Unveiling the Anti-Inflammatory Potential of Urena lobata: Insights into Nitric Oxide Suppression and Protein Targets

Urena lobata is recognized for its traditional medicinal use, particularly in addressing inflammation-related ailments. This study examined the anti-inflammatory properties of U. lobata extract and its fractions, focusing on their ability to suppress nitric oxide (NO) synthesis, a key mediator of inflammation. In vitro experiments using LPS-stimulated RAW 264.7 macrophages showed that the crude extract of U. lobata had an IC₅₀ of 58.05 ± 5.87 µg/mL, while the ethyl acetate fraction showed greater suppression of NO formation with an IC₅₀ of 31.40 ± 10.56 µg/mL. On the other hand, the n-butanol fraction and the water-soluble fraction did not have a significant effect on inhibition. Toxicity tests also showed that the n-hexane fraction was good at reducing NO formation (IC₅₀ of 49.73 ± 9.49 µg/mL), but was toxic to cells at higher concentrations (> 200 µg/mL). The ethyl acetate fraction also inhibited the formation of important pro-inflammatory mediators, such as inducible nitric oxide synthase (iNOS), interleukin (IL)-12, and tumor necrosis factor-alpha (TNF-α). Protein target analysis revealed 40 proteins associated with the inflammatory cascade as potential targets for active chemicals in U. lobata. Molecular docking studies identified quercetin, apigenin, and luteolin as key bioactive compounds with strong binding affinity for inflammation-related proteins such as AKR1B1, NOX4, and CDK5, which subsequently influence NO suppression during inflammation, suggesting a multi-target mechanism of action. These results emphasize the therapeutic potential of U. lobata and its bioactive chemicals as candidates for natural anti-inflammatory drug formulations, while also underscoring the need to evaluate potential cytotoxicity in future studies.