Isolation and Characterization of Novel Capsorubin-Like Carotenoids from the Red Mamey ( Pouteria sapota) by Enrique Murillo a ), Yesury Mosquera a ), Tibor Kurta ´n b ), Gergely Gulya ´s-Fekete c ), Veronika Nagy c ), and Jo ´ zsef Deli* c ) a )Department of Biochemistry, Faculty of Exact Natural Sciences and Technology, University of Panama, Panama b )University of Debrecen, Faculty of Sciences, Department of Organic Chemistry, Egyetem te ´r 1, H-4032, Debrecen c ) University of Pe ´cs, Medical School, Department of Biochemistry and Medical Chemistry, Szigeti u ´ t 12, H-7624, Pe ´cs (phone: þ 36-72-536356; fax: þ 36-72-536225; e-mail:jozsef.deli@aok.pte.hu) From the ripe fruits of red mamey ( Pouteria sapota), two new carotenoids, 3’-deoxycapsorubin and 3,3’-dideoxycapsorubin, were isolated and identified based on their UV/VIS, CD, 1 H-NMR, and mass spectral data. Introduction. – The most common carotenoids have six-membered rings as end- groups (b or e rings), while carotenoids with a five-membered ring ( k-ring) are rare. Well-known carotenoids containing a k end-group, such as capsanthin, capsorubin, and cryptocapsin, are characteristic components of red paprika (Capsicum annuum) [1][2]. The k end-group of these carotenoids always bears a OH group. We have recently reported the complete isolation and characterization of sapotexanthin (b,k-caroten-6’- one) containing a non-hydroxylated k-end group, from red mamey ( Pouteria sapota) pulp [3]. Besides, pulp of red mamey contains some other interesting red carotenoids with hydroxylated or non-hydroxylated k-rings [4] [5]. In this article, we present the isolation of two new diketo-di-k-carotenoids structurally related to capsorubin. Results and Discussion. – The acetone extract of ripe fruits of mamey (500 g) was saponified with 5% KOH/MeOH. The saponified residue was chromatographed on a column of aluminum oxide ( Brockmann III ) with an increasing percentage of Et 2 O in hexane. By repeated column chromatography, compounds 1 – 3 ( Fig. 1) were separated, subsequently crystallized, and identified based on the analysis of their UV/VIS, CD, 1 H-NMR, and mass spectra. The UV/VIS spectra of the isolated compounds revealed maxima at 485 nm in EtOH (no cis peak), identical with the spectrum of capsorubin isolated from red paprika [1]. Reduction of compounds 1 – 3 with NaBH 4 gave mixtures of stereoisomeric alcohols with identical UV spectra. The UV spectra of these mixtures exhibited, as expected, an increased fine structure and a hypsochromic shift. The perfect super- imposability of the spectra of compounds 1 – 3 and of those of their reduction products suggests substantial structural similarity between these compounds ( Fig. 2). The 45-nm Helvetica Chimica Acta – Vol. 95 (2012) 983  2012 Verlag Helvetica Chimica Acta AG, Zürich