ABSTRACT
Saponin is a kind of complex compounds with triterpenoid or spiral aglycones.Natural saponins are used as substrates,and many novel compounds are obtained by biotransformation technology. Especially, converted products of saponins with strong activities provide valuable lead compounds for the research and development of new drugs. Saponins can be divided into triterpenoid saponin and steroidal saponin according to the structure of the mother nucleus. There are about 89 reported saponin components,including 56 triterpenoid saponins and 33 steroidal saponins. Biological enzyme catalysis,microbial transformation and intestinal microflora transformation are the main bioconversion technologies and key development directions of saponins. The research and optimization technology of biological enzyme and microbial transformation of saponins are the effective methods to prepare active secondary saponins. The biotransformation reaction of saponins mainly includes hydrolysis,redox and rearrangement,resulting in the formation of aglycones,secondary glycosides and their derivatives. The hydrolysis of saponin sugar chains was the main biological transformation pathway, and could generate a number of secondary saponins with less glycosyl groups. The secondary saponins could be absorbed into blood and become real active ingredients in body. Preparation of rare secondary saponins,discovery of lead compounds and development of new drugs are the main directions of biotransformation of saponins. The studies on the metabolism and mechanism of natural saponins by microbial and intestinal microbial biotransformation will also become hotspots. According to relevant papers at home and abroad,the researches on transformation technique,transformation approach and transformation reaction of saponins from natural products in the past thirty years were summarized, and the prospects of research and development were also analyzed to provide scientific basis for further study and comprehensive utilization of these conversion products.
ABSTRACT
ObjectiveToinvestigatetheinflammatoryresponseandapoptosisof peripheral blood mononuclear cells(PBMCs) and their regulation by triptolide(TP) in IgA nephropathy(IgAN) patients.MethodsBlood samples were collected from 29 IgAN patients and 16 healthy individuals.TNF-α and IL-6 concentrations were measured by ELISA and NO concentration by Griess reagent in the plasma of samples.PBMCs were isolated from IgAN patients and cultured in vitro,and subsequently activated by PHA(10 mg/L).The cytotoxicity of different TP concentrations was assayed by MTT and two non-toxic concentrations (12.5 μg/L or 25.0 μg/L)were selected for treatment.TNF-α,IL-6 and NO concentrations were measured in the culture media collected from PBMCs cultures activated by PHA (10 mg/L) and treated with TP (12.5 μg/L or 25.0 μg/L).The PHA-activated,TP-treated cells apoptotic rate was analyzed by FACS using Annexin V-FITC staining.The expression of Bcl-2,Bax,caspase-9 and caspase-3 were detected by RT-PCR and Western blotting from lyses of PHA-activated with or without TP-treated cells.ResultsThe serum concentrations of TNF-α[(131.57±50.61) ng/L vs(30.24±18.93) ng/L,P＜0.01],IL-6[(76.36±25.21) ng/L vs(35.08±16.59) ng/L,P＜0.01] and NO[(46.36±12.93) μmol/Lvs (26.61 ±10.87) μmol/L,P＜0.01] were significantly increased in IgAN patients compared to healthy individuals.PBMCs viability in culture decreased after TP treatment in a dose-dependent manner.TP also inhibited TNF-α,IL-6 and NO levels in the media of PHA-activated PBMCs in culture and induced PBMCs apoptosis.The expression of Bcl-2 decreased markedly and Bax,caspase-9 and caspase-3 increased significantly after TP treatment (all P＜0.05).Conclusions The PBMCs from IgAN patients are in a highly activated state,and have a high apoptotic rate.TP treatment induces benificial effects in IgAN patients by inhibiting the activation of PBMCs by activating pro-apoptotic pathway.