The latex of Euphorbia tirucalli L. (LET) has great etnopharmacological relevance for several traditional communities. In this study, the in vitro and in vivo (using Tenebrio molitor larvae) antimicrobial effects of LET were evaluated. LET did not inhibit the growth of S. aureus, however a reduction on staphyloxanthin production (an important virulence factor of S. aureus) was observed. LET (at 10 μL/kg) was also able to enhance the survival of larvae infected with a lethal dose of S. aureus, an effect associated with reduction in the haemocytes. These results encourage us to carry out new studies to better characterize the anti-infective effects of this latex in order to guide the development of new therapies for the treatment of infections caused by S. aureus.
Punica granatum L. possesses known antimicrobial and anti-inflammatory actions. Preparations of different parts of this plant have been commonly used in the folk medicine to prevent and treat infections; and studies have supported the use of P. granatum extracts for this purpose. However, little is known of the effects of P. granatum-derived fractions in severe infectious diseases such as sepsis. Here, we investigated the actions of the hexane fraction (HF), rich in lipophilic compounds, obtained from the leaves of this plant, in a murine model of polymicrobial sepsis. Oral pre-treatment with HF increased mortality in septic mice. The same animals presented with lower levels of interleukin-6, nitric oxide and hydrogen peroxide in their peritoneal lavage samples than vehicle mice. HF also increased polymorphonuclear cell accumulation in to the peritoneum of mice with sepsis. Macrophage-derived nitric oxide upon lipopolysaccharide stimuli was markedly reduced by incubation with HF. Diterpenes, triterpenes, phytosterols, vitamin E and ascorbyl palmitate were detected in the HF. These results indicate that P. granatum leaf lipophilic fractions may worsen sepsis outcome. This effect may be associated with its bioactive compounds which act synergistically or not, increasing sepsis mortality in vivo.
The coronavirus disease 19 (COVID-19) is caused by the highly transmissible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has affected the global population despite socioeconomic status and amazed surveillance agencies for its incidence, mortality, and recovery rates. COVID-19 affects all age groups; however, it is suggested to progress into severe disease and cause mortality in over 10% of the confirmed cases, depending on the individual characteristics of the affected population. One of the biggest unanswered questions it is why only some individuals develop into the severe stages of the disease. Current data indicate that most of the critically ill are the elderly or those with comorbidities such as hypertension, diabetes, and asthma. However, it has been noted that, in some populations, severe disease is mostly observed in much younger individuals (<60-years old) with no reported underlying medical conditions. Certainly, many factors may contribute to disease severity including intrinsic host factors such as genetic variants, the expression levels of tissue proteins, among others. Considering all these aspects, this review aims to discuss how the expression levels of tissue proteases and the different profiles of immune responses influence the susceptibility to COVID-19 as well as disease severity and outcome.
Despite advances in the development of antimicrobial drugs in the last centuries, antimicrobial resistance has consistently raised in the last decades, compromising their effectiveness. Novel antimicrobial compounds, especially from natural sources, including plants, microorganisms, and animals, have since become a growing area of research. In this context, studies covering the investigation of their ability to combat resistant microorganisms, either by neutralization or inactivation of pathogen resistance mechanisms and virulence properties, have gained attention. Herein, a collection of 19 manuscripts focused on the antimicrobial and anti-infective activity of natural products, including their mechanisms of action, in silico evidence of antimicrobial activity, synergistic associations with antibiotics, and other aspects, will be discussed.
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