ALLICIN: AS A NOVEL PHYTOMOLECULE IN MODERN PHARMACY

About Authors:
Marvinkumar I. Patel*, Jyoti P. Patel, Ravi P. Patel, Hitesh P. Patel
Nootan Pharmacy College,
Visnagar, Gujarat
*patel.marvin62@gmail.com

Abstract:
Allicin is a novel molecule obtain from garlic. It is a molecule which is biologically active and give a good activity again so many disease in the treatment. It has mainly the virtu of killing the microorganisms which can not be killed by the regular antibiotics. It is not widely used in the pharmafield till today but widely used as food supplement but it has a wide scope to use as a novel tool to treat gastric cancer and microbial infection.

Reference Id: PHARMATUTOR-ART-1312

History
Garlic is probably one of the earliest known medicinal plants. Its bulbs (cloves) had been used as a cure-all in ancient Egypt and are mentioned in the Ebers Papyrus, one of the earliest treatises on medicinal plants. In the Ayurvedic medical texts of ancient India, garlic was recommended against leprosy. Garlic is still popular as a cure all among the traditional healing traditions of Mexico, as well as a health supplement in the United States.

Active Principles
Sulfur containing compounds. Alliin, is converted to the anti-microbially active allicin, when the bulb is cut or bruised. Ajoene, which is a secondary degradation product of alliin, is presumably the most active compound responsible for the antithrombotic activity of garlic¹. The fresh bulb contains alliin, alicin and volatile oils. When the garlic clove is crushed, the odorless compound alliin is converted to allicin, via the enzyme a0llinase. Allicin gives garlic its characteristic pungent smell.Vitamins and minerals².
Trace elements: selenium and germanium³.

Figure:1 Structure of Allicin

Applications in Herbal Therapy

• Antilipidemic⁴: Garlic purportedly lowers circulating triglycerides, and cholesterol, although certain garlic preparations were not effective in the treatment of hypercholesterolemia in children. Alliin, one of its sulfur containing compounds, apparently has an inhibitory effect upon key enzymes involved in cholesterol biosynthesis, such as HMG Co A reductase. A meta analysis of selected clinical trials employing garlic preparations showed significant reduction on total serum cholesterol levels in human subjects.
• As a potential treatment against atherosclerosis, although some research suggests effects are negligible⁵.
• Antiseptic, antifungal and antimicrobial, both internally as well as externally. Some of garlic’s constituents possess broad-spectrum antibiotic effects⁶.
• As prophylactic treatment against the common cold⁷.
• Raw and cooked garlic, as well as other preparations, are sometimes used to treat various vaginal infections , although raw garlic applied as a vaginal suppository can be potentially irritating to mucous membranes.
• Against gastrointestinal parasites of humans and animals, albeit with variable results.
• For the treatment of ulcers caused by Helicobacter pylori , although no conclusive evidence exists of its effectiveness at this time⁸.
• Against venomous stings from insects and other arthropods , as well as an insect repellant.
• As a preventive against stomach, colon and other types of cancers, due to possible immune enhancing and antitumorigenic effects of its sulfur containing compounds⁸.
• By acting on certain forms of Cytochrome P450 and some of its detoxifying activities, allyl sulfides may inhibit the metabolism of certain chemical carcinogens, such as nitrosamines, for example, although some researchers state that garlic’s potential anticancer effects may be due to its content of the trace mineral selenium⁹.
• Garlic has also been shown to have antioxidant properties, which could have a protective nature against gastrointestinal neoplasias.
• Ajoene, a constituent of garlic, may have an application in the treatment of acute myeloid leukaemia (AML). This compound was shown to inhibit proliferation and induce apoptosis of several human leukaemia CD34-negative cells including HL-60, U937, HEL and OCIM-1.
• To treat hypertension and reduce the risk of other cardiovascular disease¹⁰.
• Garlic possesses a mild diuretic action¹¹.
• Against blood clots (antiplatelet action) due in part to the compounds alliin and ajoene, which have fibrinolytic activity. Ajoene inhibits thromboxane synthesis through the inhibition of the cyclo-oxygenase and lipoxygenase enzymes¹².
• For the treatment of hepatopulmonary syndrome ¹³.
• Against heavy metal poisoning¹⁴.
• Due to its hypoglycemic and antioxidant properties, garlic may be useful as coadjuvant therapy in the treatment of type 2 diabetes and some of its physiological complications, although more clinical studies in humans are needed in order to fully assess its efficacy. Allicin, garlic’s active ingredient, competes with insulin for hepatic insulin-activating sites¹⁵.
• Aged garlic extract possesses antioxidant properties, which could be useful in the treatment of sickle-cell anemia¹⁶.
• Garlic compounds may also have neuroprotectant effects , as well as a protective effect against the effects of certain anti tumor drugs ¹⁷.
• Research in Thailand showed that treatment with an enteric garlic-coated Thai garlic extract additional to dietary advice did not produce any significant changes in lipid levels in subjects with hypercholesterolemia¹⁸.
• Researchers in Russia have found that dietary supplement containing garlic may be effective in the management of chronic atrophic gastritis, a precursor of stomach cancer; as well as to relieve the symptoms of benign breast disease. It is important to note that various garlic products may differ widely in their biochemical composition, and hence, may possess different pharmacological properties, depending upon the method of processing or preparation. This accounts for the accompanying differences in efficacy¹⁹.

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Safety/Precautions
• Garlic in small amounts applied as a food condiment does not usually pose any important risk, aside for rare specific allergic reactions in hypersensitive people²⁰.
• Do not ingest in large amounts for at least 2 weeks before surgery. Garlic’s antiplatelet factors may interfere with normal blood clotting and may increase bleeding time. Avoid ingesting garlic in therapeutic amounts during post surgical care, to allow for proper tissue cicatrisation²¹.
• Do not use in large amounts in persons with bleeding disorders, such as hemophilic Patients²².
• Do not use medicinally in patients with bleeding ulcers or gastritis, due to potential gastric irritation²³.
• Do not apply raw garlic cloves or garlic preparations (such as poultices, for example) directly to the skin for any extended period of time, as this may cause a severe burn, Contact dermatitis can occur in hypersensitive people²⁴.
• Do not use in large amounts in patients with thyroid dysfunction, as garlic’s active constituents may theoretically interfere with iodine metabolism.
• Do not use ingest in large amounts during pregnancy, as this may theoretically induce labor, although no clinical evidence in humans seems to support this²⁴.
• It has been stated that lactating women should not consume garlic in large quantity, as the sulfur containing compounds may pass from the milk to the baby and cause gastrointestinal upset, such as colic and diarrhea, although some studies suggest that garlic ingested by the lactating mother will actually increase feeding time and interest in nursing, presumably by the odor present in milk, by the baby. This and other studies did not report any adverse effects on the children.
• The amounts of garlic constituents transmitted through breast milk to an infant are deemed to be very small. In any case, it is advisable to consult with your pediatrician if a large amount of garlic (more than 4 grams per day) is to be consumed during lactation.

Potential Herb/Drug Interactions
• Do not ingest medicinal amounts of garlic concurrently with other herbs that may interfere with blood clotting, such as ginger, ginkgo or feverfew²⁵.
• Do not ingest garlic in large amounts along with drugs that have anticoagulant activity, such as warfarin, heparin, aspirin or protacyclin. Interestingly, a study involving the intake of garlic and warfarin, found no INR differences between the groups of subjects who took garlic and warfarin together, suggesting no significant interaction^26.
• Avoid using large amounts of garlic while taking acetaminophen (paracetamol) or other drugs metabolized by the enzyme CYP 450 system, as their metabolism may be reduced.
• A study assessed the influence of a garlic extract on the activity of cytochrome P450 (CYP) 2D6 and 3A4 in healthy volunteers. The results indicated that garlic extracts are unlikely to alter the disposition of coadministered medications primarily dependent on the CYP2D6 (dextromethorphan) or CYP3A4 (alprazolam) pathway of metabolism²⁷.
• Do not take medicinal amounts of garlic concomitantly with oral antidiabetic medications or insulin, as blood glucose levels could theoretically be further decreased ²⁸.
• Use medicinal amounts of garlic (more than 4 grams per day) with caution if patient is under treatment with drugs that may affect the thyroid gland.
• Garlic supplements may affect the pharmacokinetics and delay absorption of the protease inhibitor Saquinavir (Fortovase) and perhaps other anti HIV medications . Avoid using together²⁹.
• Acute dosing of 400 mg. garlic capsules over a period of 4 days did not significantly alter the single-dose pharmacokinetics of the antiviral drug ritonavir in healthy volunteer, although the researchers mention that longer duration studies are needed to evaluate the possibility of an interaction³⁰.

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