Su Hui Seong1, Anupom Roy1, Hyun Ah Jung2, Hee Jin Jung1, Jae Sue Choi3. 1. Department of Food and Life Science, Pukyong National University, Busan 608-737, Republic of Korea. 2. Department of Food Science and Human Nutrition, Chonbuk National University, Jeonju 561-756, Republic of Korea. Electronic address: jungha@jbnu.ac.kr. 3. Department of Food and Life Science, Pukyong National University, Busan 608-737, Republic of Korea. Electronic address: choijs@pknu.ac.kr.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE: Pueraria lobata root was used to treat wasting-thirst regarded as diabetes mellitus and was included in the composition of Okcheonsan, which is prescribed for thirst-waste in traditional Chinese medicine. AIM OF THE STUDY: The objective of this study was to evaluate the anti-diabetic potential of the root of Pueraria lobata and its constituents via protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase inhibitory activities. MATERIALS AND METHODS: In this study, anti-diabetic activities of the 70% ethanolic (EtOH) extract from P. lobata roots and its solvent soluble fractions with the isolated compounds were investigated by evaluating in vitro PTP1B and α-glucosidase inhibitory activities. We also examined the potentials of active compounds as PTP1B and α-glucosidase inhibitors via enzyme kinetics and in silico molecular docking simulation between the enzymes and active compounds. RESULTS: Triterpenoids lupeol and lupenone were potent PTP1B inhibitors with IC50 values of 38.89±0.17 and 15.11±1.23μM. Kinetic study using the Lineweaver-Burk and Dixon plots demonstrated that these compounds showed a noncompetitive-type inhibition against PTP1B with respective Ki values of 13.88μM and 21.24μM. In addition, molecular docking simulation showed lupeol and lupenone has negative binding energy values of -8.03 and -8.56kcal/mol. Considering the α-glucosidase inhibitory potential, daidzein, genistein, and calycosin exhibited the most potent α-glucosidase inhibition with IC50 values of 8.58±0.94, 2.37±0.52 and 6.84±1.58μM, respectively. Kinetic study demonstrated that these 3 compounds showed a noncompetitive-type inhibition against α-glucosidase with respective Ki values of 17.64μM, 5.03μM and 13.83μM. Moreover, molecular docking simulation showed daidzein, genistein and calycosin has more lower binding energy (-7.16kcal/mol, -7.42kcal/mol and -7.31kcal/mol) with higher binding affinity and tight binding capacity in the molecular docking studies than standard ligand α-D-glucose (-6.74kcal/mol). CONCLUSION: Our results of the present study clearly demonstrate the potential of P. lobata extract and its constituents to inhibit PTP1B and α-glucosidase, contributing to the development of therapeutic or preventive agents that can be used in the treatment of diabetes.
ETHNOPHARMACOLOGICAL RELEVANCE: Pueraria lobata root was used to treat wasting-thirst regarded as diabetes mellitus and was included in the composition of Okcheonsan, which is prescribed for thirst-waste in traditional Chinese medicine. AIM OF THE STUDY: The objective of this study was to evaluate the anti-diabetic potential of the root of Pueraria lobata and its constituents via protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase inhibitory activities. MATERIALS AND METHODS: In this study, anti-diabetic activities of the 70% ethanolic (EtOH) extract from P. lobata roots and its solvent soluble fractions with the isolated compounds were investigated by evaluating in vitro PTP1B and α-glucosidase inhibitory activities. We also examined the potentials of active compounds as PTP1B and α-glucosidase inhibitors via enzyme kinetics and in silico molecular docking simulation between the enzymes and active compounds. RESULTS:Triterpenoidslupeol and lupenone were potent PTP1B inhibitors with IC50 values of 38.89±0.17 and 15.11±1.23μM. Kinetic study using the Lineweaver-Burk and Dixon plots demonstrated that these compounds showed a noncompetitive-type inhibition against PTP1B with respective Ki values of 13.88μM and 21.24μM. In addition, molecular docking simulation showed lupeol and lupenone has negative binding energy values of -8.03 and -8.56kcal/mol. Considering the α-glucosidase inhibitory potential, daidzein, genistein, and calycosin exhibited the most potent α-glucosidase inhibition with IC50 values of 8.58±0.94, 2.37±0.52 and 6.84±1.58μM, respectively. Kinetic study demonstrated that these 3 compounds showed a noncompetitive-type inhibition against α-glucosidase with respective Ki values of 17.64μM, 5.03μM and 13.83μM. Moreover, molecular docking simulation showed daidzein, genistein and calycosin has more lower binding energy (-7.16kcal/mol, -7.42kcal/mol and -7.31kcal/mol) with higher binding affinity and tight binding capacity in the molecular docking studies than standard ligand α-D-glucose (-6.74kcal/mol). CONCLUSION: Our results of the present study clearly demonstrate the potential of P. lobata extract and its constituents to inhibit PTP1B and α-glucosidase, contributing to the development of therapeutic or preventive agents that can be used in the treatment of diabetes.