Brine shrimp toxicity of acidic fractions of Boswellia dalzielii gum resin

Boswellia dalzielii is the West African species of the frankincense producing genus ( B. carterii, B. frereana and B. serrata are the more popular congeners). Its ethnobotanical uses include the treatment of rheumatism, venereal diseases and gastro-intestinal disorders, swellings/ growths on the skin, among other things. The anti-inflammatory, anti-hyperlipidemic and immunomodulatory activities of B. serrata gum resin have been established as being due to triterpenoic (boswellic) acid derivatives such as b-boswellic acid, 3–O-acetyl–b–boswellic acid, 11–keto-b-boswellic acid and 3–O-acetyl–11-keto-b-boswellic acid. It was therefore considered pertinent to study the cytotoxic activity of the acidic fraction of B. dalzielii gum resin. The gum resin of B. dalzielii was extracted with diethyl ether and partitioned into acidic and neutral/basic fractions. These fractions had earlier been shown to have significant anti-inflammatory activity. The acidic fraction was fractionated into four sub-fractions (A-D) using Accelerated Gradient Chromatography (AGC). The fractions and sub-fractions, when tested for brine shrimp lethality, showed very high activity (LC5050µg/mL). Also the acidic fraction had a significantly higher activity over the neutral fraction. Being the most active, sub-fraction D (LC50 = 0.0013µg/mL) was subjected to AGC on silica. This afforded two pure compounds which, from preliminary chemical tests, were shown to be triterpenoids. Journal of Pharmacy & Bioresources Vol. 2(2) 2005: 137-14