ABSTRACT
Background & objectives: The pathogenicity of the nosocomial pathogens, Pseudomonas aeruginosa and Acinetobacter baumannii is regulated by their quorum sensing (QS) systems. The objective of the present study was to examine the effect of the cold ethyl acetate extract of Tinospora cordifolia stem on virulence and biofilm development in the wild type and clinical strains of P. aeruginosa and A. baumannii. The study was further aimed to identify the probable active constituents in the plant extract. Methods: P. aeruginosa virulence factors viz., LasA protease, LasB elastase and pyocyanin production were analyzed spectrophotometrically. Biofilm formation was studied using crystal violet staining-microtitre plate assay. The plant extract was fractionated using silica gel column chromatography and the most active fraction was derivatized using silylation and analyzed by gas chromatography-mass spectrometry (GC-MS). In silico testing of the molecules identified in GC-MS was performed, for binding to the P. aeruginosa LasI and LasR proteins, to predict the QS inhibitory molecules. Results: The plant extract inhibited three major virulence factors in P. aeruginosa; it exhibited enhanced biofilm formation in P. aeruginosa while decreased biofilm development in A. baumannii. The most active fraction obtained from column chromatography, exhibited suppression of virulence as well as biofilm in both the organisms. Docking scores were calculated for all the molecules identified in GC-MS, and high docking scores were obtained for 2,3,4-triacetyloxybutyl acetate, methyl 16-methyl heptadecanoate, 2-(5-ethenyl-5-methyloxolan-2-yl)propan-2-ol, methyl hexadecanoate and 2-methoxy-4-vinyl phenol. Interpretation & conclusions: The compounds showing high docking scores could probably be the QS inhibitors. These molecules can be screened further for the development of new anti-infective drugs.
ABSTRACT
Phenolic compounds occur in all fruits as a diverse group of secondary metabolites. When cut fruits are exposed to oxidation leads to browning reactions. Browning of fruits and fruit products is one of the major problems in the fruit industry and is believed to be probably the first cause of quality loss during postharvest handling, processing and storage. Browning can also adversely affect flavor and nutritional value. Hence the present study has been undertaken to explore the indigenous method of preserving cut fruits in the refrigeration. The cut fruits of apple is rapped in 7 types of leaves such as Badam leaf, Banana leaf, Lotus leaf, Mandarai leaf, Papaya leaf, Pumpkin leaf and Teak leaf and kept inside the fridge, simultaneously a control of cut fruits were also maintained .The results were quite interesting to note that cut fruits of apple wrapped in lotus leaf and banana leaf delayed the browning process till 7 days the browning started only from 8th day of preservation. Indicates that theses two leaves can be used for preservation of cut fruits .whereas fruits wrapped in other leaves showed browning from the second day it self. This type of study can be further extended to explore the active ingredient present in the aforesaid leaves will help us to a most viable indigenous method to preserve the cut fruits in large scale.