Isovitexin (homovitexin or saponaretin) is a flavonoid, namely the apigenin-6-C-glucoside. In this case, the prefix 'iso' does not imply an isoflavonoid (the position of the B-ring on the C-ring), but the position of the glucoside on the flavone, in comparison to vitexin.
It can be found in the passion flower, Cannabis, oat, and the açaàpalm.
Saponarin is the isovitexin-7-O-glucoside.