Anti-inflammatory effect of longan seed extract in carrageenan stimulated Sprague-Dawley rats.

OBJECTIVES: Longan seeds have been used as a folk medicine in China. Longan seed extract (LSE) is known for antioxidative, antiproliferative, hypoglycemic, and hypouremic effects. However, its anti-inflammatory effect has not been shown.

MATERIALS AND METHODS: In this study, Sprague-Dawley (SD) rats were given LSE orally (vehicle, 10, and 30 mg/kg) for 3 days to its test anti-inflammatory effect by injecting λ-carrageenan (CARR) in the right hind paw or lipopolysaccharide (LPS), IP. For the positive control, animals were given aspirin (20 mg/kg) orally and treated likewise. Serum or tissue samples from treated rats were collected after 3 hr of stimulation. Regarding the in vitro study, BV2 microglial cells were stimulated with LPS in the presence of LSE or normal saline for 10 min or 24 hr for Western blot and ELISA assay, respectively.

RESULTS: LSE reduced CARR-induced edema in the experimental animals. LSE also reduced LPS/CARR-induced nitric oxide (NO), interleukin-1β (IL1β), IL6, and COX2 productions. These inflammatory factors were also reduced dose dependently by LSE in LPS-stimulated BV2 cells. Furthermore, Western blot analysis revealed that LSE inhibited LPS activated c-Jun NH2-terminal protein kinase (JNK), extracellular signal-regulated kinases (ERKs), and p38 MAP kinases signaling pathways, caspase-3, inducible NO synthase, and COX2 expressions.

CONCLUSION: LSE pretreatment suppressed CARR- and LPS-induced inflammations and these effects might be through the inhibition of MAP kinases signaling pathways and inflammatory factors.