Antimicrobial activity of Amazonian oils against Paenibacillus species

Plants and Their Derivatives as Promising Therapeutics for Sustainable Control of Honeybee (Apis mellifera) Pathogens

The most important pollinator for agricultural crops is the Western honeybee (Apis mellifera). During the winter and summer seasons, diseases and stresses of various kinds endanger honeybee numbers and production, resulting in expenses for beekeepers and detrimental effects on agriculture and ecosystems. Researchers are continually in search of therapies for honeybees using the resources of microbiology, molecular biology, and chemistry to combat diseases and improve the overall health of these important pollinating insects. Among the most investigated and most promising solutions are medicinal plants and their derivatives. The health of animals and their ability to fight disease can be supported by natural products (NPs) derived from living organisms such as plants and microbes. NPs contain substances that can reduce the effects of diseases by promoting immunity or directly suppressing pathogens, and parasites. This literature review summarises the advances that the scientific community has achieved over the years regarding veterinary treatments in beekeeping through the use of NPs. Their impact on the prevention and control of honeybee diseases is investigated both in trials that have been conducted in the laboratory and field studies.

Aloe vera and copaiba oleoresin-loaded chitosan films for wound dressings: microbial permeation, cytotoxicity, and in vivo proof of concept

Chitosan films are commonly used for wound dressing, provided that this polymer has healing, mucoadhesiveness and antimicrobial properties. These properties can be further reinforced by the combination of chitosan with polysaccharides and glycoproteins present in aloe vera, together with copaiba oleoresin's pharmacological activity attributed to sesquiterpenes. In this work, we developed chitosan films containing either aloe vera, copaiba oil or both, by casting technique, and evaluated their microbial permeation, antimicrobial activity, cytotoxicity, and in vivo healing potential in female adult rats. None of the developed chitosan films promoted microbial permeation, while the cytotoxicity in Balb/c 3 T3 clone A31 cell line revealed no toxicity of films produced with 2 % of chitosan and up to 1 % of aloe vera and copaiba oleoresin. Films obtained with either 0.5 % chitosan or 0.5 % copaiba oleoresin induced cell proliferation which anticipate their potential for closure of wound and for the healing process. The in vivo results confirmed that tested films (0.5 % copaiba-loaded chitosan film and 0.5 % aloe vera-loaded chitosan film) were superior to a commercial dressing film. For all tested groups, a fully formed epithelium was seen, while neoformation of vessels seemed to be greater in formulations-treated groups than those treated with the control. Our work confirms the added value of combining chitosan with aloe vera and copaiba oil in the healing process of wounds.

Photo-Phytotherapeutic Gel Composed of Copaifera reticulata, Chlorophylls, and k-Carrageenan: A New Perspective for Topical Healing

Chronic wound healing represents an impactful financial burden on healthcare systems. In this context, the use of natural products as an alternative therapy reduces costs and maintains effectiveness. Phytotherapeutic gels applied in photodynamic therapy (PDT) have been developed to act as topical healing medicines and antibiotics. The bioactive system is composed of Spirulina sp. (source of chlorophylls) and Copaifera reticulata oil microdroplets, both incorporated into a polymeric blend constituted by kappa-carrageenan (k-car) and F127 copolymer, constituting a system in which all components are bioactive agents. The flow behavior and viscoelasticity of the formulations were investigated. The photodynamic activity was accessed from studies of the inactivation of Staphylococcus aureus bacteria, the main pathogen of hospital relevance. Furthermore, in vivo studies were conducted using eighteen rabbits with dermatitis (grade III and IV) in both paws. The gels showed significant antibiotic potential in vitro, eliminating up to 100% of S. aureus colonies in the presence or absence of light. The k-car reduced 41% of the viable cells; however, its benefits were enhanced by adding chlorophyll and copaiba oil. The animals treated with the phytotherapeutic medicine showed a reduction in lesion size, with healing and re-epithelialization verified in the histological analyses. The animals submitted to PDT displayed noticeable improvement, indicating this therapy's viability for ulcerative and infected wounds. This behavior was not observed in the iodine control treatment, which worsened the animals' condition. Therefore, gel formulations were a viable alternative for future pharmaceutical applications, aiming at topical healing.

Design and Optimization of a Natural Medicine from Copaifera reticulata Ducke for Skin Wound Care

In this study, we developed a bioadhesive emulsion-filled gel containing a high amount of Copaifera reticulata Ducke oil-resin as a veterinary or human clinical proposal. The phytotherapeutic system had easy preparation, low cost, satisfactory healing ability, and fly repellency, making it a cost-effective clinical strategy for wound care and myiasis prevention. Mechanical, rheological, morphological, and physical stability assessments were performed. The results highlight the crosslinked nature of the gelling agent, with three-dimensional channel networks stabilizing the Copaifera reticulata Ducke oil-resin (CrD-Ore). The emulgel presented antimicrobial activity, satisfactory adhesion, hardness, cohesiveness, and viscosity profiles, ensuring the easy spreading of the formulation. Considering dermatological application, the oscillatory responses showed a viscoelastic performance that ensures emulgel retention at the action site, reducing the dosage frequencies. In Vivo evaluations were performed using a case report to treat ulcerative skin wounds aggravated by myiasis in calves and heifers, which demonstrated healing, anti-inflammatory, and repellent performance for the emulsion-filled gel. The emulgel preparation, which is low in cost, shows promise as a drug for wound therapy.

Cytotoxicity and Lipase Inhibition of Essential Oils from Amazon Annonaceae Species

Essential oils from Amazonian species are gaining increasing interest worldwide due to their medicinal and cosmetic applications; however, the relation among the chemical constituents and their biological properties are not well explored. Therefore, the present research aims to obtain an understanding of the bioactivity of chemical compounds in the essential oils of plants from the Annonaceae family (Bocageopsis pleiosperma, Onychopetalum amazonicum, Unonopsis duckei, U. floribunda, U. rufescens, U.stipitata, U. guatterioides, Duguetia flagellaris and Xylopia benthamii). By means of gas chromatography coupled to mass spectrometry, in vitro cytotoxic and anti-lipase assays, principal component analysis and molecular docking, it was possible to establish the main compounds that may be responsible for the cytotoxic effect of O. amazonicum and B. pleiosperma. Moreover, the anti-lipase potential of D. flagellaris was also established, as well as its composition related to the activity. Thus, by the employed strategy, allo-aromadendrene, cryptomerione, δ-cadinene and β-bisabolene were suggested as plausible cytotoxic agents against cancer cell lines, and dehydroaromadendrene, spathulenol and elemol, against lipase. The present study provides significant information on the chemical profile and bioactivity studies of Amazon Annonaceae aromatic plants.

Fractionation of hexane extracts from Achyrocline satureioides and their biological activities against Paenibacillus larvae

Previous studies carried out in our laboratory described the antimicrobial activity of the whole hexanic extract (HE) of Achyrocline satureioides (Lam.) DC against Paenibacillus larvae, the causal agent of American Foulbrood (AFB) a disease of the honey bee larvae. In this study, the HE was partitioned into five main fractions by chromatographic techniques leading to the isolation of four known compounds: two prenylated phloroglucinol α-pyrones (1 and 3), 5,7-dihydroxy-3,8-dimethoxyflavone (gnaphaliin A) (2), and 23-methyl-6-O-demethylauricepyrone (4). Isolated compounds were further analyzed towards structural elucidation using 1H RMN and 13C RMN spectroscopic techniques. For the first time, the antimicrobial activity of the isolated compounds was evaluated against P. larvae strains by broth microdilution method and compared with that of the whole HE. Compounds 1-4 displayed minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranging between 0.07 and 62.5 μg/mL and 0.26 and 12.5 μg/mL, respectively. The lowest MIC and MBC values were obtained with compounds 3 and 4, respectively. The antimicrobial activity of each single compound and the combination of them showed that the presence of all compounds is needed for the antimicrobial efficacy of whole HE.

Functional Properties and Antimicrobial Activity from Lactic Acid Bacteria as Resources to Improve the Health and Welfare of Honey Bees

Simple Summary

Honey bees play a pivotal role in the sustainability of ecosystems and biodiversity. Many factors including parasites, pathogens, pesticide residues, forage losses, and poor nutrition have been proposed to explain honey bee colony losses. Lactic acid bacteria (LAB) are normal inhabitants of the gastrointestinal tract of honey bees and their role has been consistently reported in the literature. In recent years, there have been numerous scientific evidence that the intestinal microbiota plays an essential role in honey bee health. Management strategies, based on supplementation of the gut microbiota with probiotics, may be important to increase stress tolerance and disease resistance. In this review, recent scientific advances on the use of LABs as microbial supplements in the diet of honey bees are summarized and discussed.

Abstract

Honey bees (Apis mellifera) are agriculturally important pollinators. Over the past decades, significant losses of wild and domestic bees have been reported in many parts of the world. Several biotic and abiotic factors, such as change in land use over time, intensive land management, use of pesticides, climate change, beekeeper’s management practices, lack of forage (nectar and pollen), and infection by parasites and pathogens, negatively affect the honey bee’s well-being and survival. The gut microbiota is important for honey bee growth and development, immune function, protection against pathogen invasion; moreover, a well-balanced microbiota is fundamental to support honey bee health and vigor. In fact, the structure of the bee’s intestinal bacterial community can become an indicator of the honey bee’s health status. Lactic acid bacteria are normal inhabitants of the gastrointestinal tract of many insects, and their presence in the honey bee intestinal tract has been consistently reported in the literature. In the first section of this review, recent scientific advances in the use of LABs as probiotic supplements in the diet of honey bees are summarized and discussed. The second section discusses some of the mechanisms by which LABs carry out their antimicrobial activity against pathogens. Afterward, individual paragraphs are dedicated to Chalkbrood, American foulbrood, European foulbrood, Nosemosis, and Varroosis as well as to the potentiality of LABs for their biological control.

In-Field Detection of American Foulbrood (AFB) by Electric Nose Using Classical Classification Techniques and Sequential Neural Networks

American foulbrood is a dangerous bee disease that attacks the sealed brood. It quickly leads to the death of bee colonies. Efficient diagnosis of this disease is essential. As specific odours are produced when larvae rot, it was investigated whether an electronic nose can distinguish between colonies affected by American foulbrood and healthy ones. The experiment was conducted in an apiary with 18 bee families, 9 of which showed symptoms of the disease confirmed by laboratory diagnostics. Three units of the Beesensor V.2 device based on an array of six semiconductor TGS gas sensors, manufactured by Figaro, were tested. Each copy of the device was tested in all bee colonies: sick and healthy. The measurement session per bee colony lasted 40 min and yielded results from four 10 min measurements. One 10-min measurement consisted of a 5 min regeneration phase and a 5 min object-measurement phase. For the experiments, we used both classical classification methods such as k-nearest neighbour, Naive Bayes, Support Vector Machine, discretized logistic regression, random forests, and committee of classifiers, that is, methods based on extracted representative data fragments. We also used methods based on the entire 600 s series, in this study of sequential neural networks. We considered, in this study, six options for data preparation as part of the transformation of data series into representative results. Among others, we used single stabilised sensor readings as well as average values from stable areas. For verifying the quality of the classical classifiers, we used the 25-fold train-and-test method. The effectiveness of the tested methods reached a threshold of 75 per cent, with results stable between 65 and 70 per cent. As an element to confirm the possibility of class separation using an artificial nose, we used applied visualisations of classes. It is clear from the experiments conducted that the artificial nose tested has practical potential. Our experiments show that the approach to the problem under study by sequential network learning on a sequence of data is comparable to the best classical methods based on discrete data samples. The results of the experiment showed that the Beesensor V.2 along with properly selected classification techniques can become a tool to facilitate rapid diagnosis of American foulbrood under field conditions.

Antimicrobial potentials of medicinal plant's extract and their derived silver nanoparticles: A focus on honey bee pathogen

Infectious (or Communicable) diseases are not only the past but also the present problem in developing as well as developed countries. It is caused by various pathogenic microbes like fungi, bacteria, parasites and virus etc. The medicinal plants and nano-silver have been used against the pathogenic microbes. Herbal medicines are generally used for healthcare because they have low price and wealthy source of antimicrobial properties. Like medicinal plants, silver nanoparticles also have emergent applications in biomedical fields due to their immanent therapeutic performance. Here, we also explore the various plant parts such as bark, stem, leaf, fruit and seed against Gram negative and Gram-positive bacteria, using different solvents for extraction i.e. methanol, ethyl acetate, chloroform, acetone, n. hexane, butanol, petroleum ether and benzene. Since ancient to date most of the countries have been used herbal medicines, but in Asia, some medicinal plants are commonly used in rural and backward areas as a treatment for infectious diseases. In this review, we provide simple information about medicinal plants and Silver nanoparticles with their potentialities such as antiviral, bactericidal and fungicidal. Additionally, the present review to highlights the versatile applications of medicinal plants against honey bee pathogen such as fungi (Ascosphaera apis), mites (Varroa spp. and Tropilaelaps sp.), bacteria (Melissococcus plutonius Paenibacillus larvae), and microsporidia (Nosema apis and Nosema ceranae). In conclusion, promising nonchemical (plant extracts) are innocuous to adult bees. So, we strongly believed that this effort was made to evaluate the status of medicinal plants researches globally.

Antibacterial Activity of Phytochemical Extracts and Endophytic Fungi of Carapa Guianensis Against Enterococcus Faecalis in Endodontic Infections An In Vitro Study

Objective:

The objective of this study was to evaluate the antibacterial activity of phytochemical extracts and endophytic fungi of Carapa guianensis against Enterococcus faecalis. Carapa guianensis leaves and stems were collected to obtain phytochemical extracts and fungal metabolites and evaluated for in vitro antibacterial activity against E. faecalis using the disc diffusion method and dentin blocks with bacterial biofilm.

Methods:

Thirty dentin blocks were prepared and contaminated for 60 days with E. faecalis. The specimens were randomly divided into 6 experimental groups according to the test solution used: G1 – hexane stem extract of Carapa guianensis; G2 – methanol stem extract of Carapa guianensis; G3 – methanol leaf extract of Carapa guianensis; G4 – ethyl acetate extract of the endophytic fungus Penicillium isolated from Carapa guianensis; G5 – negative control, with no addition of bacterial inoculum; G6 – positive control.

Results:

Bacterial growth was analyzed by spectrophotometry after 14 days of direct contact between the extracts and dentin blocks. The hexane-stem, methanol-stem, methanol-leaf, and ethyl-acetate endophytic fungus Penicillium extracts inhibited bacterial growth in 100% of the samples.

Conclusion:

The present study demonstrated the antibacterial potential of phytochemical extracts and endophytic fungi of Carapa guianensis against E. faecalis.

Antifungal activity of the essential oil obtained from Cryptocarya alba against infection in honey bees by Nosema ceranae

The honeybee disease nosemosis type C is a serious problem since its causative agent, microsporidium Nosema ceranae, is widespread among adult honey bees. Some of the feasible alternative treatments that are used to control this disease are plant extracts. The aim of the present work was to evaluate the effects of essential oils of Chilean plant species, such as Cryptocarya alba, which is used against N. ceranae, and to identify and quantify the majority active compounds in the EO as well as their potential use for the control of nosemosis. Essential oils were obtained using the stripping steam technique with Clevenger equipment and were subsequently analyzed by Gas chromatography-mass spectrometry. Mortality was recorded daily over at least 8days as worker honeybees were exposed to a range of doses of EO dispersed in a sucrose solution. C. alba oil appears to be nontoxic to A. mellifera adults at the tested concentration (the same concentration inhibits the growth of N. ceranae), showing that this oil can be used for the treatment of nosemosis. EO effectiveness was demonstrated against N. ceranae by calculating the percentage of decrease in infected bees from untreated infected groups vs infected groups treated with EO or the reference drug fumagillin. It was determined that a dose of 4µg EO/bee was most effective in controlling N. ceranae development. We determined innocuous doses of C. alba essential oil for honeybees. We demonstrated the antifungal activity of C. alba EO at 4μg/bee against N. ceranae and compared it to its major monoterpenes, such as β-phellandrene (20μg/bee), eucalyptol (20μg/bee) and α-terpineol (20μg/bee). The major compounds of C. alba EO, α-terpineol, eucalyptol and β-phellandrene, had significant effects against Apis mellifera infection by N. ceranae, but the antifungal effect of the complete essential oil on N. ceranae was larger than the effect of α-terpineol, eucalyptol or β- phellandrene separately, showing that C. alba oil may be a candidate for the treatment or prevention of nosemosis.

In vitro growth-inhibitory effect of Brazilian plants extracts against Paenibacillus larvae and toxicity in bees

American foulbrood (AFB) is a serious worldwide spreading disease in bees caused by Paenibacillus larvae. Plants extracts are known to decrease or inhibit the growth of these bacteria. The purpose of this study was to evaluate the antimicrobial activity of Calendula. officinalis, Cariniana domestica, and Nasturtium officinale extracts against the P. larvae and to evaluate the toxicity of the extracts in bees. In vitro activity against P. larvae of the extracts was evaluated by micro dilution method and the minimal inhibitory concentrations (MICs) were also determined. The concentrations used in the toxicity test were established based on the MIC values and by the spraying application method. The P. larvae was susceptible to the evaluated crude extract of C. officinalis and N. officinale. To C. domestica, only the ethyl acetate (EtAc) fraction and n-butanol (BuOH) fractions had activity against P. larvae. Toxicity analysis in bees showed no toxicity for N. officinale crude extract and for C. domestica BuOH fraction during 15 days of treatment, however, some deaths of bees occurred during the first three days of treatment with C. officinalis and C. domestica EtAc fraction. The results with these species were firstly described and showed that N. officinale crude extract and C. domestica BuOH fraction both presented not toxic effects in the concentration tested by the spraying application method, and can be a useful alternative for treatment or prevention of AFB.

Insecticidal and repellent effects of tea tree and andiroba oils on flies associated with livestock

This study aimed to evaluate the insecticidal and repellent effects of tea tree, Melaleuca alternifolia (Myrtales: Myrtaceae), and andiroba, Carapa guianensis (Sapindales: Meliaceae), essential oils on two species of fly. For in vitro studies, free-living adult flies were captured and reared in the laboratory. To evaluate the insecticidal effects of the oils, adult flies of Haematobia irritans (L.) and Musca domestica L. (both: Diptera: Muscidae) were separated by species in test cages (n = 10 per group), and subsequently tested with oils at concentrations of 1.0% and 5.0% using a negative control to validate the test. Both oils showed insecticidal activity. Tea tree oil at a concentration of 5.0% was able to kill M. domestica with 100.0% efficacy after 12 h of exposure. However, the effectiveness of andiroba oil at a concentration of 5.0% was only 67.0%. The insecticidal efficacy (100.0%) of both oils against H. irritans was observed at both concentrations for up to 4 h. The repellency effects of the oils at concentrations of 5.0% were tested in vivo on Holstein cows naturally infested by H. irritans. Both oils demonstrated repellency at 24 h, when the numbers of flies on cows treated with tea tree and andiroba oil were 61.6% and 57.7%, respectively, lower than the number of flies on control animals. It is possible to conclude that these essential oils have insecticidal and repellent effects against the species of fly used in this study.

Effects of Copaifera duckei Dwyer oleoresin on the cell wall and cell division of Bacillus cereus

The aim of this work was to evaluate the antibacterial activity of Copaifera duckei oleoresin and to determine its possible mechanism of action against bacteria of clinical and food interest. The antibacterial activity was determined by agar diffusion and dilution methods; the mechanism of action by transmission electron microscopy and by SDS-PAGE; the bioactive compounds by bioautography; and the chemical analysis by GC/MS. Oleoresin showed activity against nine of the 11 strains of bacteria tested. Bacillus cereus was the most sensitive, with a MIC corresponding to 0.03125 mg ml−1 and with a bactericidal action. Oleoresin acted on the bacterial cell wall, removing proteins and the S-layer, and interfering with the cell-division process. This activity probably can be attributed to the action of terpenic compounds, among them the bisabolene compound. Gram-negative bacteria tested were not inhibited. C. duckei oleoresin is a potential antibacterial, suggesting that this oil could be used as a therapeutic alternative, mainly against B. cereus.

Chemistry and biological activities of terpenoids from copaiba (Copaifera spp.) oleoresins

Copaiba oleoresins are exuded from the trunks of trees of the Copaifera species (Leguminosae-Caesalpinoideae). This oleoresin is a solution of diterpenoids, especially, mono- and di-acids, solubilized by sesquiterpene hydrocarbons. The sesquiterpenes and diterpenes (labdane, clerodane and kaurane skeletons) are different for each Copaifera species and have been linked to several reported biological activities, ranging from anti-tumoral to embriotoxic effects. This review presents all the substances already described in this oleoresin, together with structures and activities of its main terpenoids.