Germacrane sesquiterpenes from leaves of Eupatorium chinense inhibit protein tyrosine phosphatase

Effectiveness of Jena DM® Herbal Formulation as Complementary Therapy to Conventional Oral Hypoglycemic Agents in Type-2 Diabetes Mellitus: A Quasi-experimental Study

BACKGROUND

 There is vast preclinical evidence that indicates that extracts from several Artemisia plant species have significant antidiabetic benefits. However, clinical evidence is limited to this effect.

OBJECTIVE

 We sought to evaluate the effectiveness of Jena DM®  (an Artemisia annua-based poly-herbal formulation) on glycemic control (Hb A1C) and insulin metabolism (HOMA), when administered as a complementary therapy in type-2 diabetes mellitus (T2DM). This study was supported by a research grant (JRD005) from Jena Herbals (U) Ltd, which is a local herbal medicines manufacturing facility in Uganda.

METHODS

We conducted a 12-week quasi-experimental study, involving 118 patients under routine follow-up at a diabetes and endocrinology clinic. Random assignment to either conventional or experimental study groups was done using a random number generator (Microsoft Excel version 16.0). Participant sociodemographic and clinical data as well as whole blood samples (3-5 mL) were obtained at scheduled clinic visits. Medication adherence was assessed using the Hill-Bone Scale, and adverse drug events (ADEs) using the Naranjo causality and the National Institute of Allergy and Infectious Diseases, Division of AIDS (DAIDS) scales. Group differences in glycemic control (HbA1C), fasting serum insulin (FSI) indices (% HOMA2-B, HOMA-IR), and other cardiometabolic parameters were assessed using independent samples t-test, and Pearson chi-square statistical tests were used. A p-value <0.05 was considered statistically significant. Ethical approvals were obtained before the study commencement.

RESULTS

12-week daily complementary therapy with Jena DM®  showed no significant effect on Hb A1C reduction (0.1 (95% CI: -0.56, 0.80) %; p=0.798); however, we observed a significant reduction in total body weight (2.0 (95% CI: 0.73, 3.28) kg; p=0.002). The overall frequency of self-reported ADEs including dizziness was significantly higher among patients that used Jena DM®  (p=0.001). Epigastric pain was the most severe ADE necessitating clinical management. There was no significant difference in the homeostatic model assessment for insulin resistance (HOMA2-IR) between study groups.

CONCLUSION

 In contrast to a few studies that previously showed significant hypoglycemic effects of Artemisia-based extracts, this study did not show a statistically significant reduction on HbA1C during a 12-week complementary use of Jena DM®  in patients with T2DM. Based on the findings of this study, future research should evaluate the long-term effects of Jena DM®  on body weight, overall insulin metabolism, and the subsequent effect on glycemic control in T2DM.

Dual PTP1B/TC-PTP Inhibitors: Biological Evaluation of 3-(Hydroxymethyl)cinnoline-4(1H)-Ones

Dual inhibitors of protein phosphotyrosine phosphatase 1B (PTP1B)/T-cell protein phosphotyrosine phosphatase (TC-PTP) based on the 3-(hydroxymethyl)-4-oxo-1,4-dihydrocinnoline scaffold have been identified. Their dual affinity to both enzymes has been thoroughly corroborated by in silico modeling experiments. The compounds have been profiled in vivo for their effects on body weight and food intake in obese rats. Likewise, the effects of the compounds on glucose tolerance, insulin resistance, as well as insulin and leptin levels, have been evaluated. In addition, the effects on PTP1B, TC-PTP, and Src homology region 2 domain-containing phosphatase-1 (SHP1), as well as the insulin and leptin receptors gene expressions, have been assessed. In obese male Wistar rats, a five-day administration of all studied compounds led to a decrease in body weight and food intake, improved glucose tolerance, attenuated hyperinsulinemia, hyperleptinemia and insulin resistance, and also compensatory increased expression of the PTP1B and TC-PTP genes in the liver. The highest activity was demonstrated by 6-Chloro-3-(hydroxymethyl)cinnolin-4(1H)-one (compound 3) and 6-Bromo-3-(hydroxymethyl)cinnolin-4(1H)-one (compound 4) with mixed PTP1B/TC-PTP inhibitory activity. Taken together, these data shed light on the pharmacological implications of PTP1B/TC-PTP dual inhibition, and on the promise of using mixed PTP1B/TC-PTP inhibitors to correct metabolic disorders.

[Characterization and biological activity of new 4-oxo-1,4-dihydrocinnoline-based inhibitors of the tyrosine phosphatase PTP1B and TCPTP]

Functional disorders in obesity are largely due to a decrease in tissue sensitivity to insulin and leptin. One of the ways to restore it is inhibition of protein phosphotyrosine phosphatase 1B (PTP1B) and T-cell protein phosphotyrosine phosphatase (TCPTP), negative regulators of the insulin and leptin signaling. Despite progress in the development of inhibitors of these phosphatases, commercial preparations based on them have not been developed yet, and the mechanisms of action are poorly understood. The aim of the work was to study the effect of new derivatives of 4-oxo-1,4-dihydrocinnoline (PI04, PI06, PI07) on the activity of PTP1B and TCPTP, as well as to study the effect of their five-day administration (i.p., 10 mg/kg/day) to Wistar rats with diet-induced obesity on body weight and fat, metabolic and hormonal parameters, and gene expression of phosphatase and insulin and leptin receptors in the liver. It has been shown that PI04 is a mild, low selective inhibitor of both phosphatases (PTP1B, IC50=3.42(2.60-4.51) μM; TCPTP, IC50=4.16(3.49-4.95) μM), while PI06 and PI07 preferentially inhibit PTP1B (IC50=3.55 (2.63-4.78) μM) and TCPTP (IC50=1.45(1.18-1.78) μM), respectively. PI04 significantly reduced food intake, body weight and fat, attenuated hyperglycemia, normalized glucose tolerance, basal and glucose-stimulated levels of insulin and leptin, and insulin resistance index. Despite the anorexigenic effect, PI06 and PI07 were less effective, having little effect on glucose homeostasis and insulin sensitivity. PI04 significantly increased the expression of the PTP1B and TCPTP genes and decreased the expression of the insulin and leptin receptor genes. PI06 and PI07 had little effect on these indicators. Thus, PI04, the inhibitor of PTP1B and TCPTP phosphatases, restored metabolic and hormonal parameters in obese rats with greater efficiency than inhibitors of PTP1B (PI06) and TCPTP (PI07). This indicates the prospect of creating mixed PTP1B/TCPTP inhibitors for correction of metabolic disorders.