Hanqing Chen

Luteolin protects dopaminergic neurons from inflammation-induced injury through inhibition of microglial activation.

Parkinsons disease is a neurodegenerative disorder characterized by progressive degeneration of dopaminergic neurons in the substantia nigra. Accumulating evidence has suggested that inflammation in the brain participates in the pathogenesis of Parkinsons disease. Luteolin, a polyphenolic compound found in foods of plant origin, belongs to the flavone subclass of flavonoids, and has been shown to possess antimutagenic, antitumorigenic, antioxidant and antiinflammatory properties. In this study, we found that luteolin concentration-dependently attenuated the lipopolysaccharide (LPS)-induced decrease in [(3)H]dopamine uptake and loss of tyrosine hydroxylase-immunoreactive neurons in primary mesencephalic neuron-glia cultures. Moreover, luteolin also significantly inhibited LPS-induced activation of microglia and excessive production of tumor necrosis factor-alpha, nitric oxide and superoxide in mesencephalic neuron-glia cultures and microglia-enriched cultures. Our results demonstrate that luteolin may protect dopaminergic neurons from LPS-induced injury and its efficiency in inhibiting microglia activation may underlie the mechanism.

Protective effect of isoflavones from Trifolium pratense on dopaminergic neurons.

In the present study, protective effect of five isoflavones (formononetin, daidzein, pratensein, calycosin and irilone) from Trifolium pratense on lipopolysaccharide-induced dopaminergic neurodegeneration was studied for the first time. The results showed that all five isoflavones attenuated LPS-induced decrease in dopamine uptake and the number of dopaminergic neurons in a dose-dependent manner in rat mesencephalic neuron-glia cultures. Moreover, they also significantly inhibited LPS-induced activation of microglia and production of tumor necrosis factor-alpha, nitric oxide and superoxide in mesencephalic neuron-glia cultures and microglia-enriched cultures. In addition, the rank order of protective potency of five isoflavones was: pratensein>daidzein>calycosin>formononetin>irilone. This study suggested that all five isoflavones protected dopaminergic neurons against LPS-induced injury through inhibition of microglia activation and proinflammatory factors generation.

Kinetic study of thermal inactivation of potato peroxidase during high-temperature short-time processing

Thermal inactivation curves for peroxidase in potato extracts were determined in the range of 100 to 140°C for 10 to 100 sec. The capillary tube method was used to obtain isothermal conditions. The come-up time for the capillary tubes was accurately calculated by analysis method by which thermal inactivation kinetics of enzymes in relation to high temperature processing would be more easily detected. Heat inactivation of potato peroxidase followed first-order reaction kinetics and yielded a curved Arrhenius plot for the temperature dependence at high temperatures. Kinetics parameters, k and Ea, were calculated for potato peroxidase. At temperature range of 100–140°C, the activation energy of peroxidase was lower than that in the range of 78–84°C. It could be elucidated by the scheme of thermal inactivation pathway.

New source of α-d-galactosidase: Germinating coffee beans.

Enzyme activities of α-Gal from dormant and germinating coffee beans (Coffea arabica) were studied and compared to develop one new source of α-d-galactosidase (α-Gal). During the germination, enzyme activity showed a continuous improvement: it increased slowly within 25 days and then rapidly increased. At the beginning of the germination, enzyme activity was lower than that from dormant coffee beans (DCB). It became higher than the latter around the 30th day, and rose to a maximum at the 35th day. The partially purified enzymes from germinating coffee beans (GCB) and DCB were obtained through ammonium sulphate precipitation, acetone precipitation and DEAE Sepharose ion exchange chromatography. The results showed that enzyme activity of purified α-Gal from GCB was 1.73 times greater than that from DCB. It was most stable for six weeks at its optimal pH (4.8) during the storage. GCB could become a new source of α-Gal instead of DCB.

Konjac Glucomannan as a Carrier Material for Time-Temperature Integrator

Hardness, springiness and water retention of konjac glucomannan gel (g-KGM) as a novel carrier material for time—temperature integrator (TTI) in aseptic processing were determined and compared with those of sodium alginate gel (g-SA). Hardness of both g-KGM and g-SA increased with temperature: values of g-SA were significantly higher (p < 0.05) than those of g-KGM at all temperatures. No significant difference in springiness between g-KGM and g-SA from 40°C to 90 °C and significant differences (p < 0.05) between 100 °C and 140 °C were found. Water retention property of g-KGM was lower than that of g-SA between 60 °C and 100 °C, but much higher between 100 °C and 140 °C. Heat transfer tests performed on g-KGM alone as well as on g-KGM as a carrier, embedded with TTI, α-amylase as an integrator, indicated that g-KGM was suitable for industrial ultrahigh temperature sterilization test.