Chapter 10 – Commercial OEs Evaluation
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Chapter 10
Commercial EOs Evaluation
During the PhD project, I evaluated the chemical profile of several commercial essential oils. Their antimicrobial activity was tested on animal pathogens, in collaboration with the research groups of prof. Francesca Mancianti and dr. Valentina V. Ebani, Department of Veterinary Sciences of the University of Pisa.
After many years of researches, it is well known that essential oils have many pharmaceutical properties as antibacterials, antivirals and antimycotics. EOs are considered promising natural products for the development of broad-spectrum, safe and cheap antifungal agents, in particular they are an alternative to the use of synthetic drugs.
Before testing all the selected EOs they were analyzed by gas chromatography accomplished to a mass spectrometer (GC-MS), to verify their real chemical composition, and understand what compounds could be responsible of the antimicrobial activity.
Many commercial EOs were tested on different agents responsible for many veterinary diseases able to infect humans too.
In particular antimycotic activity of EOs was evaluated versus dermatophytes, molds responsible for mainly Tinea capitis and Tinea corporis, in humans.
These fungi are able to invade keratinized tissue and produce infections that are generally restricted to the corneous layer of skin, hair and nails. Three broad ecological groups of dermatophyte species are recognized, namely anthropophilic, zoophilic and geophilic. In general, zoophilic and geophilic species cause lesions in humans that are more inflammatory than those induced by anthropophilic species. Human infection is acquired by contact with soil for geophylic species, and with infect animals or fomites for zoophilic dermatophytes.
Among dermatophytic species Microsporum canis, Trichophyton mentagrophytes,Trichophyton erinacei,Microsporum gypseum and Trichophyton terrestre were investigated.
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The main animal reservoirs of M. canis, T. mentagrophytes,and T. erinacei are cats, rodents and hedgehogs, respectively. However, a large number of pet animals can be infected and transmit dermatophytes to humans.
In Europe M. canis is the commonest agent for overall. Its incidence is increasing, and it is the dominant agent in southern Europe, with countries such as Austria, Spain, Italy, and Greece reporting the highest numbers and proportions of M. canis cases, even if T. mentagrophytes and T. erinacei frequently occur. Among geophilic species, Microsporum gypseum is the dermatophyte more frequently involved in human mycoses. It has been associated with Tinea corporis and with favic lesions and kerion of the scalp, while Trichophyton terrestre has rarely been identified as causal agent of Tinea capitis.
Regarding the both the antimycotic and antibacterial activity of the selected EOs a Gram-negative zoonotic pathogens of the Enterobacteriaceae family, Salmonella was chosen. Many members of Salmonella genus cause important diseases on poultry: the host-adapted serovars Pullorum and Gallinarum are the agent of Pullorum disease and Fowl typhoid, respectively, whereas other serotypes, particularly Typhimurium and Enteritidis, are cause of infections in birds and mammals, including humans.
Yeasts are unicellular fungi,
they are part of normal microflora and can cause invasive infections when barrier leakage or
impaired immune function occurs. So both environmental yeasts such as Candida non-albicans
species and endosaprophytes such as C. albicans can act as opportunist pathogens leading to
mucosal and invasive diseases, in animals and both in immunocompetent and in
immunocompromised patients showing different patterns of antimycotic sensitivity.
Poultry often shed with feces pathogen bacteria and yeasts that can pollute the environment and infect other animals and humans.
In particular, the EO activity was tested against pathogenic bacteria and yeasts that may be shed in feces by poultry. In particular, the analysis were carried out against reference and wild bacterial strains of Salmonella enterica serovar Typhimurium, Yersinia enterocolitica, Listeria monocytogenes, Enterococcus durans, E. faecalis, and E. faecium, and wild isolates of Candida albicans, C. tropicalis, C. guilliermondii, C. krusei, C. parapsilosis and Saccharomyces cerevisiae.
Here the titles of the manuscripts published after these works:
1) “Susceptibility of Microsporum canis Arthrospores to a Mixture of Chemically Defined Essential Oils: A Perspective for Environmental Decontamination”;
2) “In vitro activity of twenty commercially available plant-derived essential oils against selected dermatophyte species”;
3) “Antibacterial and antifungal activity of essential oils against some pathogenic bacteria and yeasts shed from poultry”.
Chapter 10 – Commercial OEs Evaluation
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