Phytochemical and biological studies on Saudi Commiphora opobalsamum L

The aerial part of Commiphora opobalsamum L. (Burseraceae) growing in Saudi Arabia was subjected to a phytopharmacological investigation in order to identify its major chemical constituents and to evaluate its extracts and isolated compounds in preliminary in vitro assays for antimicrobial, antimalarial, antitumor, anti-inflammatory (COX-2 inhibition), antioxidant and estrogenic activity. Six compounds were isolated and identified as the triterpenes friedelin, canophyllal, and oleanonic acid; the flavonols mearnsetin and quercetin; and syringic acid. The ethyl acetate extract was moderately active against Staphylococcus aureus, Pseudomonas aeruginosa, and Plasmodium falciparum; while the petroleum ether and chloroform extracts inhibited COX-2 at 5 and 10 microg mL(-1), respectively. Of the isolated compounds, syringic acid showed moderate antimalarial, anticandidal, and antimycobacterial activity; while mearnsetin and quercetin exhibited antioxidant activity comparable to ascorbic acid and trolox. This is the first detailed phytochemical investigation of C. opobalsamum L. growing in Saudi Arabia and elsewhere. The isolated compounds are reported from this plant for the first time and their full (1)H and (13)C NMR assignments are included.