[Synthesis of derivatives of active compound from Ginkgo Semen and their anti-inflammatory activities]

GK-A is a new compound previously isolated by our research group from TCM Ginkgo Semen, which is traditionally used for relieving cough. Pharmacological results showed that it possessed good antitussive and anti-inflammatory activities, yet its low bioavailability is a significant problem. To search for candidate molecules with strong activity and high bioavailability, this study aimed to achieve this goal through structural modification. To evaluate the effects of different N-substituents in GK-A on the activity of active compounds, the study developed a concise synthetic route for these GK-A derivatives, synthesizing 15 derivatives(compounds 10-24) based on this route. Among these derivatives, compounds 10-21 were new compounds. An in vitro inflammatory model was established by inducing RAW264.7 cells with lipopolysaccharide(LPS). The cytotoxicity of different concentrations of the derivatives on mouse RAW264.7 macrophages was assessed using the CCK-8 assay to determine the appropriate dosing concentration. Nitric oxide(NO) levels in the cell supernatant were measured via the Griess assay, and the expression levels of inflammatory cytokines(interleukin-6(IL-6), tumor necrosis factor-α(TNF-α), and cyclooxygenase-2(COX-2) were detected by enzyme-linked immunosorbent assay(ELISA). The results showed that at a concentration of 100 μmol·L~(-1), all tested compounds significantly inhibited NO expression. Specifically, compounds 13 and 16 markedly reduced the expression levels of TNF-α, IL-6, and COX-2 in the cell supernatant. Compound 14 exhibited a significant inhibitory effect on TNF-α expression, while compound 17 significantly suppressed the expression of IL-6 and COX-2. These findings demonstrated that compounds 13, 14, 16, and 17 possessed promising anti-inflammatory activity in vitro. This discovery provides an experimental basis for screening antitussive drug candidates with high pharmacological activity, good bioavailability, and minimal side effects.