IN-VITRO ALPHA- AMYLASE INHIBITORY ACTIVITY, ANTIOXIDANT POTENTIAL, AND GC-MS ANALYSIS OF CREPE GINGER (COSTUS SPECIOSUS (J. KOENIG.) SM) LEAVES

The leaves of crepe ginger (Costus speciosus (J. Koeng.) Sm. are utilized by the Subanen tribe of Lapuyan, Zamboanga del Norte, Philippines to treat diabetes. However, the hypoglycemic potential of this plant is not yet well-established. Thus, the present study investigated the in-vitro alpha-amylase inhibitory and antioxidant activities of the leaves of C. speciosus. The evaluation of the alpha-amylase inhibitory activity was conducted in-vitro using soluble starch. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was employed in the evaluation of antioxidant activity. Total phenolics content was investigated using Folin-Ciocalteu reagent. The presence of phytoactive compounds that might contribute to its activities was determined through phytochemical screening and Gas chromatography – Mass spectrometric analysis. The results revealed that the leaf extracts exhibited alpha-amylase inhibitory potential and antioxidant activity which might be due to the presence of bioactive compounds such as eicosane, nonadecane, squalene, phenol, 2, 4-bis (1, 1-dimethylethyl), d-limonene, and hexadecanoic acid, ethyl ester. Negative and low correlation between DPPH scavenging activity and total phenolics content were obtained from both extracts. Nevertheless, the extracts may serve as source of natural antidiabetic and antioxidant agent.