Investigation of Copaifera genus as a new source of antimycobaterial agents

AIM

This paper reports on the antimycobacterial activity of the oleoresins and extracts obtained from Copaifera spp.

MATERIALS & METHODS

The minimum inhibitory concentration (MIC) and fractional inhibitory concentration index techniques helped to evaluate the effect of these oleoresins and extracts against six strains of mycobacteria that cause tuberculosis.

RESULTS & CONCLUSION

Among the assayed oleoresins and plant extracts, the Copaifera langsdorffii, Copaifera duckei, Copaifera reticulata and Copaifera trapezifolia oleoresins provided the lowest MIC values against some of the tested strains. The combination of Copaifera spp. samples with isoniazid did not evidence any synergistic action. Some Copaifera spp. oleoresins may represent a future source for the discovery of new antimycobacterial drugs due to their low MIC values.

In vitro studies of the antibacterial activity of Copaifera spp. oleoresins, sodium hypochlorite, and peracetic acid against clinical and environmental isolates recovered from a hemodialysis unit

Background

Patients submitted to hemodialysis therapy are more susceptible to infection, especially to infection by Gram-positive bacteria. Various research works have attempted to discover new antimicrobial agents from plant extracts and other natural products.

Methods

The present study aimed to assess the antibacterial activities of Copaifera duckei, C. reticulata, and C. oblongifolia oleoresins; sodium hypochlorite; and peracetic acid against clinical and environmental isolates recovered from a Hemodialysis Unit. The Minimum Inhibitory Concentration and the Fractionated Inhibitory Concentration Index were determined; the ability of the tested compounds/extracts to inhibit biofilm formation was evaluated by calculating the MICB50 and IC50.

Results

C. duckei was the most efficient among the assayed Copaifera species, and its oleoresin was more effective than peracetic acid and sodium hypochlorite. Copaifera oleoresins and disinfectants did not act synergistically at any of the tested combinations. Certain of C. duckei oleoresin, peracetic acid, and sodium hypochlorite concentrations inhibited biofilm formation and eradicated 50% of the biofilm population.

Conclusion

C. duckei oleoresin is a potential candidate for disinfectant formulations. Based on these results and given the high incidence of multi-resistant bacteria in hemodialysis patients, it is imperative that new potential antibacterial agents like C. duckei oleoresin, which is active against Staphylococcus, be included in disinfectant formulations.

Assessment of the antibacterial, cytotoxic and mutagenic potential of the phenolic-rich hydroalcoholic extract from Copaifera trapezifolia Hayne leaves

Copaifera trapezifolia Hayne occurs in the Atlantic Rainforest, which is considered one of the most important and endangered tropical forests on the planet. Although literature works have described many Copaifera spp., their biological activities remain little known. In the present study, we aimed to evaluate (1) the potential of the hydroalcoholic extract from C. trapezifolia leaves (CTE) to act against the causative agents of tooth decay and apical periodontitis and (2) the cytotoxicity and mutagenicity of CTE to ensure that it is safe for subsequent application. Concerning the tested bacteria, the MIC and the minimum bactericidal concentration of CTE varied between 100 and 400 µg ml-1. The time-kill assay conducted at a CTE concentration of 100 µg ml-1 evidenced bactericidal activity against Porphyromonas gingivalis (ATCC 33277) and Peptostreptococcus micros (clinical isolate) within 72 h. CTE at 200 µg ml-1 inhibited Porphyromonas gingivalis and Peptostreptococcus micros biofilm formation by at least 50 %. A combination of CTE with chlorhexidine dichlorohydrate did not prompt any synergistic effects. The colony-forming assay conducted on V79 cells showed that CTE was cytotoxic at concentrations above 156 µg ml-1. CTE exerted mutagenic effect on V79 cells, but the micronucleus test conducted on Swiss mice and the Ames test did not reveal any mutagenicity. Therefore, the use of standardized and safe extracts could be an important strategy to develop novel oral care products with antibacterial action. These extracts could also serve as a source of compounds for the discovery of new promising biomolecules.

Activity of the Lichen Usnea steineri and its Major Metabolites against Gram-positive, Multidrug-resistant Bacteria

The antimicrobial activity and possible synergistic effects of extracts and compounds isolated from Usnea steineri were evaluated against four resistant bacterial species. A phytochemical study of the acetone extract of U. steineri resulted in the isolation and characterization of difractaic acid and (+)-usnic acid as the main compounds. The acetone extract showed strong activity (less than 10 µg/mL) against resistant strains of Staphylococcus epidermidis and Enterococcus faecalis, and (+)-usnic acid exhibited strong activity against S. epidermidis (MIC 3.12 µg/mL), S. aureus and S. haemnolyticus (MIC 12.5 µg/mL). Combinations of penicillin and tetracycline with (+)-usnic acid did not show any synergistic antimicrobial effects. Difractaic acid was inactive. Our results showed that the acetone extract of U. steineri possesses significant in vitro antimicrobial activity, which is likely related to the presence of (+)-usnic acid.

Activity of the Lichen Usnea steineri and its Major Metabolites against Gram–positive, Multidrug–resistant Bacteria

The antimicrobial activity and possible synergistic effects of extracts and compounds isolated from Usnea steineri were evaluated against four resistant bacterial species. A phytochemical study of the acetone extract of U. steineri resulted in the isolation and characterization of difractaic acid and (+)–usnic acid as the main compounds. The acetone extract showed strong activity (less than 10 μg/mL) against resistant strains of Staphylococcus epidermidis and Enterococcus faecalis, and (+)–usnic acid exhibited strong activity against S. epidermidis (MIC 3.12 μg/mL), S. aureus and S. haemolyticus (MIC 12.5 μg/mL). Combinations of penicillin and tetracycline with (+)–usnic acid did not show any synergistic antimicrobial effects. Difractaic acid was inactive. Our results showed that the acetone extract of U. steineri possesses significant in vitro antimicrobial activity, which is likely related to the presence of (+)–usnic acid.

Antifungal activity of plant-derived essential oils on Candida tropicalis planktonic and biofilms cells

Dental prosthesis supports Candida species growth and may predispose the oral cavity to lesions. C. tropicalis has emerged as a colonizer of prosthesis and has shown resistance to clinically used antifungal agents, which has increased the search for new antifungals. This work describes the effectiveness of fifteen essential oils (EOs) against C. tropicalis The EOs were obtained by hydrodistillation and were chemically characterized by gas chromatography-mass spectrometry. The antifungal activities of the EOs were evaluated by the microdilution method and showed that Pelargonium graveolens (Geraniaceae) (PG-EO) was the most effective oil. Geraniol and linalool were the major constituents of PG-EO. The 2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide (XTT) assay showed that all the clinical C. tropicalis strains formed viable biofilms. Scanning electron microscopy examination of the biofilms revealed a complex architecture with basal layer of yeast cells and an upper layer of filamentous cells. Treatments with PG-EO, linalool, and geraniol significantly reduced the number of viable biofilm cells and inhibited biofilm formation after exposure for 48 h. PG-EO, geraniol, and linalool were not toxic to normal human lung fibroblasts (GM07492A) at the concentrations they were active against C. tropicalis Together, our results indicated that C. tropicalis is susceptible to treatment with PG-EO, geraniol, and linalool, which could become options to prevent or treat this infection.