Apple juice is the most

Apple juice is the most consumed apple derivative since more than 20% of freshly harvested apples are consumed as juice (Schulze et al., 2014). Apple juice production implies several technological interventions, among which are skin and pomace removal, enzymatic depectinization, and pasteurization. These technological treatments, which are intended to improve the stability of fruit and vegetable derivatives, significantly affect the phenolic content of the final product (Schulze et al., 2014; Van Buren, De Vos, & Pilnik, 1976) and thus its potential health benefits. To our knowledge, no data regarding the effect of pasteurization on the ability of apple juice to inhibit α-glucosidase are available. Therefore, the aim of the present study was to investigate the effect of pasteurization on the in vitro inhibitory activity of apple juice against α-glucosidase. Apple juice was subjected to a conventional thermal treatment to obtain 5 Log reductions of Cryptosporidium parvum (FDA, 2004), or to a more intense pasteurization to achieve 2 Log reductions of Alicyclobacillus acidoterrestris (Silva & Gibbs, 2001). Further, since the drugs currently used to treat type 2 diabetes often carry undesired side effects (Kumar & Sinha, 2012), for the first time the interaction between apple juice and acarbose was studied. Acarbose was chosen because it is widely used as a therapy for type 2 diabetes. The purpose was to understand whether the combination of juice and acarbose might allow drug dosage reduction while keeping the efficacy against α-glucosidase.
Materials and methods
Results and discussion
Conclusions The results of the present study draw attention to the ability of apple juice in inhibiting α-glucosidase that is one of the key enzymes involved in different expression digestion. Acquired data demonstrated that conventional pasteurization, which is aimed to kill Cryptosporidium parvum oocysts, did not significantly affect the physical and chemical properties of apple juice, nor its inhibiting ability against α-glucosidase. By contrast, severe pasteurization, aimed to destroy Alicyclobacillus acidoterrestris spores, caused up to 35% loss of the inhibiting capacity of apple juice. This suggests that food functionality relies upon an adequate choice of processing parameters. Moreover, results showed that the apple juice-acarbose combined system played a synergistic effect up to 40% α-glucosidase inhibition, whereas higher concentrations led to an antagonistic behavior. Obtained results may represent a starting point to further investigate the potential effect of apple juice in bolstering the efficacy of conventional drugs used for the treatment of type 2 diabetes. Nonetheless, it should be considered that apple juice is an important source of sugars. The latter should be taken into account when designing foods aimed at reducing type 2 diabetes incidence. Thus, further studies may consider apple juice derivatives with low sugar concentration to be exploited for their antidiabetic effect.
Acknowledgments
Introduction As one of the major worldwide health problems, diabetes mellitus is a multifarious metabolic disorder characterized by hyperglycemia, an abnormal postprandial increase of blood glucose, which is in context of insulin resistance and relative insulin deficiency [1]. Diabetes is mainly classified as type 1 diabetes, type 2 diabetes, gestational diabetes and uncommon types of diabetes relying on their pathogenesis. Many severe complications usually occur accompanied by type 2 diabetes, such as uremia, kidney failure, neuropathy and cardiovascular diseases [2,3]. Epidemiology studies have suggested that diabetes mellitus can increase the mortality of cardiovascular diseases as well as that from all causes. Generally, type 2 diabetes is mainly induced by insulin resistance, in which insulin levels can be sufficient. In recent years, several effective approaches have been developed for the clinical treatment of type 2 diabetes mellitus, such as oral anti-diabetic drugs, α-glucosidase inhibitors, glucagon-like peptide-1 (GLP-1) agonists, bile acid sequestrants and glycosurics [4]. One of the main therapeutic strategies is to effectively decrease the postprandial blood glucose levels through inhibiting α-glucosidase [5]. α-Glucosidase (α-d-glucoside glucohydrolase; EC 3.2.1.20) is a kind of membrane-bounded enzyme and mainly distributed in the epithelium of the small intestine. The enzyme is closely associated with carbohydrate metabolism and glycoprotein processing, and both are the most critical physiological functions of the protein in mammals [6]. α-Glucosidase can specifically hydrolyze the α-glucopyranosidic bond, which plays an important role in converting oligosaccharides and disaccharides into glucose [7]. Then the resulting monosaccharides are absorbed into bloodstream, which leads to a significant increase of blood glucose levels [8,9]. Currently, α-glucosidase has been emerged as a potential target protein for the clinical treatment of type 2 diabetes. The inhibition of α-glucosidase plays an essential role in controlling the disease by delaying digestion of dietary carbohydrate and monosaccharides absorption after a meal, which contributes to maintaining postprandial blood glucose at normal levels [10,11]. Therefore, the discovery of novel α-glucosidase inhibitors has attracted extensive attentions of medicinal chemists, and many studies have been performed to develop excellent α-glucosidase inhibitors with potential use [12]. In clinical practices, a limited number of known α-glucosidase inhibitors, including miglitol, acarbose, 1-deoxynojirimycin (DNJ) and voglibose (Fig. 1), are widely used to treat type 2 diabetes by suppressing the hyperglycemia. However, in some cases, a variety of severe side effects ensue such as abdomen pain, diarrhea, flatulence and skin problems [13,14]. Hence, there is an urgent need to discover better α-glucosidase inhibitors having fewer adverse effects for the treatment of α-glucosidase-related diseases.