title: Isolation and characterization of chemical constituents of Stoechospermum marginatum (Dictyotales, Phaeophyta) and their antimicrobial activity.
abstract: From chloroform and methanolic extracts of Stoechospermum marginatum (C. Ag.) Kutz. Five saturated and four unsaturated fatty acids, three sterols, four diterpenes and D-mannitol were isolated. The fatty acids, analysed as methyl esters, were myristate, pentadecylate, palmitate, margarate and nonadecylate among saturated and tetradecatrienoate, pentadecenoate, hiragonate and oleate among unsaturated ones. The sterols were identified as cholesterol [1], 24-methylene cholesterol [2] and 24-methyl cholesterol [3]. The diterpenoids were determined as 19-acetoxy-5 (R), 15, 18 (R and S)-trihydroxyapata-13, 16 (E)-diene [4], 5 (R), 15, 18 (R and S), l9-tetrahydraxyspata-13, 16 (E)-diene [5], 5 (R), 18-dihydroayspata-13, 16 (E)-diene [6] and 5 (R), 16-dihydroxyspata-13, 17-diene [7]. All these diterpenes showed strong antibacterial activity against three gram +ve and six gram -ve bacteria. The crude extract was found active against three fungi in 10 mg/ml concentration, whereas the diterpene [5] exhibited activity against only one fungus.
authors.affiliation: Department of Botany, University of Karachi, Karachi-75270, Pakistan.
authors.forename: W
authors.initials: W
authors.lastname: Shaikh
authors.forename: M
authors.initials: M
authors.lastname: Shameel
authors.forename: A
authors.initials: A
authors.lastname: Hayee-Memon
authors.forename: K
authors.initials: K
authors.lastname: Usmanghani
authors.forename: S
authors.initials: S
authors.lastname: Bano
authors.forename: V U
authors.initials: VU
authors.lastname: Ahmad