3’-(Phenyl alkynyl) Analogs of Abscisic Acid: Two Step Synthesis of Potent ABA Antagonists

2021 ◽  
Author(s):  
Naveen Diddi ◽  
Leon Lai ◽  
Benjamin P Brookbank ◽  
Saad Hussain ◽  
Eiji Nambara ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Biological Testing ◽  
New Class ◽  
Rigid Framework ◽  
Aba Analogs

We report here the synthesis and biological testing of 3’-phenyl alkynyl abscisic ABA analogs, a new class of potent ABA antagonists. These ABA analogs incorporate a rigid framework of eight...

The effect of abscisic acid and abscisic acid metabolites on the germination of cress seed

1992 ◽  
Vol 70 (8) ◽  
pp. 1550-1555 ◽  
Author(s):  
L. V. Gusta ◽  
B. Ewan ◽  
M. J. T. Reaney ◽  
S. R. Abrams
Keyword(s):  
Abscisic Acid ◽  
Seed Germination ◽  
Optical Isomers ◽  
Phaseic Acid ◽  
Naturally Occurring ◽  
Maximum Inhibition ◽  
Cress Seed ◽  
Acid Metabolites ◽  
Aba Analogs ◽  
Optically Pure

Optical isomers of abscisic acid (ABA) and racemic mixtures of both abscisic acid and abscisic acid metabolites were studied to determine their effects on the emergence of root primordia and cotyledons from cress seed. The relative emergence sensitivity of cress seed to the racemic compounds was (±)-ABA aldehyde ≥ (±)-ABA alcohol > (±)-ABA > (±)7′-hydroxy ABA > (±)-phaseic acid. Thus ABA and ABA precursors were effective inhibitors whereas the ABA catabolites, phaseic acid, and 7′-hydroxy ABA had little or no effect on germination. The naturally occurring optically pure enantiomer (+)ABA was a more potent germination inhibitor than synthetic (−)-ABA. An ABA analog, 2′,3′-cis dihydro ABA (DHABA), that is not metabolized to phaseic acid was also studied for inhibitory activity. Although optically pure DHABA has the same configuration at C-1 as (+)-ABA, it was less inhibitory than (+)-ABA and its (−) enantiomer was inactive. The pattern of activity observed in treatments with the enantiomers of DHABA indicates that the configuration at C-1′ is important for maximum inhibition of cress seed germination. It also suggests that in contrast to monocot seeds, the formation of phaseic acid is not required for the inhibition of cress seed germination. Key words: abscisic acid, phaseic acid, ABA alcohol, ABA aldehyde, 7′OHABA, germination, ABA analogs.

scholarly journals Evaluation of Abscisic Acid Analogs as Holding Agents for Bedding Plant Seedlings

2006 ◽  
Vol 16 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Nirmala Sharma ◽  
Doug R. Waterer ◽  
Suzanne R. Abrams
Keyword(s):  
Abscisic Acid ◽  
Methyl Ester ◽  
Moisture Loss ◽  
Dependent Manner ◽  
Negative Effects ◽  
Aesthetic Quality ◽  
Bedding Plant ◽  
Aba Analogs ◽  
Term Performance ◽  
Plant Seedlings

The marketing period of nursery-raised bedding plant seedlings is limited by the loss of aesthetic quality associated with undesirable growth and/or excess moisture loss during storage and handling. Long-lasting synthetic analogs of abscisic acid (ABA) (8′-methylene ABA methyl ester and 8′-acetylene ABA methyl ester) were evaluated for their potential use in controlling growth and extending the marketing period of seedlings of tomato (Lycopersicon esculentum), snapdragon (Antirrhinum majus), and nasturtium (Tropelaum majus). ABA analogs, applied as root-dips, slowed moisture use and reduced seedling growth in a dosage-dependent manner with no significant phytotoxic effects over the short term. The nature and duration of the responses of the three test crops to the ABA analog treatments were similar. ABA analogs were more effective at reducing moisture use by tomato seedlings than regular ABA and also had fewer negative effects on plant appearance. Before ABA analogs can be recommended for commercial-scale use, their impact on long-term performance needs to be determined, along with an evaluation of their cost and safety relative to other plant growth retardants.

scholarly journals Synthesis of New Abscisic Acid (ABA) Analogs Possessing a Geometrically Rigid Cyclized Side Chain

1992 ◽  
Vol 56 (4) ◽  
pp. 624-629 ◽  
Author(s):  
Bum-Tae Kim ◽  
Tadao Asami ◽  
Kensuke Morita ◽  
Chang-Ho Soh ◽  
Noboru Murofushi ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Side Chain ◽  
Aba Analogs

Quinazoline–tyrphostin as a new class of antitumor agents, molecular properties prediction, synthesis and biological testing

2012 ◽  
Vol 53 ◽  
pp. 133-140 ◽  
Author(s):  
Ahmed M. Alafeefy ◽  
Saleh I. Alqasoumi ◽  
Abdelkader E. Ashour ◽  
Vijay Masand ◽  
Nabila A. Al-Jaber ◽  
...  
Keyword(s):  
Antitumor Agents ◽  
Molecular Properties ◽  
Biological Testing ◽  
New Class ◽  
Molecular Properties Prediction

Effects of abscisic acid (ABA) and ABA analogs on freezing tolerance, low-temperature growth, and flowering in rapeseed

1994 ◽  
Vol 13 (4) ◽  
pp. 235-241 ◽  
Author(s):  
Ronald W. Wilen ◽  
Lawrence V. Gusta ◽  
Bo Lei ◽  
Suzanne R. Abrams ◽  
Bruce E. Ewan
Keyword(s):  
Abscisic Acid ◽  
Low Temperature ◽  
Freezing Tolerance ◽  
Temperature Growth ◽  
Low Temperature Growth ◽  
Aba Analogs

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

The microtubule associated protein (MAP) tau forms a new class of triple-stranded left-hand helical fibrous protein polymer

1992 ◽  
Vol 50 (1) ◽  
pp. 540-541
Author(s):  
G. C. Ruben ◽  
K. Iqbal ◽  
I. Grundke-Iqbal ◽  
H. Wisniewski ◽  
T. L. Ciardelli ◽  
...  
Keyword(s):  
Axial Ratio ◽  
Normal Structure ◽  
Paired Helical Filaments ◽  
Left Hand ◽  
New Class ◽  
Protein Polymer ◽  
Fibrous Protein ◽  
Protein Map ◽  
Neurotransmitter Transport ◽  
Alzheimer Neurofibrillary Tangles

In neurons, the microtubule associated protein, tau, is found in the axons. Tau stabilizes the microtubules required for neurotransmitter transport to the axonal terminal. Since tau has been found in both Alzheimer neurofibrillary tangles (NFT) and in paired helical filaments (PHF), the study of tau's normal structure had to preceed TEM studies of NFT and PHF. The structure of tau was first studied by ultracentrifugation. This work suggested that it was a rod shaped molecule with an axial ratio of 20:1. More recently, paraciystals of phosphorylated and nonphosphoiylated tau have been reported. Phosphorylated tau was 90-95 nm in length and 3-6 nm in diameter where as nonphosphorylated tau was 69-75 nm in length. A shorter length of 30 nm was reported for undamaged tau indicating that it is an extremely flexible molecule. Tau was also studied in relation to microtubules, and its length was found to be 56.1±14.1 nm.

Study of segregation in La1.8Sr0.2CuO4 superconductor by STEM-EDS microanalysis

1987 ◽  
Vol 45 ◽  
pp. 54-55
Author(s):  
T. F. Kelly ◽  
P. J. Lee ◽  
E. E. Hellstrom ◽  
D. C. Larbalestier
Keyword(s):  
Rare Earth ◽  
High Field ◽  
Transport Current ◽  
Total Thickness ◽  
New Class ◽  
Ceramic Superconductors ◽  
Current Densities ◽  
Group Ii ◽  
Eds Microanalysis

Recently there has been much excitement over a new class of high Tc (>30 K) ceramic superconductors of the form A1-xBxCuO4-x, where A is a rare earth and B is from Group II. Unfortunately these materials have only been able to support small transport current densities 1-10 A/cm2. It is very desirable to increase these values by 2 to 3 orders of magnitude for useful high field applications. The reason for these small transport currents is as yet unknown. Evidence has, however, been presented for superconducting clusters on a 50-100 nm scale and on a 1-3 μm scale. We therefore planned a detailed TEM and STEM microanalysis study in order to see whether any evidence for the clusters could be seen.A La1.8Sr0.2Cu04 pellet was cut into 1 mm thick slices from which 3 mm discs were cut. The discs were subsequently mechanically ground to 100 μm total thickness and dimpled to 20 μm thickness at the center.

Electronic structure studies of conducting polymers by electron energy-loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 160-161
Author(s):  
J. Fink
Keyword(s):  
Electronic Structure ◽  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Light Emitting ◽  
One Dimensional ◽  
New Class ◽  
Electrical Conductivities ◽  
Electron Energy Loss

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.

Mechanochemical changes on cyclometalated Ir(iii) acyclic carbene complexes – design and tuning of luminescent mechanochromic transition metal complexes

2020 ◽  
Vol 7 (3) ◽  
pp. 786-794 ◽  
Author(s):  
Jingqi Han ◽  
Kin-Man Tang ◽  
Shun-Cheung Cheng ◽  
Chi-On Ng ◽  
Yuen-Kiu Chun ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Carbene Complexes ◽  
New Class

A new class of luminescent cyclometalated Ir(iii) complexes with readily tunable mechanochromic properties derived from the mechanically induced trans-to-cis isomerization have been developed.

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