Triterpenes and Sterols from Leaves of Hoya meliflua Merr

Introduction: Hoya plants are also called wax plants due to the waxy appearance of their leaves and flowers. Most species are cultivated as ornamental plants. In the Philippines, there are at least 109 species of Hoya; 88 of these are endemic to the country. One of the endemic species is Hoya meliflua often confused with H. diversifolia, which can also be found in other countries. This study is part of our research on the chemical constituents of Philippine native Hoyas. Methods: The compounds were isolated by silica gel chromatography and identified by NMR spectroscopy. Results: Chemical investigation of the dichloromethane extract from the leaves of Hoya meliflua afforded squalene and mixtures of β-amyrin (1a), α-amyrin (1b) and lupeol (1c) in about 1:1:0.25 ratio; oleanone (2a), ursenone (2b) and lupenone (2c) in about 1:1:0.3 ratio; β-amyrin cinnamate (3a), α-amyrin cinnamate (3b) and lupenyl cinnamate (3c) in about 0.5:0.3:1 ratio; and β-sitosterol and stigmasterol in about 5:1 ratio. Conclusion: The results of our study indicate that Hoya meliflua shares similar chemical characteristics with other members of the genus Hoya. The triterpenes and sterols obtained from H. meliflua were also identified from other Hoya species. It is interesting to note that although most Hoya plants have no known biological activity and medicinal property, the compounds isolated from H. meliflua possess diverse bioactivities.