Identification and anti-inflammatory activity of flavonoids from Cardiospermum halicacabum in murine RAW 264.7 macrophage-A bioassay-guided approach

Abstract

Cardiospermum halicacabum Linn. (CH), known as balloon vine, is used for food and medicinal purposes, including inflammation treatment. In Tamil cuisine, CH stems and leaves feature in curries, crepes, sauces, and soups. While CH's anti-inflammatory effects are documented, its therapeutic compounds are unclear. This study aims to isolate anti-inflammatory constituents from CH using a bioassay-guided approach. CH aerial part was extracted with three different solvents and evaluated for their anti-inflammatory activity. The active ethanol-water extract (CH-EW) was subjected to solvent-solvent partitioning to get five fractions. Among fractions, the methanol fraction (CH-EW-ML) showed potent anti-inflammatory as well as antioxidant activity along with high flavonoid content. Further fractionation of the active methanol fraction resulted in the isolation of two flavonoids, apigenin-7-O-β-D-glucuronide (AAG) and diosmetin-7-O-β-D-glucuronide (DMG). DMG was isolated from CH for the first time. The compounds were evaluated for their nitric oxide (NO) inhibition activity in the RAW 264.7 cell line. DMG showed the most potent activity (IC50 = 16.72 ± 1.01 μM). Further studies showed that DMG can inhibit the production of reactive oxygen species (ROS) and proinflammatory cytokines as well as upregulate the expression of anti-inflammatory cytokines. This study represents the first evidence that DMG can inhibit NO, ROS, TNF-α, and IL-6 while upregulating IL-10. Our findings suggest that incorporating CH infusion into the diet may alleviate inflammation, with DMG being a promising therapeutic component for its anti-inflammatory effects.