Elsevier

Journal of Functional Foods

Volume 7, March 2014, Pages 246-256
Journal of Functional Foods

Red peppers with different pungencies and bioactive compounds differentially modulate energy and glucose metabolism in ovariectomized rats fed high fat diets

https://doi.org/10.1016/j.jff.2014.02.004Get rights and content

Highlights

  • Different kinds of red peppers contain different contents of bioactive compounds.

  • Moderate and severely pungent red pepper was best for increasing energy expenditure.

  • Moderate and severely pungent red pepper was best for potentiating insulin secretion.

  • Less pungent red pepper was best for enhancing insulin sensitivity.

  • Different red peppers differently modulate energy and glucose homeostasis.

Abstract

We hypothesized that differences in red peppers pungencies and bioactive compounds are associated with different effects on obesity and glucose tolerance, and tested the hypothesis in ovariectomized (OVX) rats fed high fat diets. Increasing red pepper pungency was associated higher concentrations of capsaicin, dihydrocapsaicin and total capsaicinoids; and lower concentrations of β-carotene, total carotenoids and chlorogenic acid. After 8 weeks of consuming 1% different types of red peppers, moderately and severely pungent red peppers (MSP and SSP) improved energy homeostasis better than less pungent red pepper (LSP): MSP and SSP increased energy expenditure and decreased visceral fat mass. This was related to elevated uncoupling proteins (UCP)-1, UCP-2 and UCP-3 expressions and decreased expressions of genes involved in fatty acid synthesis. LSP enhanced insulin sensitivity and improved hepatic insulin signaling. In conclusion, red peppers with different color and pungency differently modulate energy and glucose homeostasis in OVX rats fed high fat diets.

Introduction

Koreans have a much lower average body mass index (BMI) than most of the developed world with only 31.3% of the adult population having a BMI above 25 (Rhee, Park, Kim, & Woo, 2013). In contrast, among adult Americans 72.3% of men and 64.1% of women have BMIs of 25 or more (Flegal, Carroll, Kit, & Ogden, 2012). Undoubtedly, many dietary and lifestyle factors as well as genetic differences contribute to the difference, but the high consumption of red pepper in the Korean diet could be one contributing factor.

Koreans have traditionally consumed relatively large amounts of red pepper, which has been show to improve energy balance via elevating resting energy expenditure (Kim and Park, 2005, Yu et al., 2012). Many human and animal studies have investigated the modulation of energy intake and expenditure by capsaicin, a major component of red pepper (Kwon et al., 2013, Saito and Yoneshiro, 2013). Red pepper intake has increased from 5.2 g/day in 1998 to 7.2 g/day in 2005 in Korea, and the increased intake might be associated with the low prevalence of obesity in the Korean population. Kim and Park (2005) revealed that red pepper intake was positively correlated with energy intake (r = 0.05) in 100 female undergraduate students; but despite the increased energy intake, it was negatively correlated with waist circumferences (r = −0.2) and fat mass (r = −0.2) as measured by bioelectrical impedance analysis, suggesting that red pepper intake might decrease fat mass by increasing energy expenditure. In our previous study (Kwon et al., 2013) 0.025% capsaicin intake decreased body weight gain, visceral fat accumulation, and serum leptin levels without modulating energy intake in diabetic rats. In addition, capsiate, a non-pungent capsinoid, also improved energy homeostasis. Snitker et al. (2009) reported that oral intake of 6 mg/day of non-pungent capsinoids resulted in abdominal fat loss by increasing fat oxidation in 40 obese men and 40 obese women. Another non-pungent capsinoid, dihydrocapsiate (3 or 9 mg/day), is reported to have caused a small thermogenic effect of about 50 kcal/day for 1 month in seventy-eight healthy men. Although no study has reported a direct effect on energy homeostasis, serum levels of β-carotene, another red pepper component, are negatively associated with abdominal fat mass in children (Canas et al., 2012) and β-carotene suppresses fat accumulation in 3T3-L1 adipocytes (Lobo et al., 2010). Overall, all of the major red pepper components including capsaicinoids, capsinoids, and carotenoids have the potential to modulate energy and glucose metabolism in experimental animals and humans.

Different varieties of red peppers contain different combinations of carotenoids, capsaicinoids and capsinoids which give the peppers various colors and pungencies and possibly different effects on energy and glucose homeostasis. However, few studies have investigated the effects of different types of red pepper on energy and glucose homeostasis in experimental animals. Therefore, we hypothesized that different varieties of red peppers having more or less pungency and different colors due to carotenoid content might differently modulate energy and glucose homeostasis in diet-induced obese rats. The objective of the study was to test the hypothesis using three varieties of red pepper from Young Yang County (Gungsangbuk-Do, Korea) according to the intensity of pungency: less pungent red pepper (LSP; Geumdang), moderately pungent red pepper (MSP; Chilsung) and severely pungent red pepper (SSP; Subicho) in ovariectomized (OVX) rats fed a high fat diet and also to explore possible mechanisms. OVX rats have similar symptoms as post-menopausal women with increased visceral fat mass and bone loss (Santollo, Wiley, & Eckel, 2007), making them a good model for studying dietary interventions for preventing obesity and related pathologies.

Section snippets

Extraction and lyophilization

Three varieties of red pepper powders (LSP, MSP, and SSP) were extracted with 70% ethanol by shaking for 24 h at 25 °C, centrifuged, and supernatants lyophilized (Il Shin) 8000g for 30 min.

Analysis of bioactive compounds

Bioactive components in the red pepper extracts were analyzed by HPLC using a YMC ODS-AM (250 mm × 4.6 mm I.D.; particle size, 5 μm) reversed-phase column (JASCO-ChromNAV, Japan). The mobile phase consisted of solvents, 0.1% acetic acid in water (A) and 0.1% acetic acid in acetonitrile (B). The following gradient was

Bioactive components of red peppers

As expected from the pungency, the contents of capsaicin, dihydrocapsaicin and total capsaicinoid concentrations were in an ascending order of LSP < MSP < SSP (Table 1). Capsiate was not detected in any of the red pepper extracts. In red peppers, β-carotene, zeaxanthin, capsanthin, total carotenoids and chlorogenic acid were present in inverse concentrations as capsaicin contents (Table 1). The contents of total flavonoid and total phenolic compounds were higher in descending order of SSP > LSP > MSP (

Discussion

Consistent with our hypothesis, we found that different varieties of red pepper with different pungencies had different concentrations of bioactive compounds which were associated with differential effects on body weight regulation and blood glucose control. The more pungent red peppers, as expected, had higher concentrations of capsaicin and capsaicinoids. However, the higher pungency red peppers had lower concentration of carotenoids. The more pungent peppers were more effective for

Conclusion

Different varieties of red pepper differently modulated energy and glucose metabolism due to different compositions of bioactive compounds such as carotenoids, capsaicinoids, and capsinoids in OVX rats fed a high fat diet. MSP and SSP decreased visceral fat mass but increased brown adipose tissues, resulting in a greater increase in energy expenditure and improved glucose tolerance by potentiating glucose-stimulated insulin secretion and increasing β-cell mass, However, LSP enhanced insulin

Authors’ contribution

HJY, DYK and SP designed research; HJY, MJK, DSK, SK, MNR, LJJ and BKS conducted animal study and biochemical assays; SP DYK and JWD analyzed data and wrote the paper. SP had primary responsibility for final content. All authors contributed to writing drafting of the manuscript and approved the final version of manuscript.

Conflict of interest declaration

The authors declare that there are no conflicts of interest.

Acknowledgements

This work was supported by “Food Functionality Evaluation program” under the Ministry of Food, Agriculture, Forestry and Fisheries and the Korea Science and Engineering Foundation in Korea and partly by Young Yang County.

References (49)

  • F. Mauvais-Jarvis

    Estrogen and androgen receptors: Regulators of fuel homeostasis and emerging targets for diabetes and obesity

    Trends in Endocrinology & Metabolism

    (2011)
  • P.G. Reeves et al.

    AIN-93 purified diets for laboratory rodents: Final report of the American Institute of Nutrition ad hoc writing committee on the reformulation of the AIN-76A rodent diet

    Journal of Nutrition

    (1993)
  • V.L. Singleton et al.

    Analysis of total phenols and other oxidation substrates and antioxidants by means of folin–ciocalteu reagent

    Methods in Enzymology

    (1999)
  • S. Snitker et al.

    Effects of novel capsinoid treatment on fatness and energy metabolism in humans: Possible pharmacogenetic implications

    American Journal of Clinical Nutrition

    (2009)
  • K. Suzuki et al.

    Association of abdominal obesity with decreased serum levels of carotenoids in a healthy Japanese population

    Clinical Nutrition

    (2006)
  • H.J. Yang et al.

    Anti-diabetic effects of Korean red pepper via AMPK and PPAR-γ activation in C2C12 myotubes

    Journal of Functional Foods

    (2012)
  • E. Alvarez-Parrilla et al.

    Antioxidant activity of fresh and processed Jalapeño and Serrano peppers

    Journal of Agricultural Food Chemistry

    (2011)
  • A.M. Berryman et al.

    Influence of treatment of diabetic rats with combinations of pycnogenol, beta-carotene, and alpha-lipoic acid on parameters of oxidative stress

    Journal of Biochemical and Molecular Toxicology

    (2004)
  • J.A. Canas et al.

    Insulin resistance and adiposity in relation to serum β-carotene levels

    Journal of Pediatrics

    (2012)
  • S.B. Choi et al.

    Estrogen and exercise may enhance beta-cell function and mass via insulin receptor substrate 2 induction in ovariectomized diabetic rats

    Endocrinology

    (2005)
  • S.D. Clarke et al.

    Differential effects of acute and chronic estrogen treatment on thermogenic and metabolic pathways in ovariectomized sheep

    Endocrinology

    (2013)
  • W.B. Davis

    Determination of flavanones in citrus fruits

    Analytical Chemistry

    (1947)
  • X. Dong et al.

    Irs1 and Irs2 signaling is essential for hepatic glucose homeostasis and systemic growth

    Journal of Clinical Investigation

    (2006)
  • K.M. Flegal et al.

    Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999–2010

    Journal of American Medical Association

    (2012)
  • Cited by (0)

    1

    Equal contribution.

    View full text