Large-scale separation of alkaloids from Corydalis decumbens by pH-zone-refining centrifugal partition chromatography and their anticomplement activity

Centrifugal partition chromatography in the pH-zone-refining mode was successfully applied to the separation of alkaloids from the crude extract of Corydalis decumbens. The experiment was performed with a two-phase solvent system composed of petroleum ether-ethyl acetate-ethanol-water (5:5:3:7, v/v/v/v) where triethylamine (10 mM) was added to the stationary phase and hydrochloric acid (10 mM) to the mobile phase. From 1.6 g of the crude extract, 43 mg protopine, 189 mg (+)-egenine, and 158 mg tetrahydropalmatine were obtained with a purity of 98.2%, 94.6%, and 96.7%, respectively. Tetrahydropalmatine showed an interesting anticomplement effect with CH50 0.11 and AP50 0.25 mg/mL, respectively. In a mechanistic study, tetrahydropalmatine interacted with C1, C3, C4, and C5 components in the complement activation cascade.

Two Natural Flavonoid Substituted Polysaccharides from Tamarix chinensis: Structural Characterization and Anticomplement Activities

Two novel natural flavonoid substituted polysaccharides (MBAP-1 and MBAP-2) were obtained from Tamarix chinensis Lour. and characterized by HPGPC, methylation, ultra-high-performance liquid chromatography-ion trap tandem mass spectrometry (UPLC-IT-MSⁿ), and NMR analysis. The results showed that MBAP-1 was a homogenous heteropolysaccharide with a backbone of 4)-β-d-Glcp-(1→ and →3,4,6)-β-d-Glcp-(1→. MBAP-2 was also a homogenous polysaccharide which possessed a backbone of →3)-α-d-Glcp-(1→, →4)-β-d-Glcp-(1→ and →3,4)-β-d-Glcp-2-OMe-(1→. Both the two polysaccharides were substituted by quercetin and exhibited anticomplement activities in vitro. However, MBAP-1 (CH₅₀: 0.075 ± 0.004 mg/mL) was more potent than MBAP-2 (CH₅₀: 0.249 ± 0.006 mg/mL) and its reduced product, MBAP-1R (CH₅₀: 0.207 ± 0.008 mg/mL), indicating that multiple monosaccharides and uronic acids might contribute to the anticomplement activity of the flavonoid substituted polysaccharides of T. chinensis. Furthermore, the antioxidant activity of MBAP-1 was also more potent than that of MBAP-2. In conclusion, these two flavonoid substituted polysaccharides from T. chinensis were found to be potential oxidant and complement inhibitors.

Quassinoids from seeds of Brucea Javanica and their anticomplement activities

An investigation on seeds of Brucea javanica led to the acquisition of a new quassinoid, 20-hydroxyyadanzigan (1), along with five known quassinoids (2-6). The structure of the new compound was elucidated on the basis of extensive spectral analysis. All of the compounds were assayed for their anticomplement activities through classical and alternative pathways. Compounds 1-6 exhibited potent anticomplement activity with CH₅₀ and AP₅₀ values of 0.032-0.075 mg/mL and 0.061-0.118 mg/mL, respectively. Moreover, the structure-activity relationships of these compounds are discussed.[Formula: see text].

Steroids from herbs of Reineckia carnea and their anticomplement activities

A new polyhydroxylated pregnane, named lβ,2β,3β,4β,5β,6β-hexolhydroxy-pregn-16-en-20-one (1), along with nine known (2-10) steroidal saponins were isolated from the whole plant of Reineckia carnea. Structure elucidations of all compounds were established by interpretation of their NMR spectral data, HR-ESI-MS and comparing with literatures. In addition, these compounds were evaluated with anticomplement activity. The result showed that compound 1 exhibited anticomplement effects with the CH₅₀ values of 0.043 mg/mL, but saponins (2-10) showed no inhibition. Interestingly, hydrolysis of steroidal saponins (2-10) resulted in its aglycones (2a-10a) correspondingly which showed anticomplement activity with the CH₅₀ values of 0.049-0.156 mg/mL.

Cycloartane triterpenes from Beesia calthaefolia and their anticomplement structure-activity relationship study

Fifteen cycloartane triterpenes were isolated from Beesia calthaefolia and among them one was new cycloartane triterpenoid. The structure of new compound was determined by the application of spectroscopic analyses and chemical methods. The fifteen compounds were evaluated for their anticomplement activity by classic pathway. The structure-activity relationship analysis indicated that the configurations of 12-OH is preferable to be α than β, and 18-OH can decrease while 15-OH can increase the anticomplement activity, but saponin with both 15-OH and 18-OH lost most of its activity. The glycosyl moiety of most isolated cycloartane triterpenes is xylosyl. When xylosyl was substituted by glucosyl or galactosyl, their anticomplement activities were decreased or increased, respectively. Further structure-activity relationship (SAR) studies must be carried out to achieve general conclusions regarding the effect of further functionalizations on the anticomplement saponins.