Chemistry of Natural Compounds最新文献

The influence of the 7-O-acetyl group of acetylhaplophyllidine (2) on the bromination process was studied. Acetylhaplophyllidine in bromination by molecular Br₂ and N-bromosuccinimide under various conditions formed multicomponent mixtures consisting of bromination products of intramolecular annelation (3, 4, and 6) and bromo-derivatives of 4-oxofuranoquinolines (5 and 7).

β-D-Glucopyranosides of 3β, 12α,20S-trihydroxydammar-24-ene (1) and 3α,12α,20S-trihydroxydammar-24-ene (2), close structural analogs of ginsenoside-Rh2 and a metabolite of Panax ginseng glycosides (compound K), were synthesized. Glycosylation of 20S-hydroxydammar-24-ene-3,12-dione (5) and 3α-acetoxy-20S-hydroxydammar-24-en-12-one (6) by 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (8) under classical Koenig-Knorr reaction conditions followed by deacetylation by NaOMe in MeOH gave free 20-O-β-D-glucopyranosides 10 and 13, treatment of which with NaBH₄ in i-PrOH formed 20-O-β-D- glucopyranosides of the 12α-epimers of 20S-protopanaxadiol 11 and betulafolientriol 14. Condensation of 3β,12α,20S-trihydroxydammar-24-ene (1) and glycosyl donor 8 in the presence of Ag₂O in CH₂Cl₂ followed by removal of the protecting groups gave 3-O-β-D-glucopyranoside 16; of 3α,12α,20S-trihydroxydammar-24-ene (2) under the same conditions, a mixture of 3- and 12-O-β-D-glucopyranosides 19 and 20.

A synthetic method for betulin 3-O-propionate 28-O-acylates via the reaction of betulin 3-O-propionate with melts of benzoic, phthalic, cinnamic, and succinic acids at 185–195°C for 5–6 min was proposed.

(+)-Zishenine (1), a new benzylisoquinoline, along with eight known compounds including two oxoaporphines, liriodenine (2), and oxoxylopine (3), two aporphines, (–)-anonaine (4) and (–)-xylopine (5), two lignans, (+)-sesamin (6) and (+)-diasesamin (7) and two benzenoids, ferulic acid (8) and p-hydroxybenzaldehyde (9), were isolated from the fruits of Michelia compressa var. compressa (Magnoliaceae). The structure was characterized and identified by spectral analysis.

To further explore powdery mildew (caused by Golovinomyces cichoracearum) natural products, an extract from the fermentation of endophytic Aspergillus fumigatus was investigated. As a result, six isoindole alkaloid derivatives (1–6) were isolated. Among them, two compounds (1 and 2) were newly discovered and the activity evaluation of the purified compounds 1–6 against G. cichoracearum was studied. The results revealed that compounds 1–6 demonstrated obvious anti-G. cichoracearum activities for cigar tobacco in the range of 40.6% ± 5.4 to 66.5% ± 4.9 at a concentration of 250 μg/mL, respectively. However, these rates are lower than that of positive control. By isolating and structurally identifying the above isoindole alkaloids, new materials conducive to improving the utilization of N. tabacum-derived fungi could be developed for screening anti-powdery mildew drugs.

A new compound, comazaphilone I (1), was isolated from Mycolicibacterium aurum WYQ isolated from marine sediment samples collected in the East China Sea. Its structure was elucidated based on spectroscopic data, comparison with literature data, and ECD calculation. The newly discovered compound, while bearing a similar planar structure to the known compound comazaphilone A, features a distinct 6S7S configuration. However, no bioactivities were screened from the bioassay experiments.

A new hederagenin-type triterpene saponin was found in the aqueous-ethanolic extract of the seeds of Cassia fistula L. The structure of this compound was established as 3-O-β-D-xylopyranosyl-(1→2)-β-D- xylopyranosylhederagenin 28-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl ester (1), mainly by extensive 2D NMR analysis in combination with spectral data of known compounds.

A new isopimarane-type diterpenoid, named inonotolide E (1), and four known compounds (2–5) were isolated from cultures of the fungus Inonotus sinensis. The new structure was established by extensive spectroscopic techniques (1D and 2D NMR and HR-ESI-MS). Compound 1 was evaluated for its cytotoxicities against five human cancer cell lines.

A new lanostane-type triterpene, uvariaol (1), was isolated from the branches of Thai Uvaria siamensis, along with three known compounds, polycarpol (2), fisetinidol (3), and stigmast-4-en-3-one (4). Their structures were elucidated through extensive spectroscopic analyses and comparison with existing literature. The α-glucosidase inhibitory potential of compounds 1–4 was evaluated. Compound 1 exhibited significant inhibitory activity against α-glucosidase, surpassing the potency of the positive control, with an IC₅₀ value of 30.8 ± 1.5 μM.