Rat health status affects bioavailability, target tissue levels, and bioactivity of grape seed flavanols

Studying the flavanol metabolism is essential to identify bioactive compounds, as beneficial effects of flavanols have been attributed to their metabolic products. However, host-related factors, including pathological conditions, may affect flavanol metabolism and, thus, their bioactivity. This study aims to elucidate whether hypertension affects grape seed flavanol metabolism, influencing their bioactivity in relation to hypertension.

Grape seed flavanols' effect on blood pressure (BP) was studied in spontaneously hypertensive rats (SHR) and healthy Wistar rats 6 h after grape seed extract administration (375 mg/kg). Animals were then sacrificed, and plasma bioavailability and aorta distribution of flavanol metabolites were studied by HPLC-MS/MS in both the groups. Grape seed flavanols were only able to decrease BP in SHR. Plasma total flavanol metabolites showed similar levels, being the difference noticed in specific metabolites' concentrations. Specifically, microbial metabolites showed quantitative and qualitative differences between both health states. Moreover, aorta total concentrations were found decreased in SHR. Interestingly, flavanol microbial metabolites were specifically increased SHR aortas, showing qualitative differences in small phenolic forms.

This study demonstrates important differences in bioactivity and target tissue metabolite levels between healthy and diseased rats, indicating potential metabolites responsible of the anti-hypertensive effect.