We evaluated the acute (single-dose) and subacute (repeated-dose) oral toxicity of alcalase-hydrolyzed whey protein concentrate. Our acute study revealed no death or treatment-related complications, and the median lethal dose of whey protein concentrate hydrolysate was >2,500 mg/kg. In the subacute study, when the hydrolysate was fed at 3 different concentrations (200, 400, and 800 mg/kg), no groups showed toxicity changes compared with controls. Then, whey protein concentrate hydrolysate was orally administered to spontaneously hypertensive rats. Results revealed significant reductions in blood pressure in a dose-dependent manner, and dosing at 400 mg/kg led to significant blood pressure reduction (-47.8 mm Hg) compared with controls (blood pressure maintained) and the findings of previous work (-21 mm Hg). Eight peptides-RHPEYAVSVLLR, GGAPPAGRL, GPPLPRL, ELKPTPEGDL, VLSELPEP, DAQSAPLRVY, RDMPIQAF, and LEQVLPRD-were sequentially identified and characterized. Of the peptides, VLSELPEP and LEQVLPRD showed the most prominent in vitro angiotensin-I converting enzyme inhibition with half-maximal inhibitory concentrations of 0.049 and 0.043 mM, respectively. These findings establish strong evidence for the in vitro and in vivo potential of whey protein concentrate hydrolysate to act as a safe, natural functional food ingredient that exerts antihypertensive activity.
Poor aqueous solubility and unfavourable de-esterification of olmesartan medoxomil (a selective angiotensin II receptor blocker), results in low oral bioavailability of less than 26%. Improvement of oral bioavailability with prolonged pharmacodynamics activity of olmesartan in Wistar rats had been approached by nanoemulsification strategy in our previous article [Colloid Surface B, 115, 2014: 286]. In continuation to that work, we herewith report the biodistribution behaviour and 28-day repeated dose sub-chronic toxicity of olmesartan medoxomil nanoemulsion in Wistar rats following oral administration. The levels of olmesartan in collected biological samples were estimated using our validated LC-MS/MS technique. Our biodistribution study showed significantly higher brain concentrations of olmesartan (0.290 ± 0.089 μg/mL, 0.333 ± 0.071 μg/mL and 0.217 ± 0.062 μg/mL at 0.5, 2.0 and 8.0 h post dosing, respectively) when administered orally as nanoemulsion formulation as compared to the aqueous suspension. In addition, the olmesartan nanoemulsion was found to be safe and non-toxic, as it neither produced any lethality nor remarkable haematological, biochemical and structural adverse effects as observed during the 28-days sub-chronic toxicity studies in experimental Wistar rats. It is herewith envisaged that the developed nanoemulsion formulation approach for the delivery of olmesartan medoxomil via oral route can further be explored in memory dysfunction and brain ischemia, for better brain penetration and improved clinical application in stroke patients.