Vasculoprotective and vasodilatation effects of herbal formula (Sahatsatara) and piperine in spontaneously hypertensive rats

Background The herbal formula (Sahatsatara, STF), the Thai traditional poly-herbal recipe, has been used for treatment of muscle pain, anti-flatulence and numbness on hands and feet, with the caution when used in hypertensive patients. However, there is no scientific evidence to prove its effects on cardiovascular system. Piperine is the proposed major active compound in STF. It is shown to have antihypertensive effect in the L-NAME-induced endothelial dysfunction rats. Purpose This study investigated the pharmacokinetics, mechanism of action, as well as the hemodynamic and vasoactive effect and toxicity of STF and piperine using spontaneously hypertensive rats (SHR) and normal Wistar rats (NWR). Methods The amount of piperine in STF was measured by ultra performance liquid chromatography (UPLC). SHR and NWR were gavaged with piperine (50 mg/kg/day) or STF (100, 300, or 1000 mg/kg/day) alone or together with L-NAME (in drinking water) for 28 days. Hemodynamic effects were monitored by noninvasive tail cuff every 7 days. Vasorelaxation effect on the thoracic aorta in organ chamber was observed through force transducer at the end of the experiment. Biochemical parameters for kidney and liver toxicity were measured. In addition, pharmacokinetic study was performed using non-compartment analysis. Results The amount of piperine in STF was 1.29% w/w. Both STF and piperine did not affect blood pressure and heart rate in both SHR and NWR. Interestingly, STF and piperine increased acetylcholine-induced vasorelaxation of isolated thoracic aorta and have vascoluprotective effect in nitric oxide (NO) impaired rats. No liver or kidney toxicity was found in this study. Non-compartment pharmacokinetic analysis showed that the time to reach maximum concentration (T_max) of plasma piperine after administration of piperine and STF were 3.9 and 1.7 h, respectively. This result suggested that piperine in the recipe had better absorption than the pure standard piperine. Conclusions STF had no effect on blood pressure in both SHR and NWR. However, it was able to relax isolated thoracic aorta and had the potential for vasculoprotective effect in hypertensive and NO impaired condition. The effects of STF were comparable to those of piperine.