DEVELOPMENT OF CONTROLLED RELEASE FORMULATIONS OF AZOXYSTROBIN BASED ON AMPHIPHILIC POLYMERS
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Date
2014
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DIVISION OF AGRICULTURAL CHEMICALS INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI ā
Abstract
Amphiphilic polymers were synthesized and screened using poly(ethylene glycols) (PEGs) of
different molecular weights, viz. 1000, 1500, 2000 and 4000 as hydrophilic block and linkers
namely azelaic acid, terephthaleic acid, suberic acid and glycolic acid as hydrophobic block in
the presence of catalyst Conc. H2SO4. Synthesized polymers were characterized by using 1H
NMR, 13C NMR and IR spectroscopy. Micellar sizes of the polymers were determined using
Dynamic Light Scattering (DLS) which ranged from 32.1ā308 nm. Transmission Electron
Microscope (TEM) results confirmed the findings of DLS. Critical Micelle Concentrations
(CMC) of the synthesized polymers were determined using electrical conductivity meter which
ranged from 105 to 650 mg Lā1
.
Amphiphilic copolymers, synthesized from poly(ethylene glycols) and various aliphatic
and aromatic diacids and monoacids(glycolic acid), which self assemble into nano-micellar
aggregates in aqueous media, were used to develop controlled release (CR) formulations of
azoxystrobin Methyl (E)-2-{2[6-(2-cyanophenoxy)pyrimidin-4-yloxy] phenyl}-3-
methoxyacrylate using encapsulation technique. Formulations were characterized by Infrared
(IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope
(TEM). Encapsulation efficiency and loading capacity of polymers were checked. Accelerated
storage test of the developed formulations were carried out to check the stability of a.i. in
formulations. The kinetics of azoxystrobin release in water from the different formulations was
also studied. The release of a.i. from the commercial formulation was faster than the CR
formulations. The diffusion exponent (n value) of azoxystrobin, in water ranged from 0.21 to
0.56 in the tested formulations. The time taken for release of 50 % of azoxystrobin ranged from
2.05 to 7.63 days for the CR formulations.
The bioefficacy of the prepared CR formulations was evaluated in vitro against major
pathogens of rice namely Rhizoctonia solani and Fusarium fujikuroi and also in pot experiment
against Fusarium fujikuroi along with a commercial formulation in a glass house of Indian
Agricultural Research Institute (IARI), New Delhi. Most of the CR formulations of azoxystrobin
provided superior control of both fungi compared to commercial formulation and control. Most
of the developed CR formulations recorded higher efficacy over commercial formulation and
control. The percent inhibition ranged from 55.4-86.0% and 55.8-87.5% against Rhizoctonia
solani and Fusarium fujikuroi respectively from different CR formulation of azoxystrobin
obtained in in-vitro study. In the pot experiments all the treatments resulted in a significant
reduction of foolish seedlings infestation as compared to untreated control. The seedling treated
formulation based on amphiphilic polymer Poly [poly (oxyethylene-4000)-oxy glycoyl] and
Poly [poly (oxyethylene-1500)-oxyglycoyl] with recommended dose of azoxystrobin i.e. @
1000 ppm against Fusarium fujikuroi showed best performance in terms of number of survived
seedlings compared to commercial formulation. The study revealed that the CR products of the
azoxystrobin may be used for efficient pest management of rice
Description
t-9048
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