Fermented rice bran extract improves blood pressure and glucose in stroke-prone spontaneously hypertensive rats

Purpose The purpose of this study was to evaluate the in vitro and in vivo effects of three varieties of Indonesian fermented rice bran (RB) (Inpari 6, Inpari 30 and Inpara 1). Design/methodology/approach Three types of RB were fermented using Rhizopus oligosporus. The total phenolic content (TPC) was determined using the Folin–Ciocalteau method, and antioxidant activity was analyzed by measuring the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (RSA). For in vivo analyses, one week after acclimatization, stroke-prone spontaneously hypertensive rats (n = 4, 12 weeks of age) were divided into two groups and orally administered fermented RB (40 mg/kg body weight) or distilled water as a control after 16 h of fasting. Blood pressure (BP) was measured before and 2, 4 and 6 h after administration with a BP monitor without warming. Six days later, the rats were subject to the same procedure and sacrificed after 6 h of oral administration. Blood was collected and the plasma was separated to measure nitric oxide, glucose and insulin levels. Findings The highest TPC and RSA of fermented RB were obtained from Inpari 30 after incubation for 72 h (260.33 ± 0.39 mg GAE/100 g dry basis and 83.71 ± 0.61 per cent), respectively. Furthermore, single oral administration of fermented RB improved BP (p < 0.05) and glucose metabolism after 6 h of administration (p < 0.05). Originality/value This is the first study to evaluate the effects of fermented RB on improving high BP and glucose profiles by using a spontaneously hypertensive animal model.