Isolation and Structural Elucidation of Phytochemicals from Canarium luzonicum Leaves and Evaluation of Anti-Lung Cancer and Antileishmanial Activity

Canarium luzonicum (Blume) A. Gray, a tree endemic to the Philippines, is the source of Manila elemi, an oleoresin shown to have anti-infective properties owing to its rich terpenoid content. However, its leaves have not yet been subjected to in-depth phytochemical studies. C. luzonicum leaf compounds were isolated by multiple chromatographic techniques and elucidated by 1D and 2D NMR, MS, Polarimetry, IR, CD, and chemical reaction techniques. As a result, four new megastigmane glycosides, canariluzoniosides A–D (1–4), and two new monoterpenoid glycosides, canariluzoniosides E and F (5–6), were identified along with 29 additional known compounds. Canariluzonioside A (1) was a unique megastigmane featuring a tricyclic ring system. The new glycosides’ sugar moieties were obtained by acid hydrolysis and confirmed by HPLC-OR. Aglycones were liberated by enzymatic hydrolysis and were structurally characterized, one of which was the new compound, named canariluzonol A (1a). Finally, most compounds were screened for cytotoxicity against A549 human lung cancer cell line and for inhibition against Leishmania major promastigotes. Notable bioactivity was observed in known 3,4-seco-A-ring triterpenoids such as canaric acid and nyctanthic acid, for which revision of spectroscopic data is also proposed.