allicin by the alliinase-induced cleavage and then in the presence of a polar
solvent such as water or alcohol, allicin forms ajoene. Ajoene is chemically more
stable than allicin (Viswanathan et al. 2014). Garlic bulbs upon steam distillation
yield oil dimethyl mono to hexasulfides (6% of oil), allyl methyl sulfides (37% of
oil), and diallylsulphides (57% of oil), which are reported for excellent antibacterial
properties (Abubakar 2009; Tripathi 2009). On average, a garlic bulb contains up to
0.9%—glutamylcysteines and up to 1.8% alliin. The pungent offensive odor and its
health benefits are generally due to the presence of sulfur compounds. Chemical
structures of chief constituents are illustrated in Fig. 12.3. Besides these compounds, garlic also contains 17 amino acids such as leucine, methionine,
S-propyl-L-cysteine, S-propenyl-L-cysteine, S-allyl cysteine sulphoxide (alliin),
12 Antimicrobial Application Potential …
415