Introduction Turraeanthus mannii (Baill.) (Meliaceae) is a small tree, 3±5 m high [1]. In Cameroon, the wood bark and the leaves are used as fish poison, while the stem bark is used as an anthelmintic drug [2]. Previous chemical studies on the genus Turraeanthus have led to the isolation of triterpenoids, diterpenoids, limonoids, and alkaloids [3], [4]. Inthispaper,wereporttheisolationandstructuralelucidationof three new diterpenoids 1±3 from the stem bark of T. mannii. These compounds, together with the known ones and the crude methanol extract were evaluated for antibacterial and antifungal activities. Materials and Methods General Procedures Optical rotations were recorded on a Perkin-Elmer polarimeter 343. CD spectra were recorded on a JASCO J-810 spectropolari- meter. IR spectra were recorded on a Perkin-Elmer 1600 Series FT-IR spectrometer from films. ESI-HR-MS were measured on a Bruker FTICR 4.7 T mass spectrometer. EI-MS were taken on a Finnigan MAT 95 spectrometer (70 eV) with perfluorokerosene as reference substance. NMR spectra were measured on Varian Unity 300 (300.145 MHz) and Varian Inova 500 (499.876 MHz) spectrometers. Flash chromatography was carried out on silica gel (Macherey Nagel & Co; Düren, Germany; 230±400 mesh). Plant material The stem Bark of Turraeanthus mannii (Baill.) was collected in Bakinguili, Cameroon in August 2005 and authentification was carried out at the National Herbarium Yaounde where a voucher specimen is deposited (18312/SRF/Cam). Diterpenoids from Turraeanthus mannii Juliette Catherine Vardamides 1 Valerie Tedjon Sielinou 2 Brigitte Ndemangou 2 Augustin Ephrem Nkengfack 2 Zacharias Tanee Fomum 2 Herve Martial Poumale Poumale 3 Hartmut Laatsch 3 Affiliation 1 Department of Organic Chemistry, University of Douala, Douala, Cameroon 2 Department of Organic Chemistry, University of Yaounde I, Yaounde, Cameroon 3 Institute for Organic and Biomolecular Chemistry, Georg-August-University Göttingen, Göttingen, Germany Correspondence Juliette Catherine Vardamides ´ Department of Organic Chemistry ´ University of Douala ´ P.O. Box 24157 ´ Douala ´ Cameroon ´ Phone: +237-791-9603 ´ Fax: +237-340-7569 ´ E-mail: jucthmas@yahoo.fr Received November 23, 2006 ´ Revised February 12, 2007 ´ Accepted February 23, 2007 Bibliography Planta Med 2007; 73: 491±495  Georg Thieme Verlag KG Stuttgart ´ New York DOI 10.1055/s-2007-967170´ Published online April 4, 2007 ISSN 0032-0943 Abstract Three new compounds, 15-acetoxy-12-hydroxy-16-methyl-lab- da-8(17),13E-diene (1), ent-labda-8(17),13-dien-15,16-olid-19- oic acid methyl ester (2), and 12-hydroxy-labda-8(17),13-dien- 15,16-olide (3), together with two known compounds, 19-acet- oxy-ent-labda-8(17),13-dien-15,16-olide (4), and 16-acetoxy- 12,15-epoxy-15û-hydroxy-labda-8(17),13(16)-diene (5) were isolated from the stem bark of Turraeanthus mannii (Meliaceae). The structures of compounds 1±3 were elucidated by analysis of the spectroscopic data. The crude methanol extract and com- pound 5 exhibited weak antibacterial and antifungal activity. Key words Turraeanthus mannii ´ Meliaceae ´ antibacterial activity ´ antifun- gal activity ´ diterpenes ´ labdanes Original Paper 491