Asian J. Research Chem. 2(1): Jan.-March, 2009 , ISSN 0974-4169 www.ajrconline.org REVIEW ARTICLE A Review –Garlic, the Spice of Life-(Part –I) Kishu Tripathi Surya College of Pharmacy, Lucknow ABSTRACT Garlic [Allium sativum] is among the oldest of all cultivated plants. It has been used as a medicinal agent for thousands of years. It is a remarkable plant, which has multiple beneficial effects such as antimicrobial, antithrombotic, hypolipidemic, antiarthritic, hypoglycemic and antitumor activity etc KEY WORDS Garlic,Allium INTRODUCTION: Garlic has played an important dietary and medicinal role Preparations of garlic are available as tablets, capsules, throughout the history of mankind. Garlic is a nature’s boon to syrup, tinctures and oil. In ointment form, garlic has been mankind. For over 5000 years garlic has been consumed both used externally for treatment of ring worm; boiled with as food and used for medicine by ancient scholars. Garlic, vinegar and sugar for treatment of asthma; made into an Allium sativum L. is a member of the Alliaceae family, has infusion for treatment of epilepsy; pounded with honey for been widely recognized as a valuable spice and a popular use against rheumatism; and mixed with milk for use as a remedy for various ailments and physiological disorders. The vermifuge. Garlic is commonly used in Europe and Asia for name garlic may have originated from the Celtic word 'all' medicinal benefits in healing wounds, etc.In Germany, sale meaning pungent. As one of the earliest cultivated plants, of garlic preparations competes with sales of leading garlic is mentioned in the Bible and in the literature of Ancient drugs.Garlic produces a variety of volatile sulfur-based Israel (The Talmud), Egypt (Codex Ebers) and India (Vedas compounds which are effective as insect repellents and and Purans, Charak Sanghita).Chinese strongly believe that insecticides. Diallyl disulfide is one of such compounds garlic prolongs longevity and is useful in treating most human which has a strong odor and acts as a powerful diseases, including infections, cancer and heart diseases. In insecticide.Commercial preparations of garlic are certified historical writings of India and in literature like Vedas and as insecticide against mites, nematodes and mosquito larvae Purans, garlic is reported to have medicinal as well as nutritive affecting a variety of crops. value in food items. Clinical indications of garlic include It has been used as a medicinal agent for thousands of years. hemorrhoids, rheumatism, dermatitis, abdominal pain, It is a remarkable plant, which has multiple beneficial cough,loss of appetite and loss of weight. effects such as antimicrobial, antithrombotic, hypolipidemic, antiarthritic, hypoglycemic and antitumor The medicinal qualities of garlic were described by Pliny the activity. Allicin has antibacterial and antioxidant activity. It Elder, Aristophanes, and Galen. may possibly increase blood levels of catylase and glutathione peroxidase activity. Ajoene decreases the Hippocrates, the Father of Medicine, observed that garlic was activity of factors needed for lipid synthesis by reducing the excellent for curing tumors and is an effective diuretic. thiol group in coenzyme A and HMG CoA reductase and Aristotle attributed garlic as a cure for rabies, and the Prophet also by oxidizing NADPH. Ajoene has antiplatelet activity Mohammad recommended it for treating scorpion stings. In and interferes with thromboxane synthesis and decreases Historia Naturalis by Pliny, garlic was recommended for platelet aggregation1. gastro-intestinal disorders as well as dog and snake bites. Desired medicinal results of garlic are obtained when bulbs So where do we stand today on this issue of garlic? Is garlic are chewed and swallowed or mixed with food and eaten. always good for health? How safe is it? Is it necessary to isolate the antioxidant compounds for its medicinal use in a more effective way? Received on 19.01.2009 Modified on 30.01.2009 Accepted on 14.03.2009 © AJRC All right reserved Asian J. Research Chem. 2(1): Jan.-March, 2009;Page 08-13 8 Asian J. Research Chem. 2(1): Jan.-March, 2009 , CHEMISTRY water are diallyltrisulfide, diallyl disulfide and allyl methyl Intact garlic cloves contain only a few medicinally active. The trisulfide. Incubation of allicin or allyl methane thiosulfinate main chemical constituent of intact garlic is the amino acid in low polarity solvents (or without solvent) primarily alliin, an alkyl derivative of cysteine alkyl sulfoxide, which produces 1, 3-vinyldithiin (2-vinyl-4H-, 3-dithiin) (51% of may varies from 0.2 to 2.0% fresh weight. The efficacy of total), 1,2-vinyldithiin (3-vinyl-4H-1,2-dithiin) (19% of chemical constituents of garlic chiefly depends on the mode of total) and lesser amounts of ajoene (E,Z-4,5,9-trithiododeca- preparation of its extract. Crushing, chewing or cutting (or 1,6,11-trien 9-oxide) (12% of total) and sulfides (18% of exposing dehydrated, pulverized garlic to water) of garlic total).Incubation of pure allicin in methanol yields 8% cloves release the vacular enzyme allinase that rapidly lyses diallyl trisulfide and about equal amounts (20-25% of total) the cytosolic cysteine sulfoxide to form sulfenic acid (R- of ajoene and the vinyldithiins. Steam distillation of garlic SOH). Which immediately condenses to form allicin: the bulbs yields a garlic oil that consists of diallyl (57% of oil), compound which produces the odor of freshcut garlic? Garlic allyl methyl (37% of oil), and dimethyl (mono to hexa contains at least 100 sulfur-containing compounds basic to sulfides; 6% of oil of total). The essential oil content of medicinal uses. Allicin represents 70-80 % of the total fresh garlic bulbs is between 0.09 to 0.352. thiosulfinates formed (Fig. 1). Other thiosulfinates formed include allyl-ss(o)-methyl (6-16% of total), methyl-ss(o)-allyl BIOLOGICAL EFFECTS (3-9% of total), trans-1-propenyl (0.2-0.4% of total), trans-1- The biological activity of an extract of garlic depends on the propenyl-ss (o)-methyl+methyl-ss(o)-trans-1-propenyl (0.1- mode of its preparation. The extract prepared at room 2.5% of total) and methyl-ss(o)methyl (2% of total) temperature contains mainly allicin, which has a powerful thiosulfinates. The formation of allicin (allyl 2-propene antibacterial property and a strong smell. Besides allicin, thiosulfinate or diallyl thiosulfinate) is complete in 0.2 to 0.5 small amounts of several other thiosulfinates and complex min at room temperature. Formation of the methyl sulphinyl components, including the antithrombotic ajoenes, thiosulfinate takes 1.5 to 5.0 min. All possible combinations of are also present. The enzyme allinase responsible for 2-propene, 1-propene and methane sulfenic acids result in converting alliin to allicin is inactivated by heat. The water thiosulfinates extract of heat-treated garlic mainly contains alliin, which is odour-free. Garlic powder is a simply dehydrated, pulverized garlic clove. The allinase activity of garlic powder is identical to that of fresh garlic. It may be emphasized here that dehydration temperature should not exceed 60 ºC, above which allinase is inactivated. When distilled in steam, garlic yields an oily mass consisting of diallyl, methyl allyl, dimethyl, all originating from the thiosulfinates.Garlic oil has been shown to possess biological properties such as antitumor and antioxidant effects.Another widely studied garlic preparation is aged garlic extract (AGE). When garlic is subjected to cold aging process, organosulphur compounds, such as s-allyl cysteine, s-allyl mercaptocysteine, and several sulphur-containing amino acids, are produced. S-allyl cysteine and s-allyl mercaptocysteine have been shown to be anticarcinogenic and provides protection against liver damage. Garlic is one of the most investigated medicinal plants. During 1960 to 2007, more than three thousand research papers have been published on the chemistry and biological effects of garlic and garlic preparations. These studies mainly focus on the cardiovascular, anti-microbial and anti- cancer effects of garlic and, to a lesser extent, on the therapeutic indications for the treatment of hypoglycemia, The thiosulfinates released from crushed garlic are reactive heavy metal poisoning and liver dysfunction and molecules and undergo a number of transformations, hyperthyroidism. depending on the temperature, pH and solvent conditions. Allyl-s- thiosulfinates (allicin) are the least stable of the eight Sickle cell anemia thiosulfinates. The half-life of allicin (concentration of 0.1- Sickle cell anaemia is a life threatening hereditary disease, 0.4mg/ml) at room temperature is 10 days in 1mM citric acid in which oxidative stress plays a prominent role. AGE with (pH 3), 4 days in water, 48 h in methanol or chloroform, 24 h its high antioxidant activity, has therapeutic effects on the in ethanol, 24 h in hexane and 3 h in ether. The principal disease. In a 4 week study 5 patients with sickle cell transformation products after incubation of thiosulfinate in anaemia ingested AGE at 5 ml a day. The results showed 9 Asian J. Research Chem. 2(1): Jan.-March, 2009 , antioxidant protection of the red blood cells and a significant activity after acute and chronic garlic powder intake. reduction in the sickle cell markers3,4. Chutani and Bordia (1981) designed one study to show that both raw and fried garlic significantly enhance FA. Frying Potential effect of aged garlic extract (AGE) as an anti-oxidant removes the strong acrid smell of garlic, but preserves it in sickle RBC. Previously, AGE has been shown to useful effects on FA. The rise in FA has been observed significantly improve erythrocyte deformability through within 6 hours of garlic administration, which showed that stabilization of erythrocyte membranes in non-sickle RBC. garlic has a rapid onset of action and the effect is well These phenomenons were attributed to the anti-oxidant maintained as long as garlic is being taken.