13-labdene-8α,15-diol

Eight sesquiterpenoids were isolated from petroleum ether extract of Aquilariae Lignum Resinatum by various column chromatography techniques including silica gel, ODS, and semi-preparative HPLC. Their structures were identified on the basis of physicochemical properties, UV, IR, MS, and NMR spectroscopic data as(4S,5S,7R,10S)-5,7-dihydroxy-11-en-eudesmane(1),(7R,10S)-eudesma-4-en-11,15-diol(2),(2R,4S,5R,7R)-2-hydroxyeremophila-9,11-dien-8-one(3), 7α-H-9(10)-ene-11,12-epoxy-8-oxoeremophilane(4),(+)-9β,10β-epoxyeremophila-11(13)-en(5), 4(14)-eudesmene-8α,11-diol(6), 12,15-dioxo-selina-4,11-dien(7), and 2β,8 aα-dihydroxy-11-en-eremophilane(8). Compounds 1 and 2 are new compounds, and their absolute configurations were determined by calculating ECD. Compounds 1, 4, and 6-8 could significantly improve taurocholic acid(TCA)-induced gastric mucosal GES-1 cell injury at a concentration of 20 μmol·L~(-1), and the cell protection rates were 23.51%±2.79%, 16.10%±1.25%, 24.45%±4.89%, 17.48%±2.93%, and 21.44%±2.39%, respectively.

Practical total syntheses of africane-type sesquiterpenoids were realized by reexamination of a divergent strategy employing optimized three-component coupling followed by ring-closing metathesis and substrate-controlled cyclopropanation. This sequential eight-step conversion provided Δ9(15) -africanene, a common bicyclo[5.3.0]decane intermediate for the syntheses of africane derivatives, in more than twice the yield as in the previous approach. The scalability and robustness of this improved synthetic route were confirmed by gram-scale preparation of Δ9(15) -africanene. In vitro cell-based assays of the synthesized africane-type sesquiterpenoids disclosed that ester-incorporating derivatives showed cytotoxic activity against HeLa cells. The effect of relative and absolute configuration of africane-9,15-diol monoacetates on the cytotoxicity against HeLa cells was also investigated.

The adaption of Ambrosia trifida to the environment to which it has been introduced is crucial to its successful invasion. Microbial diversity analyses suggested that the abundance of Proteobacteria was relatively high in rhizospheric soil surrounding A. trifida roots. Three of these bacterial taxa were isolated and identified as Acinetobacter sp. LHD-1, Pseudomonas sp. LHD-12, and Enterobacter sp. LHD-19. Furthermore, three sesquiterpenoids were authenticated as the main metabolites in the root exudates of A. trifida, and include one new germacrane sesquiterpenoid (1E,4E)-germacrdiene-6β,15-diol (2) and two known sesquiterpenoids, (E)-4β,5α-epoxy-7αH-germacr-1(10)-ene-2β,6β-diol (1) and (2R)-δ-cadin-4-ene-2,10-diol (3). Their chemical structures were elucidated using NMR spectroscopy and single crystal X-ray diffraction analyses. In UPLC-MS/MS analyses, compounds 1-3 showed values of 10.29 ± 2.21, 0.02 ± 0.01, and 0.78 ± 0.52 μg/g FW, respectively, in A. trifida rhizospheric soil. Interestingly, those compounds were able to inhibit the growth of Acinetobacter sp. LHD-1 and promote the growth of Enterobacter sp. LHD-19 where concentrations were close to those secreted into rhizospheric soil. Furthermore, the rhizospheric bacteria Acinetobacter sp. LHD-1 and Enterobacter sp. LHD-19 were able to regulate the growth of A. trifida seedlings in potted planting verification experiments. Interestingly, root exudate sesquiterpenoids could also improve the concentration of IAA in Enterobacter sp. LHD-19, indicating that this bacterium may promote plant growth through regulating the IAA pathway. These results provided new evidence for the rapid adaptation of plants to new environments, allowing their invasive behavior.