New lignans from Cedrela odorata L. stem bark

Introduction Cedrela odorata L., a plant member of the Meliaceae family, is a timber tree native to tropical regions of America, also introduced as a cultivated species in Africa and many tropical countries of Asia and Oceania. The infusion of C. odorata stem bark is used in South American folk medicine for the treatment of fever, hemorrhage, inflammation, and digestive diseases, including diarrhea, vomiting, and indigestion. The decoction of the bark is also used in Africa as a remedy for malaria and fever1. Meliaceae plants, particularly species of Cedrela genus, are distinguished by the occurrence of limonoids, alkaloids, and polyphenols such as lignans and proantocianydins2,3. Limonoids has been suggested to be the main responsible of C. odorata pest resistence, however, other biological studies have shown that polyphenols contained in several parts of the plant can have detrimental effects on insects4. This consideration prompted us to investigate C. odorata stem bark polar extracts. Method The dried and powdered C. odorata stem bark (300 g), collected in Merida, Venezuela, was sequentially extracted with n-hexane, CHCl3, CHCl3-MeOH (9:1), and MeOH. The CHCl3-MeOH extract was subjected to silica gel chromatography, using CHCl3 and increasing concentrations of MeOH in CHCl3 (0-100%) as eluents, while the MeOH extract was separated on Sephadex LH-20 column eluting with MeOH as eluent. Subsequently, the fractions obtained from both silica gel and Sephadex LH-20 column chromatographies were submitted to RP-HPLC. Results / Discussion / Conclusion The phytochemical study of C. odorata stem bark polar extracts led to the isolation of eight compounds including two new lignans (1–2) (Fig. 1), which structures are shown in Fig.1, and six known substances that were characterized as 4,5-dihydroblumenol A (3), 7-megastigmene-3α,6,9-triol (4), catechin (5), scopoletin (6), homovanillic alcohol (7), and 2-(3,4-dimethoxyphenyl)ethyl-O-β-D-glucopyranoside (8). The structural determination of the isolated secondary metabolites was performed by 1D- and 2D-NMR spectroscopic techniques, and by mass spectrometry analyses. All compounds obtained from this species are in accordance with the ones found in other Meliaceae plants. Bibliographic References 1. Kipassa NT, Iwagawa T, Okamura H, Doe M, Morimoto Y, Nakatani M (2008). Phytochemistry 69: 1782-1787. 2. Pérez-Flores J, Eigenbrode SD, Hilje-Quiroz L (2012). Am J Plant Sci 3: 988-994. 3. Chatterjee AT, Chakraborthy T, Chandrasekharan S (1971). Phytochemistry 10: 2533-2535. 4. Newton AC, Watt AD, López F, Cornelius JF, Mesén JF, Corea EA (1999). Agr Forest Entomol 1: 11-18.