Natural products have been the center of attraction ever since they were discovered. Among them, plant-based natural products were popular as analgesics, anti-inflammatory, antidiabetic, and cosmetics and possess widespread biotechnological applications. The use of plant products as cosmetics and therapeutics is deep-rooted in Nepalese society. Although there are few ethnobotanical studies conducted, extensive research of these valuable medicinal plants has not been a priority due to the limitation of technology and infrastructure. Here, we selected 4 traditionally used medicinal plants to examine their bioactive properties and their enzyme inhibition potential. α-Glucosidase and α-amylase inhibitory activities were investigated using an in vitro model followed up by antioxidant and antimicrobial activities. The present study shows that ethyl acetate fraction of Melastoma melabathrium (IC₅₀ 9.10.3µg/mL) and water fraction Acacia catechu (IC₅₀ 9.00.6µg/mL) exhibit strong α-glucosidase inhibition. Likewise, the highest α-amylase inhibition was shown by crude extracts of Ficus religiosa (IC₅₀ 29.21.2µg/mL) and ethyl acetate fractions of Shorea robusta (IC₅₀ 69.31.1µg/mL), and the highest radical scavenging activity was shown by F. religiosa with an IC₅₀ 67.40.6µg/mL. Furthermore, to identify the metabolites within the fractions, we employed high-resolution mass spectrometry (LC-HRMS) and annotated 17 known metabolites which justify our assumption on activity. Of 4 medicinal plants examined, ethyl acetate fraction of S. robusta, ethyl acetate fraction of M. melabathrium, and water or ethyl acetate fraction of A. catechu extracts illustrated the best activities. With our study, we set up a foundation that provides authentic evidence to the community for use of these traditional plants. The annotated metabolites in this study support earlier experimental evidence towards the inhibition of enzymes. Further study is necessary to explore the clinical efficacy of these secondary molecules, which might be alternatives for the treatment of diabetes and pathogens.

Diabetes is a metabolic disorder of high blood sugar levels which leads to various chronic health-related complications. The digestive enzymes α-amylase and α-glucosidase play a major role in the hydrolysis of starch to glucose; hence, inhibiting these enzymes is considered an important strategy for the treatment of diabetes. Medicinal plants such as Bergenia ciliata, Mimosa pudica, and Phyllanthus emblica are commonly used in traditional remedies due to their numerous health benefits. This study aimed to determine the phytochemicals as well as TPC and TFC contents in these plant extracts along with their antioxidant and enzyme inhibitory activity against α-glucosidase and α-amylase. The ethyl acetate extracts of selected plants have shown higher TPC and TFC contents. The aqueous extract of B. ciliata (IC₅₀: 16.99±2.56μg/mL) and ethyl acetate extract of P. emblica (IC₅₀: 11.98±0.36μg/mL) and M. pudica (IC₅₀: 21.39±3.76μg/mL) showed effective antioxidant activities. Furthermore, ethyl acetate extract of B. ciliata showed significant inhibitory activity against α-amylase and α-glucosidase with IC₅₀ values of 38.50±1.32μg/mL and 3.41±0.04μg/mL, respectively. Thus, secondary metabolites of these medicinal plants can be repurposed as effective inhibitors of digestive enzymes.

Globally, obesity is a serious health concern that causes numerous diseases, including type 2 diabetes, hypertension, cardiovascular diseases, etc. Medicinal plants have been used to aid in weight loss since ancient times. Thus, this research is focused on the exploration of pancreatic lipase inhibitory activity and secondary metabolite profiling of Bergenia ciliata, Mimosa pudica, and Phyllanthus emblica, selected based on an ethnobotanical survey. The lipase inhibition was investigated using 4-nitrophenyl butyrate (p-NPB) as a substrate. To uncover further therapeutic potentials of these medicinal plants, antimicrobial activity and minimum inhibitory concentration (MIC) of the extracts were also determined. The ethyl acetate plant extracts showed higher antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella typhi, and Shigella sonnei. The MIC of ethyl acetate extracts of medicinal plants considered in this study ranges from 1.56 to 6.25 mg/mL. The hexane fraction of Mimosa pudica and Phyllanthus emblica showed a higher lipase inhibitory activity as compared to others, with IC₅₀ values of 0.49 ± 0.02 and 2.45 ± 0.003 mg/mL, respectively. In the case of Bergenia ciliata, the methanolic extract inhibited lipase more effectively than others, with an IC₅₀ value of 1.55 ± 0.02 mg/mL (IC₅₀ value of orlistat was 179.70 ± 3.60 µg/mL). A mass spectrometry analysis of various solvent/solvent partition fractions (extracts) revealed 29 major secondary metabolites. The research offers a multitude of evidence for using medicinal plants as antiobesity and antimicrobial agents.