In vitro assessment of the glucose-lowering effects of berberrubine-9-O-β-D-glucuronide, an active metabolite of berberrubine

Abstract

Berberrubine (BRB) is the primary metabolite of berberine (BBR) that has shown a stronger glucose-lowering effect than BBR in vivo. On the other hand, BRB is quickly and extensively metabolized into berberrubine-9-O-β-D-glucuronide (BRBG) in rats after oral administration. In this study we compared the pharmacokinetic properties of BRB and BRBG in rats, and explored the mechanisms underlying their glucose-lowering activities. C57BL/6 mice with HFD-induced hyperglycemia were administered BRB (50 mg· kg -1 ·d -1 , ig) for 6 weeks, which caused greater reduction in the plasma glucose levels than those caused by BBR (120 mg· kg -1 ·d -1 ) or BRB (25 mg· kg -1 ·d -1 ). In addition, BRB dose-dependently decreased the activity of α-glucosidase in gut of the mice. After oral administration of BRB in rats, the exposures of BRBG in plasma at 3 different dosages (10, 40, 80 mg/kg) and in urine at different time intervals (0-4, 4-10, 10-24 h) were dramatically greater than those of BRB. In order to determine the effectiveness of BRBG in reducing glucose levels, we prepared BRBG from the urine pool of rats, and identified and confirmed it through LC-MS-IT-TOF and NMR spectra. In human normal liver cell line L-O2 in vitro, treatment with BRB or BRBG (5, 20, 50 μmol/L) increased glucose consumption, enhanced glycogenesis, stimulated the uptake of the glucose analog 2-NBDG, and modulated the mRNA levels of glucose-6-phosphatase and hexokinase. However, both BBR and BRB improved 2-NBDG uptake in insulin-resistant L-O2 cells, while BRBG has no effect. In conclusion, BRB exerts a stronger glucose-lowering effect than BBR in HFD-induced hyperglycemia mice. Although BRB significantly stimulated the insulin sensitivity and glycolysis in vitro, BRBG may have a greater contribution to the glucose-lowering effect because it has much greater system exposure than BRB after oral administration of BRB. The results suggest that BRBG is a potential agent for reducing glucose levels.

Inhibitory Effects of Endogenous Linoleic Acid and Glutaric Acid on the Renal Glucuronidation of Berberrubine in Mice and on Recombinant Human UGT1A7, 1A8, and 1A9

“…Berberrubine (BRB), an active lipid-lowing metabolite of berberine (Li et al, 2010;Zhou et al, 2014), showed a high proportion of glucuronidation metabolism in vivo in our previous study (Yang et al, 2017a). In our present study, for the first time, based on the specific metabolic pattern of BRB, our data suggested that some important endogenous molecules are potentially effective endogenous inhibitors on mouse renal glucuronidation via the employment of an integrated strategy of metabolomics and pharmacokinetics.…”

“…HFD Decreased the Ratio of BRBG to BRB in Urinary Excretion. A simultaneous assay of BRB and BRBG was developed using an LC-MS/MS analytical approach based on our previous studies (Yang et al, 2017a). The plasma concentration-time curves and urinary excretion of both BRB and BRBG in the three groups (CSB, CMB, and HMB) were investigated.…”

“…Reagents. BRB (purity .95%) was synthetized by Chemzam Pharmtech (Nanjing, People's Republic of China), and berberrubine-9-O-b-D-glucuronide (BRBG) was prepared and identified by the Key Laboratory of Drug Metabolism and Pharmacokinetics at China Pharmaceutical University (Yang et al, 2017a). The control diet (AIN-93M) and high-fat diet (HFD, 60% calories from fat and 1% cholesterol) were purchased from Trophic Animal Feed High-Tech (Nantong, People's Republic of China).…”

Enhanced Anti-diabetic Effect of Berberine Combined With Timosaponin B2 in Goto-Kakizaki Rats, Associated With Increased Variety and Exposure of Effective Substances Through Intestinal Absorption

“…However, the major drawback of BBR is the low bioavailability (usually <1% in various species) (Liu et al, 2016), especially considering that high oral doses of BBR (>900 mg/day) carry a risk of clinical gastrointestinal side effects (Yin et al, 2008). Moreover, the major BBR metabolites, M1–M5 (Figure 1A), were also verified to have hypoglycemic activity in cells or animals (Li et al, 2011; Wang K. et al, 2017; Yang et al, 2017). M1 even showed more hypoglycemic capacity than BBR in diabetic animals (Yang et al, 2017).…”

Contribution of Hepatic Retinaldehyde Dehydrogenase Induction to Impairment of Glucose Metabolism by High‐Fat‐Diet Feeding in C57BL/6J Mice

“…High‐fat‐diet mice were developed using HFD feeding according to a method described previously with some modifications . Briefly, the mice were allowed for 3‐day acclimation before the initiation of the study and were randomly divided into normal control (CON) group and HFD groups.…”