Gynura Procumbens: an Overview of the Biological Activities

MINI REVIEW published: 15 March 2016 doi: 10.3389/fphar.2016.00052 Gynura procumbens: An Overview of the Biological Activities Hui-Li Tan 1, Kok-Gan Chan 2, Priyia Pusparajah 1, Learn-Han Lee 1* and Bey-Hing Goh 1* 1 Biomedical Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia, 2 Division of Genetic and Molecular Biology, Faculty of Science, Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia Gynura procumbens (Lour.) Merr. (Family Asteraceae) is a medicinal plant commonly found in tropical Asia countries such as China, Thailand, Indonesia, Malaysia, and Vietnam. Traditionally, it is widely used in many different countries for the treatment of a wide variety of health ailments such as kidney discomfort, rheumatism, diabetes mellitus, constipation, and hypertension. Based on the traditional uses of G. procumbens, it seems to possess high therapeutic potential for treatment of various diseases making it a target for pharmacological studies aiming to validate and provide scientific evidence for the traditional claims of its efficacy. Although there has been considerable progress in the research on G. procumbens, to date there is no review paper gathering the reported Edited by: biological activities of G. procumbens. Hence, this review aims to provide an overview of Lyndy Joy McGaw, the biological activities of G. procumbens based on reported in vitro and in vivo studies. University of Pretoria, South Africa In brief, G. procumbens has been reported to exhibit antihypertensive, cardioprotective, Reviewed by: antihyperglycemic, fertility enhancement, anticancer, antimicrobial, antioxidant, organ Bhekumthetho Ncube, University of KwaZulu-Natal, protective, and antiinflammatory activity. The commercial applications of G. procumbens South Africa have also been summarized in this paper based on existing patents. The data compiled Adeyemi Oladapo Aremu, University of KwaZulu-Natal, illustrate that G. procumbens is a potential natural source of compounds with various South Africa pharmacological actions which can be utilized for the development of novel therapeutic *Correspondence: agents. Learn-Han Lee [email protected]; Keywords: Gynura procumbens, medicinal plant, biological activity, ethnopharmacology, Bai Bing Cao Bey-Hing Goh [email protected] INTRODUCTION Specialty section: This article was submitted to Gynura procumbens (Lour.) Merr. (Family Asteraceae), is a small plant ∼1–3 m in height. The stems Ethnopharmacology, are fleshy and the leaves are ovate-elliptic or lanceolate (Rahman and Asad, 2013). It has scientific a section of the journal synonym names such as Gynura sarmentosa DC and Cacalia sarmentosa Blume (Quattrocchi, Frontiers in Pharmacology 2012). The plant leaf is commonly consumed and scientifically it has been shown to be safe for Received: 17 December 2015 consumption (Rosidah et al., 2008). In Malaysia, the fresh leaves of G. procumbens are commonly Accepted: 26 February 2016 eaten raw and in Thailand, the leaves are also used for cooking (Kaewseejan et al., 2015). In Malay, Published: 15 March 2016 G. procumbens is called Sambung Nyawa which means “prolongation of life” whereas in Chinese, Citation: it is called Bai Bing Cao which means “100 ailments” (Bodeker et al., 2009). This is because it has Tan H-L, Chan K-G, Pusparajah P, been utilized in traditional medicine both systemically and for topical application for treatment of Lee L-H and Goh B-H (2016) Gynura procumbens: An Overview of the different types of illnesses and diseases (Krishnan et al., 2015). For example, it is widely used to Biological Activities. relieve kidney discomfort in Indonesia and people have been using it for the treatment of fever Front. Pharmacol. 7:52. in Vietnam. In Thailand, it is commonly used to alleviate inflammation, rheumatism, and to cure doi: 10.3389/fphar.2016.00052 viral ailments (Wiart, 2006). The beneficial properties of G. procumbens have been attributed to the Frontiers in Pharmacology | www.frontiersin.org 1 March 2016 | Volume 7 | Article 52 Tan et al. Biological Activities of Gynura procumbens presence of bioactive compounds such as flavonoids and as an antihypertensive agent with cardioprotective activity glycosides in this plant (Akowuah et al., 2001, 2002). due to its ability to target various mechanisms including the Throughout the years, intensive research done on G. renin-angiotensin system and calcium influx which are crucial procumbens has provided extensive scientific evidence of its players in the pathophysiology of hypertensive conditions. therapeutic potential. The present review aims to provide an overview of the biological activities of G. procumbens with Antihyperglycemic Activity reference to the available literature. The vast potential medical G. procumbens is commonly used for diabetes treatment in applications of G. procumbens based on the consolidation of the traditional medicine and its hypoglycemic effect has been scientific findings of research on this plant are also highlighted. reported in in vivo studies (Hamid et al., 2004; Algariri et al., 2014). One intriguing finding on G. procumbens, is its specificity in inducing hypoglycemic effect only in diabetic animals as BIOLOGICAL ACTIVITIES it has been shown to cause a significant decrease in fasting blood glucose levels and suppression of glucose elevation during Antihypertensive and Cardioprotective glucose tolerance test in diabetic rats but not normal rats (Zhang Activity and Tan, 2000; Algariri et al., 2013). Hypertension is a key risk factor for several cardiovascular The effect of G. procumbens treatment on insulin level diseases including coronary vascular disease and stroke (Lu has been investigated. Hamid et al. (2004) has reported the et al., 2012). Over the past few decades, significant effort has stimulation of insulin secreting cell lines by G. procumbens been expended to explore medicinal plants with antihypertensive extract. However, the exposure of clonal pancreatic cells with therapeutic effect, including G. procumbens (Lam et al., 1998). To extract of G. procumbens did not stimulate insulin secretion date, the administration of G. procumbens has been reported to (Hassan et al., 2008). These contradicting results might be due result in significant lowering of systolic blood pressure and mean to the differing response of different cell lines when treated with arterial pressure in hypertensive rats (Hoe and Lam, 2005; Kim G. procumbens. Therefore, its effect on insulin secretion has et al., 2006; Hoe et al., 2007). Additionally, the treatment with been further tested using in vivo studies. However, no significant G. procumbens extract has also resulted in significant decrease in change has been observed in plasma insulin level in diabetic rats heart rate, strong negative chronotropic, and negative ionotropic treated with the extracts, implying that the hypoglycemic activity effects at rats’ right atrium and left atrium respectively (Hoe et al., of G. procumbens does not rely on insulinotropic activity but may 2011; Kaur et al., 2012; Abrika et al., 2013). instead be due to its extra-pancreatic effect (Hassan et al., 2008; Angiotensin (Ang)-converting enzyme is important for blood Lee et al., 2012). pressure regulation. It converts Ang I into Ang II, the Other pathways explored in the research include experiments peptide hormone with potent vasoconstrictive effects (Lote, on the antidiabetic effect of G. procumbens focusing on glucose 2006). Interestingly, the blood pressure-lowering effect of uptake activity. The findings showed G. procumbens treatment G. procumbens was associated with its inhibitory effect on stimulated glucose uptake on 3T3 adipocytes. Furthermore, an angiotensin-converting enzyme activity (Hoe et al., 2007). In enhancement of activity was found in the presence of insulin addition to that, G. procumbens has direct inhibitory effect on (Bohari et al., 2006). Further validation was then conducted via the activity of Ang II. This was demonstrated in the study in vivo work. The report showed an enhanced uptake of glucose that reported the inhibition of Ang II- induced contraction by muscle tissue of diabetic rats, indicating a direct effect of of aortic rings treated with fraction of G. procumbens (Poh G. procumbens extract on glucose uptake and utilization at the et al., 2013). In terms of mechanism of action, G. procumbens peripheral levels (Hassan et al., 2010). possibly antagonizes the vasoconstrictive effect of Ang II through With reference to metabolic pathways, G. procumbens was endothelium-dependent pathways that involve the activation of found to exert an effect on glucose metabolism in liver. It nitric oxide and prostaglandin release (Poh et al., 2013). This is was demonstrated to cause phosphorylation and inactivation of supported by the reduction of inhibitory effect of G. procumbens glycogen synthase kinase 3 (GSK3) in the liver of diabetic rats, aqueous fraction on Ang II-induced contraction in the presence suggesting that the hypoglycemic action of G. procumbens is due of cyclooxygenase inhibitor and endothelial nitric oxide synthase to either direct or indirect effects on the upstream component(s) inhibitor (Poh et al., 2013). This was also supported by another activities in the insulin signaling pathway (Gansau et al., 2012). research finding which found increased serum nitric oxide level In addition, it stimulated an increase in activity of glucokinase in hypertensive rats treated with G. procumbens extract (Kim

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