Inhibition of lipoxygenase activity from Averrhoa Carambola L. leaf extracts

Objective: Inflammation is a protective response to tissue injury caused by physical trauma, harmful chemicals, or microbiological substances. Leukotriene, which originates in the lipoxygenase pathway, is a mediator of inflammation. Averrhoa carambola L. leave contains flavones, including apigenin, which exhibits potential anti-inflammatory activity through the inhibition of lipoxygenase activity. The present study aimed to examine the lipoxygenase inhibition activity of A. carambola leaf extracts. Methods: A. carambola leaf extracts were obtained using multilevel maceration using the solvents n-hexane, ethyl acetate, and ethanol. Subsequently, total flavonoid contents in the three extracts were determined using the colorimetric method. Apigenin content in the most active extract was determined using high-performance liquid chromatography. Results: The extract with the highest lipoxygenase inhibition activity was the ethyl acetate extract with an IC₅₀ value of 10.17±0.83 ng/mL followed by the n-hexane and ethanol extracts with IC₅₀ values of 40.99±0.51 and 35.61±0.66 ng/mL, respectively. Total flavonoid content from the n-hexane, ethyl acetate, and ethanol extracts was 3.01, 24.24, and 8.24 mg quercetin equivalent/g extract, respectively. A qualitative test using thin-layer chromatography showed that all extracts contained apigenin. The most active (ethyl acetate) extract contained 5.39% apigenin with a high-performance liquid chromatography method. Conclusion: The ethyl acetate extract of A. carambola leaf is the most active extract to inhibit lipoxygenase activity. Flavonoid content has a strong correlation to the inhibitory activity of each extract.