Search

Background The combination between antibiotic drugs and extracts derived from medicinal plants is one of the promising strategies against multidrug-resistant (MDR) bacterial strains to overwhelm the antimicrobial resistance.Hypothesis/Purpose We aimed to evaluate the antibacterial effect of hybrid combinations of ethanolic extract (EREE) or alkaloid-enriched fraction (ERAF) obtained from Erythroxylum revolutum leaves and conventional antibiotic drugs.Methods We tested the antimicrobial activity of EREE and ERAF in vitro against gram-positive (Staphyloccocus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) standard and MDR strains. Additionally, we performed phytochemical studies using GC/MS, 1H, 13C NMR spectra, and two-dimensional techniques.Results Although the minimum inhibitory concentration (MIC) values of EREE or ERAF alone against bacterial growth were ≥ 1024 µg/ml, we denoted a total synergism effect in the hybrid combinations ERAF + gentamicin, ERAF + norfloxacin, and ERAF + erythromycin against MDR S. aureus strain, with a significant MIC reduction of 84.7%, 75.0%, and 89.85%, respectively. Although EREE demonstrated a total synergism effect in the hybrid combination gentamicin + EREE (with a significant decrease of MIC of 68.8%), on the contrary, EREE also elicited a strong antagonist effect in some hybrid combinations against the MDR bacteria strains tested. Phytochemical studies revealed in ERAF the presence of two tropane alkaloids described for the first time in the family Erythroxylaceae: 6-(2’-methylbutyryloxy)-3-hydroxytropane (87.07%) and 6-butyryloxy-3-hydroxytropane (12.93%).Conclusion Together, these data can highlight the first evidence of enriched-alkaloid fractions of E. revolutum in hybrid combinations with antibiotics, and propose tropane alkaloids from E. revolutum as new potential candidates in drug combinations for the treatment of infections caused by MDR S. aureus, which is one of the main agents causing infections with death worldwide.

Fungal pathologies caused by the genus Candida have increased in recent years due to the involvement of immunosuppressed people and the advance of resistance mechanisms acquired by these microorganisms. Liposomes are nanovesicles with lipid bilayers in which they store compounds. α-Bisabolol is a sesquiterpene with proven biological activities, and in this work it was tested alone in liposomes and in association with Fluconazole in vitro to evaluate the antifungal potential, Fluconazole optimization, and virulence inhibitory effect in vitro. Antifungal assays were performed against standard strains of Candida albicans, Candida tropicalis, and Candida krusei by microdilution to identify the IC50 values and to obtain the cell viability. The Minimum Fungicidal Concentration (MFC) was performed by subculturing on the solid medium, and at their subinhibitory concentration (Matrix Concentration (MC): 16,384 µg/mL) (MC/16), the compounds, both isolated and liposomal, were associated with fluconazole in order to verify the inhibitory effect of this junction. Tests to ascertain changes in morphology were performed in microculture chambers according to MC concentrations. Liposomes were characterized from the vesicle size, polydispersity index, average Zeta potential, and scanning electron microscopy. The IC50 value of the liposomal bisabolol associated with fluconazole (FCZ) was 2.5 µg/mL against all strains tested, revealing a potentiating effect. Liposomal bisabolol was able to potentiate the effect of fluconazole against the CA and CT strains by reducing its concentration and completely inhibiting fungal growth. α-Bisabolol in liposomal form inhibited the morphological transition in all strains tested at a concentration of MC/8. The liposomes were homogeneous, with vesicles with diameters of 203.8 nm for the liposomal bisabolol and a surface charge potential of −34.2 mV, conferring stability to the nanosystem. Through scanning microscopy, the spherical shapes of the vesicles were observed.

The genus Berberis includes about 500 different species and commonly grown in Europe, the United States, South Asia, and some northern areas of Iran and Pakistan. Leaves and fruits can be prepared as food flavorings, juices, and teas. Phytochemical analysis of these species has reported alkaloids, tannins, phenolic compounds and oleanolic acid, among others. Moreover, p-cymene, limonene and ocimene as major compounds in essential oils were found by gas chromatography. Berberis is an important group of the plants having enormous potential in the food and pharmaceutical industry, since they possess several properties, including antioxidant, antimicrobial, anticancer activities. Here we would like to review the biological properties of the phytoconstituents of this genus. We emphasize the cultivation control in order to obtain the main bioactive compounds, the antioxidant and antimicrobial properties in order to apply them for food preservation and for treating several diseases, such as cancer, diabetes or Alzheimer. However, further study is needed to confirm the biological efficacy as well as, the toxicity.