Effect of fresh papaya leaf extract on vascular smooth muscle

Abstract

Carica papaya is a common tree or shrub cultivated across various tropical counties including India mainly for its ripe or unripe fruit although multiple parts of the plant have been in use of late. Papaya leaves have been used in traditional medicine for the treatment of Dengue fever. The use of C. papaya leaf juice had been shown to improve the platelet count in patients suffering from dengue fever. The increase in platelet count may be due to direct effect on bone marrow or due to release of sequestered splenic platelets as a result of its contraction brought about by the juice. In his study, we assessed whether C. papaya fresh leaf aqueous extract (FLP-AE) has any direct effect on vascular smooth muscle using an isolated goat artery preparation in the form of a spiral arterial strip. This strip was suspended in an organ bath containing bicarbonate Ringer at 37 degree C and aerated with carbogen. The change in tone was recorded by an isometric force transducer connected to a data acquisition system (PowerLab). A resting tension of 2 g was applied and tissue allowed to equilibrate for 30 minutes following which viability was assessed by using high potassium bicarbonate Ringer. Intervention in the form of FLP-AE 140 mg in 20 ml bicarbonate Ringer was given (n-6). To rule out the effect of any ions (like potassium) present in the aqueous extract, chloroform extract was also used in two experiments. The results showed that FLP-AE in the dose of 140 mg in 20ml, did not cause significant change in vascular tone as compared to values obtained when tissue was perfused with bicarbonate ringer (P- 0.188, n- 6). The experiments performed with the chloroform extract also corroborated well with the results obtained from the aqueous extract. We therefore conclude that fresh papaya leaf extract does not cause change in contractility of vascular smooth muscle and hence the increase noted in platelet count following consumption of fresh papaya leaf juice may not be due to splenic contractions.