Date of Graduation

12-2011

Document Type

Thesis

Degree Name

Master of Science in Food Science (MS)

Degree Level

Graduate

Department

Food Science

Advisor

Sun-Ok Lee

Committee Member

Pengyin Chen

Second Committee Member

Latha Devareddy

Keywords

Health and environmental sciences; Biological sciences; Colon cancer; In vitro; Soy; Soyasaponin

Abstract

Group B saponins, the predominant form of saponins in heat-treated soy products, have been shown to possess hypocholesterolemic, antimutagenic, and anticarcinogenic properties. Previous studies have evaluated crude mixtures of soyasaponins, but studies evaluating a single purified soyasaponin as an anticarcinogenic agent are limited. The goal of this study is to examine the effects of purified soyasaponins I and III as well as their aglycone form, soyasapogenol B, as anticarcinogenic agents on the human colon adenocarcinoma cell line Caco-2. Experiments were conducted to determine the effects of purified soyasaponins on cell proliferation, Protein Kinase C (PKC) activity, and cell morphology in cultures of Caco-2 cells. Treatment of cells with soyasaponins I and III at concentrations of 300-900 ppm significantly reduced viable cell numbers after 48 and 72 hours of exposure by 10-35% (p<0.05). Soyasapogenol B at a concentration of 100 and 150 ppm significantly reduced viable cell numbers after 24 hours by 15 and 62%, respectively (p<0.05). Cell morphology changes demonstrated that as concentrations and lipophilicity of soyasaponins increased, cell membranes became rougher and more irregular. Treatment of cells for 72 hours significantly reduced the amount of PKC activity by 9-40% (p<0.05). Results indicate that purified soyasaponins I, III and soyasapogenol B, at physiologically relevant doses, can suppress Caco-2 colon cancer cell proliferation. These findings suggest that purified group B soyasaponins and their final metabolite soyasapogenol B may be a colon-cancer suppressive component of soy that warrants further examination as a potential nutraceutical or functional food.

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