Antihypertensive activity of spray-dried nanoemulsion containing Asiatic acid-Palm oil in high salt diet-fed rats

Abstract

Asiatic acid (AA) is a compound isolated from Centella asiatica, which possesses significant antihypertensive activity. Several studies have shown that its hypertensive activity can be attributed to various mechanisms, such as Angiotensin-Converting-Enzyme (ACE) inhibition in the renin-angiotensin-aldosterone system (RAAS) pathway. Meanwhile, palm oil (PO) is an antioxidant, which has proven to have synergistic effects with the compound by preventing arterial thrombosis and atherosclerosis. Despite these synergistic effects, AA dosage in antihypertensive therapy has been reported to be relatively high compared to the common synthetic drug captopril. Therefore, this study aimed to produce spray-dried powder of nanoemulsion to enhance the solubility of AA, decrease the possibility of oxidation, and increase its activity. Redispersed AA nanoparticles were also successfully obtained during the synthesis process. Several evaluations were carried out, including particle size, particle distribution, zeta potential, cell viability, and antihypertensive activity in rats to ensure the improvement of physicochemical characteristics and activity as antihypertensive agent. The results showed that AA succeeded in forming nanoemulsion with excipients. In addition, it was encapsulated in a maltodextrin carrier, exhibiting good physicochemical characteristics and safety to the Caco-2 cells. The redispersion of the spray-dried powder yielded nanoparticles with a size of 217.4 ± 10.196 nm. The spray-dried nanoemulsion of AA also had faster effect than non-formulated AA (raw powder) in lowering the blood pressure of hypertensive Sprague-Dawley (SD) rats. Graphical abstract: