Chlorella is nutritious and has been used as a functional food much earlier than the other microalgae. C. pyrenoidosa, the potential microalgae which is currently cultured and developed for the new strategic industry of biofuels production and biological CO2 fixation, is a new resource food announced by the Ministry of Health of the People's Republic of China late 2012. Accumulation of high value-added substances in C. pyrenoidosa during the cultivation for lipid makes it possible to reduce the costs for C. pyrenoidosa-based biofuels production. Among these potential substances, hot water extract of Chlorella (CE), commercially known as "Chlorella growth factor", is the unique one that makes Chlorella more precious than the other algae, and the market price of CE is high. It is believed that CE is effective in growth promotion and immunoregulation. However, there is no systematic analysis on the research status of CE and its bioactivity. The present report summarized recent research progress of CE and its bioactivity. Generally, besides the main effect on immunoregulation and tumor inhibition, CE was efficient in improving metabolic syndrome, scavenging for free radicals, protecting against ultraviolet damage, chelating heavy metals, and protecting liver and bowel. Several major challenges in CE research as well as its prospects were also analysed in the present report.
Biofuels ; Chlorella ; chemistry ; Humans ; Lipids ; chemistry ; Plant Extracts ; chemistry ; pharmacology ; Water

Objective To study changes in synaptic plasticity in the contralesional mirror area of the cortexes of rats with cerebral infarction treated by low-frequency electrical stimulation(LFES)and to explore the therapeutic mechanism of LFES on the molecular level.Methods Forty-eight Sprague-Dawley rats were randomly allocated into a LFES group,a placebo group and a sham-operation group.Following middle cerebral artery occlusion(MCAO),rats in the LFES group were treated with LFES for 7 d(20 min/d),while the ones in placebo group were connected with the same LFES device but without electricity.Rats in the sham-operation group were subjected to a MCAO operation without occlusion and then received no special treatment.Synaptic ultra-structures and the expression levels of glia fibrillary acidic protein(CFAP)and synaptophysin in the contralesional mirror area of the cortexes of the rats in each group were measured with electron-microscopy and Western blotting.Results Compared with the placebo group or the rats before treatment,rats treated with LFES exhibited ultra-structural changes in the form of larger curvature of synaptic interfaces and narrower synaptic clefts.GFAP expression levels did not fluctuate significantly,but the expression of synaptophysin was significantly up-regulated.Conclusion LFES treatment can induce active changes in synaptic plasticity in the contralesional mirror area of the cortex of rats after cerebral infarction.

Objective To study the effects of low-frequency electrical stimulation(LFES)on motor function and the expression of glia fibrillary acidic protein(GFAP)around cerebral infarction sites in rats.Methods Fifty-four male adult Sprague-Dawley rats were randomly divided into a LFES group,a placebo group and a sham operation group(18/group).All groups were randomly divided into 3 treatment groups.A rat model of middle cerebral artery occlusion(MCAO)was established using intraluminal filament occlusion.Treatment was carried out 3 d after the operation.Rats in the LFES treatment groups were stimulated with LFES for 3,7 or 14 days (10 min/d);the placebo groups were treated in the same way without electric stimulation;the sham operation subgroups didn't receive any therapy.Scores on a beam-walking test,a rotating pole test and a screen test were assessed at each time point mentioned above.Expression of GFAP was also assessed using immunohistochemcal techniques.Results The paralysed limbs recovered motor function better in the LFES groups than in the control groups.GFAP-positive cells were more numerous at the margins of the infarction area in the treated groups than in the control groups.Conclusions LFES might increase the expression of GFAP,which might be an important mechanism in improving brain plasticity after cerebral ischemia,aiding the recovery of the central nervous system and rebuilding its functioning.

The main functional ingredients of hot water extract of Chlorella pyrenoidosa (CPE) were investigated through a bioassay-guided fractionation based on free radical scavenging and macrophage proliferation effects. The main functional ingredients of CPE were polysaccharides (PS) that were isolated by high pressure extraction, Sevag method, ethanol precipitation and ultrafiltration separation. Crude polysaccharides were further separated and purified by ion exchange chromatography DEAE52 and size exclusion chromatography Sephadex G-100. The purified fractions were analyzed by gel permeation chromatography. Molecular weights of the purified fractions PS-1-4-2, PS-1-3-2 and PS-2-3-3 were 3.97×10⁴, 2.28×10⁴ and 4.1×10³ Da, respectively. Bioassay-guided fractionation results indicated that CPE could remove free radicals and promote Ana-1 cells proliferation, mainly due to its various components working together. The components of free radicals scavenging mainly concentrated in PS-1-3, PS-1-4, PS-2-3 and PS-2-4. The components of Ana-1 proliferation mainly concentrated in PS-1-3, PS-1-4 and PS-2-3. This study established the activity screening method of main functional component from CPE, and got three new functional ingredients. It can be used to guide the development of high value products, further promote the industrialization process of microalgae energy, and realize microalgae 'high value products, microalgae energy and microalgae carbon' integration of exemplary role.