Preventive Effects of Ananas comosus Juice on Obesity Risk Factors in Female Wistar Rats Preventive Effects of Juice on Obesity Risk Factors in Female Rats.

The present study aim was to assess the preventive effects of Ananas comosus juice consumption on the risk factors of obesity in female Wistar rats. 108 rats were tested for 90 days. After randomization, they were shared out into six groups including four experimental groups (GTc, GPlp, GEns and GBrS) and two control groups ( +CT G and CT G − ). The control group consumed 1.20 ml of distilled water, the experimental rats received in oral, 1.20 ml of drinks made from the different parts of Ananas comosus fruit. The measurements of morphometric and biochemical parameters were carried out on Day 0 (D0), Day 30 (D30), Day 60 (D60) and Day 90 (D90). The analysis showed that compared to the positive control rats, the consumption of the various drinks slowed down significantly (P < 0.001); the evolution of the morphometric and biochemical parameters likely to induce obesity in experimental rats which have an increase in a protective factor (HDL; P < 0.001). These results indi-cate that consumption of different parts of Ananas comosus’s juices had preventive effects on risk factors related to obesity. Moreover, the fruit juice treatment has been found to be more effective.


Introduction
Public health problems in underdeveloped countries, once dominated by infectious and parasitic pathologies, are increasingly contrasted by a galloping evolu-tion of nontransmissible pathologies [1] (WHO, 2003). Among these metabolic diseases, obesity appears as a pandemic of the century because it is developing at high speed [1]. considering its worldwide expansion and its consequences on physical, psychological and social well-being, obesity has aroused significant interest within the scientific community [2]. Several strategies are implemented for its management. The aim of obesity treatment is to ensure sufficient weight loss, to maintain the results obtained and to treat complications by means, among other drugs, psychotherapy or surgery [3]. For this, the current WHO recommendations for the treatment of obesity aim to reduce weight by around 5 to 10%. Studies show that a 5% decrease in weight considerably reduces the risk of developing chronic diseases and improves general physical condition [4]. Regular physical and sporting activities of moderate intensity and/or consumption of foods rich in fiber and unsaturated fats improve the lipid and morphometric profile [5] [6] [7].
Furthermore, regular consumption of the juices from different parts of Ananas comosus and its association with physical activity such as swimming can reduce weight, abdominal circumference and fat mass while improving biochemical parameters in obese rats [8]. If these curative treatments combining physical activity with Ananas comosus juice have already shown satisfactory results at the end of the experiment, their effects during the obesity induction process still seem to be poorly understood. Therefore, it would be interesting to study the preventive effects of Ananas comosus consumption on morphometric and biochemical parameters related to obesity. The objective of this study is to assess the preventive effects of consumption of juices made from different parts of the pineapple on the risk factors for obesity in rats. Specifically, it is a matter of to determine the type of pineapple juice that best delays the onset of obesity. This work is motivated to popularize the consumption of endogenous products that can intervene in the prevention of metabolic disorders such as obesity.

Plant Material
It consists of the fruits of Ananas comosus and synthesized bromelain. Ananas comosus fruits, of Cayenne smooth variety, harvested in Mbamkomo (Mfoundi Department, Center Region of Cameroun) were used to make raw juices. The plant is identified with the national herbarium of Yaoundé where each specimen is kept under sample n˚ 18648/SRF/CAM.
The synthesized bromelain is supplied in capsules by "SMART City". Each vegetable capsule contains 500 mg of bromelain with 1000 GDU of digestive activity.

Animal Material
The animals material is composed of young female Wistar rats used (Rattus norvegicus). for the experiment are female albino rats of the wistar strain (Rattus norvegicus). They are 90 days old with an average weight 121.45 ± 8.65 g at the start of the experiment. They were acclimated to the conditions of the Pharmacology and Biochemistry Laboratory of the Faculty of Medicine and Biomedical Sciences of the University of Yaoundé I. These animals were reared at 25˚C -30˚C temperature, 70% to 80% for relative humidity and 12 h/12h for light/dark duration. Their have food and water ad libitum.

Rat Nutrition
During the first phase of breeding which lasted 03 months, the rats received a normal diet for their maintenance and their growth. After this phase, they were subjected to a high-calorie and hyperlipidic diet aimed at inducing obesity. However, the experimental group simultaneous received hyperlipid food and preventive treatment based on juices made from different parts of Ananas comosus.
This second phase also lasted 03 months. The formulation of the rat diet is based on the recommendations of the [9] American Institute of Nutrition (1997), with some modifications according to a local adaptation made by the National Veterinary Laboratory (LAVANET).
Distribution of rats (Table 1) The animals were accommodated in 06 metabolic cages at the dimension by 29.5 cm × 40 cm in base and 17 cm in height.
Preparation of reference solution The reference solution is prepared with a capsule of synthesized bromelain dosed at 500 mg which is diluted in 500 ml of distilled water.

Experimental Protocol
Three types of juice are prepared according to the different parts of the Ananas comosus: the central stem (Tc), the pulp (Plp) and the whole consisting of the central stem and the pulp (Ens). Thus, after sorting, washing and peeling, the fruits or the different isolated parts (central stem or pulp) are crushed and filtered in a centrifuge, then bottled and stored in the refrigerator at a temperature of 4˚C.
The reference group received 10 mg/kg of bromelain [10], knowing that 100 g of fresh Ananas comosus contains 100 mg of bromelain.  The animals consumed 1.20 ml of pineapple juice. Bromelain is concentrated in the central stem compared to the pulp.
The experimental rats consumed a daily amount of 1.20 ml by gavage according to their batch in the morning between 7 hours and 9 hours for 90 days. The control rats received 1.20 ml of distilled water during the same period and at the same times (Figure 1).

Statistical Analysis
The results are expressed as Mean values ± Standard Error of Mean (SEM). The data collected were organized using MS Excel 2010 software which made it possible to observe the central trends and dispersion characteristics such as the mean and the standard deviation, as well as the evolution curves of the parameters and finally, create diagrams illustrating the digital summaries of the information sought. The software R version 3.2.3 was used to carry out the statistical tests, in particular the Wilcoxon test which was used to compare the mean values of the parameters obtained at the beginning and at the end of the experience.
Furthermore, the comparison of effects between the treatments required the implementation of an analysis of variance (ANOVA) with the treatment as a fixed factor. A filing between the treatments was obtained using the Student-Newman-Keuls test. The difference between two means is significant if P < 0.05 (*), very significant if P < 0.01 (**) and highly significant if P < 0.001 (***).

Results
At the start of this study, the rats had an average weight of 121.45 ± 8.65 g, abdominal circumference of 12.33 ± 0.67 cm and a fat mass of 1.15 ± 0.017 g.

Effects of Ananas comosus Juice on Morphometric Parameters
The mean values of the body mass, abdominal circumference and fatty mass of the rats submited to a high-calorie diet and various treatments show several modifications. Treatments with Ananas comosus juice or bromelain had effects on rats parameters. After 90 days of experimentation, except for the abdominal circumference which had a significant increase (p < 0.05; 8.10%) the rats which consumed the juice had, the body mass, body fat and abdominal circumference increased very significantly (p < 0.01) in all groups. The large increasing variations are pronounced in the groups of positive control rats. These average values are illustrated in Figures 2(a)-(c).

Comparison of Final Values of Morphometric Parameters of Rats
The final mean values of the morphometric parameters of rats are represented in

Discussion
The comparison of morphometric and biochemical parameters values during the experience allowed to observe significant modifications (P < 0.01). These variations compared to the values of negative control rats (normo-weighted rats) showed no significant difference. The consumption of the juices did not have any harmful effects on the growth of the experimental rats. The comparative analysis of the final values of the morphometric parameters, between the experimental rats Open Journal of Applied Sciences  With regard to the final values of the experimental rats and those of the negative control rats, no significant difference (P > 0.05) was observed. This could be explained by the fact that the preventive treatment did not have harmful effects on the growth of rats during obesity induction. With regard to the comparative reading of the final values of the biochemical parameters (total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides and glycemia) between the positive control rats and the experimental rats, a significant difference (P < 0.001) was revealed. The normalized evolution of biochemical parameters (P < 0.001) during the experience would be due to the consumption of raw Ananas comosus juice. Which is in perfect agreement with literature. Indeed, several studies have demonstrated the influence of bromelain and dietary fiber on the levels of atherogenic blood lipids in animals and humans [6] [8] [12] as well as on blood sugar [12] [13].

Conclusion
After 90 days of experimentation, the various preventive treatments based on Ananas comosus juice have influenced the evolution of risk factors related to obesity. The different treatments reduced the morphometric and biochemical parameters of the experimental rats. Moreover, the best modifications are observed in the group having consumed the juice of the whole "central stem with pulp". Thus, Ananas comosus juice made from the whole fruit "central stem with pulp" have the most positive effects on the risk factors linked to obesity in female albino wistar.