4. Benzoin
Synonyms Bitter-almond-oil camphor.
Biological Source Benzoin in the balsamic resin obtained from Styrax benzoin Dryander and Styrax paralleloneurus Perkins, generally known in trade as Sumatra Benzoin; whereas, Styrax tonkinensis (Pierre) Craib ex Hartwich, or other species of the section Anthostyrax of the genus Styrax, known commonly in the trade as Siam Benzoin both belong to the family: Styraceae.
Preparation Benzoin is also a pathological product that is obtained by incising a deep-cut in the bark. It has been observed that after a span of about eight weeks, the exudating balsamic resin tends to become less sticky in nature and firm enough to collect. The entire exudate is usually collected in two stages, namely:
Stage 1: First tapping-yields almond tears, and
Stage 2: Second tapping-yields a more fluid material.
Characteristic Features
Sumatra Benzoin: It is pertinent to mention here that in pharmacy, only the Sumatra Benzoin is used. It occurs as blocks or irregular masses of tears having variable sizes usually imbedded either in an opaque or translucent matrix. It is rather brittle, and from within the tears are milky white in appearance. It generally becomes soft when warmed and gritty when chewed. The matrix is grayish brown to reddish in colour. Its taste is quite agreeable, balsamic and resembles to that of storax. It has a resinous and aromatic taste.
Siam Benzoin: The smaller tears of Siam Benzoin are darker in colour. It occurs largely in separate concavo-convex tears which are yellowish brown to rusty brown externally, whereas milky white internally. The tears are fairly brittle but normally become soft and plastic like on being chewed. It has a vanilla-like fragrance.
Chemical Constituents The chemical constituents of the two types of Benzoin are given below:
(a) Sumatra Benzoin: It contains free balsamic acids, largely cinnamic acid (10%), benzoic acid (6%)-along with their corresponding ester derivatives. Besides, it also contains teriterpene acids, namely: 19-hydroxyloleanolic and 6-hydroxyoleanolic acids, cinnamyl cinnamate, phenyl propyl cinnamate, phenylethylene and lastly the traces of vanillin. It yields not less than 75% of alccohol-soluble extractives.
(b) Siam Benzoin: It chiefly comprises of coniferyl benzoate (60-70%), benzoic acid (10%), triterpene siaresinol (6%) and traces of vanillin. It yields not less than 90% of alcoholsoluble extractives.
Chemical Tests
1. When 0.5 g of Sumatra Benzoin powder is warmed with 10 ml of KMnO4 solution (5% w/v) in a test tube, a faint and distinct odour of benzaldehyde is developed. Siam Benzoin gives a negative test.
2. When 0.2 g of Siam Benzoin powder is digested with 5 ml of ether for 5 minutes and filtered; 1 ml of the filtrate is poured into a clean china-dish containing 2-3 drops of concentrated H2SO4 and mixed carefully, a deep purplish red colouration is developed instantly. Sumatra Benzoin gives a negative test.
Uses
1. Compound benzoin tincture is frequently employed as a topical protectant.
2. It is valuable as an expectorant when vapourized.
3. It finds its usage as a cosmetic lotion usually prepared from a simple tincture.
4. Siam Benzoin has been proved to be a better preservative for lard than the Sumatra Benzoin.
