Chemistry of Natural Compounds最新文献

The mnestic activity of synthetic derivatives of the alkaloid (–)-cytisine with a thiourea substituent in the 3- and 9-position was studied in a conditioned passive avoidance response (CPAR) test. Four candidate compounds with mnestic activity comparable to or exceeding that of the reference drug piracetam were identified among 26 tested derivatives. One of the compounds, the ethyl ester of 2{3-[(1R,5S)-3-methyl-8-oxo-2,3,4,5,6,8-hexahydro-1H-1,5-methanopyrido[1,2-a][1,5]diazocin-9-yl]thioureido}acetic acid, which was prepared by reacting methylcytisine 9-isothiocyanate with ethyl glycinate, exhibited 100% mnestic activity.

A synthetic scheme for new triterpene A-azepano-oleananes with 19β,28-diol and 18(19)-ene fragments was demonstrated using modification of 28-oxo-allobetulone on rings A and E as an example. Cytotoxicity screening on an NCI-60 panel revealed activity for A-azepano-olean-19β,28-diol 5 against three types of human cancer cells with the highest activity against COLO 205 colon cancer. A-azepano-moradiol 10 was active against five types of cells with an inhibitory interval of 31.88–6.16%, while N-tert-butyloxycarbonyl-azepane 11 inhibited the growth of six types of cancer cells (from 31.84 to 14.32%), including MCF7 breast cancer, MDA-MB-468, and HCT-116 colon cancer cells.

Three new sesquiterpenoids, aphanamols S–U (1–3), were isolated from the 90% EtOH extract of the stems and leaves of Aphanamixis polystachya (Wall.) R. Parker (Meliaceae). Compound 1 is the first trinor-guaiane sesquiterpenoid isolated from the genus Aphanamixis, and the structures of these new compounds were established mainly by analysis of the NMR and MS data. The antifungal activities of compounds 1–3, applied alone or in combination with fluconazole against drug-resistant Candida albicans were evaluated.

Two new benzo[c]oxepins (1 and 2), together with three known analogues (3–5) were isolated from the cultures of the fungus Xylaria polymorpha. Their structures were determined by means of HR-ESI-MS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1 and 2 were evaluated for their antibacterial activities against five nitrosobacteria strains (Nitrosomonas communis, Nitrosomonas nitrosa, Nitrosospira multiformis, Nitrobacter winogradskyi, and Nitrospira inopinata). Interestingly, compounds 1 and 2 exhibited notable antibacterial activity with bacteriostatic diameters within the range 14.8–21.8 mm against five nitrosobacteria strains, and some of the bacteriostatic diameters are greater than that of the positive control. Owing to the nitrosobacteria having the ability to convert nitrogen components into nitrite in tobacco, and then convert to tobacco-specific nitrosamines (TSNAs), compounds 1 and 2 have the potential to reduce TSNAs in tobacco by inhibiting nitrosobacteria during the fermentation process of tobacco leaves.

A new biflavonoid derivative, named 4′,5′′-dimethoxy-6,7-(4′′′′,5′′′′-dimethoxy-9′′′′-hydroxymethyl)- phenylpropyl-2′′-(4′′′-hydroxyphenyl)-biflavonoid (1), and seven known biflavonoid derivatives (2–8) were isolated from Citrus medica var. sarcodactylis (Siebold ex Hoola van Nooten) Swingle for the first time. These compounds were elucidated by analyzing their spectral data and comparing them with related references. Among them, compounds 1 and 3 exhibited obvious hepatoprotective activities against paracetamol-induced HepG2 cell damage at 10 μM. The results suggested that these compounds could be potential hepatoprotective agents.