Two Labdane Diterpenoids and a seco‐Tetranortriterpenoid from Turreanthus africanus.

Abstract

Terpenes U 0200Two Labdane Diterpenoids and a seco-Tetranortriterpenoid from Turreanthus africanus. -(TANE*, P.; AKAM, M. T.; TSOPMO, A.; NDI, C. P.; STERNER, O.; Phytochemistry 65 (2004) 23, 3083-3087; Dep. Chem., Univ. Dschang, Dschang, Cameroon; Eng.) -Klein 18-169

A New Bis-Labdanic Diterpene from the Rhizomes of Alpinia pahangensis

“…The geometry between C-12 and C-13 was further verified to have an E-configuration as indicated by the absence of a ROESY correlation between H-12 and H-14 [10]. Biogenetically, for known labdane diterpenes bearing the same skeleton, the orientation of Me-18, being equatorial while that of Me-19 is axial, in the partial structure 1a, was confirmed based on comparison of the chemical shifts of C-18 and C-19 with literature values which indicate that the equatorial methyl group is usually located further downfield compared to the axial methyl group at C-4 [11,12]. The ROESY correlation between H-5 and H-18 and the absence of it with H-20 suggested the axial orientation of H-5, substantiating that the AB ring junction between the two cyclohexane rings in the decalin moiety of partial structure 1a was trans (l " Table 1, Fig.…”

A Pregnane Derivative and an Anti-plasmodial Labdane Diterpenoid from the Stem Bark of Turraenthus Africanus

“…In Cameroon, the stem bark is used in the treatment of intestinal worms and malaria, and also by the Bakweris to stupefy fish. We recently reported the isolation and characterization of two labdane diterpenoids and a seco-tetranortriterpenoid from the seeds of T. africanus [5]. In continuation of our investigation of this species for new antiplasmodial agents, a pregnane derivative, and three known diterpenoids were isolated from the stem bark.…”

“…Dried and powdered stem bark of T. africanus was extracted with CH 2 Cl 2 -MeOH (1:1). Evaporation in vacuo yielded a crude extract, a portion of which was subjected to silica gel chromatography and gel permeation chromatography over Sephadex LH-20 to afford a new steroid (1) and three known diterpenoids, methyl 14,15-epoxylabda-8(17),12Edien-16-oate (2) [6], 16-oxolabda-8(17),12E-dien-15oic acid [7], and 16-acetoxy-12R,15-epoxylabda-8(17),13(16)-dien-15β-ol [5].…”

Antioxidant and vasorelaxant activities of theTurraeanthus africanusmethanol extract

“…T. africanus is a medium-sized tree of the rainforest where it forms fairly dense but localized and discontinuous timber stands. Species of the Meliaceae family are well known for the production of terpenoid and limonoid compounds (Kimbu et al, 1984;Ayafor et al, 1994;Tane et al, 2004). Recently, studies carried out by Vardamides et al (2006) on T. africanus led to the isolation of two new alkaloids, 10-O-demethyl-17-O-methyl isoarnottianamide and 11-demethoxyl-12-methoxyl oxynitidine, together with known compounds such as sesamin, decarine, and oxynitidine.…”