Flavanones and 3-hydroxyflavanones from Lonchocarpus oaxacensis☆
Introduction
As part of a chemotaxonomical study and survey of biologically active compounds from Lonchocarpus (Leguminosae, Papilionoideae, Millettieae) species growing in Mexico (Gomez-Garibay et al., 1990, Reyes-Chilpa et al., 1995), we have now investigated the flavonoids present in the roots of Lonchocarpus oaxacensis, a small tree endemic to the State of Oaxaca, Mexico. To the best of our knowledge, this plant has not been studied previously from the phytochemical point of view. According to a revised taxonomic classification, L. oaxacensis belongs to subgenus Lonchocarpus, section Lonchocarpus, subsection Minimiflori (M. Sousa-Sánchez, in preparation). This subsection comprises 15 species, only four of which have been chemically studied. At the present time, it is known that the seeds of L. minimiflorus (Mahmoud and Waterman, 1985), and L. orotinus (=L. parviflorus) (Waterman and Mahmoud, 1987) contain prenylated flavanones and 3-hydroxyflavanones. These types of flavonoids have also been obtained from the leaves of L. minimiflorus (Roussis et al., 1987), and the roots of L. guatemalensis (Ingham et al., 1988).
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Results and discussion
The pooled petroleum ether and methylene chloride extracts from the roots of L. oaxacensis afforded, after column chromatography, a new 3-hydroxyflavanone, which was named jayacanol (Fig. 1, 1). Mundulinol (2), and two flavanones, mundulin (3) and minimiflorin (4) were also obtained. The molecular structure of 1 was established by spectroscopic methods, including HMQC, HMBC and NOESY NMR experiments.
Compound Fig. 1, 1 was isolated as a yellow gum. The infrared spectrum displayed absorption
Plant material
L. oaxacensis was collected near Jayacatlán, District of Etla, State of Oaxaca, Mexico. The specimen was identified by one of us (M. Sousa-Sánchez). A voucher specimen (No. 739,650) is deposited in the Mexican National Herbarium (MEXU).
Extraction and isolation
The roots (939.2 g) were dried at room temperature and cut in small pieces. Extraction was carried out at room temperature with petroleum ether, CH2Cl2, ethyl acetate, and methanol. The petroleum ether and CH2Cl2 extracts were similar as judged by TLC and were
Acknowledgements
Research was supported by DGAPA-UNAM, grant IN214996. This paper is based in part on the PhD. thesis (Facultad de Ciencias. UNAM) by Mr. Alavez who acknowledges CONACyT support. We are grateful to Wilber Matus, Hector Rı́os, Rocı́o Patiño, Javier Pérez and Luis Velasco for recording the NMR, IR, CD and EIM spectra.
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Contribution 1723 from Instituto de Quı́mica, UNAM.