Seasonal acclimatization in anuran amphibians: Changes in lactate dehydrogenase specific activities and isoenzyme patterns in several tissues from a naturally occurring population of Discoglossus pictus pictus (Otth.)

Rapid screening and purification of potential inhibitors from Medicago sativa by ultrafiltration-liquid chromatography combined with stepwise flow rate counter-current chromatography

INTRODUCTION

Medicago sativa contains flavonoids, saponins, coumarins, sterols, monoterpenes, and organic acids, with flavonoids being the main active constituents. Flavonoids naturally contain a 2-phenylchromone structure with antioxidant, free radical scavenging, cardiovascular, and trace estrogen-like effects.

OBJECTIVE

Screening and isolation of neuraminidase, lipoxidase, and lactate dehydrogenase inhibitors from M. sativa via ultrafiltration-liquid chromatography-mass spectrometry (UF-LC-MS) combined with stepwise flow rate counter-current chromatography (CCC).

METHOD

Utilising the medicinal plants M. sativa as the research objects and UF-LC-MS was used for activity screening followed by isolation and purification of the inhibitors by stepwise flow rate CCC. Finally, identification of the three active compounds was achieved by MS and nuclear magnetic resonance.

RESULTS

Three major compounds, viz. quercetin, genistein, and formononetin, were identified as potent neuraminidase, lipoxidase, and lactate dehydrogenase inhibitors, respectively. A two-phase solvent system of ethyl acetate/methanol/n-butanol/water (5.0:1.5:5.0:10; v/v/v/v) was subsequently selected for separation by stepwise flow rate CCC.

CONCLUSION

This novel approach based on UF-LC-MS and stepwise flow rate CCC represents a powerful tool for the screening and isolation of neuraminidase, lipoxidase, and lactate dehydrogenase inhibitors from complex matrices. Therefore, a useful platform for the large-scale production of bioactive and nutraceutical ingredients was developed herein.

Thermal relationships and exercise physiology in anuran amphibians: Integration and evolutionary implications

Thermal and water balance are coupled in anurans, and species with particularly permeable skin avoid overheating more effectively than minimizing variance of body temperature. In turn, temperature affects muscle performance in several ways, so documenting the mean and variance of body temperature of active frogs can help explain variation in behavioral performance. The two types of activities studied in most detail, jumping and calling, differ markedly in duration and intensity, and there are distinct differences in the metabolic profile and fiber type of the supporting muscles. Characteristics of jumping and calling also vary significantly among species, and these differences have a number of implications that we discuss in some detail throughout this paper. One question that emerges from this topic is whether anuran species exhibit activity temperatures that match the temperature range over which they perform best. Although this seems the case, thermal preferences are variable and may not necessarily reflect typical activity temperatures. The performance versus temperature curves and the thermal limits for anuran activity reflect the thermal ecology of species more than their systematic position. Anuran thermal physiology, therefore, seems to be phenotypically plastic and susceptible to adaptive evolution. Although generalizations regarding the mechanistic basis of such adjustments are not yet possible, recent attempts have been made to reveal the mechanistic basis of acclimation and acclimatization.