Antioxidants and Radical Scavenging Activities of Nigerian Soybeans (Glycine max (L.) Merr.)

Aim: To evaluated the antioxidant and radical scavenging ability of three different accessions (TGx-1835-10E, TGx-1987-62F and TGx 1951-3F) of soybean.

Study Design: In vitro evaluation of antioxidant assays: Total phenol, Total flavonoid, Total antioxidant capacity, Ferric reducing antioxidant capacity, Cupric reducing antioxidant capacity, Ferrous Ion-chelating Ability, 2, 2-Diphenyl-2-Picryl-Hydrazyl (DPPH) and Nitric oxide (NO) radical scavenging activities.

Place and Duration: Department of Biochemistry, Obafemi Awolowo University, Ile-Ife, Nigeria (August–December, 2016).

Methodology: Hydroalcoholic crude extracts of TGx-1835-10E, TGx-1987-62F and TGx 1951-3F were obtained through soxhlet apparatus using 80% methanol and concentrated in a rotary evaporator at 4°C. The crude extract was then subjected to different antioxidant assays (Total phenol, Total flavonoid, Total antioxidant capacity, Ferric reducing antioxidant capacity, Cupric reducing antioxidant capacity, Ferrous Ion-chelating Ability , DPPH and NO radical scavenging activities.) following standard procedures.

Results: The results shows that TGx 1951-3F elicited the highest DPPH and NO radical scavenging activity with IC50 value of 2.61± 0.02 mg/ml and 2.58 ± 0.02 mg/ml, compared to TGx-1835-10E and TGx-1987-62F. Similarly, Ferrous Ion-chelating Ability (FIC) of TGx 1951-3F was higher with IC50 value of 1.38 ± 0.07 mg/ml, compared to TGx-1835-10E and TGx-1987-62F with an IC50 of 1.86 ± 0.16 and 2.07 ± 0.16 mg/ml. The reducing power of the three accessions expressed in terms of ascorbic acid equivalent tested using FRAP, TAC and CUPRAC assays showed that TGx 1951-3F has highest antioxidant activity follow by TGx-1835-10E and TGx-1987-62F. This same trend was also observed in antioxidant constituent present in the samples as TGx-1951-3F has higher phenolic and flavonoid content compared to TGx-1835-10E and TGx-1987-62F.

Conclusion: The result of this present study revealed that Accession TGx 1951-3F elicit the highest antioxidant potential nevertheless, accessions TGx-1835-10E and TGx-1987-62F also contain significant amounts of flavonoids and phenolic compounds. Consequently, the plant seeds might be an important source of natural antioxidant, and helpful in prevention and management of various diseases associated with oxidative stress.