Elucidating the antioxidant properties of Eleutherine palmifolia (L.), Merr, Arcangelisia flava (L.) Merr, and Myrmecodia tuberosa Jack / Shally Pilet

Eleutherine palmifolia (L.) Merr, Arcangelisia flava (L.) Merr, and Myrmecodia tuberosa Jack are indigenous plants traditionally used by the Dayak Iban tribe to treat various diseases as natural medicines. Previous research on these plants revealed a variety of bioactivities, including anticancer, antifungal, antidiabetic, and antibacterial effects. However, information on these plants is scarce. In addition, despite being prevalent in Borneo, M. tuberosa has received little interest in research unlike its other species from the same genus. This study aims to investigate the phytochemicals from E. palmifolia, A. flava and M. tuberosa using cold maceration and Soxhlet extraction. In this study, the weight of E. palmifolia, A. flava and M. tuberosa before extraction processes were 51.94 g, 87.83 g and 21.25 g respectively, which were grounded into powder and extracted using both extraction techniques using different solvents (n-hexane, chloroform, ethyl acetate and methanol). The total phenolic content (TPC), total flavonoid content (TFC), and radical scavenging assay (RSA) using 2,2-diphenyl-1-picrylhydrazyl (DPPH) were investigated to assess the antioxidant potential. The extraction of E. palmifolia, A. flava and M. tuberosa extracts yielded various crude extracts, with the methanolic extract of A. flava through cold maceration showing the highest RSA with IC50 value (10.06±2.89 µg/mL). The methanolic extract of M. tuberosa obtained using the Soxhlet method exhibited the highest RSA with IC50 value (78.89±7.13 µg/mL). For cold maceration, the ethyl acetate extract of M. tuberosa exhibited the highest TPC value (343.74±11.26 mg GAE/g extract), whereas the n-hexane extract of M. tuberosa obtained using the Soxhlet method displayed the highest TPC value (251.00±363.43 mg GAE/g extract). The TFC values varied across extracts, with the ethyl acetate extract of E. palmifolia through cold maceration displaying the highest TFC value (74.23±1.68 mg RE/ g extract). The n-hexane extract of E. palmifolia obtained using the Soxhlet method showed the highest TFC value (61.51±0.65 mg RE/ g extract). The antioxidant analysis showed that the methanolic extracts of A. flava obtained through cold maceration and methanolic extracts of M. tuberosa extracted from the Soxhlet method exhibited the uppermost capacity to inhibit free radicals by 50%. However, the cold maceration technique yields an extract richer in phenolic compounds than the Soxhlet extraction method.