ABSTRACT
Aim To explore mechanism of epigallocatechin-3-gallate (EGCG) on alleviation of hippocampal neuronal autophagy in APP/PSI transgenic mice. Methods 8-month old APP/PSI transgenic mice were randomly divided into three groups;model group (Tg), EGCG low dose group (Tg/EGCG-L), high dose group (Tg/EGCG-H). C57BL/6J mice were utilized as control. Learning and memory were detected by Morris water maze test. The hippocampal ULK1, P62, LC3 I I / LC3 I,mT0R and Aß M2 expressions were detected by Western blot, immunohistochemical staining and ELISA. Results Compared with NT mice, Tg mice showed a marked prolongation of the escape latency in MWM test (P <0. 05). Decreased ULK1 expression and increased P62, LC3 II/LC3 I and A ßM 2 were detected (P < 0. 05). EGCG-treated group showed marked improvement of all these abnormal changes (P < 0. 05). Conclusions EGCG treatment is able to improve cognitive function, which may be attributed to ameliorated autophagic networks dysfunction and reduced Aß plaques in the the hippocampi of APP/PS1 transgenic mice.
ABSTRACT
BACKGROUND: Microalgae are aquatic chlorophyll-containing organisms comprising unicellular microscopic forms, and their biomasses are potential sources of bioactive compounds, biofuels and food-based products. However, the neuroprotective effects of microalgal biomass have not been fully explored. In this study, biomass from two Chlorella species was characterized, and their antioxidant, anticholinesterase and anti-amyloidogenic activities were investigated. RESULTS: GCMS analysis of the extracts revealed the presence of some phenols, sterols, steroids, fatty acids and terpenes. Ethanol extract of Chlorella sorokiniana (14.21 mg GAE/g) and dichloromethane extract of Chlorella minutissima (20.65 mg QE/g) had the highest total phenol and flavonoid contents, respectively. All the extracts scavenged 2,2-diphenyl-1-picrylhydrazyl, 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate) and hydroxyl radicals. The highest metal chelating activity of the extracts was observed in the ethanol extracts of C. minutissima (102.60 µg/mL) and C. sorokiniana (107.84 µg/mL). Furthermore, the cholinesterase inhibitory activities of the extracts showed that ethanol extract of C. sorokiniana (13.34 µg/mL) exhibited the highest acetylcholinesterase inhibitory activity, while dichloromethane extract of C. minutissima (11.78 µg/mL) showed the highest butyrylcholinesterase inhibitory activity. Incubation of the ß-amyloid protein increased the aggregation of amyloid fibrils after 96 h. However, ethanol extract of C. sorokiniana and C. minutissima inhibited further aggregation of Aß142 and caused disaggregation of matured protein fibrils compared to the control. This study reveals the modulatory effects of C. sorokiniana and C. minutissima extracts on some mediators of Alzheimer's disease and provides insights into their potential benefits as functional food, nutraceutics or therapeutic agent for the management of this neurodegenerative disease.