Psoralea corylifoliaL. Seed Extract Attenuates Methylglyoxal-Induced Insulin Resistance by Inhibition of Advanced Glycation End Product Formation

Abstract

Accumulation of advanced glycation end products (AGEs) in the body has been implicated in the pathogenesis of metabolic conditions, such as diabetes mellitus. Methylglyoxal (MGO), a major precursor of AGEs, has been reported to induce insulin resistance in both in vitro and in vivo studies. Psoralea corylifolia seeds (PCS) have been used as a traditional medicine for several diseases, but their potential application in treating insulin resistance has not yet been evaluated. This study is aimed at investigating whether PCS extract could attenuate insulin resistance induced by MGO. Male C57BL/6N mice (6 weeks old) were administered 1% MGO in their drinking water for 18 weeks, and the PCS extract (200 or 500 mg/kg) was orally administered daily from the first day of the MGO administration. We observed that both 200 and 500 mg/kg PCS extract treatment significantly improved glucose tolerance and insulin sensitivity and markedly restored p-Akt and p-IRS1/2 expression in the livers of the MGO-administered mice. Additionally, the PCS extract significantly increased the phosphorylation of Akt and IRS-1/2 and glucose uptake in MGO-treated HepG2 cells. Further studies showed that the PCS extract inhibited MGO-induced AGE formation in the HepG2 cells and in the sera of MGO-administered mice. PCS extract also increased the expression of glyoxalase 1 (GLO1) in the liver tissue of MGO-administered mice. The PCS extract significantly decreased the phosphorylation of ERK, p38, and NF-κB and suppressed the mRNA expression of proinflammatory molecules including TNF-α and IL-1β and iNOS in MGO-administered mice. Additionally, we demonstrated that the PCS extract attenuated oxidative stress, as evidenced by the reduced ROS production in the MGO-treated cells and the enhanced expression of antioxidant enzymes in the liver of MGO-administered mice. Thus, PCS extract ameliorated the MGO-induced insulin resistance in HepG2 cells and in mice by reducing oxidative stress via the inhibition of AGE formation. These findings suggest the potential of PCS extract as a candidate for the prevention and treatment of insulin resistance.

Another Player in the Field: Involvement of Glycotoxins and Glycosative Stress in Insulin Secretion and Resistance

“…Insulin resistance was observed after MG i.v. injection (50 mg/Kg) or administration in the drinking water (1%) to Sprague-Dawley rats [54][55][56]. Moreover, diets enriched with AGEs and MG-BSA were also shown to produce similar results, namely glucose intolerance and lower insulin receptor activation in muscle, liver, and adipose tissue.…”

Isobavachalcone ameliorates diabetic nephropathy in rats by inhibiting the NF‐κB pathway

“…Our result was also consistent with and similar to previous reports. Seo E et al found that P. corylifolia L. could improve renal function by repressing insulin resistance, renal fibrosis, and apoptosis in diabetic mice (Seo, Kang, Oh, & Jun, 2017;Seo et al, 2014;Truong et al, 2019). P. corylifolia L. oral extract taken at a dose of 500 mg/kg showed hypoglycaemic effects on diabetic mice, but no hypoglycaemic effects were observed from P. corylifolia L. extract at a dose of 200 mg/kg.…”

“…Moreover, in in vitro studies, ISO has been proven to block the activation of several inflammatory molecules and reduce intercellular cell adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase expression in vitro (Lee, Kim, Baik, Ryu, & Lee, 2015;Shin, Shon, & Youn, 2013). Specifically, certain recent studies found that P. corylifolia L. seed extract not only improves insulin resistance but also ameliorates diabetes by the inhibition of oxidative stress (Seo et al, 2014;Truong, Seo, & Jun, 2019).…”

Evaluation of Reference Genes for Expression Normalization in Psoralea Corylifolia L. under Abiotic Stress

“…Owing to its extensive clinical effects [10, 11], P. corylifolia has earned a high reputationthroughout the history of traditional Chinese medicine. In recent years, it has also been found to be effective in treating diabetes, psoriasis and other diseases [12][13][14][15][16].Compared with synthetic compounds,, natural active components in plants have been pre-screened by the natural environment, which ensures their stability, bioavailability, and biological activity. Understanding their biosynthetic pathways is important for the effective synthesis of these natural products in vitro [17].…”

“…Owing to its extensive clinical effects [10, 11], P. corylifolia has earned a high reputationthroughout the history of traditional Chinese medicine. In recent years, it has also been found to be effective in treating diabetes, psoriasis and other diseases [12][13][14][15][16].…”