Background Since Nicotiana tabacum (tobacco) has important significance to humans for their medicinal uses, to find antivirus activities inhibitors from tobacco, increase its medicinal value, and comprehensive utilization of its by-products, our group had investigated the chemical constituents of the stems of Y-202, a cultivar of tobacco which high resistance to tobacco mosaic virus (TMV). Results Four new isoindolinone-type alkaloids, nicoisoindoles A–D (1–4), along with four known isoindole derivatives (5–8) were isolated. Compounds 1–4 represent a new subclass of isoindolinone alkaloids with rare cyclopenta[f]isoindole-1-one frameworks. Among them, nicoisoindole C (3) possesses an unusual N-2-(5-methoxy-6-methylpyridin-2-yl) ethyl moiety, while nicoisoindole D (4) has a novel a N-(3-methyl-6-oxo-1,6-dihydropyridin-2-yl)methyl substituent. Interestingly, compounds 1, 3, and 4 showed high anti-TMV activities with inhibition rates of 43.8%, 58.8%, and 67.8% at the concentration of 20 μM, and IC50 values of 23.6, 19.5 and 15.4 μM, respectively, even more potent than that of positive control. Conclusions The successful isolation and structure identification of new oxocyclopenta[f]isoindole-1-ones provide materials for the screening of antivirus activities inhibitors, and contribute to the development and utilization of the waste from tobacco cultivation. Graphical Abstract

No abstract

Chamaecrista rotundifolia (C. rotundifolia) is a perennial herb of leguminosae, which increasingly being grown as a forage in China. In our search for original bioactive metabolites from Cassia plants, the phytochemical reinvestigation of the C. rotundifolia was carried out, which led to the isolation of three new (1-3) and six known (4-9) chromones. Their structures were confirmed by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-9 were evaluated for their anti-rotavirus activities, and the results revealed that compounds 1-9 exhibited potential anti-rotavirus activities with therapeutic index (TI) valves in the range of 12.0~20.2, respectively.

Background The large scale tobacco planting in Yunnan produces a large amount of waste, including stems, roots, low grade and defective tobacco leaves. Therefore, the multipurpose utilization of the by-product of tobacco is an interesting topic. In order to increase medicinal value of tobacco and the comprehensive utilization of its by-products, our group had investigated the chemical constituents of the stems of Y-202, a cultivar of tobacco with high resistance to tobacco mosaic virus (TMV), which originated from K326 by ethylmethane sulfonate (EMS) mutagenesis. Results As a result, four new isoindolinone-type small molecule alkaloids named nicoisoindoles A–D (1–4), along with four known isoindole derivatives (5–8) were isolated. Nicoisoindoles A–D represent a new subclass of isoindolinone alkaloids with rare cyclopenta[f]isoindole-1-one frameworks. Among them, nicoisoindole C (3) possesses an unusual N-2-(5-methoxy-6-methylpyridin-2-yl)ethyl moiety, while nicoisoindole D (4) has a novel a N-(3-methyl-6-oxo-1,6-dihydropyridin-2-yl)methyl substituent. Interestingly, compounds 1, 3, and 4 showed high anti-TMV activities with inhibition rates of 43.8, 58.8, and 67.8% at the concentration of 20 µM, and IC50 values of 23.6, 19.5 and 15.4 µM, respectively, even more potent than that of positive control. In order to study whether the oxocyclopenta[f]isoindole-1-ones have more broad antiviral activities, compounds 1–4 were also tested for their anti-rotavirus activities, and they exhibited potential anti-rotavirus activities with therapeutic index (TI) valves in the range of 13.0-18.5. Conclusions The successful isolation and structure identification of oxocyclopenta[f]isoindole-1-ones provide materials for the screening of anti-virus activities inhibitors, and also contribute to the development and utilization of the waste from tobacco cultivation.