Effects of gamma‐irradiated soybean pod extract on oxidative stress, cancer cell viability, and tyrosinase inhibition

Soybean pods contain abundant dietary fiber and phytochemicals, including phenolic compounds. However, few bioactivity studies have been conducted using soybean pods, while soybean leaves, and seeds have been well characterized. In this study, the effect of gamma irradiation on the physiological properties of soybean pod extract (SPE) was investigated. SPE was irradiated at 0, 5, 10, and 20 kGy, and the phenolic compound concentration and antioxidant activity were investigated. The total phenolic compounds were increased and total flavonoids were decreased as the irradiation dose increased. Antioxidant activity, which was measured using the 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid, and 2-thiobarbituric acid reactive substances assays, improved as the irradiation dose increased. In addition, cancer cell viability, and tyrosinase activity were reduced by gamma irradiation. These results show that soybean pods can be utilized as functional food materials after gamma irradiation. Practical applications Gamma irradiation modified the chemical composition of soybean pod extract (SPE). Such irradiation improved the antioxidant, anti-pigmentation, and anti-carcinogenesis effects compared to those of control SPE. Therefore, this material, previously considered a byproduct of soybean processing, can be used as a functional food to prevent such disorders as oxidative damage, cancer, and hyperpigmentation.