International audienceThe Red River (North Vietnam) is a typical example of a subtropical Asian river system undergoing high human pressure. During the last 50 years, major changes have occurred in its watershed, extending over an area of 156,450 km(2) in Vietnam and China. We provide a detailed account of these changes, related to intensification of agriculture, deforestation, increase in population and urbanization, impoundment of reservoirs, etc. This information is used in a modeling approach of the nutrient transfers and transformations along the river system, in order to evaluate the changes in water quality of the Red River and its potential for coastal eutrophication. We conclude that the combination of increased nitrogen release from agriculture and retention of phosphorus in the reservoirs has considerably changed the balance of nutrients delivered at the outlet of the river, bringing the system close to a turning point in its nutrient biogeochemistry and its potential for coastal eutrophication. The upcoming impoundment of four new major dams in the watershed makes this conclusion particularly relevant

A rapid screening by (1)H and (1)H-(13)C HSQC NMR spectroscopy of EtOAc extracts of Endiandra and Beilschmiedia species allowed the selection of Beilschmiedia ferruginea leaves and flowers extract for a chemical investigation, leading to the isolation of 11 new tetracyclic endiandric acid analogues, named ferrugineic acids A-K (1-11). Their structures were determined by 1D and 2D NMR spectroscopic analysis in combination with HRMS data. These compounds were assayed for Bcl-xL and Mcl-1 binding affinities. Ferrugineic acids B, C, and J (2, 3, and 10) exhibited significant binding affinity for both antiapoptotic proteins Bcl-xL (Ki = 19.2, 12.6, and 19.4 μM, respectively) and Mcl-1 (Ki = 14.0, 13.0, and 5.2 μM, respectively), and ferrugineic acid D (4) showed only significant inhibiting activity for Mcl-1 (Ki = 5.9 μM).

The chemical study of Momordica charantia fruits led to the isolation of three new cucurbitane triterpene glycosides, momordicosides U, V, and W (1-3). The structures of these compounds were determined to be (19R, 23R)-5beta, 19-epoxy-19-methoxycucurbita-6,24-diene-3beta, 23-diol 3-O-beta-D-allopyranoside (1), (23R)-5beta, 19-epoxycucurbita-6,24-diene-3beta, 23-diol 3-O-beta-D-allopyranoside (2), and (19R)-5beta, 19-epoxy-19,25-dihydroxycucurbita-6,23(E)-diene-3beta-ol 3-O-beta-D-glucopyranoside (3), by chemical and spectroscopic methods.

Three new C29 sterols with a cyclopropane ring cyclized between C-26 and C-27 of the side chain, aragusterol I (1), 21-O-octadecanoyl-xestokerol A (4), and 7β-hydroxypetrosterol (5b), were isolated from the Vietnamese marine sponge Xestospongia testudinaria, along with the known compounds, aragusterol B (2), xestokerol A (3), 7α-hydroxypetrosterol (5a), 7-oxopetrosterol (6), and petrosterol (7). The structures of the new compounds were established by analysis of spectroscopic data including 1D and 2D NMR, and high-resolution electrospray ionization mass spectrometry (HRESIMS). Their capacity to inhibit the adhesion of isolated bacteria from marine biofilms was evaluated against the bacterial strains Pseudoalteromonas sp. D41, Pseudoalteromonas sp. TC8, and Polaribacter sp. TC5. Aragusterol B (2) and 21-O-octadecanoyl-xestokerol A (4) exhibited the most potent antifouling activity with EC50 values close to these reported in the literature for tributyltin oxide, a marine anti-biofouling agent now considered to be a severe marine pollutant. Due to its comparable activity to tributyltin oxide and its absence of toxicity, the new 26,27-cyclosterol, 21-O-octadecanoyl-xestokerol A (4) constitutes a promising scaffold for further investigations.

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