RESUMO
BACKGROUND: Evaluation of herbicidal activity and identification of active compounds are important bases for the development of new botanical herbicides. RESULTS: This study confirmed that Symphoricarpos orbiculatus has high herbicidal activities against mono-dicotyledonous weeds, including Echinochloa crusgalli, Digitaria sanguinalis, Amaranthus retroflexus and Portulaca oleracea. By bioassay-guided isolation, 12 compounds were isolated and identified from S. orbiculatus for the first time, including iridoids: naucledal (K1), loganin (K2), loganigenin (K3), loganin acid (K4), glucologanin (K5) and vogeloside (K6), as well as flavonoids: quercetine (K7), luteolin (K8), nobiletin (K9), astragalin (K10), isorhamnetin 3-d-glucoside (K11) and rutin (K12). Biological assays showed that iridoids are the main active ingredients of S. orbiculatus. The compounds of K5 and K6 could inhibit both the root (IC50 = 37.54 and 38.91 µg mL-1, respectively) and shoot (IC50 = 42.78 and 45.72 µg mL-1, respectively) of Portulaca oleracea, which have a weeding toxicity similar to that of the commercialized plant-based herbicide pelargonic acid. In addition, the results of pot culture assay showed that S. orbiculatus ethanol extracts had high fresh weight control effect against Digitaria sanguinalis and P. oleracea at the concentration of 40 g L-1. After 7 days, both the soil treatment and the stem and leaf spray method resulted in severe leaf necrosis and significant leaf etiolation. CONCLUSION: Symphoricarpos orbiculatus and its herbicidal active compounds have the potential to develop into botanical herbicides, and are first reported in the present study. © 2024 Society of Chemical Industry.
RESUMO
Piperidines are widely present in small molecule drugs and natural products. Despite many methods have been developed for their synthesis, new approaches to polysubstituted piperidines are highly desirable. This work presents a radical (4+2) cycloaddition reaction for synthesis of piperidines featuring dense substituents at 3,4,5-positions that are not readily accessible by known methods. Using commercially available diboron(4) compounds and 4-phenylpyridine as the catalyst precursors, the boronyl radical-catalyzed cycloaddition between 3-aroyl azetidines and various alkenes, including previously unreactive 1,2-di-, tri-, and tetrasubstituted alkenes, has delivered the polysubstituted piperidines in generally high yield and diastereoselectivity. The reaction also features high modularity, atom economy, broad substrate scope, metal-free conditions, simple catalysts and operation. The utilization of the products has been demonstrated by selective transformations. A plausible mechanism, with the ring-opening of azetidine as the rate-limiting step, has been proposed based on the experimental and computational results.
RESUMO
In the present study, a total of 21 natural or synthetic small-molecule organic acids were selected and determined for their activity against postharvest gray mold caused by B. cinerea. Overall, cuminic acid, which was extracted from the seed of Cuminum cyminum L, showed the most promising antifungal activity against B. cinerea both in vitro and in vivo. The study on action mechanism showed that cuminic acid could inhibit the development of sclerotia and the secretion of oxalic acid, destroy the cell membrane integrity, and down regulate the expression of several key genes involved in sclerotia development and pathogenicity of B. cinerea. Furthermore, cuminic acid could potentially reduce the degradation of TSS and TA content, while it had no significant effect on the weight loss, firmness, and VC content of apple and tomato. Importantly, cuminic acid could enhance the antioxidant enzyme activities of the fruits. All these results demonstrate the antifungal activity and highlight the great potential of cuminic acid as an alternative environmental-friendly agent for the control of postharvest gray mold both on fruits and vegetables.
