Chromatographic fractionation of proanthocyanidin oligomers from an aqueous ethanolic extract of Pelargonium sidoides roots (EPs[R] 7630) gave a diverse set of epigallo- and gallocatechin based oligomers, which are connected by A and B-type bonds. Additionally, two series of monosubstituted oligomers were detected by mass spectroscopy, sulphates and aminoconjugates. In vivo studies investigating motility, body weight gain, body temperature, motoric coordination, anticonvulsant effects and central analgesic activities, showed no or only moderate pharmacological effects, indicating, that they have no intrinsic behavioural activities.
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Keywords: Pelargonium sidoides; Mass spectroscopy; Aminoconjugates; Oligomers; Proanthocyanidins; Chromatography; Behavioural Activities
Oligomers and polymers of prodelphinidins and procyanidins (proanthocyanidins, PAs) are frequent natural products that are contained in many medicinal plants, like Stryphnodendron adstringens (deMello et al., 1996), Ribes nigrum (Tits et al., 1992), Croton lechleri (Cai et al., 1991), Iryanthera megistophylla (Ming et al., 2002), Ecdysanthera utilis (Lin et al., 2002) and Crataegus spec. (Svedstrom et al., 2002) which are claimed to exert diverse pharmacological activities. The assessment of biological actions of these polymers is often influenced by unspecific denaturation of proteins (Wink, 2005; tanning; Sun et al., 1987) or metabolisation by the intestinal colonic microflora (Deprez et al., 2000; McDougall et al., 2005). But very recently it was demonstrated that procyanidin oligomers are readily adsorbed in rats (Shoji et al., 2006). In consequence, oligomers can be bioavailable as such and may have structure dependent activities even on receptor systems. EPs[R] 7630, an aqueous ethanolic extract from roots of Pelargonium sidoides, is the pharmacologically active constituent of Umckaloabo[R], a herbal medicinal product for the treatment of upper respiratory tract infections. EPs[R] 7630 contains a significant amount of PAs (Kolodziej, 2000) that have beneficial effects on LPS induced sickness behaviour (Noldner et al., 2007), arguing for effecting neuroimmunological functions involved in this behaviour.
It was the aim of this study to get more detailed information about the Umckaloabo[R] PAs and their intrinsic properties on the central nerveous system (CNS) detected by a panel of behavioural tests.
Materials and methods
Fractionation of oligomers
Crude fractionation of oligomers
Fractionation of oligomers was performed as described by Czochanska et al. (1980). For this, 10 kg of Umckaloabo[R] tincture (content: 0.8% dry extract) were filtrated over a bed of LH-20 (d = 25 cm, h = 10 cm, conditioned with water) on a glass frit. Then the adsorbed material was washed with 101 of water and subsequently eluted with 41 EtOH, 41 MeOH and 3 portions of 70% acetone (101). The fractions of equal polarity were evaporated in vacuum to remove the organic solvents, the residues dissolved in water and finally freeze dried: EtOH-eluat: 9 g (11.3%); MeOH-eluat: 11.0 g (13.8%); 70% Aceton-eluat: 20.4 g (25.5%).
Isolation of aminosubstituted oligomers
10.0g EtOH-eluat dissolved in about 50 ml water was filtrated in two portions over two Strata-X-C columns, the filtrates combined, freeze dried and finally kept in vacuum over [P.sub.2][O.sub.5] and KOH at 40 [degrees]C for 48 h: 8.5 g low molecular weight oligomers. The...
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