A new source of Proanthocyanidins with antiarthritic activity: Purple marshlocks (Comarum palustre L.) rhizome and roots

Abstract

Purple marshlocks ( Comarum palustre ) is a wellknown and promising medicinal plant that is widely used in traditional medicine in the form of tinctures, decoctions, and extracts of rhizomes. It is used as a wound-healing and analgetic remedy for treatment of gastralgias, bronchitis, tuberculosis, and especially often for treatment of various diseases of joints. The commercially available dietary supplement Sabel’nikEvalar, which is manufactured in the form of tincture, pills, and cream, is efficiently used in cases of increased load on the locomotor system as a general healthimproving supplement, in complex therapy of rheumatoid arthrites, metabolic dystrophic osteoarthroses, arthritis, spondyloarthrosis, and vertebral osteochondrosis [1]. The chemical composition of C. palustre is highly diverse and includes the polyphenol complex, essential oils, gums, organic and phenolcarboxylic acids and their derivatives, saponins, and tannins (primarily condensed); the latter are the dominant components and account for approximately 10% [2‐4]. Condensed tannins, as was shown for many plant species, are highmolecular-weight derivatives of proanthocyanidins [5]. It was established that proanthocyanidins possess a broad spectrum of pharmacological activity and exhibit antioxidative (they are the best of known antioxidants), gastro- and cardioprotective, antisclerotic, and antiinflammatory properties [6‐10]. Since searching for new sources of proanthocyanidins is a topical problem, the goal of this work was to study the content of these compounds in the polyphenol complex of C. palustre and thereby to assess the possibility of broadening the spectrum of application of this plant as a medicine. The study was performed with three series of C. palustre samples collected in natural sites. Tannins were quantitated by a modified Porter method [11], which is based on acid hydrolysis of oligomeric and polymeric proanthocyanidins to anthocyanidins in the presence of a catalyst ( Fe 3+ ions). Although this method is highly sensitive, changes in the ratio of reagents and temperature conditions significantly decrease the yield of the colored reaction product and the measurement sensitivity [11]. When selecting the optimal conditions of extraction of total proanthocyanidins from various organs of C. palustre , we studied the influence of several factors, including the extracting solvent type