Biological potential of methanol extracts from plants of the genus Spiraea L. growing in Russia

The genus Spiraea is well-represented in the flora of Russian Federation which were only minimally addressed so far in respect of their metabolite profiles and characteristic biological activities. Therefore, phytochemical profiling of the major secondary metabolites in the first year Spiraea shoot extracts, accompanied with comprehensive screening of the activities exerted by these isolates, appears to be a remarkable step forwards. Obviously, this work will deliver new valuable information on the structure-activity relationships (SAR) for the major natural product constituents of these extracts. Indeed, although numerous phytochemical studies with Spiraea plants were reported so far, these works relied on limited numbers of species (or even on individual accessions), while, to the best of our knowledge, no full-scale screening with any logically completed set of Spiraea species was accomplished till now. Because of this, the data on the quantitative profiles of the principal secondary metabolites in the isolates prepared from different Spiraea species are quite fragmentary and require further supplementation and systematization. Therefore, our study aims filling this gap and covers the whole list of the Spiraea species naturally occurring in Russia. Moreover, here we successfully combined a metabolite profiling survey with a comprehensive screening of biological activities of the same extracts to address the Russian spirea species as promising sources of biologically active complexes for use in medical practice. For this, we address the relationships between the relative abundances of individual natural products occurring as their major extract constituents and the biological effects of the corresponding isolates in reliable laboratory models. Specifically, altogether 33 major components representing flavonoids (quercetin and kaempferol derivatives) and hydroxycinnamic acids (caffeic acid, ferulic acid, coumaric acid derivatives) were identified based on chromato-mass spectrometric (LC-MS) analysis. Further, the relative contents of these identified major components in the extracts, obtained from different Spiraea species, were addressed. The analysis of antioxidant potential revealed high activity of all extracts in the models of antiradical activity (DPPH assay), activity against cation radicals (TEAC assay) and superoxide anion radical (NBT assay). The screening of antiviral and antimicrobial activities of the same extracts revealed significant antiviral activity at a concentration of 2 µg/mL, and was assessed high (MIC < 1 mg/mL) or moderate (1 mg/mL ≤ MIC ≤ 4 mg/mL) antibacterial activity against the Gram-positive and Gram-negative bacteria strains.