Suppressive Effect of a Proanthocyanidin-rich Extract from Longan (Dimocarpus longan Lour.) Flowers on Nitric Oxide Production in LPS-Stimulated Macrophage Cells

Abstract

Anthocyanidins found in certain flowers have been shown to act as strong antioxidants in various systems, exhibiting multiple biological actions. The antioxidative effects of water extract and ethanolic extract of longan (Dimocarpus longan Lour.) flowers were evaluated by radical scavenging activity and compared to those of gallic acid, myricetin, and epigallocatechin gallate. In this study, the suppressive effects of longan flower extracts on nitric oxide and prostaglandin E2 production were investigated using a lipopolysaccharide-stimulated RAW 264.7 cell model. Abundant levels of phenolic compounds including flavonoids, condensed tannins, and proanthocyanidins were found in water or ethanolic extracts prepared from dried longan flowers. The antioxidative effect of longan flower extract was similar to the effect exhibited by pure antioxidants. Moreover, longan flower extract showed prominent inhibitory effects on prostaglandin E2 production. Significant concentration-dependent inhibition of nitric oxide production was detected when cells were cotreated with lipopolysaccharide and various concentrations of longan flower extracts. These inhibitory effects were further attributed to suppression of inducible nitric oxide synthase protein expression and not to reduced enzymatic activity. These results suggest that longan flower crude extracts, especially ethanolic extract, have antioxidant and anti-inflammatory effects, and the probable mechanism involves inhibition of inflammation by proanthocyanidins. Preliminary observations suggest that longan flower extract, especially alcoholic extract, could be another potential source of natural dietary antioxidant and anti-inflammatory agent.

Polymeric proanthocyanidins from Sicilian pistachio (Pistacia vera L.) nut extract inhibit lipopolysaccharide-induced inflammatory response in RAW 264.7 cells

“…Values not sharing the same letter were significantly different (p \ 0.05, Fisher's test) PGE 2 , and TNF-a, with oligomers poorly effective with respect to polymers that contributed almost entirely to the HPE activity. These data may be the reflection of the amounts of proanthocyanidins assayed and/or indicate a different ability of oligomers and polymers to affect the macrophage response, as observed in other researches [44,[46][47][48][49]. To further highlight the role of these components, PF was also found almost effective as the whole HPE in inhibiting phosphorylation, and then activation, of IjB-a.…”

Potential roles of longan flower and seed extracts for anti-cancer

“…We have demonstrated that the hot water reflux or ethanol extract of the longan flower, contained abundant proantocyanidins and rarely anthocyanins, suppresses nitric oxide and prostaglandin E2 production in lipopolysaccharide -stimulated macrophage cell line RAW264.7 and may be the potential source of natural dietary anti-oxidants and antiinflammatory agent [20] . The longan flower extract (LFE), analyzed by Professor Hwang and colleagues, exhibits a strong anti-oxidant activity, which is mainly due to (-)epicatechin and proanthocyanidin A2 [26] .…”

“…Non-steroidal antiinflammatory drugs have been documented in animal and human studies to reduce the risk of colorectal cancer and adenomatous polyps and have been implicated as a cancer prevention and treatment strategy [1,[17][18][19] . Longan flowers and seeds have been analyzed and were found to possess rich amounts of polyphenols, including proanthocyanidin A2, (-)-epicatechin, gallic acid and ellagic acid, and exhibit strong antioxidant and inflammatory activities [20][21][22][23][24] . Recently, several studies by our research group have further revealed that longan flower and seed extracts exhibit an anti-cancer activity towards colorectal, liver, lung, cervical and breast cancer.…”

Anti‐inflammatory and anti‐insulin resistance activities of aqueous extract from Anoectochilus burmannicus

“…Several Thai traditional plants such as ginger (Grzanna, Lindmark, & Frondoza, 2005), longan (Ho, Hwang, Shen, & Lin, 2007; Wang, Tang, Chiu, & Huang, 2012), and Gymnema inodorum (Shimizu et al., 2001) have been reported for their antioxidant and anti‐inflammatory activities. Thus, they have potential value in treating various diseases including diseases involving inflammation.…”