Antibacterial and Antibiofilm Activities of Psychorubrin, a Pyranonaphthoquinone Isolated From Mitracarpus frigidus (Rubiaceae)

Abstract

Psychorubrin, a natural pyranonaphthoquinone found in different plants, has become an interesting compound in the search for new antimicrobial therapeutic agents. Here, we investigated the potential antagonistic activity of psychorubrin against planktonic and biofilm bacteria. First, psychorubrin was tested against several Gram-positive and Gram-negative bacteria strains by a broth microdilution susceptibility method. Second, bacterial killing assay, bacterial abundance, and membrane viability were evaluated. The nucleotide leakage assay was used to verify membrane destabilization while antibiofilm activities were analyzed by the effect on established biofilm, static biofilm formation, isolation of biofilm matrix assay and scanning electron microscopy. In parallel, the combinatorial effect of psychorubrin and chloramphenicol was evaluated by the checkerboard method. Psychorubrin was active against Gram-positive bacteria, showing rapid time-dependent kinetics of bacterial killing, amplified nucleotide leakage, and greater activity against the methicillin-resistant species (MRSA) Staphylococcus aureus 33591 and 33592 and Staphylococcus pyogenes 10096. Psychorubrin also interfered with the composition of the biofilm matrix by reducing the total content of carbohydrates and proteins. A synergic effect between psychorubrin and chloramphenicol was observed for S. aureus 33592 and S. pyogenes 10096 while an additive effect was detected for S. aureus 33591. Our findings demonstrate, for the first time, an antagonistic activity of psychorubrin against bacteria not only in their planktonic forms but also in biofilms, and identify bacterial membranes as primary targets for this compound. Based on these observations, psychorubrin has a good potential for the design of novel antimicrobial agents.

Herbal Tea for the Management of Pharyngitis: Inhibition of Streptococcus pyogenes Growth and Biofilm Formation by Herbal Infusions

“…Usually, biofilms make bacteria more resistant to antibiotics than their planktonic cells. Several other studies have shown that extractions or infusions from medicinal plants inhibit the biofilm formation in different bacteria, including S. pyogenes [41,48,49]. Our findings suggest that these HWIs of licorice roots, barberry roots, oregano, and thyme flowering shoots could be used against drug resistant- S. pyogenes .…”

“…Spices and herbs (flavor foods) comprise a large number of phytochemicals [39], which have been revealed to possess antimicrobial properties. For example, anti- S. pyogenes ability of phenolic compounds [40,41], flavonoids [35], alkaloids [42], terpenoids [43], and tannins [35] have been reported. Qualitative UPLC analysis in the present study for HWI revealed the presence of polyphenols, flavonoids, alkaloids, terpenoids, steroids, and tannins.…”

Bio-Guided Fractionation of Prenylated Benzaldehyde Derivatives as Potent Antimicrobial and Antibiofilm from Ammi majus L. Fruits-Associated Aspergillus amstelodami

“…Bacterial resistance in their free-living forms is a main concern for the health system, however, when they are present in biofilm, the problem is even aggravated [42]. National institutes of health announced that more than 75% of microbial infections that occur in the human body are corroborated by the development and firmness of biofilms.…”

“…This finding is very promising in searching for a broad-spectrum antimicrobial agent with potent effect on established biofilm that may be used alone or in combination with antibiotics as this compound can interfere with the biofilm matrix allowing the antibiotic to reach the bacterial cells. In that context, Lemos et al, reported the synergistic effect between psychorubrin isolated from Mitracarpus frigidus and chloramphenicol in inhibition of biofilm of S. aureus and Streptococcus pyogenes [42].…”

“…The effect of both AME and FEA extracts on established biofilms was tested by static microtiter plate method according to Lemos et al [42,60]. Briefly, the biofilm-forming microorganisms: S. aureus (ATCC 25923), S. mutans (ATCC 25175), E. coli (ATCC 25922), and P. aeruginosa (ATCC 9027) were cultured at 37 °C in TSB for 18 h and C. albicans (ATCC 10231) was cultured at 37 °C for 48 h. Biofilm cells were produced with each of these organisms using 96-well polystyrene microtiter plates loaded with 180 µL TSB for all bacterial strains and SDB for C. albicans and 20 µL of 10 7 cells/mL inoculums for bacteria and 10 6 cells/mL for yeast.…”