Chamaejasnoids A-E, a 2,3-seco-guaiane sesquiterpenoid with a 5/6/7 bridged ring system and related metabolites from Stellera chamaejasme L

Four new guaiane sesquiterpenes from Agarwood of Aquilaria sinensis and their biological activity toward renal fibrosis

Four undescribed guaiane sesquiterpenes, aquisinenoids I-L (2-5) and five known compounds were isolated from the resins of Aquilaria sinensis. Their structures were deduced based on spectroscopic data analysis, X-ray crystallography and ECD calculations. Biologically, compounds 1, 5, 6 and 9 showed anti-renal fibrosis activity, significantly reducing the levels of fibronectin, collagen I, and α-SMA. Compounds 2-4, 7 and 8 could reduce one or two of these proteins at non-toxic concentrations in TGF-β1 induced NRK-52E cells.

Terpenoids from the Roots of Stellera chamaejasme (L.) and Their Bioactivities

An undescribed diterpene, stellerterpenoid A (1), and two undescribed sesquiterpenoids, stellerterpenoids B and C (2-3), together with six known compounds, prostratin (4) stelleraguaianone B (5), chamaejasnoid A (6), auranticanol L (7), wikstronone C (8), and oleodaphnone (9), were isolated from the roots of Stellera chamaejasme L. Their structures were elucidated by extensive spectroscopic data (1D, 2D NMR, IR, UV, and HR-ESI-MS). The absolute configuration of 1-3 was elucidated based on ECD calculation. Among them, stellerterpenoid A was a rare 13, 14-seco nortigliane diterpenoid and stellerterpenoid B was a guaiacane-type sesquiterpenoid with an unusual 1, 2-diketone moiety. The known stelleraguaianone B (5) exhibited moderate activity for suppressing NO production in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages cells with an IC50 value of 24.76 ± 0.4 μM. None of the compounds showed anti-influenza virus or anti-tumor activity in vitro.

Stelleratenoids A-F, macrocyclic daphnane orthoesters with anti-HIV activity from the roots of Stellera chamaejasme L

Six undescribed macrocyclic daphnane orthoesters, stelleratenoids A-F (1-6), were isolated from the roots of Stellera chamaejasme L. Their structures were elucidated by extensive spectroscopic analyses, including HRESIMS and NMR spectra. Compound 1 features an unusual terminal double bond at C-2/C-19 in the 1α-alkyldaphnane lactone skeleton. Compounds 2-4 are unique in the presence of different long chain fatty acyl groups. Compounds 5 and 6 are unique examples of modified macrocyclic daphnane diterpenoids. All the isolates were evaluated for anti-HIV activity in MT-2 cells. Among them, compounds 1, 5 and 6 exhibited highly potent anti-HIV activity with EC₅₀ values of 66.70, 10.62 and 55.10 nM, respectively, possessing high potential to develop new anti-HIV drugs.

Guaianolides from Achillea millefolium L. and their anti-inflammatory activity

Seven previously undescribed guaianolides, millefolactons A-G, and three known analogues, millefoliumins A-C, were isolated from the whole plant of Achillea millefolium L. growing in Xinjiang, China. Their structures were elucidated using the HR-ESI-MS and NMR data analyses. The absolute configurations of millefolactons A-G were determined by single-crystal X-ray crystallography, ECD data analysis, and quantum-chemical ECD calculations. Millefolactons A-E are rare 3-oxa-guaianolides. Millefolacton C, millefolacton E, millefoliumin A and millefoliumin B exhibited enzymatic inhibition of 15-LOX. Molecular docking simulations were conducted to visualize interactions between the four active compounds and 15-LOX and determine binding mechanisms. Moreover, a LPS-induced BV2 cell model was used to further investigate the anti-inflammatory mechanism of millefolacton C. As a result, millefolacton C significantly inhibited NO release, repressed levels of pro-inflammatory cytokines including TNF-α, IL-18, PGE2 and IL-6, and inhibited the protein expression of iNOS and COX2 proteins. In addition, millefolacton C could potently decreased the expression of NLRP3, ASC, and IL-1β proteins in LPS-stimulated BV2 cells. These results indicate that the 3-oxa-guaianolides from A. millefolium L. offer great potential as leads for anti-inflammatory drug development.

Diversity of sesquiterpenoids from Stellera chamaejasme with neuroprotective effects

Chromatographic fractionation of the 95% EtOH extract of the roots of Stellera chamaejasme yielded 20 sesquiterpenoids of four different types, guaiane-, carotane-, sesquicarane-, and alpiniane-types. Among them, sesquistrachanoids A-F were previously undescribed ones, whose structures including absolute configurations were elucidated by spectroscopic methods, the Mo₂(OAc)₄-induced ECD experiment, and analysis of experimental and calculated 1D NMR and ECD data. Sesquistrachanoid A is a 2,3-seco-guaiane-type sesquiterpenoid with a α-pyrone core and sesquistrachanoid B is the first example of 8,9-seco-guaiane-type sesquiterpenoid featured with an 1,8-δ-lactone core. Sesquistrachanoid C is a guaiane sesquiterpenoid characterized by a peroxide bridge between C-8 and C-10. All sesquiterpenoids were evaluated for their neuroprotective effects on cell damage induced by sodium nitroprusside in PC-12 cells. The bioassay results showed that six compounds at 10 μM could restore the cell viability, being comparable to that of the positive control edaravone. The mechanistic study on the most pronounced activity compound, stelleraguaianone B, demonstrated that it played a neuroprotective role by promoting the mRNA expression of antioxidant enzymes to reduce oxidative stress.