Synergistic Antileishmanial Effect of Oregano Essential Oil and Silver Nanoparticles: Mechanisms of Action on Leishmania amazonensis.

American tegumentary leishmaniasis, a zoonotic disease caused by the Leishmania genus, poses significant challenges in treatment, including administration difficulty, low efficacy, and parasite resistance. Novel compounds or associations offer alternative therapies, and natural products such as oregano essential oil (OEO), extracted from Origanum vulgare, have been extensively researched due to biological effects, including antibacterial, antifungal, and antiparasitic properties. Silver nanoparticles (AgNp), a nanomaterial with compelling antimicrobial and antiparasitic activity, have been shown to exhibit potent leishmanicidal properties. We evaluated the in vitro effect of OEO and AgNp-Bio association on L. amazonensis and the death mechanisms of the parasite involved. Our results demonstrated a synergistic antileishmanial effect of OEO + AgNp on promastigote forms and L. amazonensis-infected macrophages, which induced morphological and ultrastructural changes in promastigotes. Subsequently, we investigated the mechanisms underlying parasite death and showed an increase in NO, ROS, mitochondrial depolarization, accumulation of lipid-storage bodies, autophagic vacuoles, phosphatidylserine exposure, and damage to the plasma membrane. Moreover, the association resulted in a reduction in the percentage of infected cells and the number of amastigotes per macrophage. In conclusion, our findings establish that OEO + AgNp elicits a late apoptosis-like mechanism to combat promastigote forms and promotes ROS and NO production in infected macrophages to target intracellular amastigote forms.

Biogenic silver nanoparticles (AgNp-Bio) restore testosterone levels and increase TNF-α and IL-6 in Leydig cells infected with Toxoplasma gondii.

Toxoplasma gondii, a protozoan parasite, is responsible for toxoplasmosis. The available therapy for patients with toxoplasmosis involves a combination of pyrimethamine and sulfadiazine, which have several adverse effects, including bone marrow suppression, megaloblastic anemia, leukopenia, and granulocytopenia. The development of therapeutic alternatives is essential for the management of toxoplasmosis, emphasizing the recent advances in nanomedicine. This study aimed to evaluate the in vitro effects of biogenic silver nanoparticles (AgNp-Bio) on tachyzoite forms and Leydig cells infected with T. gondii. We observed that the AgNp-Bio reduced the viability of the tachyzoites and did not exhibit cytotoxicity against Leydig cells at low concentrations. Additionally, treatment with AgNp-Bio reduced the rate of infection and proliferation of the parasite, and lowered the testosterone levels in the infected cells. It increased the levels of IL-6 and TNF-α and reduced the levels of IL- 10. Among the morphological and ultrastructural changes, AgNp-Bio induced a reduction in the number of intracellular tachyzoites and caused changes in the tachyzoites with accumulation of autophagic vacuoles and a decrease in the number of tachyzoites inside the parasitophorous vacuoles. Collectively, our data demonstrate that the AgNp-Bio affect T. gondii tachyzoites by activating microbicidal and inflammatory mechanisms and could be a potential alternative treatment for toxoplasmosis.

Chalcone-rich extracts from Lonchocarpus cultratus roots present in vitro leishmanicidal and immunomodulatory activity.

OBJECTIVES: This study aimed to evaluate the in vitro anti-Leishmania activity of chalcone-rich three extracts (LDR, LHR and LMR) from Lonchocarpus cultratus (Vell.) A.M.G. Azevedo & H.C. Lima against L. amazonensis. Also, the immunomodulatory and antioxidant capacity was assessed. METHODS: Successive extraction with hexane, dichloromethane and methanol were performed to obtain LHR, LDR and LMR extracts from L. cultratus roots, which were characterized by 1H NMR. Promastigotes, amastigotes and peritoneal macrophages were exposed to crescent concentrations of the three extracts, and after incubation, the inhibition rates were determined to both types of cells, and morphological analyses were performed on the parasite. The immunomodulatory activity was determined against stimulated macrophages. KEY FINDINGS: LDR, LHR and LMR inhibited promastigote cell growth (IC50 0.62 ± 0.3, 0.94 ± 0.5 and 1.28 ± 0.73 µg/ml, respectively) and reduced the number of amastigotes inside macrophages (IC50 1.36 ± 0.14, 1.54 ± 0.26 and 4.09 ± 0.88 µg/ml, respectively). The cytotoxicity against murine macrophages resulted in a CC50 of 13.12 ± 1.92, 92.93 ± 9.1 and >300 µg/ml, resulting in high selectivity index to promastigotes and amastigotes. The extracts also inhibited the nitric oxide secretion in RAW 264.7 macrophages. The antioxidant capacity resulted in a higher scavenger LMR ability. CONCLUSIONS: These results suggest that L. cultratus extracts have anti-Leishmania potential, are non-toxic, and immunosuppress macrophages in vitro.

Recent Advances in Biotransformation by Cunninghamella Species.

The goal of the biotransformation process is to develop structural changes and generate new chemical compounds, which can occur naturally in mammalian and microbial organisms, such as filamentous fungi, and represent a tool to achieve enhanced bioactive compounds. Cunninghamella spp. is among the fungal models most widely used in biotransformation processes at phase I and II reactions, mimicking the metabolism of drugs and xenobiotics in mammals and generating new molecules based on substances of natural and synthetic origin. Therefore, the goal of this review is to highlight the studies involving the biotransformation of Cunninghamella species between January 2015 and March 2021, in addition to updating existing studies to identify the similarities between the human metabolite and Cunninghamella patterns of active compounds, with related advantages and challenges, and providing new tools for further studies in this scope.

Moringa oleifera extract promotes apoptosis-like death in Toxoplasma gondii tachyzoites in vitro.

Toxoplasma gondii is the causative agent of toxoplasmosis, and an important problem of public health. The current treatment for toxoplasmosis is the combination of pyrimethamine and sulphadiazine, which do not act in the chronic phase of toxoplasmosis and have several side-effects. This study evaluated the anti-T. gondii activity and potential mechanism of Moringa oleifera seeds' aqueous extract in vitro. The concentration of M. oleifera extract in HeLa cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell viability assays. The presence of T. gondii was assessed by quantitative polymerase chain reaction and toluidine blue staining. Pyrimethamine and sulphadiazine were used as drug controls. Modifications in T. gondii morphology and ultrastructure were observed by electron microscopy. In vitro, the M. oleifera extract had no toxic effect on HeLa cells at concentrations below 50 µg mL−1. Moringa oleifera extract inhibits T. gondii invasion and intracellular proliferation with similar results for sulphadiazine + pyrimethamine, and also shows cellular nitric oxide production at a concentration of 30 µg mL−1. Electron microscopy analyses indicated structural and ultrastructural modifications in tachyzoites after treatment. We also observed an increase in reactive oxygen species production and a loss of mitochondrial membrane integrity. Nile Red staining assays demonstrated a lipid accumulation. Annexin V­fluorescein isothiocyanate and propidium iodide staining demonstrated that the main action of M. oleifera extract in T. gondii tachyzoites was compatible with late apoptosis. In conclusion, M. oleifera extract has anti-T. gondii activity in vitro and might be a promising substance for the development of a new anti-T. gondii drug.

A 21st Century Evil: Immunopathology and New Therapies of COVID-19.

Coronavirus Disease 2019 (COVID-19) has been classified as a global threat, affecting millions of people and killing thousands. It is caused by the SARS-CoV-2 virus, which emerged at the end of 2019 in Wuhan, China, quickly spreading worldwide. COVID-19 is a disease with symptoms that range from fever and breathing difficulty to acute respiratory distress and death, critically affecting older patients and people with previous comorbidities. SARS-CoV-2 uses the angiotensin-converting enzyme 2 (ACE2) receptor and mainly spreads through the respiratory tract, which it then uses to reach several organs. The immune system of infected patients has been demonstrated to suffer important alterations, such as lymphopenia, exhausted lymphocytes, excessive amounts of inflammatory monocytes and macrophages, especially in the lungs, and cytokine storms, which may contribute to its severity and difficulty of establishing an effective treatment. Even though no specific treatment is currently available, several studies have been investigating potential therapeutic strategies, including the use of previously approved drugs and immunotherapy. In this context, this review addresses the interaction between SARS-CoV-2 and the patient's host immune system during infection, in addition to discussing the main immunopathological mechanisms involved in the development of the disease and potential new therapeutic approaches.

Diethyldithiocarbamate encapsulation reduces toxicity and promotes leishmanicidal effect through apoptosis-like mechanism in promastigote and ROS production by macrophage.

The use of compounds from natural or synthetic sources and nanotechnology may represent an alternative to develop new drugs for the leishmaniasis treatment. DETC is an inhibitor of the SOD1 enzyme, which leads to increased ROS production, important for the elimination of Leishmania. Thus, our objective was to assess the leishmanicidal in vitro effect of free Diethydithiocarbamate (DETC) and DETC loaded in beeswax-copaiba oil nanoparticles (DETC-Beeswax-CO Nps) on L. amazonensis forms and elucidate the possible mechanisms involved in the parasite death. DETC-Beeswax-CO Nps presented size below 200 nm, spherical morphology, negative zeta potential, and high encapsulation efficiency. Free DETC reduced the viability of promastigotes and increase ROS production, lower the mitochondrial membrane potential, cause phosphatidylserine exposure, and enhance plasma membrane permeability, in addition to promoting morphological changes in the parasite. Free DETC proved toxic in the assessment of toxicity to murine macrophages, however, the encapsulation of this compound was able to reduce these toxic effects on macrophages. DETC-Beeswax-CO Nps exerted anti-amastigote effect by enhancing the production of ROS, superoxide anion, TNF-α, IL-6, and reduced IL-10 in macrophages. Therefore, free DETC induces antipromastigote effect by apoptosis-like; and DETC-Beeswax-CO Nps exerted anti-leishmanial effect due to pro-oxidant and pro-inflammatory response.