Studies Of β-Glucans From Marine Microalgaes

Marine microalgaes produce polysaccharides through photosynthesis. Products ofphotosynthesis in microalga from Baeillariophyta, Chrysophyta and Xanthophyta are β-glucans, the polymers of glucoses linked by glucose through β-glycosidic bond andhave lots of bioactivities.12species of Baeillariophytas and6species of Chrysophyta werechosen in the studies. The relationship between the population growth and β-glucanproductivity was studied.6species of the microalga with high population growth andhigh β-glucan productivity were chosen to extracte the β-glucans. The bioactivities ofthe β-glucans from the microalga were detected.The results showed that, at the exponential phase, the content ofβ-glucans were low,while at stationary phase, the content increased obviously, reached the highest at last whenthe population began to decline. Theβ-glucan accumulation efficiency of differentmicroalgae was different accordingly.The growth and metabolic condition of the microalga obviously influenced theaccumulation of cellular β-glucans. We detected the effects of NO3+and PO43+on thecontent of β-glucans，and found that, by adding NO3+or PO43+at the later satinary phase,the content of β-glucans changed. By Single-factor analysis of variance we found that,adding P, helped a notably accumulation whlie NO3+had no effect. Different concentrationof PO4+had different effects on the accumulation of β-glucans, the most properconcentration helped accumulation best, under or above the most proper concentrationwould limite the accumulation, even kill the microalage cells.The bioactivities of anti-tumor activity, antioxidant activity, cytotoxic and inhibitoryactivity were detected to the β-glucans. In our research, the β-glucans from6microalgaes could induce TNF-αin Raw246.7. The clearance of DPPH was not high,when the concentration of β-glucan was400μg/ml, the clearance of DPPH was only25%; the clearance of Hydroxyl radical was much higher, when the concentration of β-glucan was400μg/ml, the clearance reached72.%. The β-glucans acted cytotoxic onHela cancer cell, when the concentration of β-glucan was200μg/ml, the death rate of Hela cell was under50%. The β-glucans obviously inhibited the growth of E. coil, butpromoted the growth of Staphylococcus aureus.