Facile Synthesis and In Vitro Nitric Oxide Production Inhibitory Activity of Benzoxazoles

摘要

A Facile synthesis of natural benzoxazoles, nocarbenzoxazoles F (1), G (5) and their derivatives (2-4 and 6-8) was achieved from the commercially available inexpensive precursors with overall yields ranging from 15 to 49%. Our strategy to access this family of benzoxazoles was enabled by POCl3-mediated cyclodehydration, selective and/or complete demethylation and reduction as the key steps. Their in vitro nitric oxide (NO) inhibitory effect was further evaluated as an indicator of anti-inflammatory activity in LPS-induced RAW 264.7 cells and found to display weak to moderate activity in a concentration-dependent manner without marked cytotoxicity. Overall, compound 8 (53.5% at 10 μM; IC_(50) = 8.17 μM) followed by compound 6 (12.7% at 10 μM; IC_(50) = 28.26 μM) exhibited significant activity, being more active than the positive control, L-NMMA (19.5% at 10 uM; IC_(50) = 18.77 μM).