Bioactivity evaluation and active compounds identification of Symphoricarpos orbiculatus as potential botanical...

Evaluation of herbicidal activity and identification of active compounds are important bases for the development of new botanical herbicides.

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.

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.