Effect of honey, as a natural deep eutectic solvent, on the phytochemical stability and anti-inflammatory activity of Eurycoma longifolia Jack†

The use of Eurycoma longifolia Jack (EL) in combination with honey is widely recognized in conventional medicine because of its aphrodisiac and pyretic properties. However, the effects of honey, a natural deep eutectic solvent (NADES), on the phytochemical stability and anti-inflammatory activity of EL remain unknown. This study aimed to investigate the effect of honey on phytochemical and anti-inflammatory effects of EL. The stabilities of bioactive compounds, including eurycomanone (EU), 9-hydroxycanthine-6-one (9HCO), and 9-methoxycanthine-6-one (9MCO), were evaluated after treating EL with honey. The anti-inflammatory activity was assessed by measuring the inhibition of NO production in lipopolysaccharide-induced RAW264.7 macrophages. The EL formulations treated with honey exhibited significantly higher yields of EU and 9HCO; however, a decrease in 9MCO was observed. After a 90 day infusion, the anti-inflammatory activities of honey-treated EL (9.19–68.73% NO inhibition) and simulated honey-NADES-treated EL (5.37–66.68% NO inhibition) were slightly lower than that of the non-treated EL extract (10.34–77.93% NO inhibition). Nonsugar honey constituents also exhibited anti-inflammatory effects. The combination of EL extract and honey resulted in a slightly lower anti-inflammatory activity (11.66–68.55% NO inhibition) compared with the EL extract. Honey and NADES enhanced the extraction and stabilization of bioactive compounds from EL. The anti-inflammatory properties of EL were preserved after honey treatment, indicating that honey-treated EL is a potential natural treatment for inflammatory conditions.