Recently, a novel online bioinformatics methodology called "Molecular Networking" was developed by P. Dorrestein and his group [1]. This approach consists in organizing and visualizing tandem mass spectrometry (MS2) data through a spectral similarity map, highlighting the presence of homologous MS2 fragmentations and their degree of similarity. Scrutinization of molecular networks enables automated comparison and annotation of complex mixtures, which reflect metabolomes of living organisms [2].
A large-scale in vitro screening of tropical plants using an antibacterial assay permitted the selection of several species with significant antibacterial activities. Bioassay-guided purification of the dichloromethane extract of the leaves of the Malaysian species Vitex vestita, led to the isolation of six new labdane-type diterpenoids, namely, 12-epivitexolide A (2), vitexolides B and C (3 and 4), vitexolide E (8), and vitexolins A and B (5 and 6), along with six known compounds, vitexolides A (1) and D (7), acuminolide (9), 3β-hydroxyanticopalic acid (10), 8α-hydroxyanticopalic acid (11), and 6α-hydroxyanticopalic acid (12). Their structures were elucidated on the basis of 1D and 2D NMR analyses and HRMS experiments. Both variable-temperature NMR spectroscopic studies and chemical modifications were performed to investigate the dynamic epimerization of the γ-hydroxybutenolide moiety of compounds 1–4. Compounds were assayed against a panel of 46 Gram-positive strains. Vitexolide A (1) exhibited the most potent antibacterial activity with minimal inhibitory concentration values ranging from 6 to 96 μM, whereas compounds 2 and 6–9 showed moderate antibacterial activity. The presence of a β-hydroxyalkyl-γ-hydroxybutenolide subunit contributed significantly to antibacterial activity. Compounds 1–4 and 6–9 showed cytotoxic activities against the HCT-116 cancer cell line (1 < IC50s < 10 μM) and human fetal lung fibroblast MRC5 cell line (1 < IC50s < 10 μM for compounds 1, 2, 7, 8, and 9).
Dysiherbaine and neodysiherbaine are two functionalized glutamate amino acids of marine origin presenting an original bicyclic pyranofuran core. Moreover, they display powerful neuropharmacological activities as CNS agents. Combination of their unique chemical structures with their pharmacological profiles makes these compounds attractive targets both for the 'synthetic' and the 'biological' communities. This review describes the different synthetic approaches published during the period 2000–2012.
Chromatographic fractionation of the cytotoxic n-hexane extract of Hopea odorata Roxb. leaves led to the isolation of 2 new 3,4-secocycloartanes bearing a unusual trihydroxylated side chain esterified with a fatty acid, together with 15 known other triterpenes (8 lupanes, 2 friedelanes, 2 oleananes, 1 cycloartane (i.e. mangiferonic acid), β-sitosterol and its palmitic acid ester) and 1 sesquiterpene (i.e. β-caryophyllene oxide). Among lupanes, 3,30-dioxolup-20(29)-en-28-oic acid was isolated for the first time from a natural source. Cytotoxic activities of lupane-type triterpenes against four human cell lines (PC3, MDA-MB-231, HT-29 and PC-3) are also reported.
