Neuritogenic and neuroprotective constituents from Aquilaria crassna leaves

The leaves of Aquilaria crassna (Thymelaeaceae) are recently become an attractive research due to their potential in antioxidative, antibacterial, antipyretic, analgesic, and laxative activities. However, the neuritogenic and neuroprotective effects of A. crassna leaves have never been reported. In this study, three phenolic glycosides were isolated from A. crassna leaves. The isolates were identified as genkwanin 5-O-β-primevoside (1), iriflophenone 3,5-C-β-d-diglucoside (2) and iriflophenone 3-C-β-d-glucoside (3). The neuroprotective and neuritogenic activities of these compounds were evaluated. Compound 1 and 2, at very low concentration (100 ng/mL of compound 1 and 1 ng/mL of compound 2), exhibited the protection of P19-derived neurons and promoted the neurite outgrowth of the cultured neurons. In addition, a preliminary study on these compounds revealed that there was no correlation between their antioxidative properties and their neuroprotective activities. Practical applications: Agarwood leaves have been used as an ingredient in foods and drinks for health promotion in Asian countries. The results of this study also suggest that Aquilaria crassna leaves are potentially sources of neuritogenic and neuroprotective constituents, which may be developed as functional foods for the prevention of neurodegenerative disorder.