The improvement of competitive saprophytic capabilities of Trichoderma species through the use of chemical mutagens

Abstract The antagonistic potential of Trichoderma strains was assayed by studying the effect of their culture filtrate on the radial growth of Sclerotium rolfsii, the causal agent of chickpea collar rot. Trichoderma harzianum-1432 (42.2%) and Trichoderma atroviride (40.3%) were found to be strong antagonists. To enhance their antagonistic potential, mutagenesis of these two selected strains was performed. Two mutants, Th-m1 and T. atroviride m1, were found to be more effective than their parent strains. The enzymatic activities of the selected parent and mutant strains were assayed, and although both mutants were found to have enhanced enzymatic activities compared to their respective parent strains, Th-m1 possessed the maximum cellulase (5.69 U/mL) and β-1,3-glucanase activity (61.9 U/mL). Th-m1 also showed high competitive saprophytic ability (CSA) among all of the selected parent and mutant strains, and during field experiments, Th-m1 was found to successfully possess enhanced disease control (82.9%).

Sythesis of new benzopyranone mannich bases

Reaction of 7-hydroxy-5-methoxy-2-methyl-4-oxo-benzopyran-6- carboxaldehyde [1] with formaldehyde and piperidine [or morpholine] to give the corresponding 8-substituted piperidinomethyl or morpholinomethyl derivatives [compounds 2 and 3, respectively]. When formaldehyde and diethylamine were used, bis-[6-formyl-7-hydroxy-5- methoxy-2-methyl-4-oxo-benzopyran-8-yl]-methane [4] was formed. Reaction of 1 with hydroxylamine gave the aldoxime [5], which upon reaction with acetic anhydride gave the corresponding 7-acetyloxy-6- cyano-5-methoxy-2-methyl-4-oxo-benzopyran [6]. Mild hydrolysis of [6] with sodium hydroxide gave 6-cyano-7-hydroxy-5-methoxy-2-methyl- 4-oxo-benzopyran [7]. Reaction of 7 with piperidine and formaldehyde afforded the corresponding Mannich base [8]. Reaction of 1 with urea in ethanol gave the unexpected 5-ethoxy-7-hydroxy-2-methyl-4-oxo- benzopyran [10] which reacted with piperidine and formaldehyde to give the corresponding Mannich base [11]. Reaction of 1 with acetic anhydride gave 3-[7-hydroxy-5-methoxy-2-methyl-4- oxo-benzopyran-6- yl]-acrylic acid [12], while with acetic anhydride in the presence of anhydrous sodium acetate afforded 5-methoxy-8-methyl-2,6- dioxo- [2H,5H]-benzo-[3,2-b:4,5-b']-dipyran [13]. The Mannich bases 3, 14 and the dimer 4 were obtained from compound 12. The dimer 4 could be also obtained by reaction of 1 with formaldehyde. Structures of the compounds prepared were determined by MS, 1H-NMR, IR and elemental analyses. The compounds prepared showed promising antimicrobial activity

Manejo antimicrobiano en la peritonitis posdiálisis / Antimicrobial management of postdialysis peritonitis

Con el propósito de conocer la incidencia y el manejo antimicrobiano en la peritonitis posdiálisis, se estudiaron 358 procedimientos dialíticos, encontrando 37 casos de peritonitis con un porcentaje de 10.3, de los cuales 35 cumplían con los criterios de inclusión para el estudio, dividiéndose en dos grupos: grupo I formado por 19 pacientes en tratamiento con pefloxacina y grupo II integrado por 16 pacientes en tratamiento con ceftazidima. Obteniendo en el grupo I una remisión del cuadro en 89.5 por ciento y en el grupo II de 93.8 por ciento, no encontrando diferencia significativa (p=0.56) entre ambos antimicrobianos