chemical composition and general toxicity of essential oil extracted from the stalks and flowers of rheum ribes l. growing in iran

the composition of the essential oil from the stalks and flowers of rheum ribes l., growing in iran, were extracted by hydrodistillation and analyzed by gc-ms. thirty constituents representing 93.84% of rheum oil were identified.  the oil was found to be rich in hydrocarbons especially long-chain n-alkanes (80.81%). the most abundant components in the oil included tricosane (26.29%), heneicosane (26.07%), pentacosane (10.63%), heptacosane (10.37%) and palmitic acid (3.64%). the essential oil was also evaluated for general toxicity bioassay using brine shrimp lethality method. the toxicity profile of the oil indicated some degree of toxicity in comparison with podophyllotoxin.