Investigation of the Anti-inflammatory Activity of Four Leaf Extracts of Rhodomyrtus tomentosa Collected in Do Son, Hai Phong

Abstract

This study was conducted on Rhodomyrtus tomentosa (commonly known as Sim), collected from the hilly region of Do Son, Hai Phong, Vietnam. Dried leaf samples of R. tomentosa were subjected to ultrasonic-assisted extraction at room temperature using three solvents: water (RT-N2), ethanol (RT-Et), and methanol (RT-Me), as well as hot water extraction (RT-N1), yielding four different extracts. The anti-inflammatory activity of these extracts was evaluated via the inhibition of nitric oxide (NO) production in RAW 264.7 macrophage cells, in order to assess the therapeutic potential of R. tomentosa in inflammation-related conditions. The results indicated that three extracts RT-Me, RT-Et and RT-N1 are all exhibited moderate to weak anti-inflammatory activity, with IC₅₀ values ranging from 13.53 ± 0.95 µg/mL to 190.75 ± 6.30 µg/mL. In contrast, the RT-N2 extract showed negligible activity compared to the positive control L-NMMA (IC₅₀ = 3.45 ± 0.5 µg/mL). Among the tested extracts, the methanolic extract (RT-Me) demonstrated the most potent inhibitory effect, with an IC₅₀ value of 13.53 ± 0.95 µg/mL. These findings suggest that leaf extracts of Rhodomyrtus tomentosa, particularly the methanolic extract, hold promise for the treatment of inflammatory conditions and may provide a basis for further studies focusing on burn therapy.