https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Dietary phenolics: chemistry, bioavailability and effects on health.

Glacial melting in the Tibetan Plateau affects the water resources of millions of people. This study finds that—partly owing to changes in atmospheric circulations and precipitation patterns—the most intensive glacier shrinkage is in the Himalayan region, whereas glacial retreat in the Pamir Plateau region is less apparent.

Different glacier status with atmospheric circulations in Tibetan Plateau and surroundings

Transition-Metal-Catalyzed C−S, C−Se, and C−Te Bond Formation via Cross-Coupling and Atom-Economic Addition Reactions

Chem. Pharm. Bull.(オピニオン)

. The retreat of sea ice is very significant in the Arctic under global warming. It is projected to continue and have great impacts on navigation. In this investigation, decadal changes in sea ice parameters were evaluated by multimodel from the Coupled Model Intercomparison Project Phase 6, and Arctic navigability was assessed under two shared socioeconomic pathways (SSPs) and two vessel classes within the Arctic transportation accessibility model. The sea ice extent is expected to decrease along the SSP5-8.5 scenario with a high possibility under current emissions and climate change. The decadal decreasing rate will increase in March but decrease in September until 2060 when the oldest ice completely disappears and sea ice changes reach an irreversible tipping point. The sea ice thickness will decrease and transit in parts of the Arctic and will decline overall by −0.22 m per decade after September 2060. Both the sea ice concentration and volume will thoroughly decline with decreasing decadal rates, while the decrease in volume will be higher in March than in September. Open water ships will be able to cross the Northeast Passage and Northwest Passage in August–October 2045–2055, with a maximum navigable area in September. The opportunistic crossing time for polar class 6 (PC6) ships will advance to October–December in 2021–2030, while the maximum navigable area will be seen in October. In addition, the Central Passage will also open for PC6 ships during September–October in 2021–2030.

/pdf/perspectives-on-future-sea-ice-and-navigability-in-the-iqnr17ui15.pdf

Perspectives on future sea ice and navigability in the Arctic

Mass-directed isolation of the large-scale CH2Cl2/Me-OH extract from the title sponge affords the new alkaloid psammaplysin H (I) together with the previously isolated analogues psammaplysins G and F.

Psammaplysin H, a New Antimalarial Bromotyrosine Alkaloid from a Marine Sponge of the Genus Pseudoceratina.

Reducing plant uptake of a brominated contaminant (2,2',4,4'‑tetrabrominated diphenyl ether) by incorporation of maize straw into horticultural soil.

Three new acylated flavonoid C-glycosides, 6‴-(-)-phaseoylspinosin (1), 6‴-(3″″,4″″,5″″-trimethoxyl)-(E)-cinnamoylspinosin (2), and 6‴-(4″″-O-β-D-gluco-pyranosyl)-benzoylspinosin (3), were isolated from the seeds of Ziziphus mauritiana (Rhamnaceae). A further 19 known compounds including eight spinosin analogues (4–11) were also isolated. Their structures were elucidated by means of spectroscopic analysis and chemical method. Among spinosin derivatives 1, 2, 4, 7, 8, and triterpenoid saponin 14, jujuboside A (14) displayed moderate acetylcholinesterase (AchE) inhibitory activity with an inhibition value of 46.2% at a concentration of 1 µM.

/pdf/new-spinosin-derivatives-from-the-seeds-of-ziziphus-2skk3loe66.pdf

New spinosin derivatives from the seeds of Ziziphus mauritiana

Time-dependent density functional theory (TDDFT) calculated electronic circular dichroism (ECD) and Mosher’s method were applied to establish the absolute configurations of six new highly oxygenated cleistanthane diterpenoid glucosides, phyllanembloids A–F (1–6), isolated from the roots of Phyllanthus emblica. Compounds 1–5 featured a carboxyl group at C-13 adjacent to the hydroxyl group at C-12, and are the first examples of cleistanthane diterpenoids with a salicylic acid fragment. The carboxyl group at C-13 can significantly affect the CD spectrum of cleistanthane diterpenoids, and make the excitations of phenylethylene dominate the Cotton effects (240 and 280 nm), rather than the benzene ring excitations dominating the Cotton effects at 220 and 240 nm as in the 13-methyl analogues. The characteristic Cotton effects of cleistanthane diterpenoids were summarized according to the experimental and calculated ECD curves, which can be applied as a common method to determine the absolute configurations of this type of diterpenoid.

Min Xu

Papers

Perspectives on future sea ice and navigability in the Arctic

Psammaplysin H, a New Antimalarial Bromotyrosine Alkaloid from a Marine Sponge of the Genus Pseudoceratina.

Reducing plant uptake of a brominated contaminant (2,2',4,4'‑tetrabrominated diphenyl ether) by incorporation of maize straw into horticultural soil.

New spinosin derivatives from the seeds of Ziziphus mauritiana

Stereochemistry of cleistanthane diterpenoid glucosides from Phyllanthus emblica