METFORMIN PYRUVATE CARBOXYLASE 1 Metformin Inhibition of Pyruvate Carboxylase in the Gluconeogenesis Pathway

Metformin is an antihyperglycemic drug prescribed for the treatment of type II diabetes. While it is known to inhibit gluconeogenesis, debate abounds regarding the exact mechanism by which metformin enacts this inhibition. The present study hypothesized that metformin, specifically in concentrations ranging from 250μM 500μM to simulate hepatic portal vein conditions, inhibits gluconeogenesis through inhibition of pyruvate carboxylase (PC), the enzyme responsible for catalysis of the first committed step of gluconeogenesis. This hypothesis was tested through observation of reaction kinetics, assessed with a diode array spectrophotometer measured at a loss of absorbance of 340nm. Enzyme-linked reactions were treated with various concentrations of metformin ranging from 250μM 5000μM of metformin, as well as a control with 0μM of metformin. Spectrophotometric data was graphed, and linear relationships between absorbance and time were observed in order to ascertain the effects of metformin concentration on reaction rate. ​13​C-NMRs were performed to assess the functional groups of metformin, pyruvate, and biotin. A loss of a carbonyl group for pyruvate, oxaloacetate, and biotin was expected when these substances were in the presence of metformin. Metformin was found to inhibit PC at concentrations above 1000μM, and a loss of a carbonyl group was found for biotin when mixed with metformin. Although this does not fully support the hypothesis, these data offer significant implications for the future of metformin study as well as for public health, as type II diabetes is a growing global problem which demands improved patient outcomes and treatment methods, and it is of benefit to study the leading prescribed drug for the treatment of this disease.