Novel Antimicrobial Diterpenoids from Turraeanthus africanus

Simplice Joel N. Tatsimo; Pierre Tane; Pullela V. Srinivas; Beibam L. Sondengam; Jacob Melissa; Christopher O. Okunji; Brian M. Schuster; Maurice M. Iwu; Ikhlas A. Khan

doi:10.1055/s-2005-873164

Planta Medica, Table of Contents

Planta Med 2005; 71(12): 1145-1151
DOI: 10.1055/s-2005-873164

Original Paper

Natural Product Chemistry
© Georg Thieme Verlag KG Stuttgart · New York

Novel Antimicrobial Diterpenoids from Turraeanthus africanus

Simplice Joel N. Tatsimo¹ , Pierre Tane² , Pullela V. Srinivas³ , Beibam L. Sondengam¹ , Jacob Melissa³ , Christopher O. Okunji⁴ ^, ⁵ ^, ⁶ , Brian M. Schuster⁶ , Maurice M. Iwu⁴ ^, ⁵ ^, ⁶ , Ikhlas A. Khan³

¹Department of Organic Chemistry, University of Yaounde, Yaounde, Cameroon
²Department of Chemistry, University of Dschang, Dschang, Cameroon
³National Center for Natural Products Research, The University of Mississippi, University, MS, USA
⁴International Centre for Ethnomedicine and Drug Development, Nsukka, Nigeria
⁵Bioresources Development & Conservation Programme, Silver Spring, MD, USA
⁶Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Washington, DC, USA

Abstract

The dichloromethane-methanol (1/1) extract of the stem bark of Turraeanthus africanus (Meliaceae) showed remarkable antimicrobial activity against Cryptococcus neoformans, Staphylococcus aureus and methicillin-resistant S. aureus. Phytochemical investigation of this extract afforded six new diterpenoid derivatives, (+)-16-acetoxy-12,15-epoxylabda-8(17),12,14-triene (3), [16(E),12S,15R]-16-acetoxy-12,15-epoxy-15-isopropoxy-ent-labda-8(17),13(16)-diene (turraeanin A, 4), [16(E),12R,15S]-16-acetoxy-12,15-epoxy-15-isopropoxy-ent-labda-8(17),13(16)-diene (turraeanin B, 5), [16(E),12S,15R]-16-acetoxy-12,15-epoxy-15-methoxy-ent-labda-8(17),13(16)-diene (turraeanin C, 6), [16(E),12R,15S]-16-acetoxy-12,15-epoxy-15-methoxy-ent-labda-8(17),13(16)-diene (turraeanin D, 7) and (12S,13S,15R)-12,15-epoxy-15-methoxy-ent-labd-8(17)-en-16-al (turraeanin E, 9) together with the known compounds, 15,16-epoxy-ent-labda-8(17),13(16),14-triene (1), (+)-pumiloxide (2), ent-labda-8(17),12 (E)-diene-15,16-dial (8) and 16-acetoxy-12(R),15-epoxy-15β-hydroxylabda-8(17),13 (16)-diene (10). Compound 10 was obtained as its acetoxy derivative (10a) and compound 11 was the product of hydrolysis of 6. Antimicrobial activity of the isolates was assayed and compounds 8, 9, 10a and 11 exhibited significant activities.

Key words

Turraeanthus africanus - Meliaceae - antimicrobial activity - diterpenes - labdanes - turraeanin

Full Text

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