Anti-inflammatory effects of water extract from bell pepper (Capsicum annuum L. var. grossum) leaves in vitro

Fruits and vegetables have been recognized as natural sources of various bioactive compounds. Peppers, one such natural source, are consumed worldwide as spice crops. They additionally have an important role in traditional medicine, as a result of their antioxidant bioactivity via radical scavenging. However, there are no reports regarding the bioac­tivity of the bell pepper (Capsicum annuum L. var. grossum), a commonly used edible vegetable. The present study aimed to evaluate the anti-inflammatory effect of water extract from bell pepper leaves on mouse spleen cells, and explore the potential mechanism underlying this effect. The extract was prepared through homogenization of bell pepper leaves in deionized water. The sterilized supernatant was added to a mouse spleen cell culture stimulated by concanavalin A. Following 72 h of culture, the levels of inflammatory cytokines in the culture supernatant were measured using a sandwich enzyme-linked immunosorbent assay system, and levels of inflammatory proteins were assessed using western blotting. The bell pepper leaf extract significantly inhibited inflammatory cytokine production, inhibited cell proliferation without producing cytotoxicity, and suppressed the expression of inflammatory proteins. These results suggest that components of the bell pepper leaf extract possess anti-inflammatory activity. The study of the anti-inflammatory mechanism of bell pepper leaf extract has provided useful information on its potential for therapeutic application.