Detection of cyclotide peptides from selected medicinal plants as potentials for diabetes management: An ethnopharmacological approach

Abstract

Cyclotide peptides have been identified with versatile biological activities. Extracts were obtained with the standard method of cyclotide peptide extraction into acetonitrile: water (1:1) with few drops of TFA (Trifloroacetic acid). This study investigated alpha-amylase and alpha-glucosidase inhibitory properties of peptide extracts of fifteen plants selected from Nigerian ethnomedicine.  In-vitro tests were carried out in triplicate and data were analyzed using Microsoft Excel and GraphPad Prism5 software. The extracts showed varying degree of enzymes inhibitory activities. Crescentia cujete with IC₅₀ of 26.52 ± 0.54 μg/mL for alpha-amylase and 47.50 ± 0.12 μg/mL for alpha-glucosidase had highest inhibitory activities for both enzymes, compared with Acarbose with IC₅₀ of 23.60 ± 0.20 μg/mL and 57.6 ± 0.13 μg/mL for α-amylase and α-glucosidase inhibition, respectively. Lophira alata (37.60 ± 0.23 μg/mL), Detarium microcarpum (37.86 ± 0.22 μg/mL), Physalis angulata (44.12 ± 0.40 μg/mL) and Hibiscus tiliaceus (44.51 ± 0.41 μg/mL), also compared favourably with Acarbose for alpha-amylase inhibitory activities. Anchomanes difformis (33.26 ± 0.14), Detarium microcarpum (35.06 ± 0.13), Lophira alata (56.52 ± 0.21), exhibited higher alpha-glucosidase inhibitory activities than Acarbose (57.6 ± 0.13 μg/mL). The remaining extracts exhibited moderate to low enzymes inhibitory activities. Peptide extracts of the selected plants showcased potential as promising candidates for the development of anti-hyperglycemic agents.