Structure elucidation of antiproliferative bisbenzylisoquinoline alkaloids from Anisocycla grandidieri from the Madagascar dry forest

Antiproliferative bioassay‐guided fractionation of the ethanol extract of the stems of Anisocycla grandidieri led to the isolation of the known alkaloids stebisimine (1), (+)‐1,2‐dehydrotelobine (2), (+)‐2'‐norcocsuline (3) and puetogaline B (4). Herein, we report the full NMR assignments of all compounds and the X‐ray crystallography of single crystals of compounds 1 and 3. Compounds 2 and 3 showed moderate antiproliferative activity against the A2780 human ovarian cancer cell line with IC₅₀ values of 4.1 ± 0.3 and 2.7 ± 0.3 μM, respectively, and they also displayed selective activity toward the H460 (large cell lung cancer), MCF‐7 (breast ductal carcinoma), and UACC‐257 (melanoma) cell lines. Copyright © 2013 John Wiley & Sons, Ltd.     

Understanding the Biosynthesis of Paxisterol in Lichen-Derived Penicillium aurantiacobrunneum for Production of Fluorinated Derivatives

The U.S. endemic lichen (Niebla homalea)-derived Penicillium aurantiacobrunneum produced a cytotoxic paxisterol derivative named auransterol (2) and epi-citreoviridin (6). Feeding assay using ¹³C₁-labelled sodium acetate not only produced C-13-labelled paxisterol but also confirmed the biosynthetic origin of the compound. The fluorination of bioactive compounds is known to improve pharmacological and pharmacokinetic effects. Our attempt to incorporate the fluorine atom in paxisterol and its derivatives using the fluorinated precursor sodium monofluoroacetate resulted in the isolation of 7-monofluoroacetyl paxisterol (7). The performed culture experiment, as well as the isolation and structure elucidation of the new fluorinated paxisterol, is discussed herein.     

Momordica charantia constituents and antidiabetic screening of the isolated major compounds

Bioguided fractionation of the methanol extract of Momordica charantia dried gourds led to the isolation of three new cucurbitane triterpenoids (1-3), together with eight known compounds (4-11). The aglycone of momordicoside I was isolated from the ether soluble fraction in a high amount. The structures of the metabolites were established on the basis of one and two dimensional NMR spectroscopic evidence, X-ray analysis, and comparison with the reported data in the literature. A number of phytochemicals have been isolated from Momordica charantia but the constituents responsible for the hypoglycaemic/antihyperglycaemic activities have not been determined. Therefore, in order to evaluate the contribution of the cucurbitane triterpenoids of the ether fraction of M. charantia methanol extract to in vivo anti-diabetic effects, the major compounds, 5beta,19-epoxy-3beta,25-dihydroxycucurbita-6,23(E)-diene (4), and 3beta,7beta,25-trihydroxycucurbita-5,23(E)-dien-19-al (5) have been tested and have shown blood hypoglycaemic effects in the diabetes-induced male ddY mice strain at 400 mg/kg. The two aglycones of charantin did not show any hypoglycaemic effects. Our finding is the first demonstration that major pure cucurbutanoid compounds of M. charantia have in vivo hypoglycaemic effects.     

Determination of Cd in sonicate slurries and leachates of biological and environmental materials by FI-CV-AAS

An analytical method for Cd analysis in solid samples which combines the ultrasonic slurry formation with cold vapour generation and atomic absorption spectrometry is described. The samples are suspended in HCl and sonicated until homogeneous and reduced particle size slurry formation. Several aspects were studied: acidity of the medium, sonication time, and slurry formation in different matrices. The procedure described permits the use of direct calibration, with KCN addition as masking agent of interfering ions (Cu, Pb, Ni and Zn) present in the environmental matrices. Supernatant analysis of these last samples experimentally shown that preparation of the suspension with 6 mol l(-1) HCl concentration led to quantitative extraction of Cd. Biological materials analysis needed the use of the standard addition calibration method due to the high matrix effect observed. Supernatant analysis in biological samples does not give a total Cd recovery for all of them. The detection limits observed for Cd were 0.05 and 0.2 mug l(-1) for supernatant and slurry analysis respectively in environmental samples, while in biological samples were 0.2 and 0.6 mug l(-1) for supernatant and slurry analysis, respectively. In all case the better precision was obtained for supernatant analysis (3-6%) than slurry analysis (6-12%). The results obtained by analysing different reference materials (sewage sludge, city waste incineration, Antarctic krill and human hair) showed good agreement with the certified value confirming the validity of such a method for Cd determination instead to wet digestion procedures.     

Cussosaponins A-E,triterpene saponins from the leaves of Cussonia racemosa,a Malagasy endemic plant

Five new triterpene saponins, cussosaponins A (2), B (3), C (4), D (5), and E (6), were isolated from the dried leaves of Cussonia racemosa BAKER. The structures of these new compounds were deduced on the basis of chemical and spectroscopic evidence.     

Ent-kaurane diterpenoid glycosides from the leaves of Cussonia racemosa, a Malagasy endemic plant

Six new ent-kaurane diterpenoid glycosides, cussoracosides A (3), B (4), C (5), D (6), E (7), and F (8) were isolated from the dried leaves of Cussonia racemosa, along with two known compounds identified as beta-D-glucopyranosyl ent-16beta,17-dihydroxykauran-19-oate (1) and paniculoside IV (2). The structures of these new compounds were deduced on the basis of chemical and spectroscopic evidence.     

Penicillium sclerotiorum catalyzes the conversion of herbertenediol into its dimers: mastigophorenes A and B

Herbertenediol was subjected to biotransformation by Penicillium sclerotiorum. Spectral data analysis of the converted metabolites revealed that the neurotrophic active compounds, mastigophorenes A and B, dimeric to the substrate were formed.     

Chemical constituents of Malagasy liverworts, part II: mastigophoric acid methyl ester of biogenetic interest from Mastigophora diclados (Lepicoleaceae Subf. Mastigophoroideae)

In the course of our chemotaxonomic study of the liverworts growing in Madagascar, mastigophoric acid methyl ester, along with eleven known compounds were isolated from Mastigophora diclados. Isolated metabolites showed that the Malagasy Mastigophora is more related to the samples from Borneo and Japan than to the Taiwanese or Malaysian ones. The biosynthesis of the herbertane type sesquiterpenoids from Mastigophora diclados is suggested to be similar to those found in the genus Herbertus. The herbertane-type sesquiterpenoids were screened for Staphylococcus aureus strain inhibition.     

Astrotricoumarin, an antiproliferative 4'-hydroxy-2',3'-dihydroprenylated methylcoumarin from an Astrotrichilia sp. from the Madagascar dry forest

Bioassay guided fractionation of the ethanol extract of a new endemic species of the genus Astrotrichilia led to the isolation of the new antiproliferative 3-(4'-hydroxy-2',3'-dihydroprenyl)-4,6-dimethoxy-5-methylcoumarin, named astrotricoumarin (8) with an IC50 value of 6.8 microM against the A2780 cell line. The structure of compound 8 was elucidated on the basis of its physical and spectroscopic data, including extensive 1D- and 2D-NMR analysis.