Recently, we isolated a new major spirosolane-type glycoside, named esculeoside A, 1,2) from the fruits of Cherry tomato [Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF.] and the pink color-type tomato (Lycopersicon esculentum MILL., Momotaro), and a novel major solanocapsine-type glycoside, named esculeoside B,2) from the red color-type tomato (Lycopersicon esculentum MILL., Italian San Marzano).Previously, Schreiber and Aurich found 3b-hydroxy-5a-pregn-16-en-20-one (allopregnenolone), in the epigeous parts of the primitive tomato species, Lycopersicon pimpinellifolium MILL., and suggested that it might be a degradation product of tomatidine.3) Heftmann and Schwimmer reported that tomatine-4-14 C incubated in ripe tomato was rapidly converted to 3b-hydroxy-5a-pregn-16-en-20-one. 4) Taking into consideration the above evidence, finding the pregnane glycoside would be significant suggesting a seasonal variation of tomato saponin; tomatine in the immature fruits, via esculeoside A in the ripe fruits, into the pregnane glycoside in the overripe fruits. Therefore, we have searched for the pregnane glycoside in the overripe tomato. This paper deals with the first isolation of tomato pregnane glycoside from the overripe fruit and its structural characterization.Tomato-pregnane (1) Therefore, the structure of 1 has been determined as 3-Ob-lycotetraosyl 3b-hydroxy-5a-pregn-16-en-20-one, which was derived from tomatine by Miyahara.5) This is the first example of a report concerning the occurrence of glycosyl pregnane from tomato fruit.A seasonal variation of tomato steroidal glycosides, that esculeosides A and B might be produced from tomatine in the immature tomato as tomato grows, they would decrease and partly derived into the pregnane glycoside in the overripe season, would be proposed.The first pregnane glycoside was isolated from Paris polypylla by one of our authors, 6) and recently several pregnane glycosides, 7,8) except digitanol pregnane glycosides, were obtained. This evidence indicates that the pregnane glycoside coexists in small amounts together with steroidal glycoside, and simultaneously might mean that pregnane glycoside could be biosynthesized from steroidal glycoside, because the intermediates of the pregnane, 16-acylated pregnane derivatives, 7,9) corresponding to the intermediate in the Marker's degradation procedure, were also found. Steroidal * To whom correspondence should be addressed. A new pregnane glycoside has been isolated from the overripe fruits of Cherry tomato (Mini tomato), Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF. The structure was determined to be 3-O-b b-lycotetraosyl 3b b-hydroxy-5a a-pregn-16-en-20-one on the basis of spectroscopic analysis. The seasonal variation of the tomato saponin is discussed.
