GC-MS analysis of metabolites from soxhlet extraction, ultrasound-assisted extraction and supercritical fluid extraction of <i>Salacca zalacca</i> flesh and its alpha-glucosidase inhibitory activity

<p>Different extraction processes were employed to extract bioactive metabolites from <i>Salacca zalacca</i> flesh by a range of aqueous and organic solvents. The highest extraction yield was obtained by 50% ethanol extract of SE (73.18 ± 4.35%), whereas SFE_1 showed the lowest yield (0.42 ± 0.08%). All extracts were evaluated for <i>in vitro</i> α-glucosidase inhibitory activity, measured by their IC<sub>50</sub> values in comparison to that of quercetin, the positive control (IC<sub>50</sub> = 2.7 ± 0.7 μg/mL). The lowest α-glucosidase inhibitory activity was indicated by water extract of SE (IC<sub>50</sub> = 724.3 ± 42.9 μg/mL) and the highest activity was demonstrated by 60% ethanol extract by UAE (IC<sub>50</sub> = 16.2 ± 2.4 μg/mL). All extracts were analysed by GC-MS and identified metabolites like carbohydrates, fatty acids, organic acids, phenolic acids, sterols and alkane-based compounds etcetera that may possess the potential as α-glucosidase inhibitor and may attribute to the α-glucosidase inhibitory activity.</p>