Antioxidant And Antibacterial Properties Of Three Natural Products

The development and utilization of natural products is the research hotspot currently.Houttuynia cordata polysaccharides,tea ethanol extracts,and plant volatile oils are common natural products,however,the research of which is not systematic and sufficient now.In this work,the polysaccharide components were isolated and purified from Houttuynia cordata leaves,and their monosaccharide composition,proportion and biological activity were clarified.The polyphenol compounds of Yingde black tea were studied,and three tea extracts in antioxidant activities and the antibacterial properties were explored and compared;Antioxidant activity of seven plant volatile oils were evaluated by the HPLC-fluorescence method which is a new dynamic radical scavenging method.The main results were listed as followings:1.Three Houttuynia cordata polysaccharides(namely HCP1,HCP2,and HCP3)were separated and purified from Houttuynia cordata by Toyopearl column chromatography.HCP1 contained mannose,glucose,and galactose,the ratio of which is 1.407:1:3.755;HCP2 contains mannose and glucose,the ratio of which is 2.919:1;HCP3 is composed of mannose only.The evaluation of antioxidant activity found that HCP1 showed the strongest antioxidant activity,and HCP3 showed the weakest.The molecular weight of HCP1 is higher than HCP2 and HCP3,which indicated that its antioxidant activities was correlated with molecular weight.The antibacterial tests showed that HCP1 and HCP2 had a high effect on Staphylococcus aureus,with a minimum inhibitory concentration of 0.9375 mg/m L.HCP3 showed high inhibitory activity against Staphylococcus aureus and E.coli relatively,with a minimum inhibitory concentration of 1.875 mg/mL.2.Five novel flavanones(namely,amelliaone A–E,compound 1-5)along with seven known compounds 6–12 from the ethanol extract of YingDe black tea.The structures of these five novel phenolic compounds were determined using extensive1D and 2D nuclear magnetic resonance spectroscopy experiments.The compounds were further evaluated for antioxidant,a-glucosidase inhibitory,and cytotoxic activities.Compound 1 exhibited higher a-glucosidase inhibitory activity with a halfmaximum inhibitory concentration value(IC50)of 10.2 mM compared with acarbose(18.2 mM).On this basis,we evaluated the antioxidant and antibacterial activities of Yingde Black Tea,Chaozhou Dancong,and Fujian Tieguanyin.The results showed that the antioxidant capacities of the three ethanol extracts were higher than V_C;The inhibitory of Staphylococcus aureus was slightly weaker than 75%ethanol(13.2 mm)with the inhibition zone diameter was 11.3 mm and the minimum inhibitory concentration was 0.15625 mg/mL.3.Taking plant volatile oil as the research object,the antioxidant activity of seven plant volatile oils was determined by HPLC-fluorescence.The order of the antioxidant capacity was:flaxseed oil>ginger oil>jojoba oil>glass Chicory oil>Grapeseed oil>Carrot oil>Rose oil.Among them,flaxseed oil and ginger essential oil with high antioxidation,the percentage of hydroxylation were 41.06%and 52.07%,respectively.The antibacterial tests showed that only the flaxseed oil had inhibitory effect on Staphylococcus aureus with the diameter of the inhibition zone was 16.43mm.In addition,ginger oil had the strongest inhibitory effect on Shigella with the diameter of the zone of inhibition is 18.85 mm and the minimum bactericidal concentration is 3200?g/mL.