Salvadora persica sticks are used for chewing and oral-hygiene measures worldwide. The growth inhibition and antibiofilm effects of various extracts on cariogenic Streptococcus mutans isolates were evaluated. Biofilm inhibition, gas chromatography-mass spectrometry (GC-MS) analyses for phytochemicals and their possible mode of interaction with biofilm response regulators were revealed using LigandFit docking protocols. All S. persica extracts showed considerable inhibitory activity and the cariogenic S. mutans showed varied susceptibility when compared with controls. The percentage reduction in biofilm inhibition obtained for methanol, ethanol, chloroform, acetone, and aqueous extracts were 87.92%, 85.75%, 72.44%, 61.66% and 58.68%, respectively. GC-MS analyses revealed 428 compounds, of which benzyl (6Z,9Z,12Z)-6,9,12-octadecatrienoate, 3-benzyloxy-1-nitro-butan-2-ol and 1,3-cyclohexane dicarbohydrazide interacted efficiently with the bacterial communication quorum-sensing (QS) regulators Streptococcus OmpP and Staphylococcus Lux proteins. The bioactive, dual-function, anti-biofilm agents in S. persica not only inhibit growth, but also control the colonization and accumulation of caries-causing S. mutans.

Self-reproducing microbial biofilm community mainly involved in the contamination of indwelling medical devices including catheters play a vital role in nosocomial infections. The catheter-associated urinary tract infection (CA-UTI) causative Staphylococcus aureus, Enterobacter faecalis, and Pseudomonas aeruginosa were selectively isolated, their phenotypic as well as genotypic biofilm formation, production and monomeric sugar composition of EPS as well as sugar, salt, pH and temperature influence on their in vitro biofilm formation were determined. From 50 culture positive urinary catheters S. aureus (24%), P. aeruginosa (18%), E. faecalis (14%) and others (44%) were isolated. The performed assays revealed their varying biofilm forming ability. The isolated S. aureus ica, E. faecalis esp, and P. aeruginosa cup A gene sequencing and phylogenetic analysis showed their close branching and genetic relationship. The analyzed sugar, salt, pH, and temperature showed that the degree of CA-UTI isolates biofilm formation is an environmentally sensitive process. EPS monosaccharide HPLC analysis showed the presence of neutral sugars (ng/μl) as follows: glucose (P. aeruginosa: 44.275; E. faecalis: 4.23), lactose (P. aeruginosa: 7.29), mannitol (P. aeruginosa: 2.53; S. aureus: 2.62; E. faecalis: 2.054) and maltose (E. faecalis: 7.0042) revealing species-specific presence and variation. This study may have potential clinical relevance for the easy diagnosis and management of CA-UTI.

The immense potential of nanobiotechnology makes it an intensely researched field in modern medicine. Green nanomaterial synthesis techniques for medicinal applications are desired because of their biocompatibility and lack of toxic byproducts. We report the toxic byproducts free phytosynthesis of stable silver nanoparticles (AgNPs) using the bark extract of the traditional medicinal plant Acacia leucophloea (Fabaceae). Visual observation, ultraviolet–visible spectroscopy, and transmission electron microscopy (TEM) were used to characterize the synthesized AgNPs. The visible yellow-brown color formation and surface plasmon resonance at 440 nm indicates the biosynthesis of AgNP. The TEM images show polydisperse, mostly spherical AgNP particles of 17–29 nm. Fourier transform infrared spectroscopy revealed that primary amines, aldehyde/ketone, aromatic, azo, and nitro compounds of the A. leucophloea extract may participate in the bioreduction and capping of the formed AgNPs. X-ray diffraction confirmed the crystallinity of the AgNPs. The in vitro agar well diffusion method confirmed the potential antibacterial activity of the plant extract and synthesized AgNPs against the common bacterial pathogens Staphylococcus aureus (MTCC 737), Bacillus cereus (MTCC 1272), Listeria monocytogenes (MTCC 657), and Shigella flexneri (MTCC 1475). This research combines the inherent antimicrobial activity of silver metals with the A. leucophloea extract, yielding antibacterial activity-enhanced AgNPs. This new biomimetic approach using traditional medicinal plant ( A. leucophloea ) barks to synthesize biocompatible antibacterial AgNPs could easily be scaled up for additional biomedical applications. These polydisperse AgNPs green-synthesized via A. leucophloea bark extract can readily be used in many applications not requiring high uniformity in particle size or shape.

Respiratory tract and device associated infections caused by biofilm forming Pseudomonas aeruginosa play a primary role in the pathogenesis and prognosis of cystic fibrosis (CF) diseases. The biofilm formed by these pathogens attributes to the antibiotic resistance and protection from host immune response. Once established, the pathogens respond poorly to therapeutic agents. Recently medicinal plants are largely explored as potential source of bioactive agents. In this context the present study reports the antibiofilm activity of the folkloric medicinal plant Andrographis paniculata against biofilm forming CF causative Pseudomonas aeruginosa isolated from CF sputum. P. aeruginosa was also assessed for their growth and development of the biofilm, phylogenetic relationship and antibiotic susceptibility. Antibiogram of the strains indicated that they were resistant to more than one antibiotic. Six extracts of A. paniculata showed significant antibiofilm activity. P. aeruginosa strains, KMS P03 and KMS P05, were found to be maximally inhibited by the methanol extract to an extent of 88.6 and 87.5% respectively. This is the first report on antibiofilm activity of A. paniculata extracts, and our results indicate scope for development of complementary medicine for biofilm associated infections.

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