The medicinal plant garlic (Allium sativum L.) is known for its synthesis of allicin, a defense molecule that exhibits various biological activities. Traditional medicine uses this medicinal plant to alleviate numerous diseases due to the wide range of effects of garlic. Allicin is produced from alliin during the cutting of garlic by the activity of the enzyme allinase and is effective against a wide range of microorganisms. Allicin is hydrophobic in nature, can efficiently cross cell membranes, and behaves as an active sulfur species inside cells. It is a physiologically active molecule with the ability to oxidize the thiol groups of glutathione and between cysteine residues in proteins. Allicin is physiologically active in microbial, plant, and mammalian cells. Allicin can inhibit the proliferation of bacteria and fungi in a dose-dependent manner or kill cells completely. In addition, in mammalian cell lines, including cancer cells, allicin causes cell death and inhibits cell proliferation. In plants, allicin prevents seed germination and reduces root growth. The study showed that allicin has a wide range of pharmacological activities. Allicin has antimicrobial, antioxidant, anticancer properties, the ability to reduce cardiovascular diseases, improve the immune system and regulate blood sugar. The antimicrobial and antioxidant functions of allicin are due to the reaction of allicin with the thiol group of various enzymes, respectively; to inhibit the metabolism of cysteine protease and to trap free radicals. Allicin prevents the occurrence and progression of cancer by blockin