| The genus Spiraea (Rosaceae) is an interesting subject for chemotaxonomic studies because of the broad distribution and various opinions about the number of species, which are complicated by hybridization and polymorphism. Flavonoids of various structural types are considered marker compounds for this genus and the family as a whole [1]. Characteristic flavonoids of the genus Spiraea are the flavonols kaempferol and quercetin and their glycosides [1], which were detected in S. canescens D. Don [2], S. cantoniensis Lour. [3], S. chamaedryfolia L. [4], S. formosana Hayata [5], S. hypericifolia L., S. media Schmidt [4], and S. salicifolia L. [6]. Methoxylated quercetin derivatives including rhamnazin and the dimeric flavonols sparin A and B, which were atypical of the genus, were relatively recently isolated from S. brahuica Boiss. [7]. Isorhamnetin was also observed in several Siberian Spiraea species [8]. This suggested that methoxylated flavonols were more broadly distributed within this genus. Previously, the isolation of kaempferol and quercetin glycosides and their acylated derivatives from S. salicifolia was reported by us [9]. In continuation of research on Spiraea flavonoids, we detected traces of rhamnetin (7-O-methylquercetin) in the hydrolysate of leaves from S. salicifolia. Herein, results from studies of several Spiraea species for the presence of rhamnetin and its derivatives are presented. Four compounds were isolated by chromatographic separation from the EtOAc fraction of S. salicifolia and were identified as rhamnetin (1), rhamnetin-3-O–D-glucopyranoside (2), and two new flavonoid glycosides 3 and 4. |
