History
Cloves appear to be have been cultivated in China as early as BC 266. At that time, it was customary for the officers of the court to hold the spice in the mouth before addressing the sovereign in order that the breath might have an agreeable odor. Sanskrit writing regarded it as light and cooling on the stomach when used as a digestive. It was also useful in releiving thirst, vomiting, flatulence and colic. A paste of clove was applied on the forehead for relief from colds. A clove roasted in the flame of a lamp and held in the mouth was used as a

popular remedy for sore throat. It was also recommended for strengthening the gums and freshening the breath. It was knowm for its pectoral, cardiac, tonic and digestive qualities. In India, clove fruits were considered male cloves and buds were female cloves. It was believed that one male clove eaten daily will prevent constipation. It was believed that the saliva after cloves have been chewed, if applied to the orifice of the male urethra before connection, increases the sexual orgasm in both parties.

Habitat
It is cultivated in Tanzania, Indonesia, Penang and to a lesser extent in the Seychelles, Reunion, Mauritius and Sri Lanka. In India, it is grown and cultivated in Tamilnadu and Kerala. It thrives in all situations ranging from the sea level up to an altitude of 900 m. But is unable to withstand long summers.

Morphology Description (Habit)
A large shrub or medium sized tree with pyramidal or conical crown 9-12 m. high and sometimes taller. The main stem is erect and often forking at a height of 1.5-1.8 m. The bark is smooth and grey. Leaves lanceolate, in pairs, acute at both ends, 7.5-12.3X 2.5-3.75 cm. in size, gland-dotted and fragrant. Flower buds borne in small clusters at the ends of branches, greenish, turning pink at the time of maturity and aromatic. Drupes (MOTHER-OF-CLOVE), fleshy, dark pink, 2.5 cm. long x 1.5 cm. thick. Seeds oblong, soft, grooved on one side and 1.5 cm. Iong.

Principal Constituents
The cloves contain 13 per cent tannin (gallotannic acid). Oleanolic acid has been isolated from spent cloves (residue from the distillation of essential oil. Steam distillation of clove buds yields a colourless (14.23%) or pale-yellow oil, with the characteristic odour and taste of cloves. The oil darkens with age or on exposure and becomes reddish brown. The product obtained from whole buds contains a higher percentage (97%) of eugenol than that in oil distilled from crushed cloves (eugenol-94%). Water distillation yields oil of better quality and lower specific gravity (eugenol 85-89 %) than that obtained by dry steam-distillation (eugenol, 91-95%). The two oils are distinguished as 'opt' and 'strong' oils; commercial oil is a mixture of both. The clove bud oil contains free eugenol, eugenol acetate (2-17%) and caryophyllene (chiefly a and ß-form) as its main constituents.Among the other constituents present, the most important is methyl-n-amyl ketone, to which the oil owes its fresh and fruity aroma. Other substances present in traces are methyl salicylate, methyl benzoate, methyl alcohol, benzyl alcohol, furfuryl alcohol, furfural, a-methyl furfural, dimethyl furfural, b-pinene, methyl-n-heptyl ketone, methyl-n-amyl carbinol (2-heptanol), methyl-n-heptyl carbinol and vanillin.

The oil, obtained by solvent extraction of cloves, contains little or no caryophyllene, but contains epoxydihydrocaryophyllene¹. The oil contains eugenone, eugenine, eugenitine and iso-eugenitol These substances are practically odourless². The oil also contains sesquiterpenes, a-cubebene, a-copaene, g- and d-cadinene, b -caryophyllene, b-caryophyllene oxide, a-humulene, a-humulene epoxide besides eugenol. The leaves yield an essential oil (3%) on steam distillation. It contains a-cubebene, a-copaene, b-caryophyllene, a-humulene, eugenol, isoeugenol acetate, eugenol acetate and farnesol. A neutral sesqueterpene fraction of an Indonesian sample contained a-cubenene, a-ylangene, a-copaene, b-bourbonene, b-caryophyllene, a-humulene, allo-aromadendrene, a-muurolene, zinziberine, d-cadinene, calamenene, a-calacorene, caryophyllene oxide, ledol, palustrol, d-cadinol, cubenol, calamenenol, cadalene, a-cadinol and humuladienone. Presence of ethyl acetate, ethanol, limonene, a& b-pinenes, p-cymene, 1,8-cineole, 4-methyl-3-pentenyl-3-furan, linalool, carvone, linalyl acetate, etc. are also reported in the clove leaf oil. The leaves also contain 3,4-dihydroxy phenethyl alcohol and 3,4-dihydroxy benzoic acid having anti-inflammatory action³.

Pharmacology
The compounds of clove show significant activity as inducers of detoxifying enzyme-glutathione S-transferase in mouse liver and intestines. This ability is correlated with their activity in inhibiting the chemical carcinogenesis, and as anticancer agents. The methanolic extract of clove exhibits anti-tumour activity. The methanolic extract showed remarkable induction of differentiation of myeloid leukaemia (MI) cells into macrophage like cells. Oleanolic acid and crategolic acid are the active principles of the extract⁴.

Toxicology
There is no adverse is reported on use of this herb as drug.

Clinical Stuides
Clove forms an ingredient of pharmaceutical powder used in treatment of gastronomic disorders caused due to alcohol consumption. A mixture of 120mg -cysteine, 300mg NaHCO3, 0.2ml Coptis rhizome tincture and 0.1ml clove tincture when administered orally before drinking is effective in treating hangover. Clove is also an ingredient in anti-inflammatory and analgesic preparation containing cinnamaldehyde and skin irritants. The preparation accelerates blood circulation and does not cause pain at the application site⁵.

Indications
The oil is used in sustained release topical analgesic preparations and used in dentifrices for removal of stain in teeth, in root canal filling material, as salivary stimulator in sublingual pharmaceutical compositions. Also in buccal deodarant tapes and in dental bandages for protection to gingival tissue. The oil is used in topical formulations for use in cryotherapy for treating circulatory diseases such as posttraumatic oedema. The Eugenol and acetyl eugenol components of the oil inhibit arachidonate-adrenaline and collagen induced platelet aggregation. The oil should be used in restricted concentration because of photo-toxic and photo-irritant activity⁶. Clove oil is also an ingredient of hair and body shampoos. It has Insulin potentiating activity. The oil exhibits anti-implantation activity.The cloves are highly esteemed as a flavouring material and are extensively used, whole or in ground form, as a culinary spice. They impart a warming quality to food, and are used for flavouring ham, roasts, pickles, preserves, ketchups and sauces, as seasoning for sausages, dressing for poultry and meat, and in specialized spices for mincemeat and pastry. Because of their pungent and aromatic taste, cloves are favoured for making cakes, pies, puddings, cookies and candy. They are used in making spiced wines and for scenting the chewing-tobacco; they form an ingredient of betel-chew. In Indonesia, cloves are used in making a special brand of cigarettes- Keretek, which crackle while burning.

References

1. Guenther, IV, 412-13, 422, 427-28, 430-35; B.P.C., 1968, 189; Goldstein, J. sci. industr. Res., 1953, 12B, 281.

2. Krishna & Badhwar, loc. cit2. Krishna & Badhwar, loc. cit.; Guenther, IV, 4273.

3. Chem Abstr, 1990, 113, 29242; Gopalakrishnan et. al., Indian Perfum, 1988, 32, 229; Lawrence, Perfumer & Flavorist, 1991, 16(4), 494.

4. Umehara, Chem Pharm Bull, 1992, 40, 401; Chem Abstr, 1993, 119, 70934; Mahmoud et. al., Int J Pharmacogn, 1992, 30, 815.

5. Chem Abstr, 1991, 114, 254021; 1992, 116, 281766.

6. Chem Abstr, 1992, 116, 154083; 1993, 119, 234079, 85713; 1991, 114, 115063; 1990, 113, 120609; Vilaplana et. al., Contact Dermatitis, 1991, 24, 225.