Elsevier

Journal of Ethnopharmacology

Volume 198, 23 February 2017, Pages 184-193
Journal of Ethnopharmacology

Aqueous seed extract of Hunteria umbellata (K. Schum.) Hallier f. (Apocynaceae) palliates hyperglycemia, insulin resistance, dyslipidemia, inflammation and oxidative stress in high-fructose diet-induced metabolic syndrome in rats

https://doi.org/10.1016/j.jep.2016.11.043Get rights and content

Abstract

Ethnopharmacological relevance

Hunteria umbellata is used in the management and treatment of diabetes and obesity in Nigeria. This study evaluates the effect of aqueous seed extract of Hunteria umbellata on insulin resistance, dyslipidemia, inflammation and oxidative stress in high-fructose diet-induced metabolic syndrome

Materials and methods

Rats were randomized into seven groups (A-G). Control (group A) and group C rats received control diet for nine weeks while rats in groups B, D – G were placed on high-fructose diet for 9 weeks. In addition to the diets, groups C – F rats orally received 400, 100, 200 and 400 mg/kg body weight aqueous seed extract of Hunteria umbellata for 3 weeks starting from 6th – 9th week.

Results

High-fructose diet (when compared to control rats) mediated a significant (p<0.05) increase in body weight, body mass index and abdominal circumference. Similarly, levels of blood glucose, insulin, leptin, adiponectin and insulin resistance were increased. It also caused a significant increase in the levels of cholesterol, triglycerides, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, atherogenic index, cardiac index and coronary artery index while high-density lipoprotein cholesterol was decreased significantly. Levels of proinflammatory factor, tumour necrosis factor-α, interleukin-6 and 8 were also increased by the high fructose diet. Moreover, it mediated decrease in activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose 6-phosphate dehydrogenase and level of glutathione reduced. Conversely, levels of malondialdehyde, conjugated dienes, lipid hydroperoxides, protein carbonyl and fragmented DNA were elevated. Aqueous seed extract of Hunteria umbellata significantly ameliorated the high fructose diet-mediated alterations.

Conclusions

From this study, it is concluded that aqueous seed extract of Hunteria umbellata possesses hypoglycemic, hypolipidemic and antioxidants abilities as evident from its capability to extenuate insulin resistance, dyslipidemia, inflammation and oxidative stress in high-fructose diet-induced metabolic syndrome rats.

Introduction

Metabolic syndrome is a cluster of physiologic and metabolic disorder characterized by increased waist circumference, fasting glycemia, dyslipidemia and hypertension (Eckel et al., 2010, Oron-Herman et al., 2008). Contrary to general believe that it is predominant in western countries, its incidence and prevalence now well documented are assuming epidemic condition across the globe including Nigeria (Das, 2014). Although, factors responsible for this increase is not clear, it is argued that increased consumption of a calorie-rich/high-fat diet, lack of exercise, and sedentary lifestyles are responsible (Das, 2014).

Available management options for metabolic syndrome are targeted towards controlling the individual components. However, regulation of dietary intakes, abstinence from smoking, moderate exercise and drug intake are preferred available options (Han and Lean, 2010). Studies have documented importance of plant foods and medicinal plants in the management and treatments of metabolic diseases (Ajboye et al., 2010, Ajiboye, 2011, Oloyede et al., 2015, Oloyede et al., 2014).

Hunteria umbellata (K. Schum), locally called madaci, mkpokiri and aberere among the Hausa, Igbo and Yoruba respectively, belongs to the family Apocynaceae. The plant is a small glabrous tree measuring 2–5 ft. in girth and 25–40 ft. high, which grows well and ubiquitous to the tropical West African forest groove (Sofowora, 1993). In African folk medicine, various parts (especially the leaves, seeds, roots and barks) of the plant are highly valued for the treatment of human diseases including fever, pain, abdominal colic and discomforts, diabetes mellitus and obesity and as an immune booster (Adeneye and Adeyemi, 2009, Falodun et al., 2006; Gills, 1992).

Studies have validated the hypoglycemic activity of the seed extract in normal, high glucose and nicotine-induced hyperglycaemic rats (Adeneye and Adeyemi, 2009). This activity was mediated via intestinal glucose uptake and adrenergic inhibition, respectively (Adeneye and Adeyemi, 2009). Similarly, the plant seeds was reported to posses antidiabetic and antiobesity properties in different animal models (Adeneye et al., 2010).

The phytochemical constituents of the plant seeds include eburnamine, eburnamonine, hunteriamine, hunterine, vincamine and corymine (Boone, 2006). Eburnamonine, eburnamine and hunterine have strong and lasting hypotensive action. Eburnamonine, which is abundantly present in the Hunteria umbellata seeds is useful as a cerebrovascular agent and improves general blood circulation while vincamine exhibits significant activity as an anti-hypertensive and sedative agent (Boone, 2006).

While studies have validated its beneficial role in hyperglycemic, insulin resistance and obesity conditions, which are components of metabolic syndrome, none of these studies evaluated the plant for hypoglycemic, insulin resistance and obesity in metabolic syndrome rats. This study was thus aimed at investigating the effect of aqueous seed extract of Hunteria umbellata on high-fructose diet induced metabolic syndrome.

Section snippets

Laboratory animals

Healthy albino rats (Rattus norvegicus) of Wistar strain were procured from the Animal holding unit of the Department of Biochemistry, University of Ilorin, Ilorin, Nigeria. They were acclimatized for one week in clean metabolic cages in a well-ventilated house with free access to rat chow and clean tap water. The animals were used according to the Guideline of National Research Council Guide (National Research Council, 2011) and in accordance with the principles of Good Laboratory Procedure

HPLC profiling of aqueous seed extract of Hunteria umbellata

Phytochemical profiling of aqueous seed extract of Hunteria umbellata using HPLC revealed the presence of seven constituents (Fig. 1). The concentrations of the phytoconstituents are presented in Table 2, with the most abundant being erinincine, ursolic acid and umbellamine (Table 2).

Effect of Hunteria umbellata on anthropometric data

The weight gain of high-fructose diet-fed rats increased significantly (p<0.05) when compared to control rats. This increase was lowered by aqueous seed extract of Hunteria umbellata with the highest dose (400 mg/kg

Discussion

Plant foods, fruits, vegetables and medicinal plants are widely used and are prospects for the development of nutraceutical and phytomedicines (Oloyede et al., 2013). This study presents the capability of aqueous seed extract of Hunteria umbellata to palliates hyperglycemia, insulin resistance, dyslipidemia, inflammation and oxidative stress in high-fructose diet-induced metabolic syndrome in rats.

The presence of corymine, umbellamine, isocorymine, erinincine and vinblastine has been previously

Conclusion

Based on the data generated from this study, aqueous seed extract of Hunteria umbellata abates metabolic syndrome in high-fructose fed rats possibly by alleviating hyperglycemia, insulin resistance, dyslipidemia, inflammation and acting as a scavenger of reactive oxygen species or enhancing the activities of enzymes that detoxify ROS. It is therefore a potential source for developing a nutraceutical for treating metabolic syndrome.

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  • Cited by (0)

    1

    Contributions: Conceptualized and designed the research, supervised the research, critically revised the manuscript and approved final manuscript.

    2

    Contributions: Acquisition of data (conducted the experiment), analysed data generated from the study and approved final manuscript.

    3

    Contributions: Acquisition of data (participated in the experimental analysis), participated in the data analysis and approved final manuscript

    4

    Contributions: Participated in the design of the research, supervised the research, drafted and approved final manuscript.

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