Composition and Chemopreventive Effect of Polysaccharides from Common Beans (Phaseolus vulgaris L.) on Azoxymethane-Induced Colon Cancer ANA A. FEREGRINO-P ´ EREZ, † LAURA C. BERUMEN, § GUADALUPE GARC ´ IA-ALCOCER, § RAM ´ ON G. GUEVARA-GONZALEZ, # MINERVA RAMOS-GOMEZ, † ROSAL ´ IA REYNOSO-CAMACHO, † JORGE A. ACOSTA-GALLEGOS, ⊥ AND GUADALUPE LOARCA-PIN ˜ A* ,† Programa de Posgrado en Alimentos del Centro de la Repu ´blica (PROPAC), Research and Graduate Studies in Food Science, School of Chemistry, Universidad Auto ´noma de Quere ´taro, Quere ´taro, Qro. 76010, Mexico; Facultad de Quı ´mica and Facultad de Ingenierı ´a, Universidad Auto ´noma de Quere ´taro, Quere ´taro, Qro, Mexico; and Instituto Nacional de Investigaciones Forestales Agrı ´colas y Pecuarias, Campo Experimental Bajı ´o (INIFAP; Celaya), Guanajuato, Mexico Common beans (Phaseolus vulgaris L.) contain a high proportion of undigested carbohydrates (NDC) that can be fermented in the large intestine to produce short-chain fatty acids (SCFA) such as acetate, propionate, and butyrate. The objective of the present study was to evaluate the composition and chemopreventive effect of a polysaccharide extract (PE) from cooked common beans (P. vulgaris L) cv. Negro 8025 on azoxymethane (AOM) induced colon cancer in rats. The PE induced SCFA production with the highest butyrate concentrated in the cecum zone: 6.7 ( 0.06 mmol/g of sample for PE treatment and 5.29 ( 0.24 mmol/g of sample for PE + AOM treatment. The number of aberrant crypt foci (ACF) and the transcriptional expression of bax and caspase-3 were increased, and rb expression was decreased. The data suggest that PE decreased ACF and had an influence on the expression of genes involved in colon cancer for the action of butyrate concentration. KEYWORDS: Polysaccharide; Phaseolus vulgaris; short-chain fatty acid; aberrant crypt foci INTRODUCTION Considerable variability exists in common beans for seed characteristics, and consumers have developed specific prefer- ences for various combinations of size, shape, and color of the dry seeds (1). Common beans are a good source of protein, some vitamins, minerals, and complex carbohydrates (2). In addition to these nutritional compounds, common bean seeds contain a number of bioactive substances including enzyme inhibitors, lectins, phytates, polyphenolic compounds (such as condensed tannins and flavonoids), and polysaccharides. Polysac- charides reaching the colon include mainly resistant starch (RS), soluble and insoluble fiber, and nondigestible oligosaccharides (NDO) that play metabolic roles in humans or animals that frequently consume these foods (3). For example, polysaccha- rides can be fermented in the colon to produce short-chain fatty acids (SCFA) such as acetic, propionic, and butyric acids, and these SCFA have been shown to decrease the incidence of colon cancer induced by azoxymethane (AOM) (4). Aberrant crypt foci (ACF) are being used as a short-term assay to identify modulators of colon carcinogenesis (5). Several studies reported that SCFA, mainly butyrate, inhibited colon cancer through modulation of genes involved in cellular proliferation and induced cell cycle arrest or even apoptosis of colonocytes (6). Butyrate up-regulates B-catenin signaling (7), increases the expression of the p21 cell cycle independent of the expression of p53 (8), and up-regulates expression of the active subunits of caspase-3. Butyrate also causes a concomitant decrease in bcl-2 expression and an increase in bax gene expression via mitochondrial protein (9). In addition, many researchers have reported that polyphenols from dry beans may act as antioxidants to inhibit the formation of damaging free radicals (10). Furthermore, flavonoids such as condensed tannins and antho- cyanins have been reported as antioxidant and antimutagenic agents (10, 11). The presence of these bioactive compounds in common beans (Phaseolus Vulgaris) is related to the decrease of chronically degenerative diseases. The objective of this research was to determine the composi- tion of bioactive substances including nondigested carbohydrates and polyphenolics by a rapid method adapted to a 96-well microplate and to evaluate the chemopreventive effect of a * Author to whom correspondence should be addressed (e-mail loarca@uaq.mx or FlaviaLoarca@yahoo.com.mx; telephone +52 (442) 192-1304; fax +52 (442) 192-1307). † Programa de Posgrado en Alimentos del Centro de la Repu ´blica (PROPAC), Universidad Auto ´noma de Quere ´taro. § Facultad de Quı ´mica, Universidad Auto ´noma de Quere ´taro. # Facultad de Ingenierı ´a, Universidad Auto ´noma de Quere ´taro. ⊥ Instituto Nacional de Investigaciones Forestales Agrı ´colasy Pecuarias. J. Agric. Food Chem. 2008, 56, 8737–8744 8737 10.1021/jf8007162 CCC: $40.75  2008 American Chemical Society Published on Web 08/29/2008