Anti-inflammatory screening of new carvone enantiomer derivatives

Abstract

Introduction: Chronic low-grade inflammation has been associated with a wide range of aging-related diseases. Thus, new molecules capable of interfering with inflammation signaling pathways are urgently needed. Our previous work showed that carvone enantiomers were the most potent compounds in inhibiting lipopolysaccharide (LPS)-induced-nitric oxide (NO) production in the Raw 264.7 cell line [2]. However, the low molecular weight, high volatility and low water solubility of carvone enantiomers could lead to difficulties in its pharmaceutical development. Therefore, previous chemical modifications of carvone enantiomers were reported but those affected their potency [3]. Thus, the aim of this work was to synthesize new ester derivatives in positions C8 and C9 of carvone and evaluate their anti-inflammatory activity. Material & Methods: Chemical derivatives of carvone enantiomers were synthesized, purified and their chemical structures confirmed. The ability of the synthesized compounds to interfere with NO production was evaluated by the Griess reaction. For that, the murine macrophage cell line, Raw 264.7, stimulated with bacterial LPS was used as a cell model of inflammation. Non-cytotoxic concentrations of each compound were selected by the resazurin reduction assay. Results are presented as means ± SEM. Statistical analysis was performed by one-way ANOVA with the Dunnett post-test for comparison to a control group and the Tukey post-test for multiple comparisons. Results were considered statistically significant at p < 0.05. Results: Among the carvone enantiomer derivatives synthesized, four compounds were further evaluated for their anti-inflammatory activity. All the compounds tested were able to decrease LPS-induced NO production in a concentration dependent manner, with IC50 values ranging from 76 to 406 µM. The IC50 value of one compound was not calculated because only one of the tested concentrations did not cause cytotoxic effects. Some of the test compounds showed higher potency than the parent compounds. Conclusions: The results pointed out that the chemical modifications done, in particular in position 9 of the S enantiomer, yield compounds with physicochemical properties and improved potency relative to the parent compound. Nevertheless, further studies are needed to validate the anti-inflammatory potential of these compounds as well as to explore the mechanism of action behind their effects. References: [1] Robinson et al., Nat Rev Rheumatol, 2016. 12(10): p. 580-92. [2] Sousa et al., Sci Rep, 2020. 10(1): p. 7199; [3] Moço et al., Int. J. Mol. Sci, 2023. 24: 2263.