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; IC50 = 8.17 μM) followed by compound 6 (12.7% at 10 μM; IC50 = 28.26 μM) exhibited significant activity, being more active than the positive control, L‐NMMA (19.5% at 10 μM; IC50 = 18.77 μM).