Elsevier

Journal of Diabetes and its Complications

Volume 25, Issue 5, September–October 2011, Pages 339-345
Journal of Diabetes and its Complications

Antidiabetic effect of flax and pumpkin seed mixture powder: effect on hyperlipidemia and antioxidant status in alloxan diabetic rats

https://doi.org/10.1016/j.jdiacomp.2010.09.001Get rights and content

Abstract

Reactive oxygen species play a crucial role in the pathogenesis of diabetes and its complications. This study aims to examine the effects of flax and pumpkin powder seed mixture on alloxan induced diabetes in Wistar rats. Animals were allocated into three groups of six rats each: a control group (CD), diabetic group (DD) and diabetic rats fed with flax and pumpkin seed mixture (DMS) group. The diabetic rats (DD) presented a significant increase in glycemia, plasma and liver lipid parameters such as total lipid, total cholesterol and triglycerides compared to the control group (CD). In addition, plasma and liver malonaldialdehyde levels (MDA, an index of lipid peroxidation) significantly increased compared to (CD). Antioxidant enzymes activities such as catalase, superoxide dismutase, and reduced glutathione (GSH) levels significantly decreased in the plasma and liver of diabetic rats compared to controls. Diet supplemented with flax and pumpkin seed mixture in the DMS group ameliorated antioxidant enzymes activities and level of GSH in diabetic rats and significantly decreased MDA levels.

The present study revealed a significant increase in the activities of aspartate aminotransferase and alanine aminotransferase on diabetic status, indicating considerable hepatocellular injury. The administration of flax and pumpkin seed mixture attenuated the increased levels of the plasma enzymes produced by the induction of diabetes and caused a subsequent recovery towards normalization comparable to the control group animals.

Our results thus suggest that flax and pumpkin seed mixture supplemented to diet may be helpful in preventing diabetic complications in adult rats.

Introduction

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by high levels of glucose in the blood due to the non-secretion of insulin or insulin insensitivity (American Diabetes Association ADA, 2005). DM affects approximately 4% of the population worldwide and is expected to increase by 5.4% in 2025 (Kim, Hyun, & Choung, 2006). Although the underlying mechanisms of diabetes complications remain unclear, clinical and preclinical evidence suggests that diabetes is associated with oxidative stress, leading to an increased production of reactive oxygen species (ROS), including superoxide radical (O2•−), hydrogen peroxide (H2O2) and hydroxyl radical (OH) or a reduction in the antioxidant defense system (Ihara et al., 1999, Rahimi et al., 2005, Rudge et al., 2007). The oxidant/antioxidant imbalance in favour of oxidants contributes to the pathogenesis of different diabetic complications which are considered to result from enhanced reactive oxygen species generation via nicotinamide adenine dinucleotide phosphate-oxidase (Baynes & Thorpe, 1999, Garg et al., 1996, Ha & Kim, 1999).

The pathophysiology of diabetes involves a very complex cascade of several interrelated mechanisms. Elevated blood glucose induces auto-oxidative glycosylation and formation of glycation product, activates protein kinase-C, and increases polyol pathway activity and hexosamine flux, which are the key components of the cascade. These pathways are responsible for the generation of reactive oxygen species (superoxide, hydroxyl radical, hydrogen peroxide) and peroxynitrite, which ultimately contribute to oxidative stress (Ahmed et al., 2004, Baynes & Thorpe, 1999, Ha & Kim, 1999). Current approaches to diabetes therapy involve mainly drugs enhancing insulin secretion or signalling as well as inhibiting endogenous glucose production (Anuradha & Selvam, 1993), while the role of antioxidants as the important agents to restore the redox balance of the organism is still underestimated. Dietary intervention, particularly the use of traditional food and medicine derived from natural sources, is a mainstay in the management of diabetes. In this context, various dietary sources are presently receiving considerable attention across the world for the potential health benefits in relation to many diseases such as diabetic disorders. Among them, flax seeds (Linum usitatissimum L., member of Linaceae family) and pumpkin seeds (Cucurbita pepo L., member of Cucurbitaceae family) are becoming new compounds of the traditional health food in Tunisia and other North African countries. Flax seeds contain high levels of Omega-3 fatty acid (Burdge & Calder, 2005), fiber components and phytochemicals such as lignans bioressource (Vijaimohan et al., 2006). The main physiological benefits of flax seeds are attributed primarily to the high linoleic acid content which contributes to their antioxidant properties (Simopoulos, 1991) against various diseases, including atherosclerosis, diabetes, hypertension, anti-inflammatory, and anticarcinogenic effects (Fukuda, Osawa, Namiki, & Ozaki, 1985). Pumpkin seeds are utilized for human consumption as snacks after salting and roasting, in Arabian countries (Al-Khalifa, 1996). These seeds are excellent sources of protein (25.2–37%), vitamins and oil (37.8–45.4%) (Barbara & Murkovic, 2004, Murkovic et al., 2004), especially Omega 6 fatty acids which have a number of biological applications along with significant antioxidant activity, in addition to anti-inflammatory and hypolipidemic effects (Suresh & Das, 2003).

In our previous study, we demonstrated that flax and pumpkin seed mixture supplemented to diet of hypercholesterolemic rats had a significant anti-atherogenic, hypolipidemic and antioxidant potency. Flax and pumpkin seed mixture had a pronounced antioxidant activity due to their richness in antioxidant components (Makni et al., 2008).

Several studies have demonstrated the beneficial effects of dietary seeds. Hence, the protective effects of flax and pumpkin seed mixture on diabetic complications would be worth studying.

The present study was carried out in order to evaluate both the problems induced by diabetes and the protective effects of flax and pumpkin seed mixture.

Section snippets

Plant material

Flax (Linum usitatissimum L.) and pumpkin (Cucurbita pepo L.) seeds were purchased from a local market, crushed at ambient temperature and stored at 4°C prior to use. The seed mixture of flax and pumpkin rich in Omega 3 and Omega 6 was prepared. The ratio of Omega 6/Omega 3 fatty acids was 5:1, as recommended by the World Health Organization and according to several reports (Blandeau & Schneider, 2006, Grigg, 2004).

Experimental design

Male Wistar rats (aged 11–12 weeks, weighing 190–210 g) were obtained from the

Blood glucose, hepatic glycogen concentration and GTT

The plasma glucose concentration in the DD group significantly increased in comparison to the normoglycemic group (CD) (Fig. 1). The administration of flax and pumpkin seed mixture to rats with hyperglycemia resulted in the significant decrease of glucose concentration in comparison to the result obtained from the DD group.

The concentration of plasma insulin (Fig. 2) of DD rats decreased by −42% in comparison to the CD group. Flax and pumpkin seed mixture supplemented to the diet of DMS group

Discussion

Our previous investigation (Makni et al., 2008) showing the potent hypolipidemic and antioxidant activity of supplemented flax and pumpkin seed mixture in hypercholesterolemic rats confirmed the ethnomedical use of these seeds against metabolic syndrome. In the present study, we investigated whether the flax and pumpkin seed mixture had any hypoglycemic, hypolipidemic, and antioxidant action in normal and alloxan-diabetic rats.

The most important result of the present study was that rats, fed a

Acknowledgments

The authors thank the skilful technical assistance of the Food Processing Department of Sidi Bouzid Institute (ISET) Tunisia. We also extend our thanks to Mr. Bejaoui Hafed, teacher of English at the Sfax Faculty of Science, who helped proofread and edited this manuscript. The present work was supported by the DGRST grants (Appui à la Recherche Universitaire de Base ARUB 99/UR/08-73), Tunisia.

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