Contribution of plant phytochemicals to organic homeostasis: focus on the aging process and opportunistic infections

Aging process is conceived as a normal stage during human life cycle, but it is also considered a hot topic among scientists and medical community. Alarming rates of premature aging and oxidative stress-related diseases have increasingly affect human individuals. Stress, pollution and exposition to chemical substances are considered the main triggering factors for those conditions; in addition, they also suppress the immune system and, therefore, improve organic vulnerability and occurrence of opportunistic infections [I]. Apart from the associated morbidity and mortality, the increasing rates of antimicrobial resistance improve the severity of the clinical conditions [2]. Botanical preparations possess a multitude of bioactive properties, namely acting as antimicrobials, antioxidants, and homeostasis modulators. Thus, upcoming alternatives, mainly based in plant phytochemicals, are necessary to improve the wellbeing as also life expectancy of individuals. The present study aims to evaluate and to compare both antioxidant and antimicrobial properties of plant extracts rich in phenolic compounds. Among the tested plants, Glycyrrhiza glabra L. (licorice) evidenced the most pronounced free radicals scavenging and antimicrobial effects, followed by Salvia officina/is L. (sage), Thymus vulgaris L. (thyme) and Origanum vulgare L. (oregano). Eucalyptus globulus Labill. (blue gum) and Juglans regia L. (walnut) also showed a high effect, while Pterospartum tridentatum (L.) Willk. (carqueja) and Rubus ulmifolius Schott (elm leaf blackberry) displayed moderate effects, and lastly, Tabebuia impetigirwsa (Mart. ex DC) Standley (pau d'arco), Foeniculum vulgare Miller (fennel), Rosa canina L. (rose hips) and Matricaria recutita L. (chamomile) gave only slight effects. In general, the most pronounced bioactivities were observed in the plant preparations (infusion>decoction>hydromethanolic extract) with higher levels of phenolic compounds (both flavonoids and phenolic acids). The observed synergisms between the phenolic compounds present in the extracts highlight the use of phytochemicals as future health promoters. However, further studies are necessary to understand the effective mode of action of individual phenolic constituents as also the existence of polyvalence relationships between them.

Antimicrobial potential of Eucalyptus globulus against biofilms of Staphylococcus aureus isolated from bovine mastitis

Staphylococcus aureus are among the most common species isolated from bovine mastitis. The pathogenesis of this bacterium is facilitated by a number of virulence factors, including the ability to adhere to abiotic surfaces and/or host tissues often leading to biofilms' formation. From the clinical perspective, the most important feature of Staphytococcus species' biofilms is their high tolerance to the conventional antimicrobial therapy. So, the increasing number of bovine mastitis and the higher levels of Staphylococcus species resistance to traditional antimicrobial agents are considered an important alert for the necessity to focus the future research on identification and development of new strategies to combat S. aureus mastitis. RecenUy, the interest in natural alternatives based on plant extracts has been rising. In add~ion to their health benefits, their antimicrobial potential has been increasingly reported. Taking this into consideration, the evaluation of hydromethanolic extracts of E. globulus against S. aureus biofilms was tested and compared with penicillin, one of the antibiotics most often used in the treatment of cattle infections. All mastitis' isolates tested were good-biofilm producers. As expected penicillin has demonstrated poor activity against S. aureus biofilms (<1 log reduction). However, E. globulus Labill was bactericidal, promoting a biofilm cell reduction of 2-3 log. Therefore, the present work showed the potential antimicrobial activity of E. g/obulus against S. aureus from bovine mastitis, namely in biofilm mode of growth and drew attention to its promising use as an alternative to penicillin.