Contents lists available at ScienceDirect Journal of Functional Foods journal homepage: www.elsevier.com/locate/jff Polyphenol-rich peach (Prunus persica L.) by-product exerts a greater beneficial effect than dietary fiber-rich by-product on insulin resistance and hepatic steatosis in obese rats Sarahí Rodríguez-González a , Iza F. Pérez-Ramírez a , Diana M. Amaya-Cruz a , Marco A. Gallegos-Corona b , Minerva Ramos-Gomez a , Ofelia Mora c , Rosalía Reynoso-Camacho a, ⁎ a Facultad de Química, Universidad Autónoma de Querétaro, C.U., Cerro de las Campanas S/N, Querétaro 76010, Qro., Mexico b Facultad de Medicina, Universidad Autónoma de Querétaro, Prados de La Capilla 200, Querétaro 76176, Qro., Mexico c Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de de México, Blvd. Juriquilla 3001, Juriquilla 76230, Querétaro, Mexico ARTICLE INFO Keywords: Peach By-product Polyphenols Dietary fiber Hepatic steatosis Insulin resistance ABSTRACT Peach juice by-product (PJBP) can prevent complications of obesity due to its high content of polyphenols and dietary fiber. This study aimed to evaluate the effect of a polyphenol-rich (PR-PJBP) and a dietary fiber-rich (DFR-PJBP) peach juice by-product on insulin resistance and hepatic steatosis in obese rats. Animals were fed with high fat and fructose diet (HFF) and supplemented with PR-PJBP and DFR-PJBP for eighteen weeks. PR- PJBP produced the greatest hypoglycemic effect by improving insulin resistance, increasing hepatic glycogen content, and decreasing hepatic PEPCK activity. Likewise, PR-PJBP decreased serum triglycerides levels, ame- liorating hepatic steatosis, decreasing hepatic expression of Srebp1 and Fasn, and increasing hepatic Cpt1 ex- pression. These results suggest that polyphenols from PJBP exert a greater beneficial effect on obesity-related complications than dietary fiber. These effects were associated with caffeoylquinic, p-coumaroylquinic and 4- feruloylquinic acids, and kaempferol derivatives. PR-PJBP could be used as an ingredient for the elaboration of functional foods. 1. Introduction Obesity leads to the development of several metabolic alterations such as insulin resistance and hepatic steatosis (Bulló, Casas-Agustench, Amigó-Correig, Aranceta, & Salas-Salvado, 2006). This latter is char- acterized by an excessive triglyceride (TG) accumulation in vacuoles in the liver as consequence of an increased de novo fatty acid synthesis (lipogenesis). Lipogenesis is regulated by the Sterol Response Element Binding Protein-1c (SREBP-1c), a transcription factor that promotes the expression of lipogenic genes such as Fatty Acid Synthase (Fasn), Acetyl CoA Carboxylase (Acaca), and Stearoyl CoA Desaturase-1 (Scd1)(Ye- Huang and Gusdon, 2013). At the same time, hepatic steatosis is also a consequence of a decreased fatty acid β-oxidation in mitochondria. Carnitine Palmitoyl Transferase-1 (Cpt1) and medium-chain Acyl CoA Dehydrogenase (Acad) are key genes involved in this metabolic pathway (McArdle, Finucane, Connaughton, McMorrow, & Roche, 2013; Postic & Girard, 2008). Hepatic steatosis is strongly associated with hepatic insulin re- sistance, since excessive TG accumulation decreases glycogen synthase activity (glycogenesis) and promotes phosphoenolpyruvate carbox- ykinase (PEPCK) activity (gluconeogenesis), leading to chronic hy- perglycemia (Postic & Girard, 2008; Varman et al., 2004). The dietary recommendations for the prevention of obesity, hepatic steatosis, and insulin resistance include the consumption of dietary fiber- and polyphenols-rich sources (Abete et al.,2011; Fan & Cao, 2013), such as fruit juice by-products. Fruit juice industry produces about 30–40% agroindustrial residues or by-products, which include peel, pulp, and seeds (Ferrentino, Asaduzzaman, & Scampicchio, 2016). Peach (Prunus persica L.) juice by-product (PJBP) contains 37% of dietary fiber and 0.5–8% of total polyphenols, mainly kaempferol and quercetin 3-O-rutinoside (Amaya-Cruz et al., 2015; de Escalada Pla et al., 2012; Calvache et al., 2015). Moreover, the administration of PJBP improved hyperglycemia and hepatic steatosis in rats fed a high fat and fructose diet (Amaya-Cruz et al., 2015). However, juice by- products (JBPs) contain high amounts of reducing sugars, which could ameliorate their health beneficial effects. Therefore, it has been pro- posed to eliminate these compounds and to concentrate dietary fiber of JBPs with water treatments, improving peach BP potential as a https://doi.org/10.1016/j.jff.2018.03.010 Received 4 July 2017; Received in revised form 22 January 2018; Accepted 6 March 2018 ⁎ Corresponding author. E-mail address: rrcamachomx@yahoo.com.mx (R. Reynoso-Camacho). Journal of Functional Foods 45 (2018) 58–66 1756-4646/ © 2018 Elsevier Ltd. All rights reserved. T