Alpha‑amylase inhibitory activity and phytochemical study of Zhumeria majdae Rech. f. and Wendelbo

Background: Zhumeria majdae (Lamiaceae) is an endemic species growing in the South parts of Iran especially Hormozgan province. The plant is so‑called Mohrekhosh locally and widely used for medicinal purposes including stomachache and dysmenorrhea. Objectives: In order to separation and identification of the main flavonoid glycosides of the plant (aerial parts including leaves, stems, flowers, and fruits were used) and evaluation of its alpha‑amylase inhibitory (AAI) activity, methanolic extract was prepared and fractionated to botanolic portion. Materials and Methods: Isolation of the main compounds of the butanol extract of the plant have been performed using different column chromatography methods such as high‑performance liquid chromatography (C₁₈ column) and Sephadex LH‑20 as well. The isolated compounds were identified by Hydrogen‑1 nuclear magnetic resonance and Carbon‑13 nuclear magnetic resonance spectra and comparison with those reported in previous literature. Moreover, inhibitory activity of the butanolic extract of the plant against alpha‑amylase enzyme was examined in different concentrations (15–30 mg/mL), where acarbose used as a positive control. Results: Three flavonoid glycosides: Linarin (1), hispidulin- 7-O-(4-O‑acetyl‑rutinoside) (2), hispidulin‑7‑O‑rutinoside (3) were successfully identified in the extract. The activity of alpha amylase enzyme was dose‑dependently suppressed by the butanol extract. The extract exhibited the highest inhibition at 30 mg/mL toward enzyme (77.9 ± 2.1%), while acarbose inhibited the enzyme at 20 mg/mL by 73.9 ± 1.9%. The inhibitory concentrations of 50% for the extract and acarbose were calculated at 24.5 ± 2.1 and 6.6 ± 3.1 mg/mL, respectively. Conclusion: Z. majdae contains glycosylated flavones and could be a good candidate for anti‑diabetic evaluations in animal and clinical trials due to possessing AAI activity.