Metforminium Decavanadate as a Potential Metallopharmaceutical Drug for the Treatment of Diabetes Mellitus.
Treviño S1, Velázquez-Vázquez D2, Sánchez-Lara E3, Diaz-Fonseca A4, Flores-Hernandez JÁ5, Pérez-Benítez A6, Brambila-Colombres E1, González-Vergara E3.
- 1Laboratorio de Investigación en Química Clínica, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Colonia San Manuel, 72570 Puebla, PUE, Mexico; Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Colonia San Manuel, 72570 Puebla, PUE, Mexico.
- 2Laboratorio de Investigación en Química Clínica, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Colonia San Manuel, 72570 Puebla, PUE, Mexico.
- 3Laboratorio de Bioinorgánica Aplicada, Centro de Química ICUAP, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Colonia San Manuel, 72570 Puebla, PUE, Mexico.
- 4Departamento de Farmacia, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Colonia San Manuel, 72570 Puebla, PUE, Mexico.
- 5Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Colonia San Manuel, 72570 Puebla, PUE, Mexico.
- 6Laboratorio de Nuevos Materiales, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 18 Sur y Avenida San Claudio, Colonia San Manuel, 72570 Puebla, PUE, Mexico.
New potential drugs based on vanadium are being developed as possible treatments for diabetes mellitus (DM) and its complications. In this regard, our working group developed metforminium decavanadate (MetfDeca), a compound with hypoglycemic and hypolipidemic properties. MetfDeca was evaluated in models of type 1 and type 2 diabetes mellitus, on male Wistar rats. Alloxan-induction was employed to produce DM1 model, while a hypercaloric-diet was employed to generate DM2 model. Two-month treatments with 3.7 μg (2.5 μM)/300 g/twice a week for DM2 and 7.18 μg (4.8 μM)/300 g/twice a week for DM1 of MetfDeca, respectively, were administered. The resulting pharmacological data showed nontoxicological effects on liver and kidney. At the same time, MetfDeca showed an improvement of carbohydrates and lipids in tissues and serum. MetfDeca treatment was better than the monotherapies with metformin for DM2 and insulin for DM1. Additionally, MetfDeca showed a protective effect on pancreatic beta cells of DM1 rats, suggesting a possible regeneration of these cells, since they recovered their insulin levels. Therefore, MetfDeca could be considered not only as an insulin-mimetic agent, but also as an insulin-enhancing agent. Efforts to elucidate the mechanism of action of this compound are now in progress.
Metabolic Syndrome (MS) and non-insulin dependent diabetes (T2DM) are a major problem of public health and an important clinical challenge worldwide, due to its prevalence that ranges from 10% until 84% in dependence of world region. The International Diabetes Federation estimates that one-quarter of the world’s adult population has the metabolic syndrome associated to overweight, with an increasing body mass index that it is reflected in a higher body fatty mass [1-2]. Both, MS and T2DM are associated to insulin resistance in variable grades depending of the tissue. Liver and adipose tissue are mainly affected by hyperinsulinemia, as a consequence of a high-caloric consumption. Particularly, in adipose tissue the hyperinsulinemia (insulin resistance in adipocytes) produces an increase of activity of hormone-sensitive lipase, which produces a free fatty acids flux into plasma; these provoke steatosis or ectopic triglycerides accumulation in muscle, heart and liver; in liver, the insulin resistance is a phenomenon associated to adipokines. Adipokines such as leptin, adiponectin and resistin are involved in the hepatic steatosis severity .
Since the decade of the 80’s, vanadium compounds have shown biological activity acting similarly to insulin on diabetes and metabolic syndrome models, both in animal and human tests in relation to physiological symptoms and biochemical parameters. Vanadate (V) and vanadyl (IV) are easily redox-interconvertible, however, vanadate is the main inorganic vanadium species available for the interaction with cellular functions. In this sense, the decavanadate ion is an oligomerized species of vanadate and has been referred as the main protein-bound species, since it is very stable in the presence of pH changes, and eventually it is converted into labile oxovanadates, allowing them to exist for some time under physiological conditions; therefore, it could be considered as a form of continuous administration [4-6].
In our working group, a salt based on decavanadate and metformin (H2Metf)3[V10O28]·8H2O, abbreviated as MetfDeca, has been synthesized and fully characterized. Additionally, this novel compound has demonstrated an anti-steatotic effect in multiple tissues; in both, insulin independent and insulin-requiring models [7-9]. However, is not clear if its action is independent of adipokines, like leptin and adiponectin regulation, or is simply linked to improved insulin resistance. We hypothesized that if lipid and glucose homeostases are recovered after MetfDeca treatment, the adipocytes diminished its hypertrophy and hyperplasia processes and thereby serum levels of hormones are recovered. The hepatic steatosis plays a key role in the homeostasis recovery, because this tissue controlled both, lipogenic and gluconeogenic pathways.
Wistar rats were exposed for 3-months to hypercaloric diet (HC) and a deregulated model was reproduced and validated as previously reported [8-9]. After validation of metabolic deregulated model, the rats were randomized into three groups. The first one was administered during 2-months with a combination of MetfDeca+HC; the second group remained fed with hypercaloric diet and the control group, which was fed only with a normocaloric diet. After two months, all animals were sacrificed and a biochemical profile was carried out, including the quantification of triglycerides in serum, liver and adipose tissues; as well as, free fatty acids, leptin and adiponectin in serum; additionally, insulin resistance was evaluated by HOMA-IR index and insulin resistance adipocyte dysfunction index (IDA-IR); and The Red Oil staining in liver and adipose tissues was also carried out. Each procedure was according to the procedures of the “Citizen’s Guide for Care and Use of Laboratory Animals of Mexico” and approved by the Institutional Committee for Care and Use of Animals.
First, we made sure that metabolic deregulated model with dyslipidemia and dysglycemia were developed in Wistar rats. Figure 1 shows that rats marked like HC developed insulin resistance in liver and adipose tissue (HOMA-IR and IDA-IR, increases); additionally, the dyslipidemia was observed with hypertriglyceridemia and rise of free fatty acids. Our working group has documented that the intake of high calorie diets without increased self-expenditure, could modify neuro-hormonal response that directly impacts on cellular metabolism. It has been shown that alterations in molecules such as serum glucose and lipid levels are present. In this regard, the β-cells can sense and compensate hyperglycemic states with an increased secretion of insulin, which can lead to a state of resistance in multiple peripheral tissues, thus, insulin resistance can be defined as a reduced responsiveness of the tissues of an organism to high insulin concentrations, while conversely reduced sensitivity to insulin is associated with an increase of basal insulin concentration (insulinemia). This progressive increase in insulin levels may be best viewed as an adaptive response by pancreas to restore glucose homeostasis. Adaptive responses to hyperinsulinemia states are often linked to in vivo insulin resistance.
Ectopic accumulation of hepatic lipids or hepatosteatosis has clearly been linked to the development of hepatic insulin resistance, that develops when the rate of hepatic triglycerides synthesis is increased, due to the rise of fatty acid uptake and its esterification into triglycerides, as well as from de novo synthesis of triglycerides from carbohydrate, as long as, it exceeds the catabolic state associated to fatty acid oxidation and export of triglycerides as very low density lipoproteins (VLDL) toward muscle and adipose tissues. In adipose tissue the triglycerides are stored unless that insulin resistance is present, so that impaired insulin action in the adipose tissue allows for increased lipolysis, which will promote re-esteriﬁcation of lipids in other tissues (such as liver) and further exacerbates peripheral insulin resistance. Particularly, adipose tissue secret adipokines such as leptin, adiponectin and resistin, mainly. These adipokines contribute with metabolic processes associated to lipids, as energy production, energetic reserves, anti-steatotic events and insulin resistance regulation, all in peripheral tissues. In rats fed with HC diet it was observed an increase in leptin, with a decrease in adiponectin, both associated to adipocyte hypertrophy (Fig. 1 and 2), which promotes hepatosteatosis (Fig 1H-HC).
The MetfDeca administration, despite to HC feeding presented insulin resistance regulation, both in liver and adipose tissues, which diminished the risk of metabolic syndrome and the development of diabetes mellitus and cardiovascular diseases. The notably amelioration in serum flux of FFA and triglycerides strongly suggests a modulation between β-oxidation and lipogenesis, both endogenous and exogenous, as well as their distribution and storing. In this sense, the adipose tissue returns to basal triglycerides content (Fig 1G), and adipokine levels almost normal which is correlated with adipocyte size (Fig 1G-MetfDeca). Normal levels of adipokines are amply associated with insulin resistance regulation and anti-steatotic effects in muscle and liver tissues. After MetfDeca administration it was observed, a diminished of stored triglycerides in hepatocytes (Fig 1H-MetfDeca), which suggest strongly a recovery of energetic balance, because before it was demonstrated that muscle steatosis also was eliminated subsequent to 2-month of MetfDeca administration.
The importance of this study: The MetfDeca administration has showed important improvement in metabolic regulation associated to glucose and lipids, with a dosage of 48,000 times less than metformin alone. Additionally, MetfDeca possesses the ability of reducing serum levels of carbohydrates and lipids by oxidative pathways; which improve the signaling pathways of insulin and adipokines, which in turn reduces steatosis in liver and muscle. This is achieved because the molecule possesses a core of associated vanadates which, in turn, could behave as a form of continuous liberation of vanadates, the same that has a biological activity probably on mitochondria, additionally, the molecule also contains metformin that act on the mitochondrial complex I and maintains the energetic metabolism pro-oxidant. The most relevant event is that MetfDeca is only administered two times a week orally, and this administration observed insulin enhancer and insulin mimetic effects, without secondary effects. However, more studies should be carried out to elucidate the mechanistic aspects of this potential prodrug.
The authors thank Vicerrectoria de Investigación y Posgrado (VIEP) and Centro Universitario de Vinculación (CUVyTT), through Dr. Ygnacio Martínez Laguna and Martín Pérez Santos, respectively, for the financial support of this research project (DITCo2016-8). Thanks are due to Dr. Carlos Escamilla for the use of the Bioterium “Claude Bernard”of the Benemérita Universidad Autónoma de Puebla.
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