THE SECALOSIDES, NOVEL TUMOR-CELL GROWTH-INHIBITORY GLYCOSIDES FROM APOLLEN EXTRACT

The pollen of rye (Secale cereale) was shown to contain a biologically highly active family of glycosides called the secalosides. Secaloside s A and B (1), both of molecular formula C46H51-NO24, were found to be epimeric esters of (2-oxo-3-indolyl)acetic acid(4). They are made up, in addition to this heterocyclic aglycon I (4), of three hexose build ing blocks and a carbocyclic aglycon II, which is an indan-derived dic arboxylic acid(5). In aqueous solution, secalosides A and B interchang ed by epimerization at the chiral center of 4. A further epimeric pair , secalosides C and D (2), contain one additional glucose building blo ck. Secalosides A and B, the racemic aglycon 1(4), and 2-oxo-1,2,3,4-t etrahydroquinoline-4-carboxylic acid (3), which results from 4 by hydr olytic rearrangement, exhibited significant antitumor activity against S180 sarcoma in vivo. IC50 values obtained were about 5 mu g/mouse fo r the secalosides and 1 mu g/mouse for 3 and 4.