Quantification of cucurbitacins B and E in <i>Coccinia grandis</i> fruit ethanolic extract and their anti-inflammatory effects in SARS-CoV-2 protein-stimulated macrophages

Food-derived bioactive compounds are increasingly being recognized for their potential in modulating inflammatory responses associated with post-infectious health conditions. Ivy gourd (Coccinia grandis), a vegetable belonging to the cucumber family (Cucurbitaceae), is widely consumed in Southeast Asia and has been reported to contain cucurbitacins exhibiting anti-inflammatory properties. However, their composition and biological relevance in viral protein-induced inflammation remain unclear. In this study, cucurbitacin B and cucurbitacin E were quantified in C. grandis fruit extract using validated HPLC–UV analysis, and their anti-inflammatory effects were evaluated in SARS-CoV-2 receptor-binding domain (RBD)-stimulated RAW 264.7 macrophages. Cucurbitacin B and cucurbitacin E contents were 0.16 ± 0.01 and 0.11 ± 0.01 mg/g dry weight, respectively. RBD stimulation significantly increased nitric oxide (NO) production by approximately 5-fold compared with the untreated control (p < 0.05). Treatment with C. grandis extract at 200 µg/mL reduced NO levels by 51.96 ± 1.33%, while treatment with cucurbitacin B and cucurbitacin E at 5 and 50 µM, respectively, inhibited NO production by 78.52 ± 1.89% and 68.71 ± 2.21%, respectively. RBD elevated inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) expression by 25-, 50-, and 30-fold, respectively, which were significantly suppressed by cucurbitacin B, cucurbitacin E, and C. grandis extract. Cell viability remained above 80% at all tested concentrations. Cucurbitacin B exhibited the strongest inhibitory effect. These findings highlight C. grandis fruit as a dietary source of anti-inflammatory bioactive compounds and support its potential application as a functional food and nutraceutical ingredient.