High-performance gas Chromatographie method for the estimation of the indole-3-acetic acid content of plant materials

Preparation of arctiin moleculary imprinted polymers with 4-vinylpyridine and Allyl-β-cyclodextrin as binary monomers under molecular crowding conditions

This paper reported a feasible method to prepare molecularly imprinted polymer (MIPs) using 4-vinylpyridine (4-VP) and Allyl-β-cyclodextrin (β-CD) as binary functional monomer in the presence of polystyrene (PS). This is the first time that a surrounding of macromolecular crowding was established to improve the imprinting effect of cyclodextrins as monomer in organic solvents. The morphological and characteristics of the polymers with macromolecular crowding reagents were investigated by scanning electron microscope (SEM), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and nitrogen adsorption experiments. The MIPs were synthesized with 4-VP and β-CD as binary functional monomers, a series of experiments were conducted to compare with the control groups. Furthermore, the selectivity of MIP for analogues experiment showed that the β-CD/4-VP MIP has higher specific recognition for arctiin than β-CD/4-VP NIP. A purification method by β-CD/4-VP MIPs coupled with macromolecular crowding reagents was developed for extraction arctiin from Arctium lappa L. In the MIP-SPE process, the optimal washing and eluting reagents are methanol/water (5:5) and methanol/acid (9:1), respectively. When using the β-CD/4-VP MIPs as SPE absorbent, the mean recoveries for arctiin were 87% with purity of 95%. All the results indicate that this synthetic method using 4-VP and β-CD as binary functional monomers in the presence of PS is a promising method for the preparation of selective adsorbents for arctiin analysis in Arctium lappa L.

Noninvasive and continuous recordings of auxin fluxes in intact root apex with a carbon nanotube-modified and self-referencing microelectrode

Auxin (also known as indole-3-acetic acid, IAA) represents an ancient signaling molecule of plants that also exerts bioactive actions on yeast and animal cells. Importantly, IAA emerges as a new anticancer agent due to the ability of oxidatively activated IAA to selectively kill tumor cells. IAA acts as a pheromone-like molecule in brown algae, whereas the hormone concept of IAA dominates current plant biology. However, recent advances also favor the morphogen- and transmitter-like nature of IAA in plants, making this small molecule one of the most unique molecules in the eukaryotic superkingdom. Here, we introduce new technology for the continuous measuring of IAA fluxes in living cells, tissues, and whole organs that is based on a carbon nanotube-modified and self-referencing microelectrode specific for IAA. This technique not only will advance our knowledge of how IAA regulates plant development but will also be applicable in medicine for its potential use in cancer therapy.

Intercalibration of chromatographic methods for auxino phytodrugs in Solanaceae

Three chromatographic methods are considered for the determination in Solanaceae of auxino-similar phytodrugs, so called because their structure resembles an auxine plant hormone. The phytodrugs studied were: 2,4-dichlorophenoxyacetic acid, 2,4-dichlorophenoxypropionic acid, 2,4-dichlorophenoxybutyric acid, 2-methyl-4-chlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, naphthylacetic acid and 2-naphthyloxyacetic acid. Three chromatographic methods, respectively based on ion-interaction HPLC, GC-MS with intra-injector derivatisation and CC-MS with pre-injection derivatisation, were developed, optimised and validated. A comparative discussion of the advantages/disadvantages of the methods suggests a strategy for their preferential use, that is essentially a function of the matrix complexity.

A novel piezoelectric biosensor for the detection of phytohormone beta-indole acetic acid

A novel piezoelectric immunosensor has been developed for the determination of beta-indole acetic acid (IAA) in dilute solutions. The detection is based on competitive immunoreaction between a hapten (IAA) and an antigen (IAA-BSA, hapten-protein conjugation) bound to an anti-IAA antibody, immobilized on a quartz crystal microbalance (QCM). The frequency change (y) of the sensor caused by antigen is linearly related to the logarithm of the concentration of IAA (x) in the range of 0.5 ng/ml - 5 microg/ml with a regression equation of the form y = -23x + 151 (r = 0.9937).

Influence of 5-Methyltryptophan-Resistant Bradyrhizobium japonicum on Soybean Root Nodule Indole-3-Acetic Acid Content

Bradyrhizobium japonicum mutants resistant to 5-methyltryptophan were isolated. Some of these mutants were found to accumulate indole-3-acetic acid (IAA) and tryptophan in culture. In greenhouse studies, nodules from control plants inoculated with wild-type bradyrhizobia contained 0.04, 0.10, and 0.58 μg of free, ester-linked, and peptidyl IAA g (fresh weight) of nodules −1 , respectively. Nodules from plants inoculated with 5-methyltryptophan-resistant bradyrhizobia contained 0.94, 1.30, and 10.6 μg of free, ester-linked, and peptidyl IAA g (fresh weight) of nodules −1 , respectively. This manyfold increase in nodule IAA content indicates that the Bradyrhizobium inoculum can have a considerable influence on the endogenous IAA level of the nodule. Further, these data imply that much of the IAA that accumulated in the high-IAA-containing nodules was of bacterial rather than plant origin. These high-IAA-producing 5-methyltryptophan-resistant bacteria were poor symbiotic nitrogen fixers. Plants inoculated with these bacteria had a lower nodule mass and fixed less nitrogen per gram of nodule than did plants inoculated with wild-type bacteria.