Dynamic changes of flavonoids in Actinidia valvata leaves at different growing stages measured by HPLC-MS/MS

Flavonoids are a large group of phenolic secondary metabolites havinga wide range of biochemical and pharmacological effects. Quantitative analysis of flavonoid profiles in the genus Actinidia, which has not been intensively conducted, is useful to a better understanding of the pattern and distribution of flavonoids. In the present work, a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed to profile the flavonoids, which was then used to determine the dynamic change of 17 biologically active flavonoids in the leaves of Actinidia valvata at the main growing stages, including glucuronides and acylated di- and triglycosides of flavonoids. The contents of flavonoid triglycosides were significantly higher than other flavonoids. The highest concentrations of kaemperol glycosides were observed in June, while other flavonoids showed highest concentrations in October. On the other hand, the contents of four isorhamnetin glycosides were increased sharply in September to October. The flavonoid profiles seem to be related to temperature, UV-B, and water deficit. Further studies are required to examine the functions of flavonoids in the Actinidia valvata and the underlying molecular mechanisms of actions.

Cadmium uptake in above-ground parts of lettuce (Lactuca sativa L.)

Because of its high Cd uptake and translocation, lettuce is often used in Cd contamination studies. However, there is a lack of information on Cd accumulation in the above-ground parts of lettuce during the entire growing season. In this study, a field experiment was carried out in a Cd-contaminated area. Above-ground lettuce parts were sampled, and the Cd content was measured using a flame atomic absorption spectrophotometer (AAS). The results showed that the Cd concentration in the above-ground parts of lettuce increased from 2.70 to 3.62mgkg(-1) during the seedling stage, but decreased from 3.62 to 2.40mgkg(-1) during organogenesis and from 2.40 to 1.64mgkg(-1) during bolting. The mean Cd concentration during the seedling stage was significantly higher than that during organogenesis (a=0.05) and bolting (a=0.01). The Cd accumulation in the above-ground parts of an individual lettuce plant could be described by a sigmoidal curve. Cadmium uptake during organogenesis was highest (80% of the total), whereas that during bolting was only 4.34%. This research further reveals that for Rome lettuce: (1) the highest Cd content of above-ground parts occurred at the end of the seedling phase; (2) the best harvest time with respect to Cd phytoaccumulation is at the end of the organogenesis stage; and (3) the organogenesis stage is the most suitable time to enhance phytoaccumulation efficiency by adjusting the root:shoot ratio.