Antidepressant-like effects of the Radix Bupleuri and Radix Paeoniae Alba drug pair.

The Radix Bupleuri and Radix Paeoniae Alba drug pair plays a pivotal role in Xiaoyaosan, a famous Chinese herbal preparation that is popular in clinical medicine. To investigate the antidepressant-like effects and potential mechanism of action of the Radix Bupleuri and Radix Paeoniae Alba drug pair, we carried out the forced swim test (FST) and tail suspension test (TST), as the mouse models of depression; and the open field test (OFT) to exclude false-positive results. Subsequently, ptosis and hypothermia induced by reserpine were assessed. Finally, the concentrations of monoamine neurotransmitters and their metabolites, namely epinephrine (NE), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in the hippocampal and cortical tissues of mice were detected with HPLC with electrochemical detector. The Radix Bupleuri and Radix Paeoniae Alba (1:1) drug pair at low, medium, and high doses decreased immobility time in both the FST and TST, and counteracted hypothermia induced by reserpine in mice. After the administration of reserpine, the concentrations of 5-HT and NE in the hippocampal and cortical tissues were decreased; however, pre-treatment with the Radix Bupleuri and Radix Paeoniae Alba drug pair significantly elevated the concentrations of 5-HT and NE in the hippocampal and cortical tissues. The results suggested that, compared with single dose of fluoxetine and the drugs used individually, the Radix Bupleuri and Radix Paeoniae Alba drug pair had an excellent antidepressant-like effect. These data revealed a possible mechanism of action, as the regulation of the central monoaminergic neurotransmitter system in the hippocampal and cortical tissues.

Murein hydrolase activity of surface layer proteins from Lactobacillus acidophilus against Escherichia coli.

The aim of this study was to investigate the murein hydrolase activities of the surface layer proteins (SLPs) from two strains of Lactobacillus acidophilus using zymography. The influence of these hydrolase activities on Escherichia coli ATCC 43893 was also evaluated by analysing their growth curve, cell morphology and physiological state. After the incubation of E. coli with SLPs, growth was inhibited, the number of viable cells was significantly reduced, examination by transmission electron microscopy showed that the cell wall was damaged and flow cytometry results indicated that the majority of the cells were sublethally injured. All of these results suggested that the SLPs of both L. acidophilus strains possessed murein hydrolase activities that were sublethal to E. coli cells.

Characterization of surface layer proteins and its role in probiotic properties of three Lactobacillus strains.

The objective of this study was the characterization of the surface layer proteins (SLPs) and their functional role in the probiotic activity of Lactobacillus helveticus fb213, L. acidophilus fb116 and L. acidophilus fb214. SLPs were extracted and identified by SDS-PAGE, circular dichroism spectra and LC-MS analysis. The results revealed that the molecular masses of the three proteins were 49.7 kDa, 46.0 kDa and 44.6 kDa, respectively. The secondary structures and amino acid compositions of the three proteins were found to be similar. After removing SLPs, the survival of the three lactobacilli in simulated gastric and intestinal juices was reduced by 2-3log as compared with survival of the intact cells. And the adhesion ability of the three strains to HT-29 cells decreased by 61%, 65% and 92%, respectively. SLPs also inhibited the adhesion and invasion of Escherichia coli ATCC 43893 to HT-29 cells. These results suggest that SLPs are advantageous barriers for lactobacilli in the gastrointestinal tract, and these proteins help make it possible for lactobacilli to serve their probiotic functions.

Exopolysaccharide from Lactobacillus planterum LP6: antioxidation and the effect on oxidative stress.

An exopolysaccharide (EPS-3) was isolated from the culture of Lactobacillus planterum LP6 and purified by ion exchange and gel chromatography. The concentrations required to scavenge 50% of the initial radical for DPPH·, OH· and O2(·-) radicals were 1.38, 3.43 and 0.11 mg/mL, respectively. The reducing power (A700 nm) was 0.632 at 5mg/mL. The cell viability of PC12 was improved by 21.67% at 200 µg/mL of EPS-3. Compared with the H2O2 group, the total-antioxidant capacity, activities of superoxide dismutase and catalase were enhanced by 65.81%, 41.34% and 59.05%, respectively. Meanwhile, the level of malondialdehyde and lactate dehydrogenase were decreased by 52.80% and 30.24%. The result indicated that EPS-3 had a notable protective effect against oxidative damage on PC12 cells. The study might lay a theoretical foundation for the comprehensive utilization of lactic acid bacteria source which could result in its application in food systems.