查看更多>>摘要：The reactivity of eight purified depsides obtained from six european lichens and that display as 2-oxoalkyl chain in ortho-position of the ester bond was explored. These depsides were found to lead to 1H-Isochromen-1-ones, which exhibit a distinctive blue fluorescence at 365 nm, in the presence of a 10% aqueous solution of KOH. A mechanistic explanation, involving the formation of an enolate intermediate and intramolecular transesterification, was proposed and validated by DFT. By exploiting this fluorescent phenomenon, we conceived a chemical probe (the KUV probe) that is useful for lichen determination, as exemplified on a selection of European Porpidia species.
查看更多>>摘要：Indole alkaloids have attracted widespread attention of chemists and biologists. Therefore, the aim of this study is to screen more bioactivities indole alkaloids from the microorganisms. In this study, five undescribed CPA-type indole alkaloids, aspergillines F-J, and three known CPA-type indole alkaloids, aspergilline A, aspergilline C, and cyclopiamide E, were obtained from the Nicotiana tabacum-derived fungus Aspergillus versicolor. Notably, aspergillines F and G represent the first examples of indole alkaloids with a benzo[cd]indol-2(1H)-one skeleton, and aspergilline J is also the firstly obtained indole alkaloids bearing a N-1-(2-(1H-imidazole-5-yl)ethyl) moiety. Aspergillines F-J and cyclopiamide E were tested for their anti-TMV activities, and the results revealed that aspergillines G and J exhibited obvious anti-TMV activities with inhibition rates of 41.2 and 56.8% at the concentration of 20 mu M, respectively. These rates are high than that of positive control (with inhibition rate of 32.5%). In addition, the molecular docking studies for the isolated CPA-type indole alkaloids may also reveal that the benzo[cd]indol-2(1H)-one substructure is the fundamental for anti-TMV activity and the oxygen-containing substituent groups at C-19 also increases the inhibitory activity. This study of structure-activity relationship is helpful to find new anti-TMV activity inhibitors.
查看更多>>摘要：A molecular networking-guided study on the Daphne genkwa Sieb. et Zucc led to the isolation of twelve daphnane-type diterpenoids including four undescribed compounds, yuanhuakines A-D. Their structures were elucidated by spectroscopic analyses, ECD calculations, and single-crystal X-ray diffraction analysis. All isolates were evaluated for their inhibitory activity against the A549, Hep3B, and MCF-7 cell lines. The majority of compounds inhibited A549 cells with IC50 values ranging from 7.77 to 20.56 mu M, and their structure-activity relationship is preliminarily discussed. Five of these compounds were selected for further experiments, and they appear to inhibit A549 cell lines by inducing apoptosis.
查看更多>>摘要：Two pairs of undescribed enantiomers including a 2,5-diketopiperazine namely (+/-)-janthinolide G and a related analogue (+/-)-janthinolide H, were isolated from the crude extract of the fungus Penicillium griseofulvum together with five known compounds. Both two structures were determined by spectroscopic method and HRESIMS, whereas absolute stereochemistry was elucidated by using theoretical NMR calculation and ECD calculation. Janthinolide G is the first example of 2,5-diketopiperazine enantiomers with a cleavage diketopiperazine ring and comprises a terminal oxime group rarely seen in natural products. Biological screening of selected compounds found that 4 and 7 both exhibited weak alpha-glucosidase inhibitory effects, and a potential correlation was afforded by docking studies of alpha-glucosidase protein (PDB: 3TOP) and bioactive molecules. The plausible biosynthetic pathways of two unreported isolates are proposed here.
NSTL
Elsevier