CLOVE STEM OIL

Chemical Properties

Clove stem oil is obtained by steam distillation of the stem upon which the clove buds grow. Prior to distillation, the stems are sun-dried, but not pulverized. See Clove and Clove Leaf Oil above. The oil has a strong spicy, somewhat woody, but quite pleasant odor. The odor is not very different from that of eugenol (which is sweeter and less woody). Typical yield of oil from clove stems is 5%. Approximately 100 tons of clove stem oil is produced each year by Tanzania, Madagascar and Indonesia. Also see Clove.

Chemical Properties

Clove stem oil is obtained in about 5% yield by steam distillation of the dried flower stems. It is a yellow to light brown oil with a sweet–spicy, slightly woody odor similar to that of bud oil but without the fresh, fruity top note. d²⁰₂₀ 1.041–1.059; n²⁰_D 1.5310–1.5360; α²⁰_D ?1 ° to +1 °; phenol content: 85–95% (v/v); content by GC: eugenol 83–92%, caryophyllene 4–12%, eugenol acetate 0.5–4%.

Physical properties

When fairly fresh and well stored it is a pale-yellow to straw-yellow liquid. It is soluble in fixed oils and in propylene glycol, but it is relatively insoluble in glycerin and in mineral oil.

Occurrence

Found in the stems of the tree Eugenia caryophyllata Thunb. (Fam. Myrtaceae) (Fenarolfs Handbook of Flavor Ingredients, 1971).

Preparation

By steam distillation of the dried stems of E. caryophyllata Thunb. after removal of the buds.

Essential oil composition

Similar to the leaf oil, clove stem oil has a high composition of eugenol, making it a preferred source for eugenol and subsequent conversion to isoeugenol, derivatives of eugenol and vanillin. Caryophyllene, furfural and methyl alcohol are also present. Trace quantities of naphthalene and a bicyclic sesquiterpene alcohol may be present in the stem oil. Little or no eugenyl acetate is present.

Toxicity evaluation

The acute oral LD₅₀ value for rats was reported as 202 g/kg with confidence limits of 1.71-2.33 g/kg (Moreno, 1974). The acute oral LD₅₀ of clove oil was found to be 372 mg/100-g rat (von Skramlik, 1959). Clove oil was toxic to mice when applied to the skin in two doses 7 days apart (Roe & Field, 1965). The acute dermal LD₅₀ value in rabbits was reported as > 5 g/kg (Moreno, 1974).

Pharmacology

In a pharmacological study using rat, guinea-pig and rabbit organs, clove oil was found to have antihistaminic and musculotropic spasmolytic activity (Debelmas & Rochat, 1967). Clove oil showed musculotropic (papaverine-like) antispasmodic activity against the isolated small intestine of the mouse (Imaseki and Kitabatake, 1962).