Operational Laboratory Methods for GDGTs Groups Separation

Glycerol dialkyl glycerol tetraethers(GDGTs), specific membrane lipids synthesized mainly by bacteria and archaea, can be divided into isoprenoids and methyl branched alkyl GDGTs(i GDGTs and brGDGTs, respectively). Three GDGTs groups(i GDGTs, brGDGTs, and other membrane lipids) in a peat sample were separated and collected in this study using semi-preparative high-performance liquid chromatography(HPLC) and silica gel column chromatography. The obtained recoveries for the whole analytical procedure were 85% – 55% using semi-preparative HPLC and 70% – 20% using gel column chromatography. In addition, in each method, the recoveries of brGDGTs and iGDGTs were similar, regardless of the huge difference in their contents. High purity was found in the fractionated groups, determined based on ether cleavage and reduction. Moreover, the semi-preparative HPLC method could realize a better separation efficiency than the silica gel method, but it was time-consuming and required expensive equipment, while the silica gel chromatography method featured merits of time saving and convenient operation at the cost of a slight reduction in separation efficiency. The advantages of the silica gel method make it an operational laboratory method for batch experiments and isotopic studies.

Extraction and purification of deguelin from Derris trifoliata Lour root

This article deals with extraction and purification of deguelin,which is a main rotenoid occurred in the root of Derris trifoliate Lour.Deguelin has gained much attention of scientists because of its potential ability to inhibit cancer cell proliferation.The dried root powder was extracted with ethanol by ultrasonic-assisted extraction for 30 min,and then filtrated and concentrated to give pasty concentrate.The concentrate was loaded onto silica gel column chromatography subsequently;and the chemical was eluted using a binary solvent mixture of petroleum ether(60-90ºC)-ethyl acetate(4:1,v/v).All tentative identification was carried out by high performance liquid chromatography(HPLC).Most crystal of deguelin was obtained after the fractions mainly containing deguelin were pooled and placed in the dark at 4ºC for three days.With recrystallization from carbon tetrachloride for three times,the purity of deguelin crystal was 99.15%and the yield was 0.55%of the dried weight of D.trifoliate Lour root.

Antibacterial and antioxidant effects from seaweed,Sargassum wightii(Greville,1848)against marine ornamental fish pathogens

Objective:To screen seaweed Sargassum wightii(S.wightii)for bioactive natural substance against marine ornamental fish bacterial pathogens,and also study the antioxidant properties,brine shrimp toxicity effect.Methods:Crude extract was made using three solvents(acetone,ethanol and methanol)and screened for antibacterial activity and purified by column chromatography,purified fractions obtained were tested for the activity.The 1st fraction of acetone extract showed maximum activity,this was again subjected for purification and obtained three sub-fractions also tested for the activity.Total phenols and flavonoid contents,reducing power,free radical scavenging activities(DPPH and H_(2)O_(2))and brine shrimp toxicity were also studied using purified acetone extract followed by standard methods.Results:The purified acetone extract showed maximum activity against eight pathogens among ten.GC-MS results revealed two major compounds such as 24-methylene cholesterol(79.9%)and methyl oleate(30.3%)which presented in higher percentage in purified extract and had highest phenols and flavonoid contents,reducing power,free radical scavenging activities,and also showed less toxicity effect.In he present study,the purified extract of S.wightii had potential antibacterial activity against Aeromonas hydrophila[(22.25±0.35)mm]and minimum activity against Streptococcus sp.[(10.00±0.00)mm].The purified extract of S.wightii also had potential total antioxidant activity of(3.87±0.04)μg at 100μg/mL concentration and the lowest activity was exhibited(1.52±0.01)μg at 25μg/mL.Conclusions:The present study concluded that the brown seaweed,S.wightii has potential antimicrobial and antioxidant activities,which can be used in aquaculture industry for treated bacterial diseases in infected fishes.