Isolation and screening endophytic bacteria producing α-glucosidase inhibitor from Sanrego plant (Lunasia amara Blanco)

Endophytic bacteria can be a potential source of new bioactive molecules which has medicinal properties like their host plant. One of the Indonesian herbs is Sanrego plant (Lunasia amara Blanco), which is empirically used as antidiabetic by people in South Sulawesi. This study aimed to isolate the endophytic bacteria producing α-glucosidase inhibitor from the Sanrego plant. The endophytic bacteria isolated from leaf and stem of Sanrego plant, and screening of the target bacteria using thin layer chromatography (TLC) with scopoletin as the control due to scopoletin is the secondary metabolite of the Sanrego plant which has antidiabetic activity by in-silico. Alpha-glucosidase inhibitory test carried out by colorimetric method using pNPG substrate, at 405 nm wavelength compared to acarbose. This study found 14 isolates from Sanrego leaf and 25 isolates from Sanrego stem. The ten isolates of them showed α- glucosidase inhibitory effect, which were three isolates from leaves (D1-D3) and seven isolates from stems (B1-B7). The appearance of the endophytic bacteria was circular, convex, and yellow in color; while the cell morphology mostly were Gram- positive bacteria. Statistical analysis indicated the D1 isolate had the highest inhibition value than the other isolates (ANOVA, p=0.002). Interestingly, the inhibition value of the D1 isolate (8.67%±2.56) was higher compared to acarbose (3.73%±1.23). It can be concluded that the endophytic bacteria from the Sanrego plant produce α-glucosidase inhibitor compound, and the D1 isolate can be further investigated its potency as a source of α-glucosidase inhibitor.