Ursolic acid, an important bioactive compound, was isolated from ethanol extract of aerial parts of Sambucus australis. In order to develop bioactive ursolic acid derivatives, two semi-synthetic compounds were obtained through modification at C-3. The antibacterial activity of the ursolic acid and its derivatives was investigated. The microdilution method was used for determination of the minimal inhibitory concentration (MIC), against twelve bacterial strains. The influence of ursolic acid and its derivatives on the susceptibility of some bacterial pathogens to the aminoglycosides antibiotics neomycin, amikacin, kanamycin and gentamicin was evaluated. The most representative synergistic effect was observed by 3β-formyloxy-urs-12-en-28-oic acid at the concentration of 64 μg/mL in combination with kanamycin against Escherichia coli (27), a multidrug-resistant clinical isolate from sputum, with reduction of MIC value from 128 μg/mL to 8 μg/mL. Ursolic acid and its derivatives were examined for their radical scavenger activity using the DPPH assay, and showed significant activity.

The use of medicinal plants with therapeutics properties represents a secular tradition in different cultures, mainly in underdeveloped countries. Lantana camara Linn and Lantana montevidensis Briq (Verbenaceae) found in tropical and subtropical areas around the world are popularly known as "camará" or "chumbinho." In popular medicines, both plants are used as antipyretic and carminative and in the treatment of respiratory system infections. In this study, the antibacterial activity of the ethanolic extracts of L. camara and L. montevidensis leaves and roots against gram-positive and gram-negative strains standard and multi-resistant bacteria isolated from clinical material are presented. In order to determine the minimal inhibitory concentration (MIC), the microdilution method was used. The extracts demonstrated antibacterial activity against all tested bacteria, but the L. montevidensis fresh leaves extract present the best result against P. aeruginosa (MIC 8 μg/mL) and against multi-resistant E. coli (Ec 27) (MIC 16 μg/mL). These results drive new researches with both species in order to isolate the constituents responsible for the activity.

Background: Cordia verbenacea is a Brazilian coastal shrub popularly known as "erva baleeira". The essential oil from fresh leaves was obtained by hydrodistillation and analyzed by CG/MS. The main components were identified as β-caryophyllene (25.4%), bicyclogermacrene (11.3%), δ-cadinene (9.%) and α-pinene (9.5%). In this study, the antimicrobial activity of Cordia verbenacea was evaluated. Materials and Methods: The minimal inhibitory concentration (MIC) of the essential oil was obtained using the broth microdilution assay (from 512 to 8 μg/ml). Results: The results showed that the essential oil presented fungistatic activity against Candida albicans and Candida krusei and antibacterial activity against Gram-positive strains (Staphylococcus aureus and Bacillus cereus) and against multiresistant Gram-negative (Escherichia coli 27), in all tests the MIC was 64 μg/ml. When the essential oil was associated to aminoglycosides (subinhibitory concentrations, MIC/8), a synergic and antagonic activity was verified. The synergic effect was observed to the amikacin association (MIC reduction from 256 mlto 64 μg/ml) in all strains tested. Conclusion: The essential oil of Cordia verbenacea influences the activity of antibiotics and may be used as an adjuvant in antibiotic therapy against respiratory tract bacterial pathogens.

Resistance to antibiotics has made diseases that previously healed easily become more difficult to treat. Staphylococcus aureus is an important cause of hospital-acquired infections and multi-drug resistant. NorA efflux pump, present in bacteria S. aureus, is synthesized by the expression of the norA gene. Menadione, also known as vitamin K₃, is one of the synthetic forms of vitamin K. Therefore, the aim of this study is to verify the menadione effect on efflux inhibition through NorA pump gene expression inhibition and assess the effects of menadione in bacterial membrane. The effect of menadione as an efflux pump inhibitor (EPI) was evaluated by the microdilution method, fluorimetry, electron microscopy, and by RT-qPCR to evaluate gene expression. In the molecular docking, association with menadione induces increased fluorescence intensity. Menadione was observed (100% of the clusters) interacting with residues ILE12, ILE15, PHE16, ILE19, PHE47, GLN51, ALA105, and MET109 from NorA. The results showed the norA gene had its expression significantly diminished in the presence of menadione. The simulation showed that several menadione molecules were able to go through the bilayer and allow the entry of water molecules into the hydrophobic regions of the bilayer. When present within membranes, menadione may have caused membrane structural changes resulting in a decline of the signaling pathways involved in norA expression. Menadione demonstrated to be an efflux pump inhibitor with dual mechanism: affecting the efflux pump by direct interaction with protein NorA and indirectly inhibiting the norA gene expression, possibly by affecting regulators present in the membrane altered by menadione.

Caesalpinia ferrea C. Mart., popularly known as “Jucá” or “Pau-ferro”, belongs to the Fabaceae family, and is classified as a native and endemic species in Brazil. Numerous studies that portray its ethnobotany, chemical composition, and biological activities exist in the literature. The present study aimed to systematically review publications addressing the botanical aspects, uses in popular medicine, phytochemical composition, and bioactivities of C. ferrea. The searches focused on publications from 2015 to March 2020 using the Scopus, Periódicos Capes, PubMed, Google Scholar, and ScienceDirect databases. The leaves, fruits, seeds, and bark from C. ferrea are used in popular medicine to treat disorders affecting several systems, including the circulatory, immune, cardiovascular, digestive, respiratory, genitourinary, musculoskeletal, and conjunctive systems. The most commonly found chemical classes in phytochemical studies are flavonoids, polyphenols, terpenoids, tannins, saponins, steroids, and other phenolic compounds. The biological properties of the extracts and isolated compounds of C. ferrea most cited in the literature were antibacterial, antifungal, antioxidant, antiproliferative, anti-inflammatory, and healing potential. However, further studies are still needed to clarify a link between its traditional uses, the active compounds, and the reported pharmacological activities, as well as detailed research to determine the toxicological profile of C. ferrea.