Peppermint oil

Dose-dependent antispasmodic effect of peppermint oil is largely mediated by its menthol constituent. It is proposed that peppermint oil relaxes gastrointestinal smooth muscle and attenuates contractile responses by reducing the influx of extracellular calcium ions. In rabbit jejunum smooth muscle cells investigated via whole cell clamp configuration technique, peppermint oil was shown to inhibit the potential-dependent calcium currents in a concentration-dependent manner. Both a reduction in peak current amplitude and an increase in the rate of current decay were observed, indicating that the pharmacological activity peppermint oil resembles that of dihydropyridine calcium antagonists. In a rat small intestine study, peppermint oil in the intestinal lumen inhibited enterocyte glucose uptake via a direct action on the brush border membrane and inhibited intestinal secretion. There is also evidence that menthol is an antagonist of L-type Ca2+ channels via interacting with dihydropyridine binding sites and blocks the currents of low-voltage-activated calcium channels. Peppermint oil may facilitate hair growth by promoting the conservation of vascularization of hair dermal papilla, which may contribute to the induction of early anagen stage of active growth phase of hair follicles.