Phenolic Content and Biological Activities of Ethanol Extracts from Medicinal Plants in East Kalimantan, Indonesia

The Dayak tribe are the indigenous people of West Kutai, East Kalimantan, Indonesia, and they have experiences in using plants for traditional medicine and the commonly used plants include Baccaurea macrocarpa (Miq.) Mull.Arg., Entada phaseoloides (L.) Merr., Goniothalamus macrophyllus (Blume) Hook. f. & Thomson, Gynura crepidioides Benth., Helicia robusta (Roxb.) R. Br var. robusta, Litsea elliptica, Pogostemon cablin (Blanco) Benth, and Rhodomyrtus tomentosa (Aiton) Hassk. Therefore, the present study aimed to analyze these plant species for their phenolic content, and antioxidant, antibacterial, anti-tyrosinase, and anticancer activities. The total phenolic content and total antioxidant capacity were analyzed using Folin-Ciocalteu reagent and the phosphomolybdenum method, respectively. The antioxidant activities were evaluated by DPPH and ABTS assays. The antibacterial activity was determined by agar well diffusion and microdilution methods against six bacterial strains. The anticancer activity of the plant extracts was assayed against MDA-MB-231 human breast cancer cells. Based on the ethanol extraction, the highest yield was obtained from L. elliptica (10.42%), while H. robusta extract contained the highest phenolic content, antioxidant capacity, and antioxidant activities. All the extracts exhibited antibacterial activities against all the tested strains of bacteria, with the highest activity found in R. tomentosa extract, which also showed the highest activity against the cancer cells. The ethanol extract from E. phaseoloides exhibited tyrosinase inhibition activity (IC50 = 543.83 +/- 51.06 mu g/mL). The results herein suggested that the ethanol extracts from some medicinal plants from East Kalimantan have potential as antioxidant, antibacterial, anticancer, and anti-tyrosinase agents.