Corn silk aqueous extracts and intraocular pressure of systemic and non-systemic hypertensive subjects

BackgroundHypotensive properties have been attributed to the stigma/style of Zea maysL (corn silk). Although the effect of corn silk extract on blood pressure has been documented in animal studies, we are not aware of any study on its effect on human blood pressure and intraocular pressure. MethodsA randomised study was carried out on the effect of water only, masked doses of corn silk aqueous extract (60, 130, 192.5 and 260mg/kg body weight) on intraocular pressure and blood pressure of 20 systemic and 20 non-systemic hypertensive subjects. Intraocular pressure and blood pressure were measured at baseline and every hour for eight hours after administering water or a masked dose of corn silk aqueous extract. Each dose was administered at two-week intervals to each subject in the two study groups. ResultsThe results showed that the last three doses of corn silk aqueous extract gave a statistically significant reduction (p < 0.001) in mean intraocular pressure and blood pressure within eight hours of administration. The peak effect on intraocular pressure was observed after four hours and this was preceded by the peak effect on blood pressure, which occurred after three hours of administration. The hypotensive effect was dose-dependent in the two groups. ConclusionCorn silk aqueous extract has a lowering effect on intraocular pressure in systemic and non-systemic hypertensive subjects. This may have resulted from the fall in blood pressure that is due to potassium-induced natriuresis and diuresis caused by the high potassium content in the high doses of the corn silk extract.