Optimized low-cost isolation of α-amyrin acetate from Alstonia boonei: toward scalable production of a bioactive triterpenoid.

Abstract

Alpha amyrin acetate is a pentacyclic triterpenoid with well-documented pharmacological activities, including anti-inflammatory, analgesic, antioxidant, hepatoprotective, antidiabetic, gastroprotective, and anticancer potentials. However, low yields and laborious purification steps from natural sources have limited its availability for advanced pharmacological studies. This study aimed to develop a simple, cost-effective, and efficient procedure by optimizing the isolation of α-amyrin acetate from Alstonia boonei stem bark with high yield and purity. Pulverized stem bark was extracted by maceration in absolute methanol and in methanol–dichloromethane (1:1) for 2–7 days. Extracts were filtered, and crude triterpenoids were precipitated via slow solvent evaporation. The crude precipitates were purified using Vacuum Liquid Chromatography (VLC) on silica gel with graded hexane–ethyl acetate solvent systems. The fractions were monitored by TLC. Methanol extracts yielded between 3.48–6.46% crude triterpenoids, with optimum yield from day 5. Methanol–dichloromethane extracts gave higher crude yields (6.46–8.16%), peaking at day 7. However, VLC purification revealed that methanol extracts produced significantly higher yields of pure α-amyrin acetate, with the highest recovery (26.52% of crude triterpenoid) while the mixed solvent system yielded a maximum of 10.29%. Maceration in methanol for six days followed by precipitation and VLC purification provides a simple, low-cost, and efficient method for isolating α-amyrin acetate from A. boonei. The optimized protocol reduces the number of purification steps, improves selectivity, and enables the recovery of sufficient quantities for pharmacological and toxicological studies.