Optimisation of the Extraction Process of Naringin and Its Effect on Reducing Blood Lipid Levels In Vitro.

The naringin extraction process was optimised using response surface methodology (RSM). A central component design was adopted, which included four parameters: extraction temperature (X1), material-liquid ratio (X2), extraction time (X3), and ultrasonic frequency (X4) of 74.79 °C, 1.58 h, 1:56.51 g/mL, and 28.05 KHz, respectively. Based on these optimal extraction conditions, naringin was tested to verify the model's accuracy. Naringin yield was 36.2502 mg/g, which was equivalent to the predicted yield of 36.0124 mg/g. DM101 macroporous adsorption resin was used to purify naringin. The effects of loading concentration, loading flow rate, and sample pH on the adsorption rate of naringin and the effect of ethanol concentration on the desorption rate of naringin were investigated. The optimum conditions for naringin purification using macroporous resins were determined. The optimal loading concentration, sample solution pH, and loading flow rate were 0.075 mg/mL, 3.5, and 1.5 mL/min, respectively. Three parallel tests were conducted under these conditions, and the average naringin yield was 77.5643%. Naringin's structure was identified using infrared spectroscopy and nuclear magnetic resonance. In vitro determination of the lipid-lowering activity of naringin was also conducted. These results showed that naringin has potential applications as a functional food for lowering blood lipid levels.

Temporal effect of acupuncture on amino acid neurotransmitters in rats with acute cerebral ischaemia.

BACKGROUND: Acupuncture stimulation at GV26 during the acute phase of cerebral ischaemia can effectively reduce brain damage induced by ischaemic injury. However, the time course of the effects of acupuncture stimulation has not yet been thoroughly studied. OBJECTIVE: To investigate the effects of manual acupuncture (MA) on glutamic acid (Glu) and γ-aminobutyric acid (GABA) expression in the cerebrospinal fluid of rats with middle cerebral artery occlusion (MCAO) and determine whether there is a temporal effect of acupuncture on the treatment of cerebral ischaemia. METHODS: We performed thread occlusion of the right middle cerebral artery in rats to establish an animal model of MCAO. Simultaneously, during acupuncture treatment, microdialysis was used to continuously and dynamically observe immediate alterations in amino acid metabolism with acupuncture stimulation after cerebral ischaemia in vivo in this rat model of MCAO. RESULTS: We found that, in comparison with an untreated MCAO group, Glu content was significantly decreased during the first acupuncture stimulation and during the course of the acupuncture treatment in the MCAO+MA group (MCAO vs MCAO+MA: day 1, P=0.032; day 2, P=0.021; day 3, P=0.017). These findings were also seen after the end of treatment when acupuncture was no longer applied (MCAO vs MCAO+MA: day 7, P=0.009). Measurements of GABA content following cerebral ischaemic injury showed that GABA peaks 24 hours after damage, falls thereafter and decreases to baseline levels on day 7. In the MCAO+MA group, GABA content on days 1 to day 2 was lower than in the MCAO group (MCAO+MA vs MCAO: day 1, P=0.003; day 2, P=0.001), although it was higher than in the control group (MCAO+MA vs control: day 1, P=0.024; day 2, P=0.009). GABA content on day 3 and day 7 was higher in the MCAO+MA group than in the MCAO group and the control group (MCAO+MA vs MCAO: day 3, P=0.008; day 7, P=0.013; MCAO+MA vs control: day 3, P=0.002; day 7, P=0.009). CONCLUSION: Acupuncture stimulation at GV26 can effectively decrease excessive release of Glu induced by ischaemia and maintain the endogenous inhibitory activity of GABA. This phenomenon was seen during the entire course of acupuncture treatment and continued for some time after the end of acupuncture treatment.