Molecular Matchmaking Between the Popular Weight-Loss Herb Hoodia Gordonii and GPR119, a Potential Drug Target for Metabolic Disorder
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Molecular matchmaking between the popular weight-loss herb Hoodia gordonii and GPR119, a potential drug target for metabolic disorder Shuyong Zhanga,b,1, Yuyong Mac,1, Jing Lib, Junjun Mac, Biao Yuc,2, and Xin Xiea,b,2 aShanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-Based Bio-Medicine, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China; bChinese Academy of Sciences Key Laboratory of Receptor Research, National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; and cState Key Laboratory of Bio-Organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China Edited by Robert J. Lefkowitz, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, and approved August 19, 2014 (received for review December 29, 2013) African cactiform Hoodia gordonii (Asclepiadaceae) has been used The plant is rich in pregnane glycosides containing 6-deoxy- for thousands of years by Xhomani Bushmen as an anorexant and 2,6-dideoxy-sugars. To date, P57AS3 (P57) is the only bi- during hunting trips and has been proposed as a new agent for ologically active constituent from H. gordonii that has been the management of body weight. However, its in vivo targets and reported to have anorexigenic activity (5). There is no evidence molecular mechanisms remain elusive. GPR119, a G protein-cou- of P57 binding to or altering activity of known receptors or pled receptor highly expressed in pancreatic β cells and intestinal proteins, but intracerebroventricular injections of P57 in rats has L cells, has been demonstrated to facilitate glucose-stimulated in- been reported to increase ATP content in the hypothalamus, sulin secretion (GSIS) and represents a novel and attractive target which might represent a signal of satiety and suppress appetitive for the therapy of metabolic disorders. Here, we disclose that responses (6). However, a recent study claimed that P57 was Gordonoside F (a steroid glycoside isolated from H. gordonii), not detectable in the brain upon oral administration in mice, but not the widely known P57, activates specifically GPR119. Suc- which makes the mechanisms of action of P57 and H. gordonii cessful synthesis of Gordonoside F facilitates further characteriza- more elusive (7). The development and commercialization of tion of this compound. Gordonoside F promotes GSIS both in vitro and in vivo and reduces food intake in mice. These effects are medi- H. gordonii and P57 have been problematic due to controversy ated by GPR119 because GPR119 knockout prevents the therapeutic about intellectual property rights and limited natural resources, effects of Gordonoside F. Interestingly, the appetite-suppressing ef- in addition to the lack of a clear mechanism, resulting in the fect of Hoodia extract was also partially blocked by GPR119 knockout. withdrawal of several major pharmaceutical companies from Our results demonstrate for the first time, to our knowledge, Hoodia projects (3). Since the isolation of P57, more new gly- that GPR119 is a direct target and one of the major mechanisms cosides, including Gordonoside A-L (8), have been disclosed in underlying the therapeutic effect of the popular “weight loss” the literature although their bioactivities remain unclear. herb H. gordonii. Given the long history of safe application of Meanwhile, many new potential drug targets related to met- this herb in weight control, it is foreseeable that the novel scaf- abolic disorders have been identified. Compounds targeting fold of Gordonoside F provides a promising opportunity to de- a number of G protein-coupled receptors (GPCRs), including velop new drugs in treating metabolic diseases. Significance besity is one of the most common health concerns, affecting Omore than 300 million people worldwide (1). Obesity is Obesity is one of the most common health concerns today. associated with and can lead to a number of diseases, including Herbal-based food supplements are widely used to treat obe- type 2 diabetes (T2D), cardiovascular disease, osteoarthritis, sity. Among them, the African cactiform Hoodia gordonii sup- dyslipidemia, and sleep apnea, many of which can be prevented plements are extremely popular. The development of Hoodia with a reduction in body weight (1). Current strategies for the and P57, the purported active ingredient, has been problematic management of body weight include calorie restriction, regular due to controversy about intellectual property rights and lim- exercise, and behavior modification. Although effective in the ited natural resources. To date, the true active components and molecular targets of Hoodia remain unclear. Here, we dem- short term, diet and exercise alone are difficult to maintain over onstrate that Gordonoside F, a compound from Hoodia, acti- the long term for the majority of patients. Thus, medications and vates GPR119, a receptor critically involved in metabolic alternative treatments have been sought. The commercial market homeostasis, and leads to increased insulin secretion and re- for antiobesity preparations is enormous, but unfortunately, there duced food intake. The successful synthesis of Gordonoside F are only two FDA-approved drugs available, phentermine and described here will provide an opportunity for developing new orlistat, both with limited efficacy but significant side effects (2). drugs in treating metabolic diseases. Herbal-based food supplements are among the most widely used alternative treatments for obesity. However, their effec- Author contributions: B.Y. and X.X. designed research; S.Z., Y.M., J.L., and J.M. performed CHEMISTRY tiveness, safety, and mechanism of actions largely remain un- research; S.Z., Y.M., J.L., J.M., B.Y., and X.X. analyzed data; and S.Z., Y.M., B.Y., and X.X. wrote the paper. known. Among them, the Hoodia gordonii supplements are extremely The authors declare no conflict of interest. popular. The African cactiform H. gordonii (Asclepiadaceae) is This article is a PNAS Direct Submission. a succulent plant growing in the Kalahari Deseret in South Freely available online through the PNAS open access option. Africa, Namibia, and Botswana (3). The plant has been used for 1S.Z. and Y.M. contributed equally to this work. thousands of years by Xhomani Bushmen as a hunger and thirst 2To whom correspondence may be addressed. Email: [email protected] or [email protected]. suppressant during hunting trips, and the natural antiobesity ac.cn. agent from the plant has attracted great attention and led to This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. PHARMACOLOGY many commercial preparations (4). 1073/pnas.1324130111/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1324130111 PNAS | October 7, 2014 | vol. 111 | no. 40 | 14571–14576 Downloaded by guest on September 26, 2021 Table 1. Biological activities of the naturally occurring Hoodigosides/Gordonosides (1–6) and synthetic Gordonoside F on the human GPR119 receptor O O O R O O OH MeO O EC50, µM dnuopmoC R cAMP assay Calcium assay P57 (1) NR NR HO O MeO O O OH MeO Hoodigoside K (2) OH NR NR HO O O O HO HO OH HO OH Gordonoside F (3) 0.53 ± 0.12 9.3 ± 0.3 HO O MeO O O O O MeO MeO Hoodigoside E/Gordonoside H (4) OH NR NR HO O O O O HO MeO O OH OH MeO Hoodigoside G (5) OH NR NR HO O HO O O O O O OH O MeO MeO OH OMe Hoodigoside I (6) OH NR NR HO O HO O O O MeO O O OH O OMe OMe Gordonoside F (3, synthetic) 0.44 ± 0.02 3.2 ± 1.4 HO O MeO O O O O MeO MeO NR, no response at concentrations up to 100 μM. GLP-1R, GPR40, GPR120, CB1, GCGR, and β2-adenoceptor activates GPR119 potently and selectively, which consequently (9), have been proposed to treat T2D and obesity. Recently, promotes GSIS both in vitro and in vivo and reduces food intake GPR119, a GPCR highly expressed in pancreatic β cells and in animals. In addition, chemical synthesis of Gordonoside F is intestinal L cells (10, 11), has been demonstrated to facilitate reported. The present results not only demonstrate unambiguously glucose-stimulated insulin secretion (GSIS) (12). The endoge- that the activation of GPR119 receptor is an important mechanism nous ligands LPC and OEA promote GSIS, directly by activating underlying H. gordonii’s therapeutic effect but also suggest that GPR119 on the β cells and indirectly by activating GPR119 on Gordonoside F or its congeners could be developed into new drugs the L cells, and induce GLP-1 secretion (13). Oral administra- in treating metabolic disorders. tion of AR231453, a synthetic agonist of GPR119, significantly improves circulating insulin, GLP-1, and GIP levels, and lowers Materials and Methods the blood glucose concentration in glucose tolerance tests in Chemicals and Reagents. Gordonoside F and its natural congeners were pur- mice (11, 14). Another GPR119 agonist, PSN632408, has been chased from AnalytiCon Discovery and/or synthesized chemically (see SI Appendix, Materials and Methods for details). Crude extract of H. gordonii (Ref: EA149464) shown to suppress food intake and reduce body weight gain was provided by Naturex. Mammalian expression vectors encoding various in rats, in addition to its blood glucose-lowering effect (15). GPCRs and Gα16 were purchased from the UMR cDNA Resource Center. Therefore, GPR119 represents an attractive target for the ther- apy of diabetes and obesity. Reporter Assay. Cells expressing GPR119 (or other GPCRs) and CRE-luc were Here, we disclose that Gordonoside F (a steroid glycoside plated at a density of 10,000 cells per well in a 96-well plate. After 24 h culture, isolated from H. gordonii), but not the widely known P57, compounds at various concentrations were added. DMSO (1%) was used as 14572 | www.pnas.org/cgi/doi/10.1073/pnas.1324130111 Zhang et al.