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ent ‐Kaurene Diterpenoids from Blepharispermum hirtum
Author(s) -
Fatope Majekodunmi O.,
Varma Gouri B.,
Alzri Nasser M.,
Marwah Ruchi G.,
Nair Rani S.
Publication year - 2010
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200900389
Subject(s) - artemia salina , brine shrimp , chemistry , absolute configuration , antimicrobial , stereochemistry , bacillus subtilis , asteraceae , fractionation , antibacterial activity , spectral analysis , botany , traditional medicine , biology , organic chemistry , bacteria , medicine , physics , toxicity , quantum mechanics , genetics , spectroscopy
The twigs and leaves of Blepharispermum hirtum Oliver (Asteraceae) were investigated for their larvicidal and antimicrobial activity. Fractionation of the extracts of the twigs, directed by brine shrimp test and antibacterial activities, led to the isolation of compounds 1 – 4 ; two of which are new ent ‐kaurene diterpenoids, blepharispins A and B ( 1 and 2 , resp.). The structures of compounds 1 and 2 were established from spectral data. The absolute configuration at C(15) in 1 was inferred from Mosher ester analysis and relative configurations were suggested by a NOESY experiment. Compound 4 was significantly larvicidal to newly hatched naupleii of Artemia salina L. (BST LC 50 =1.3 (3.7–0.0) μg/ml), but the blepharispins were not (BST LC 50 >500 μg/ml). Nevertheless, compound 1 inhibited the growth of Staphylococcus aureus and Bacillus subtilis at a MIC value of 62.5 μg/ml. The significance of the bioactivity results and the presence of ent ‐kaurene diterpenoids in B. hirtum are discussed from biosynthetic and local utilization viewpoints.