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Potato common scab is a soil-borne bacterial disease caused by Streptomyces scabies, which is ubiquitous and difficult to control. In this study, the issue of developing antimicrobial agents derived from plant extracts against S. scabieswas addressed. Three bioactive phenolic compounds, named gallic acid, 1-O-galloyl-β-d-glucose, and corilagin, were isolated and identified from Phyllanthus emblicapomace through bioassay-guided fractionation. The antibacterial effects of these compounds on S. scabieswere evaluated with MIC values of 0.63, 0.31, and 1.25 mg/mL, respectively. Furthermore, Structure-activity relationship analyses of 17 gallic acid and its structural analogs revealed that the R6position of the benzene ring was a key factor to their antibacterial activity against S. scabies, among which pyrogallol had the best antibacterial effect. Scanning electron microscopy showed that when S. scabieswas exposed to this gallic acid and its structural analogs, the cell membranes of which was damaged. The results will help promote the development and structural modification of plant-derived bacteriostatic agents.

The traditional Chinese herb Anoectochilus roxburghii (A. roxburghii)is well-known for its medicinal value, but few studies have reported its ability to combat metabolic syndrome activities in vitro. In this study, the extraction of seven compounds from A. roxburghiiusing 70% ethanol, RP-C18, thin layer chromatography (TLC), Sephadex LH-20, high performance liquid chromatography (HPLC) and subsequent identification of their structures through nuclear magnetic resonance (NMR). Among these compounds, kaempferol-3-O-rutinoside and isorhamnetin-3-O-α-l-rhamnopyranoside-7-O-β-d-glucopyranoside were obtained from A. roxburghiifor the first time. Results showed that those compounds inhibited key enzymes involved in metabolic syndrome in vitro. Molecular docking and binding free energy calculations were employed to elucidate the inhibition mechanism of these compounds, while SwissADME was used to assess their drug-like characteristics. Notably, 9-hydroxy-megastigma-4,7-dien-3-one-9-O-β-d-glucopyranoside has the potential as an α-amylase inhibitor for the first time. This research enriches the compound library of A. roxburghiiand provides new ideas for medication research and the development of metabolic syndrome.