Abstract
Phytochemical studies on the constituents of the rhizomes of Imperata cylindrica (Gramineae) were performed using high-performance liquid chromatography (HPLC). We also aimed to search for any biologically active substance capable of inhibiting nitric oxide (NO) formation in lipopolysaccharide (LPS)-activated macrophage 264.7 cells, by testing four compounds isolated from this plant. Four compounds, including a new chromone, isoeugenin, along with ferulic acid, p-coumaric acid, and caffeic acid were isolated and identified by NMR spectroscopy. The structure of isoeugenin was determined as 7-hydroxy-5-methoxy-2-methylchromone by the 2D-NMR technique. Among the four compounds, isoeugenin has the lowest IC50 value on the inhibition of NO production in LPS-activated macrophage RAW264.7 cells (IC50, 9.33 μg/mL). In addition, isoeugenin significantly suppressed the LPS-induced expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and proinflammatory cytokines mRNA levels. Taken together, these results suggest that the anti-inflammatory activity of isoeugenin is associated with the down-regulation of iNOS, COX-2, and pro-inflammatory cytokines in RAW264.7 cells. Accordingly, our results suggest that the new chromone isoegenin should be considered a potential treatment for inflammatory disease.
Highlights
Imperata cylindrica, called cogongrass, a traditional medicinal plant in Asia, is a widespread grass and is among the top 10 worst invasive weeds in the world
A singlet peak of H-3 at δ 5.60, the two doublet peaks of H-6 and 8 appearing as meta-coupled peaks (J = 1.8 Hz), together with a peak attributed to a OCH3 group at δ 3.93 (3H, s) suggests that compound 1 belongs to the chromone-type family of compounds
The molecular formula of compound 1 is the same as that of eugenin, its NMR data was different from other chromone-type compounds, compound 1 is different from known chromone-type compounds
Summary
Called cogongrass, a traditional medicinal plant in Asia, is a widespread grass and is among the top 10 worst invasive weeds in the world. Several compounds isolated from cogongrass exhibited medicinal properties, including anticancer properties, platelet aggregation inhibition, and hepatoprotective activities [1]. Several biologically active substances have been reported to be present in I. cylindrica. These include the 5-lipoxygenase inhibitor cylindol A, vasodilator cylindrene, platelet aggregation inhibitor imperanene, and neuroprotectives 5-hydroxy-2(2-phenylethyl) chromone and 5-hydroxy-2(2-(2-hydroxyphenyl)ethyl) chromone. Control of the production of proinflammatory cytokines and NO in macrophages are current research topics for the development of new anti-inflammatory agents. As a part of our on-going screening project to evaluate the anti-inflammatory potentials of natural compounds, we isolated four compounds from the rhizomes of I. cylindrica and investigated their anti-inflammatory effects on LPS-stimulated RAW264.7 macrophages
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