Search for Snail Repellents: Antimollusc Activities from Stemona parviflora and Six Other Chinese Stemona Species.

Snails are important agricultural pests difficult to control, but data regarding molluscicidal assays are scant. Stemona alkaloids are typical secondary metabolites for the taxa and have been broadly investigated for their pharmacological and toxicological effects. This makes it possible for us to further develop the toxicities of these compounds to snails. In this work, we tested the antifeedant properties of leaves from seven Chinese Stemona species against the land snail species Bradybaena ravida in choice and non-choice feeding assays. The tested leaves Stemona parviflora exhibited the most deterrent effects, and a further phytochemical investigation of aerial parts led to the identification of 16 alkaloids. Among them, three novel alkaloids could be identified. The alkaloidal fraction and single alkaloids were further assayed against this snail species, and the results suggest a cocktail effect because the impact of the alkaloidal fraction was higher than the effects caused by single alkaloids. The study can promote the search process of natural antimollusc products from plants to control snails.

Discovery of ent-labdane derivatives from Andrographis paniculata and their anti-inflammatory activity.

The plant Andrographis paniculata has a long history of cultivation in Southeast Asia, especially its extensive anti-inflammatory activity, and the famous natural antibiotic andrographolide comes from this plant. In China, A. paniculata, as the main crop, has become a major source of traditional Chinese medicine (TCM) for the clinical treatment of inflammation. To further explore the diverse diterpene lactones with better anti-inflammatory activity from A. paniculata, twenty-one ent-labdanes, including six undescribed compounds (andropanilides D-I), were isolated. Their structures with absolute configurations were thoroughly determined by comprehensive NMR spectroscopic data, HRESIMS analysis and quantum chemical calculations. All isolated compounds were evaluated for anti-inflammatory activities based on the Griess method. Meanwhile, after structure-activity relationships analysis, the anti-inflammatory activity of andropanilide D (1) (IC50 = 2.31 µM) was found to be better than that of the positive control drug (dexamethasone, IC50 = 6.52 µM) and andrographolide (IC50 = 5.89 µM). Further mechanisms of activity indicated that andropanilide D significantly reduced the secretion of TNF-α, IL-6 and IL-1ß and downregulated the protein expression of COX-2 and iNOS in LPS-induced RAW264.7 macrophages in a concentration-dependent manner based on Western blot and ELISA experiments. In conclusion, andropanilide D possesses potential medicinal value for the treatment of inflammation and further expands the material basis of the anti-inflammatory effect of A. paniculata.