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Effects of enzymatic and thermal processing on flavones, the effects of flavones on inflammatory mediators in vitro, and the absorption of flavones in vivo

Hostetler, Gregory

Abstract Details

2011, Doctor of Philosophy, Ohio State University, Food Science and Technology.

Flavones are abundant in parsley and celery and possess unique anti-inflammatory properties in vitro and in animal models. However, their bioavailability and bioactivity depend in part on the conjugation of sugars and other functional groups to the flavone core. Two studies were conducted to determine the effects of processing on stability and profiles of flavones in celery and parsley, and a third explored the effects of deglycosylation on the anti-inflammatory activity of flavones in vitro and their absorption in vivo.

In the first processing study, celery leaves were combined with beta-glucosidase-rich food ingredients (almond, flax seed, or chickpea flour) to determine test for enzymatic hydrolysis of flavone apiosylglucosides. Although all of the enzyme-rich ingredients could convert apigenin glucoside to aglycone, none had an effect on apigenin apiosylglucoside. Thermal stability of flavones from celery was also tested by isolating them and heating at 100 °C for up to 5 hours in pH 3, 5, or 7 buffer. Apigenin glucoside was most stable of the flavones tested, with minimal degradation regardless of pH or heating time. Apigenin, luteolin, and chrysoeriol were stable at pH 3, but degraded steadily at pH 5 or 7. Apigenin apiosylglucoside was least stable at pH 3, but its primary degradation product was apigenin glucoside. Further experiments with thermal processing and enzyme treatments showed that apigenin apiosylglucoside could be converted stepwise to apigenin glucoside and then to aglycone, resulting in over 95% conversion of total apigenin derivatives.

The second processing study explored the effects of juice extraction, acidification, thermal processing, and endogenous enzymes on flavone profiles and concentrations in parsley and celery. Parsley yielded 72% juice with 64% of the total flavones extracted, while celery yielded 79% juice with 56% of flavones extracted. Fresh parsley juice averaged 281 mg flavones/100 g, and fresh celery juice 28.5 mg/100 g. Flavones in steamed parsley and celery were predominantly malonyl apiosylglucoside conjugates, while those in fresh samples were primarily apiosylglucoside conjugates; this was apparently the result of endogenous malonyl esterases. Acidification and thermal processing of celery converted flavone apiosylglucosides to flavone glucosides, resulting in a juice that could improve the bioavailability and efficacy of these potentially beneficial compounds.

In the third study the anti-inflammatory activities of celery extracts, some rich in flavone aglycones and others rich in flavone glycosides, were tested on the inflammatory mediators TNF-alpha and NF-kappaB in LPS-stimulated macrophages. Pure flavone aglycones and aglycone-rich extracts effectively reduced TNF-alpha production and inhibited transcriptional activity of NF-kappaB, while glycoside-rich extracts showed no significant effects. Deglycosylation of flavones increased cellular uptake and cytoplasmic localization as shown by HPLC and by staining with DPBA. Celery diets with different glycoside or aglycone contents were formulated, and absorption was evaluated in mice fed with 5% or 10% celery diets. Relative absorption was significantly higher in mice fed aglycone-rich diets as determined by HPLC-MS/MS. The results demonstrated that deglycosylation increases absorption of dietary flavones in vivo and modulates inflammation by attenuating TNF-alpha and NF-kappaB, suggesting the potential use of flavone-rich functional foods for the treatment or prevention of inflammatory diseases.

Steven Schwartz (Advisor)
Sheryl A. Barringer (Committee Member)
Erich Grotewold (Committee Member)
Andrea Doseff (Committee Member)
131 p.

Recommended Citations

Citations

  • Hostetler, G. (2011). Effects of enzymatic and thermal processing on flavones, the effects of flavones on inflammatory mediators in vitro, and the absorption of flavones in vivo [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313595844

    APA Style (7th edition)

  • Hostetler, Gregory. Effects of enzymatic and thermal processing on flavones, the effects of flavones on inflammatory mediators in vitro, and the absorption of flavones in vivo. 2011. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1313595844.

    MLA Style (8th edition)

  • Hostetler, Gregory. "Effects of enzymatic and thermal processing on flavones, the effects of flavones on inflammatory mediators in vitro, and the absorption of flavones in vivo." Doctoral dissertation, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313595844

    Chicago Manual of Style (17th edition)