| Abstrakt: |
Anti-diabetic potential of a brown alga, Padina tetrastromatica, using bioassay-guided purification approach yielded the most active α-glucosidase inhibitor agents as fatty acids. Initially, α-glucosidase inhibition of the MeOH and 80% MeOH extracts were evaluated via a colorimetric assay. The liquid–liquid fractionation of 80% MeOH extract, as the most potent α-glucosidase inhibitor, resulted in four fractions: n-hexane, ethyl acetate, n-butanol and water. The hexane and ethyl acetate fractions were selected for further study with IC50 values of 38.0 ± 0.3 µg mL−1 and 53.7 ± 2.6 µg mL−1, respectively. α-Glucosidase inhibition of the sub-fractions from the hexane fraction using flash column chromatography gave F18-21 as the most potent enzyme inhibitor. After further purification of F18-21 by semi preparative HPLC, the mentioned fraction and two purified compounds, 8-octadecenoic acid (8) and all-cis-5,8,11,14-eicosatetraenoic acid (10) were identified by GC–MS analysis, resulting fatty acids 1-12. In addition, 1D and 2D NMR evaluations were performed for characterisation of 8-octadecenoic acid. Furthermore, three fatty acids, all-cis-8,11,14,17-eicosatetraenoic acid (6), cis-9,12-octadecadienoic acid (7), and all-cis-5,8,11,14,17-eicosapentaenoic acid (11), were isolated from the ethyl acetate fraction and identified by HPLC and GC–MS, respectively. Finally, α-glucosidase inhibition percent of the purified fatty acids were evaluated in two concentrations in microplates, showing their great potential for further investigation as anti-diabetic agents, in comparison with acarbose as the positive control. Furthermore, molecular docking analysis and MD simulation were used to investigate the structure activity of the purified compounds. [ABSTRACT FROM AUTHOR] |
