Combating Staphylococcus aureus biofilm formation: the inhibitory potential of tormentic acid and 23-hydroxycorosolic acid.

Plant extracts have been used to treat microbiological diseases for centuries. This study examined plant triterpenoids tormentic acid (TA) and 23-hydroxycorosolic acid (HCA) for their antibiofilm effects on Staphylococcus aureus strains (MTCC-96 and MTCC-7405). Biofilms are bacterial colonies bound by a matrix of polysaccharides, proteins, and DNA, primarily impacting healthcare. As a result, ongoing research is being conducted worldwide to control and prevent biofilm formation. Our research showed that TA and HCA inhibit S. aureus planktonic growth by depolarizing the bacterial membrane. In addition, zone of inhibition studies confirmed their effectiveness, and crystal violet staining and biofilm protein quantification confirmed their ability to prevent biofilm formation. TA and HCA exhibited substantial reductions in biofilm formation for S. aureus (MTCC-96) by 54.85% and 48.6% and for S. aureus (MTCC-7405) by 47.07% and 56.01%, respectively. Exopolysaccharide levels in S. aureus biofilm reduced significantly by TA (25 µg/mL) and HCA (20 µg/mL). Microscopy, bacterial motility, and protease quantification studies revealed their ability to reduce motility and pathogenicity. Furthermore, TA and HCA treatment reduced the mRNA expression of S. aureus virulence genes. In silico analysis depicted a high binding affinity of triterpenoids for biofilm and quorum-sensing associated proteins in S. aureus, with TA having the strongest affinity for TarO (- 7.8 kcal/mol) and HCA for AgrA (- 7.6 kcal/mol). TA and HCA treatment reduced bacterial load in S. aureus-infected peritoneal macrophages and RAW264.7 cells. Our research indicates that TA and HCA can effectively combat S. aureus by inhibiting its growth and suppressing biofilm formation.

Vitexin alters Staphylococcus aureus surface hydrophobicity to obstruct biofilm formation.

Cell Surface hydrophobicity is one of the determinant biophysical parameters of bacterial aggregation for being networked to form a biofilm. Phytoconstituent, like vitexin, has long been in use for their antibacterial effect. The present work demonstrates the role of vitexin in modulating Staphylococcus aureus surface hydrophobicity while aggregating to form biofilm and pathogenesis in a host. In planktonic form, vitexin shows minimum inhibitory concentration at 252 µg/ml against S. aureus. Sub-MIC doses of vitexin and antibiotics (26 µg/ml of vitexin, 55 µg/ml of azithromycin, and 2.5 µg/ml of gentamicin) were selected to treat S. aureus. Dead cell counts after treatment were studied through flow cytometry. As dead cell counts were minimal (<5 %), these doses were considered for all subsequent experiments. While studying aggregating cells, it was observed that vitexin reduces S. aureus surface hydrophobicity and membrane permeability at the sub-MIC dose of 26 µg/ml. The in silico binding analysis showed a higher binding affinity of vitexin with surface proteins (IcaA, DltA, and SasG) of S. aureus. Down-regulation of dltA and icaAB expression, along with the reduction in membrane potential with a sub-MIC dose of vitexin, explains reduced S. aureus surface hydrophobicity. Vitexin was found to interfere with S. aureus biofilm-associated protein biomass, EPS production, and swarming movement. Subsequently, the suppression of proteases production and down-regulation of icaAB and agrAC gene expression with a sub-MIC dose of vitexin explained the inhibition of S. aureus virulence in vitro. Besides, vitexin was also found to potentiate the antibiofilm activity of sub-MIC doses of gentamicin and azithromycin. Treatment with vitexin exhibits a protective response in S. aureus infected macrophages through modulation of expression of cytokines like IL-10 and IL-12p40 at protein and mRNA levels. Furthermore, CFU count and histological examination of infected mouse tissue (liver and spleen) justify the in vivo protective effect of vitexin from S. aureus biofilm-associated infection. From this study, it can be inferred that vitexin can reduce S. aureus surface hydrophobicity, leading to interference with aggregation at the time of biofilm formation and subsequent pathogenesis in a host.

The anti-biofilm potential of triterpenoids isolated from Sarcochlamys pulcherrima (Roxb.) Gaud.

Formation of biofilm is the major cause of Pseudomonas aeruginosa associated pathological manifestations in the urinary tract, respiratory system, gastrointestinal tract, skin, soft tissues etc. Triterpenoid group of compounds have shown their potential in reducing planktonic and biofilm form of bacteria. Sarcochlamys pulcherrima (Roxb.) Gaud. is an ethnomedicinal plant traditionally used for its anti-microbial and anti-inflammatory property. In the present study two triterpenoids, have been isolated from this plant, characterised and evaluated for their antibacterial and antibiofilm potential against P. aeruginosa. Compounds were characterised as 2α, 3ß, 19α-trihydroxy-urs-12-ene-28-oic acid (Tormentic acid) and 2α, 3ß, 23-trihydroxyurs-12-ene-28-oic acid (23-hydroxycorosolic acid) through spectroscopic studies viz. infrared (IR), nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Depolarization of bacterial membrane and zone of inhibition studies revealed that both the compounds inhibited the growth of planktonic bacteria. Compounds were also found to inhibit the formation of P. aeruginosa biofilm. Inhibition of biofilm found to be mediated through suppressed secretion of pyoverdin, protease and swarming motility of P. aeruginosa. Gene expression study, in silico binding analysis, in vivo bacterial load and tissue histology observations also supported the antibiofilm activity of both the compounds. In vitro and in vivo study showed that both compounds were non-toxic. The study has explored the antibacterial and antibiofilm effect of two triterpenes isolated for the first time from S. pulcherrima.

Newborn Screening for Hemoglobinopathies and Red Cell Enzymopathies in Tripura State: A Malaria-Endemic State in Northeast India.

Hemoglobinopathies are a group of inherited single gene disorders. There are reports on hemoglobin (Hb) variants identified in the tribal and non-tribal populations of Tripura State in northeastern India. This study aimed to determine the spectrum of hemoglobinopathies and enzymopathies by newborn screening in Tripura State and assess the extent of neonatal jaundice. A total of 2400 cord blood samples were collected and analyzed by high performance liquid chromatography (HPLC). Further confirmation of any abnormal HPLC was done by DNA analysis. The samples were also screened for deficiency of enzymopathies, glucose-6-phosphate dehydrogenase (G6PD) deficiency and pyruvate kinase. Of 2400 cord blood samples screened, 225 (9.3%) were Hb E (HBB: c.79G>A) heterozygotes, 80 (3.3%) were Hb E homozygotes and one carried Hb E-ß-thalassemia (ß-thal). Other Hb abnormalities were also detected including 15 Hb S (HBB: c.20A>T) heterozygotes, two Hb D-Punjab (HBB: c.364G>C) heterozygotes and two compound heterozygotes for Hb D-Punjab and Hb E. Of the 80 homozygous Hb E babies, four were non-tribal and 76 babies were tribal, and 225 patients carried Hb E trait, 141 were tribal, while 84 were non-tribal. Of 40 G6PD deficient babies identified, 13 had coinherited Hb E and two babies had pyruvate kinase deficiency. α Genotyping was performed in 162 affected babies, 50 of them carried α gene deletions. Newborn screening programs for Hb E, other hemoglobinopathies and G6PD deficiency must be encouraged in the malaria-endemic northeastern region of India. Drug-induced hemolysis can also be avoided by screening for G6PD deficiency at birth.