Synthesis , Antiinflammatory and Antibacterial Activity of Novel Indolyl-isoxazoles

Indian Journal of Pharmaceutical Sciences 684 November December 2009 that the extent of propagation of errors obtained by industry-accepted formula was found higher by a factor 100/(100-%water) in comparison with alternate formula. The cause of higher standard deviation and inaccuracy has been identified in industry-accepted formula. The drift and propagation of errors should be considered during setting specification limit of substances containing higher amount of water.

that the extent of propagation of errors obtained by industry-accepted formula was found higher by a factor 100/(100-%water) in comparison with alternate formula.The cause of higher standard deviation and inaccuracy has been identified in industry-accepted formula.The drift and propagation of errors should be considered during setting specification limit of substances containing higher amount of water.
Isoxazoles were reported for their various biological activities [1][2][3] .The reactive intermediate chalcones involved in their synthesis also exhibit wide range of biological activities [4][5][6] .The ability of indole to exhibit antiinflammatory, antimicrobial, antifungal activities [7][8][9] prompted the selection of indole as starting compound.In the light of these interesting biological activities, it appeared of interest to synthesize some new indolyl-isoxazole derivatives and to evaluate their antibacterial and antiinflammatory activities.Indole-3-aldehyde (2) prepared using Vilsemeir Haack reaction by reacting indole (1) with substituted acetophenones (a-j) in ethanolic KOH to obtain chalcones (3a-j), which were condensed with hydroxylamine hydrochloride in presence of sodium acetate and glacial acetic acid to obtain isoxazoles (4a-j).The synthetic sequence leading to the formation of targeted compounds is depicted in Scheme 1.
Melting points of the compounds were determined on a Toshniwal electric melting point apparatus and the values were uncorrected.IR spectra of the synthesized compounds were recorded on a Shimadzu-FTIR 8300 using KBr disc method. 1 H NMR spectra were recorded on a Jeol-GSX 400, (IIT Chennai) using DMSO-d 6 as solvent.Mass spectra were recorded on a Shimadzu-GCMS 50508.All the solvents used were of analytical grade.
Antiinflammatory activity was measured using the carrageenan-induced paw edema test in rats [11] .Animals were divided into different groups each consisting of six animals.Out of twelve synthesized compounds, fi ve compounds (4a, 4c, 4f, 4g, 4j) were selected as test compounds and standard ibuprofen were administered orally at a dose of 200 mg/kg as an aqueous suspension in 1% CMC, while the control group was fed with the same volume of 1% CMC suspension.The paw volume were measured using a plethysmograph immediately before and 3 h after the carrageenan injection.The percent inhibition of paw volume was calculated by using the formula, percent inhibition= (1-Vt/Vc)×100, where Vt is the mean volume of the test drug, Vc is the mean volume of the control Table 2.The one-way ANOVA (Scheffe's method [12] ) test was applied, and the test compounds were found to be significantly active compared to the control (P <0.05).The institutional animal ethics committee of Kasthurba Medical College has approved the experimental protocol (No.IACE/ KMC/030/2004-05).
All compounds synthesized (4a-4j) were screened for antibacterial activity using the cup-plate agar diffusion method [13] by measuring the zone of inhibition in mm.Ciprofl oxacin (50 mg/ml and 100 mg/ml) was used as standard for antibacterial activity.The compounds were screened for antibacterial activity against S. aureus, B. subtilis, E. coli and P. aeruginosa in Muller-Hinton agar medium.This sterilized agar medium was poured into Petri dishes and allowed to solidify.On the surface of the media microbial suspensions were spread with the help of sterilized triangular loop.A stainless steel cylinder of 8 mm diameter (pre-sterilized) was used to bore the cavities.All the synthesized compounds (50 mg/ml and 100 mg/ml) were placed serially in the cavities with the help of micropipette and allowed to diffuse for 1 h.Dimethylsulfoxide (DMSO) was used as a solvent for all compounds and as control.The plates were incubated at 37 o for 14 h.The zone of inhibition observed around the cups after incubation was measured.The results are presented in Table 3.
All six compounds evaluated for antiinflammatory activity exhibited good activity ranging from 36.6 to 73.7% reduction in edema volume.The compounds 4a, 4f and 4g showed significant antiinflammatory activity comparable to ibuprofen and the other compounds 4c and 4j showed moderate activity.The test compounds were found to be signifi cantly active when compared to control group.
The compound 4b and 4j showed good activity Scheme 1: Synthetic scheme for the formation of title compounds

TABLE 2 : ANTIINFLAMMATORY ACTIVITY OF SYNTHESIZED COMPOUNDS Group Dose in µg Mean edema ± SE % Reduction in edema volume
5% allowance value is 0.28 (Scheffe's method), *P<0.05Vs control.Note: Any two means showing a difference of 0.28 are statistically signifi cant.

TABLE 3 : ANTIBACTERIAL ACTIVITIES OF SYNTHESIZED COMPOUNDS
Indicates concentration of drug in μg/ml.Zone of inhibition in mm *