Phytochemical Screening, Antioxidant and Alpha-Amylase Inhibitory Activities of Clitoria ternatea and Melastoma malabathricum Flower Extracts

Abstract

Diabetes mellitus is a chronic disease partly caused by the imbalance between reactive oxidative stress (ROS) and endogenous antioxidant activity in the body. This study focuses on two edible flowers commonly used in traditional medicine in Malaysia namely Clitoria ternatea (bunga telang) and Melastoma malabathricum (bunga senduduk). Although considerable studies have separately shown that these flowers have high nutritional value and beneficial bioactive compounds, direct comparisons on the phytochemical, antioxidant and alpha amylase inhibitory properties of these flowers remain limited. Thus, the present study aims to examine the in vitro phytochemical constituents, antioxidant and alpha amylase inhibitory properties of both flowers. The flowers were collected, air-dried, and grounded followed by extraction using 70% ethanol. Phytochemical studies conducted were total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC). Additionally, DPPH radical scavenging assay and alpha-amylase inhibition assay were done to assess the antioxidant and in vitro antidiabetic properties, respectively Clitoria ternatea had a markedly elevated TPC: 23.54 ± 3.26 mg GAE/g, TFC: 7.28 ± 0.39 mg QE/g, TAC: 53.39 ± 5.64 mg C3G/100 g, DPPH radical scavenging, IC₅₀ : 770.99 ± 19.29 ug/ml and alpha-amylase inhibition, IC₅₀ : 276.11 ± 63.81 ug/ml while Melastoma malabathricum with TPC: 67.05 ± 0.95 mg GAE/g, TFC: 14.48 ± 0.76 mg QE/g, TAC: 34.98 ± 1.39 mg C3G/100 g, DPPH radical scavenging, IC₅₀ : 100.21 ± 8.29 ug/ml and alpha-amylase inhibition, IC₅₀ : 590.68 ± 14.40 ug/ml. Statistically significant differences were indicated by independent t-test results (p < 0.05). Preliminary findings indicate that C. ternatea and M. malabathricum flowers are good candidates as natural sources of antioxidants and antidiabetic agents, which further supports towards understanding their therapeutic benefits.