Garlic: Chemistry behind Antibiotic Nature and Uses

Garlic is extensively used in the kitchen world-wide. It is an herb. Now-a-days the price of garlic is sky-rocketing not only in South Asia but as a whole in this world. When I was in my college life, I used to wonder why this bad smelling stuff has high price in comparison to other vegetables. Later, I found that it was a natural antibiotic! Amazingly, garlic can kill the antibiotic resistant Staphylococus aureus and Salmonella enteritidis too. Here, I have posted the chemistry behind its antibiotic property and its medicinal uses.

Research has identified four major chemical compounds in garlic viz. diallyl disulfide, allyl methyl sulfide, allyl mercaptan, and allyl methyl disulfide. Sulfur-containing compounds are involved in the antibacterial properties of garlic. Researchers tested these compounds on a type of bacteria found in animal faeces (E.coli), one of the most common bacterial causes of gastroenteritis, and found that the anti-microbial activity of the compounds increased with the number of sulfur atoms present; diallyl trisulfide being the most effective, followed by diallyl disulfide, then diallyl sulfide. These compounds are effective as they can penetrate the cell membranes of bacteria cells, and cause changes in structure in thiol (-SH) containing enzymes and proteins, injuring the cell.

Garlic is best known as a flavoring for food. Some scientists have suggested that it might have a role as a food additive to prevent food poisoning. But over the years, garlic has been used as a medicine to prevent or treat a wide range of diseases and conditions. Garlic is used for many conditions related to the heart and blood system. These conditions include high blood pressure, high cholesterol, coronary heart disease, heart attack, and “hardening of the arteries” (artherosclerosis). Some of these uses are supported by science. Garlic actually may be effective in slowing the development of atherosclerosis and seems to be able to modestly reduce blood pressure. Some people use garlic to prevent colon cancer, rectal cancer, stomach cancer, breast cancer, prostate cancer, and lung cancer. It is also used to treat prostate cancer and bladder cancer.

Garlic has been tried for treating an enlarged prostate (benign prostatic hyperplasia; BPH), diabetes, osteoarthritis, hay fever (allergic rhinitis), traveler's diarrhea, high blood pressure late in pregnancy (pre-eclampsia), cold and flu. It is also used for building the immune system, preventing tick bites, and preventing and treating bacterial and fungal infections.

Other uses include treatment of fever, coughs, headache, stomach ache, sinus congestion, gout, rheumatism, hemorrhoids, asthma, bronchitis, shortness of breath ,low blood pressure, low blood sugar, high blood sugar, and snakebites. It is also used for fighting stress and fatigue, and maintaining healthy liver function.

Some people apply garlic oil to their skin to treat fungal infections, warts, and corns. There is some evidence supporting the topical use of garlic for fungal infections like ring worm, jock itch, and athlete’s foot; but the effectiveness of garlic against warts and corns is still uncertain.

Sources: WHO, WebMed