Novel Natural Agents from Lamiaceae Family: An Evaluation on Toxicity and Enzyme Inhibitory Potential Linked to Diabetes Mellitus

Medicinal plants are rich sources for drug discovery. Occurrence of Diabetes mellitus is increasing because of changes in human lifestyle. So, design or discovery of new and more effective and safer drugs is needed. At the present study, the enzyme inhibitory effects of methanol extracts of selected Lamiaceae species (Salvia syriaca L., Teucrium polium L., Phlomis olivieri Benth., Nepeta ispahanica Boiss., Scutellaria tomentosa Benth., Salvia limbata C.A. Mey., Teucrium orientale L., Salvia atropatana Bunge., Salvia nemorosa, Salvia multicaulis Vahl., Ajuga chamaecistus Ging. ex Benth., Mentha longifolia L. and Satureja khuzestanica) were evaluated. The enzyme inhibitory activities were tested against α-amylase and α-glucosidase, which are linked to diabetes. Also, brine shrimp lethality assay was used to determine the cytotoxicity of the extracts. All methanol extracts showed moderate to high inhibitory effects on the tested enzymes. Scutellaria tomentosa and Mentha longifolia exhibited the strongest α-amylase and α-glucosidase inhibitory effects, respectively. These activities were ranged from 0.135 to 0.291 mmol in α-amylase assay and 1.256 to 6.640 mmol acarbose equivalents/g extract in α-glucosidase assay. The highest cytotoxic effect was observed for the extract of S. syriaca roots (LC50 = 12.3 μg/ml). The results suggest that these Lamiaceae species could be considered as a source of natural agents for the preparing of new pharmaceuticals and functional foods especially for the management of Diabetes mellitus.