Loquat, native to East Asia, including Korea, has garnered attention for its potential health benefits. Loquat leaves have long been used in traditional medicine for their efficacy in conditions such as sore throat, bronchitis, and vomiting. They are also well known for their anti-oxidant, anti-inflammatory, and anti-diabetic properties. While physiological studies on the effects of loquat leaves are ongoing, research on its effects based on the timing of harvest remains inadequate. Therefore, in this study, inflammatory factors (nitric oxide, prostaglandin E2), inflammatory mediators (inducible nitric oxide synthase, cyclooxygenase-2), and pro-inflammatory cytokines (interferon-γ and tumor necrosis factor-α) were evaluated to confirm the anti-inflammatory efficacy of loquat leaf extracts (LLE) and the difference in efficacy according to the timing of the harvest. We also investigated the role of LLE in regulating nuclear factor kappa-B (NF-κB) and the mitogen-activated protein kinase (MAPK) signaling pathways involved in inflammation. Our results showed a decrease in the production of lipopolysaccharide-stimulated inflammatory factors and a decrease in the expression of inflammatory mediators and pro-inflammatory cytokines due to LLE irrespective of the timing of the harvest. Furthermore, LLE inhibited the protein phosphorylation of the NF-κB pathway and the activation of MAPK components, such as p38, extracellular signal-regulated kinase, and c-Jun N-terminal kinase. The anti-inflammatory effect of LLE does not vary with harvest timing, suggesting its potential use as an anti-inflammatory, functional food.

Keywords: loquat, anti-inflammatory, NF-κB/MAPK