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Through bioassay-guided isolation, eight undescribed coumarins (1–8), along with six reported coumarins (9–14), were obtained from Coriaria nepalensis.The new structures were determined by using IR, UV, NMR, HRESIMS, and ECD calculations. The results of the biological activity assays showed that compound 9exhibited broad spectrum antifungal activities against all tested fungi in vitroand a significant inhibitory effect on Phytophthora nicotianaewith an EC50value of 3.00 μg/mL. Notably, compound 9demonstrated greater curative and protective effects against tobacco balack shank than those of osthol in vivo. Thus, 9was structurally modified to obtain new promising antifungal agents, and the novel derivatives (17b, 17j, and 17k) exhibited better effects on Sclerotinia sclerotiorumthan did lead compound 9. Preliminary mechanistic exploration illustrated that 9could enhance cell membrane permeability, destroy the morphology and ultrastructure of cells, and reduce the exopolysaccharide content of P. nicotianaemycelia. Furthermore, the cytotoxicity results revealed that compound 9exhibited relatively low cytotoxicity against HEK293 cell lines with an inhibition rate of 33.54% at 30 μg/mL. This research is promising for the discovery of new fungicides from natural coumarins with satisfactory ecological compatibility.

As part of our ongoing investigation of pesticide active quinolizidine alkaloids (QAs) from the family Fabaceae, the chemical constituents of the seeds of Thermopsis lanceolataR. Br. were systematically investigated. Bioassay-guided fractionation and purification of the crude extract led to the isolation of seventeen new QAs (1–17), including three new naturally occurring compounds (15–17), along with 15 known compounds (18–32). Their structures were elucidated by comprehensive spectroscopic data analysis (IR, UV, NMR, and HRESIMS) and quantum chemistry calculations (13C NMR and ECD). The antitomato spotted wilt virus activities and insecticidal activities against Aphis fabae, Nilaparvata lugens(Stal), and Tetranychus urticaeof compounds 1–32were screened using the lesion counting method, spray method, and rice-stem dipping method, respectively. Biological tests indicated that compounds 6, 9, 10, and 18displayed significant anti-TSWV activities compared with the positive control ningnanmycin. Compounds 3, 4, and 5showed better insecticidal activities against A. fabaewith LC50values of 10.07, 12.07, and 6.56 mg/L, respectively. Moreover, compounds 5, 18, and 24exhibited moderate insecticidal activities against N. lugens(Stal) with LC50values of 37.91, 53.44, and 31.21 mg/L, respectively. Furthermore, compounds 9and 10exhibited moderate insecticidal activities against T. urticae.

As part of our ongoing investigation of natural bioactive substances from the genus Thermopsisof the tribe Fabaceae for agricultural protection, the chemical constituents of the herb Thermopsis lupinoideswere systematically investigated, which led to the isolation of 39 quinolizidine alkaloids (QAs) (1–39), including 14 new QAs (1–14) and 14 isoflavones (40–53). Their structures were elucidated through comprehensive spectroscopic data analysis (IR, UV, NMR, HRESIMS), ECD calculations, and X-ray crystallography. The antitomato spotted wilt virus (TSWV) and antifungal (against Botrytis cinerea, Gibberella zeae, Phytophythora capsica, and Alternaria alternata) and insecticidal (against Aphis fabaeand Tetranychus urticae) activities of the isolated compounds were screened using the lesion counting method, mycelial inhibition assay, and spray method, respectively. The bioassay results showed that 34exhibited excellent protective activity against TSWV, with an EC50value of 36.04 μg/mL, which was better than that of the positive control, ningnanmycin (86.03 μg/mL). The preliminary mechanistic exploration illustrated that 34induced systemic acquired resistance in the host plant by acting on the salicylic acid signaling pathway. Moreover, 1showed significant antifungal activity against B. cinerea(EC50value of 20.83 μg/mL), while 2exhibited good insecticidal activity against A. fabae(LC50value of 24.97 μg/mL). This research is promising for the invention of novel pesticides from QAs with high efficiency and satisfactory ecological compatibility.

Six novel Maillard reaction products (MRPs) (1–6) were isolated from the processed Thermopsis lanceolataR. Br. seed extract, along with one biogenetically related intermediate (7). Compounds 1–4possessed three rare dimerization patterns constructed by cytisine, whereas compounds 5and 6represented the first example of the addition products of cytisine and 5,6-dihydroxy-4-hexanolide. Their structures were elucidated by comprehensive spectroscopic data analysis and quantum chemistry calculations including GIAO 13C{1H} NMR and ECD calculation, combined with single-crystal X-ray diffraction analysis. Biologically, compound 3displayed significant anti-tobacco mosaic virus activity compared with the positive control ningnanmycin.

Hymoins A–D (1–4), two pairs of light-induced transformative polyprenylated acylphloroglucinols with an unprecedented pentacyclic skeleton, were isolated from the flowers of Hypericum monogynum. The first decarbonylative ring contraction of complex natural products was investigated by light irradiation. Their structures were elucidated by nuclear magnetic resonance analysis, X-ray crystallography, and electronic circular dichroism calculations. In addition, compound 3showed moderate inhibition efficacy of the platelet-activating-factor-induced aggregation of rabbit platelets.