Gynura procumbens (Lour.) Merr. extract attenuates monocyte adherence to endothelial cells through suppression of the NF-κB signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Gynura procumbens (Lour.) Merr. (GP) is a herbaceous plant that grows in Malaysia and other parts of Southeast Asia. The herb is consumed as a remedy for various inflammatory-associated diseases, such as cancer, rheumatism, hypertension, diabetes mellitus and hyperlipidemia. Scientific studies demonstrate that GP extract possesses cardioprotective and anti-inflammatory effects. Cardiovascular disease is mainly caused by atherosclerosis, and inflammation plays a major role in all phases of atherosclerosis. The early inflammatory events in atherogenesis are the activation of endothelial cells and the recruitment of monocytes. AIM OF THE STUDY: This study aimed to evaluate the inhibitory effect of 80% ethanol extract of GP leaves (GPE) on the adherence of monocytes to the activated human endothelial cells and its underlying mechanism. MATERIAL AND METHODS: Qualitative and quantitative analyses of the extract were carried out by using a validated HPLC and UHPLC-MS/MS methods. The MTT test was used to select the range of concentration of extract for this study. The effect of GPE on TNF-α-induced monocyte-endothelial interaction was determined by the in vitro adhesion assay. Expression of cell surface proteins (ICAM-1, VCAM-1) and phosphorylation of nuclear factor kappa B (NF-κB) were determined by western blot, while expression of a chemokine (MCP-1) was identified by an enzyme-linked immunosorbent assay. RESULTS: HPLC and UHPLC-MS/MS analyses indicated that GPE contained chlorogenic acid, nicotiflorin and astragalin as the major compounds. GPE at 20, 40 and 60 µg/mL concentrations showed a significant reduction in monocyte adherence to endothelial cells and expression of ICAM-1 and MCP-1. However, only GPE at concentrations of 40 and 60 µg/mL was able to reduce VCAM-1 expression. Furthermore, GPE significantly inhibited IKKα/ß, IκBα, NF-κB phosphorylation and NF-κB translocation. CONCLUSION: In conclusion, GPE may inhibit monocyte adherence to the activated endothelial cells and expression of ICAM-1, VCAM-1 and MCP-1, which are important proteins for monocyte-endothelial interaction, by suppressing the NF-κB signaling pathway. The results of this study support the traditional use of GPE to counteract inflammation-associated diseases and suggest that GP can be a potential source for bioactive compounds for the development of anti-inflammatory agents to prevent atherosclerosis.

Antioxidant and Anti-Inflammatory Effects of Genus Gynura: A Systematic Review.

Background: Gynura species have been used traditionally to treat various ailments, such as fever, pain, and to control blood glucose level. This systematic review critically discusses studies regarding Gynura species that exhibited antioxidant and anti-inflammatory effects, thus providing perspectives and instructions for future research of the plants as a potential source of new dietary supplements or medicinal agents. Methods: A literature search from internet databases of PubMed, Scopus, Science Direct, e-theses Online Service, and ProQuest was carried out using a combination of keywords such as "Gynura," "antioxidant," "anti-inflammatory," or other related words. Research articles were included in this study if they were experimental (in vitro and in vivo) or clinical studies on the antioxidant or anti-inflammatory effects of Gynura species and if they were articles published in English. Results: Altogether, 27 studies on antioxidant and anti-inflammatory effects of Gynura species were selected. The antioxidant effects of Gynura species were manifested by inhibition of reactive oxygen species production and lipid peroxidation, modulation of glutathione-related parameters, and enzymatic antioxidant production or activities. The anti-inflammatory effects of Gynura species were through the modulation of inflammatory cytokine production, inhibition of prostaglandin E2 and nitric oxide production, cellular inflammatory-related parameters, and inflammation in animal models. The potential anti-inflammatory signaling pathways modulated by Gynura species are glycogen synthase kinase-3, nuclear factor erythroid 2-related factor 2, PPARγ, MAPK, NF-κB, and PI3K/Akt. However, most reports on antioxidant and anti-inflammatory effects of the plants were on crude extracts, and the chemical constituents contributing to bioactivities were not clearly understood. There is a variation in quality of studies in terms of design, conduct, and interpretation, and in-depth studies on the underlying mechanisms involved in antioxidant and anti-inflammatory effects of the plants are in demand. Moreover, there is limited clinical study on antioxidant and anti-inflammatory effects of Gynura species. Conclusion: This review highlighted antioxidant and anti-inflammatory effects of genus Gynura and supported their traditional uses to treat oxidative stress and inflammatory-related diseases. This review is expected to catalyze further studies on genus Gynura. However, extensive preclinical data need to be generated from toxicity and pharmacokinetic studies before clinical studies can be pursued for their development into clinical medicines to treat oxidative stress and inflammatory conditions.