New Cytotoxic Bibenzyl and Other Constituents from Bauhinia ungulata L. (Fabaceae).

A new bibenzyl, 2'-hydroxy-3,5-dimethoxy-4-methylbibenzyl (1) and four known compounds identified as 2'-hydroxy-3,5-dimethoxybibenzyl (2), liquiritigenin (3), guibourtinidol (4) and fisetinidol (5) were isolated from the roots of Bauhinia ungulata L. Phytochemical investigations of the stems of B. ungulata led to the isolation of the known compounds identified as liquiritigenin (3), guibourtinidol (4), fisetinidol (5), taraxerol (6), betulinic acid (7), taraxerone (8), glutinol (9), a mixture of sitosterol (10) and stigmasterol (11), pacharin (12), naringenin (13) and eriodictyol (14). The structures of these compounds were elucidated on the basis of their spectral data (IR, MS, 1D- and 2D-NMR). The cytotoxicity of the bibenzyl 1 has been evaluated against four human cancer cell lines, showing the IC50 values of 4.3 and 6.5 µg ml-1 against pro-myelocytic leukemia (HL-60) and cervical adenocarcinoma (HEP-2) cell lines, respectively. This article also registers for the first time the 13 C-NMR data of the known bibenzyl 2.

In vitro acetylcholinesterase activity of peptide derivatives isolated from two species of Leguminosae.

CONTEXT: Cratylia mollis Martius ex Benth. and Cenostigma macrophyllum Tul. (Leguminosae) are both endemic Brazilian plants and they are used by the natives as medicinal plants, and the leaves of C. mollis are also employed as forage for cattle during the dry season of region. OBJECTIVE: Isolation of the compounds responsible for the acetylcholinesterase (AChE) inhibition from the CHCl3 active extract. MATERIALS AND METHODS: Two peptidic compounds were isolated by chromatographic techniques from the CHCl3 extract of the leaves of C. mollis and C. macrophyllum. They were identified by spectrometric data analysis (MS and NMR) and they were subjected to AChE inhibition employing Ellman's test. RESULTS: The peptides were identified as N-benzoylphenylalaninoyl-phenlyalaninolacetate (aurentiamide acetate) (1) and N-benzoylphenylalaninyl-N-benzoylphenylalaninate (2). Both peptides 1 and 2 exhibit AChE inhibition, with IC50 values equal to 111.34 µM and 137.6 µM, respectively. DISCUSSION AND CONCLUSION: Compound 1 (aurentiamide acetate) has rarely been isolated from the Leguminosae family, and N-benzoylphenylalaninyl-N-benzoylphenylalaninate (2) is a compound that has never previously been isolated from this family. Compound 1 is shown to be a potent inhibitor of AChE, with IC50 values similar to the physostigmine control (141.51 µM).