CA is an ursane-type pentacyclic triterpene with a molecular formula of C30H48O4 and molecular weight of 473 g/mol. The 30-carbon skeleton comprises five six-membered rings (A−E). Structurally, CA is similar to ursolic acid, asiatic acid, and 23-hydroxyl CA. Differences between these four pentacyclic triterpenes are in R1 and R2 of C-2 and C-23, respectively.
CA was first isolated from the leaf of Lagerstroemia speciosa and later from the fruit of Crataegus pinnatifida. A literature search for plant species containing CA was conducted and several interesting trends emerged. Leaves of L. speciosa remain the most important source of CA . Surprisingly, no other species of the family Lythraceae, which L. speciosa belongs, have been reported. Among the 40 species reported in the literature, Rosaceae (16 species) and Lamiaceae (six species) are the dominant families. Species of Rosaceae belong to the genera of Agrimonia, Chaenomeles, Crataegus, Eriobotrya, Potentilla, Prunus, Pyrus, and Rubus. Species of Lamiaceae are of the genera Glechoma, Hyssopus, Orthosiphon, Perilla, Phlomis, and Salvia. This indicates that species of Rosaceae and Lamiaceae are rich in CA.
Native to South and Southeast Asia, L. speciosa is a semi-deciduous small- to medium-sized tree with obovate leaves that are opposite.During each rainy season, trees would produce flushes of new leaves that are brilliant red in color before turning green. Borne on large, axillary, or terminal panicles, the attractive flowers have wrinkled pink or purple petals and yellow stamens. Flowers emit a faint honey-like fragrance. Locally known as arjuna in India, bungur in Malaysia, Singapore, and Indonesia, ta-bak in Thailand, and banaba in the Philippines, L. speciosa is a common ornamental tree planted along roadsides, and in gardens and parks. The species has been traditionally used in folk medicine as a remedy for illnesses and ailments, particularly for lowering blood sugar level and reducing body weight, and as a remedy for diabetes.