Anti-inflammatory property of Parkia speciosa empty pod extract in human umbilical vein endothelial cells

Parkia speciosa Hassk, locally known as petai papan, is a common medicinal plant found in Southeast Asia. Its empty pods were reported to contain high concentrations of polyphenols, particularly quercetin. This study aimed to evaluate the anti-inflammatory properties of P. speciosa empty pod extract in human umbilical vein endothelial cells (HUVECs). The empty pods were extracted by sequential fractionation with absolute ethanol and ethyl acetate. HUVECs were divided into four groups. HUVECs were exposed to tumor necrosis factor-α (TNF-α, 10 ng/mL) in the presence (25 μg/mL) or absence of Parkia speciosa extract. Quercetin (125 μM) served as the positive control, while another group that was not exposed to TNF-α acted as the negative control. The protein expressions of the inflammatory mediators, which were NF-κB p65, iNOS, COX-2 and VCAM-1, were significantly decreased in the P. speciosa and quercetin groups exposed to TNF-α. P. speciosa extract and quercetin also significantly reduced intracellular reactive oxygen species and nitric oxide levels as well as inducible nitric oxide synthase (iNOS) activity caused by TNF-α in HUVECs. In conclusion, P. speciosa empty pod extract exhibited potential anti-inflammatory properties against TNF-α-induced inflammation, possibly by modulating the NF-κB p65 pathway. The effects were comparable to that of quercetin.