Leaf extracts of Carlowrightia cordifolia induce macrophage nitric oxide production

Carlowrightia cordifolia (Acanthaceae) is a medicinal plant used in northeastern Mexico as a traditional remedy against inflammation. As tissue release of nitric oxide (NO) has been correlated with both inflammatory and anti-inflammatory processes, the aim of this study was to determine the effect of C. cordifolia leaf extracts on macrophage NO production. Lipopolysaccharide (LPS)-stimulated and non-LPS-stimulated mouse peritoneal macrophages were incubated with aqueous, ethanol, methanol and hexane extracts of C. cordifolia leaves. All extracts inhibited NO release from LPS-stimulated macrophages, with methanol and hexane extracts showing the greatest inhibition. On the other hand, macrophage cultures treated with extracts without LPS-stimulation produced high releases of NO. These unexpected results suggest two different ways by which leaf extracts may act, depending on cell status. On the other hand, data on NO activity in relation to inflammatory/anti-inflammatory auto-regulatory feedback and high concentrations of NO release by non-stimulated macrophages agreed with the hypothesis that NO may have an inhibitory effect in vascular inflammation.