Biofilm inhibition formation of clinical strains of Pseudomonas aeruginosa mutans, photocatalytic activity of azo dye and GC–MS analysis of leaves of Lagerstroemia speciosa

• Published in: Journal of photochemistry and photobiology. B, Biology Biology, 2017-04, Vol.169, p.148-160
• Main Authors: Sai Saraswathi, V., Kamarudheen, Neethu, Bhaskara Rao, K.V., Santhakumar, K.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Antibiofilm activity; Azo Compounds - chemistry; Azo dyes; Bioactive compounds; Biocompatibility; Biofilms - drug effects; Catalytic activity; Chemical composition; Chromatography; Cracking (chemical engineering); Degradation; E coli; Electron microscopy; Extracellular matrix; Extraction; Food; Gas chromatography; Gas Chromatography-Mass Spectrometry; GC–MS; Inhibition; L. speciosa; Lagerstroemia - chemistry; Leaves; Listeria; Listeria monocytogenes; Mass spectroscopy; Metabolites; Methyl orange; P. aeruginosa; Pathogens; Photocatalysis; Photocatalytic activity; Photochemical Processes; Plant Extracts - isolation & purification; Plant Extracts - metabolism; Plant Extracts - pharmacology; Plant Leaves - chemistry; Pseudomonas aeruginosa; Pseudomonas aeruginosa - physiology; Salmonella; Scanning electron microscopy; Secondary metabolites
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/j.jphotobiol.2017.03.007

The investigation was conducted to analyse the bioactive compounds from the leaf extracts of L. speciosa by GC–MS. The extracts were screened for antibacterial and antibiofilm activities against potential clinical strains. The bioactive compounds from the leaves of L. speciosa were extracted by soxhlet continuous extraction method and their chemical composition was analysed by Gas Chromatography–Mass Spectroscopy (GC–MS). The antibacterial activity was evaluated against clinical strain like Staphylococcus aureus, Escherichia coli, P. aeruginosa and Salmonella typhi by well diffusion technique. We also screened for antibacterial property against common food borne pathogens namely Listeria monocytogenes and Bacillus cereus at varied concentration 250μml−1 to 1000μml−1. Thereafter antibiofilm assay was carried out at from 250 to 1000μg/ml against P. aeruginosa (high biofilm forming pathogen) clinical strain by cover slip technique and the morphology of the pathogen was observed using Scanning Electron Microscopy-(SEM). It was observed that diverse class of secondary metabolites were found by GC–MS analysis for all the extracts upon the continuous extraction. It was found that only minimum inhibition was seen in alcoholic extract for antibacterial activity, whereas all other extracts showed negligible activity. P. aeruginosa biofilm inhibited to 93.0±2% and 91±2% at higher concentration (1000μg/ml) for methanolic and ethanolic extract respectively. Absence of extracellular matrix structure and the surface cracking of biofilm were viewed by SEM, which confirmed the antibiofilm activity. Hence this study reveals that L. speciosa showed significant antibiofilm activity against P. aeruginosa due to the phytoconstituents present in the leaf extracts which was well documented in the alcoholic extracts by GC–MS analysis. The methanolic and ethanolic extract showed good photocatalytic activity of 77.44% and 96.66% against azo dye degradation respectively. Further, isolating the novel phyto-compounds would yield better promising biological activities. [Display omitted] •Phytoconstituents were identified by GC–MS technique.•Secondary metabolites in alcoholic extract is responsible for antibacterial activity.•Photocatalytic azo dye degradation was found to be greater than 75%.