Distribution of Glycoalkaloids in Potato Tubers of 59 Accessions of Two Wild and Five Cultivated Solanum Species NOBUYUKI KOZUKUE, † KYUNG-SOON YOON, ‡ GWANG-IN BYUN, ‡ SHUJI MISOO, § CAROL E. LEVIN, ⊥ AND MENDEL FRIEDMAN* ,⊥ Department of Food Service Industry, Uiduk University, 780-713 Gangdong, Gyeongju, Gyongbuk, Republic of Korea; Department of Food Technology and Food Service Industry, Yeungnam University, 712-749 Gyeongsan, Republic of Korea; Department of Plant Resource Science, Kobe University, 657-8501 Rokkodai, Nada-ku, Kobe, Japan; and Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, California 94710 Steroidal glycoalkaloids are naturally occurring, secondary plant metabolites that are found in foods, including potatoes and tomatoes. Their content in plants is controlled by both genetic and environmental factors. Glycoalkaloid profiles can be passed to progenies during breeding and hybridization of wild and cultivated potatoes designed to develop improved potatoes. The most common potato, Solanum tuberosum, contains primarily the glycoalkaloids, R-solanine and R-cha- conine. However, wild-type potatoes being used for breeding new varieties contain other, less common glycoalkaloids. Because glycoalkaloid composition is a major criterion for the release of new potato cultivars, we used HPLC, TLC, GC, and GC/MS to determine their nature and content in several Solanum species widely used in potato breeding and hybridization programs. Solanum tuberosum, as well as S. andigena and S. stenotomum, contained R-solanine and R-chaconine. S. canasense was found to contain only dehydrocommersonine. S. acaule contained R-tomatine and demissine. S. juzepczukii and S. curtilobum contained demissine and two previously unidentified glycoalkaloids. We characterized them as demissidine-glucose/rhamnose (1/1 ratio) and demissidine-galactose/ glucose/rhamnose (1/1/1 ratio), tentatively named dihydro- 1 -chaconine and dihydrosolanine, respectively. We found extensive variability in the glycoalkaloid profiles in the tested potato varieties. The possible significance of these findings for plant breeding and food safety is discussed. KEYWORDS: Wild-type potatoes; HPLC; TLC; GC; GC/MS; potato glycoalkaloids; new glycoalkaloids; solanthrene; potato breeding. INTRODUCTION Germplasm of wild and cultivated potatoes is now widely used to impart desirable properties to potato tubers by sexual crosses or protoplast fusion. These properties include resistance to phytopathogens (fungi, bacteria, viruses, insects, and worms) and climatic stress (frost and heat) as well as enhancement of nutritional quality and safety (1, 2). Studies on wild and cultivated potatoes, including Solanum curtilobum, Solanum juzepczukii, Solanum stenotomum, Solanum tuberosum, and their wild progenitor Solanum acaule, indicate the inheritance of the following glycoalkaloids in their progenies: R-chaconine, commersonine, dehydrocommersonine, R-solanine, demissine, dehydrodemissine, R-tomatine, dehydrotomatine, R- and -solamarines, solamargine, solasonine, and soladulcine as well other known and unknown ones (3-16). The generally observed increased concentration of glycoalkaloids in the tubers of interspecific hybrids may be an undesirable characteristic. However, this may not always be true because glycoalkaloids have been shown to exhibit both adverse and beneficial effects in cells, animals, and humans, as reviewed in ref 17. Previously, we (18) determined the morphological character (appearance, size, and shape) as well as glycoalkaloid content of potato tubers of somatic hybrids between S. tuberosum and a wild subspecies S. acaule. All 19 somatic hybrids, except one clone, contained four glycoalkaloids (R-chaconine, R-solanine, R-tomatine, and demissine) inherited from both parents. The results also showed that character expression is influenced by ploidy level and that total glycoalkaloid content in most somatic hybrids was intermediate between those of the fusion parent clones. The objectives of the present study were (a) to determine, with the aid of high-performance liquid chromatography (HPLC), * To whom correspondence should be addressed. Phone: (510) 559- 5615. Fax: (510) 559-5777. E-mail: Mendel.Friedman@ars.usda.gov. † Uiduk University. ‡ Yeungnam University. § Kobe University. ⊥ U.S. Department of Agriculture. 11920 J. Agric. Food Chem. 2008, 56, 11920–11928 10.1021/jf802631t CCC: $40.75  2008 American Chemical Society Published on Web 11/24/2008