Objective: To examine the effect of Capsicum spp extract (CEX) and capsaicin (CAP) on endothelial nitric oxide release and protection against lipopolysaccharide (LPS)-induced cellular apoptosis.
Material and method: Human umbilical vein endothelial cells (HUVEC) were isolated from newborn cords. Evaluation of cytotoxicity was performed by MTT assay. Endothelial nitric oxide (NO) production was evaluated by Griess reaction. Alteration in eNOS expression was detected by westernblot analysis. To induce oxidative stress and apoptosis, lipopolysaccharide (LPS) was coincubated with HUVEC in the presence or absence of CEX or CAP, and the vanilloid receptor blocker capsazepine (CZP). Hoechst nuclear staining was used to determine percent apoptotic nuclei.
Results: The highest concentrations of CEX (1000 microg/mL) and CAP (25 microM) used in the study did not induce cytotoxicity in HUVEC. Significant increase in NO release was observed when cells were incubated with CEX (100 microg/mL) and CAP (25 microM) and this effect was inhibited by CZP only in CAP treatment group. Despite enhanced NO generation was observed, western blot analysis indicated no change in eNOS expression. Interestingly, endothelial cells incubated with L-arginine (L-ARG, 1000 microg/mL) alone significantly showed increased NO production while L-ARG co-incubation abrogated CEX or CAP effects on endothelialNO generation. CEX (10 microg/mL) and CAP (1 microM) decreased apoptotic nuclei in HUVEC treated with LPS.
Conclusion: CEX and CAP improved endothelial function and protected against LPS-induced apoptosis. Regular consumption of Capsicum spp. may promote endothelial health and reduce cardiovascular disease risk.