The Active Components, Antioxidant And Antibacterial Activities Of Nitraria Sibirica Pall.Fruits

The Nitraria sibirica Pall.(Zygophyllaleae) belong to deciduous leaf bush, its berries are praised for "desert cherry", and have been traditionally used in China as healthy foods or folk medicines to strengthen the spleen and stomach, and help digestion. The genus Nitraria are known to be rich source of alkaloids, flavonol glycosides, and other active ingredients. Several of them have been reported to posses cytotoxic, anti-inflammatory and analgesic, serotonergic and antioxidant activities. However, the chemical constituents of the fruits were rarely known so far, the research is limited activity in vitro experiments and some component content analysis. Thus, further studies on active compounds and activities of Nitraria sibiricapall, fruits which provides theoretic basis for exploitation have important significance.This thesis deal with the isolation and identification of actitive compouds of Nitraria sibirica Pall, fruits, and the antioxidant and methicillin-resistant Staphylococcus aureus (MRSA) inhibition activities were discussed, as well as the anti normal food-borne bacterial acticities of different polarity extracts. The main results of this study were summarized as follows:1.The preliminary study of antibacterial activity for extracts from Nitraria sibirica Pall, fruits demonstrated that ethyl acetate and n-butanol extracts have moderate inhibitory activity against the growth of MRSAs. Both of them exhibited high activity against the growth of MRSA623with a MIC of256μg/ml, equally with oxacillin. The n-butanol extract inhibited the growth of MRSA481,505,584with MIC of512μg/ml. The ethyl acetate extract exhibited the higher activity against MRSA481(MIC256μg/ml), than MRSA505and MRSA584(MIC512μg/ml)。2. ABTS and DPPH radical-scavenging assays were performed to analyze the antioxidant activities of crude extracts and fractions from Nitraria sibirica Pall, fruits for the first time. Our results revealed that N. sibirica Pall, fruits had abundant polypenolic components and exhibited high antioxidant activity. The total phenolic content of the partition fractions revealed that the ether fraction had the highest phenolic content, and was significantly more effective than others in scavenging radical.3. As part of our continuing search for bioactive natural products, we got eleven compounds comprising two β-carboline alkaloids,(1R,3S)-1,2,3,4-tetrahydroharman-3-carboxylic acid (1) and its (1S,3S)-isomer (2), together with tryptophan (3), its carbamoyl derivative N-carbamoyl-tryptophan (4), a phenolic acid β-hydroxyphenyllactic acid (5), two lignan glucosides pinoresinol-4-O-β-glucoside (6) and lariciresinol-4’-O-β-glucoside (7), together with four flavonoid glycosides isorhamnetin-3-O-β-glucoside (8), isorhamnetin-7-O-β-glucoside(9), isorhamnetin-3-O-rutinoside (10), isorhamnetin-3-O-rutinoside-7-O-glucoside (11)。4. The filter paper disc diffusion method was employed to determine the in vitro antimicrobial activities of the different extracts from Nitraria sibirica Pall. fruits. The results showed that within the concentration range of80mg/ml, the ethyl acetate extract displayed higher antibacterial activity against Escherichia coli, Bacillus subtilis, Staphyloccocus aureus. The ethanol extract presented inhibitory activity against Escherichia coli and Bacillus subtilis, the chloroform extract only demonstrated inhibitory activity against Staphyloccocus aureus,and the effect was better than other extracts, the n-butanol extract had activity against Bacillus subtilis.All of the extracts exhibited inhibitory activity against Fungus. The MICs of ethyl acetate extract against Escherichia coli, Bacillus subtilis, Staphyloccocus aureus were25mg/ml,25mg/ml,50mg/ml.