Phytochemical profile and antioxidant capacity of some wild edible plants consumed in Southwest Ethiopia

Abstract

Wild edible plants (WEPs) such as Solanum nigrum L., Vigna membranacea A. Rich., Dioscorea praehensilis Benth., Trilepisium madagascariense DC., and Cleome gynandra L. are widely used for various forms of culinary and folk medicine in Southwest Ethiopia. However, the phytochemical content of these plants is not explored. Thus, this study aimed to determine the total phenols, flavonoids, antioxidants, vitamin C, and β-carotene in edible parts of the plants. Edible parts were oven-dried and extracted with methanol. Total phenolic content (TPC) and total flavonoid content (TFC) were determined using Folin Ciocalteu and Aluminium chloride colorimetric methods, respectively. In vitro, antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) tests. β-carotene and vitamin C content were assessed using spectrophotometric and titration, respectively. TPC ranged from 0.25 ± 0.06 mg GAE/g in D. praehensilis tuber to 35.73 ± 2.52 mg GAE/g in S. nigrum leaf, while TFC varied from 0.85 ± 0.03 to 11.25 ± 0.01 mg CE/g in D. praehensilis tuber and C. gynandra leaf. In the DPPH assay, the antioxidant value ranged from 50.09% in D. praehensilis tuber to 87.63% in S. nigrum leaf; while in the FRAP assay, the value ranged from 49.16 ± 2.13 in D. praehensilis tuber to 188.12 ± 1.13 mM Fe2+/100 g in S. nigrum leaf. Similarly, β-carotene content was recorded between 11.81 ± 0.00 mg/100g in D. praehensilis tuber to 34.49 ± 0.95 mg/100g in V. membranacea leaf. The concentration of vitamin C ranged from 10.00 ± 0.61 in D. praehensilis tuber to 45 ± 1.80 mg/100g in V. membranacea leaf. The results showed strong positive correlations between FRAP and TPC (r = 0.94), and FRAP and vitamin C (r = 0.93). S. nigrum and C. gynandra contain abundant levels of TPC and TFC. V.membranacea leaf contains a good source of vitamin C and β-carotene. These WEPs contribute a natural supply of dietary antioxidants that prevent oxidative stress.