scholarly journals Lathosterol oxidase (sterol C5-desaturase) deletion confers resistance to amphotericin B and sensitivity to acidic stress in Leishmania major

2020 ◽  
Author(s):  
Yu Ning ◽  
Cheryl Frankfater ◽  
Fong-Fu Hsu ◽  
Rodrigo P. Soares ◽  
Camila A. Cardoso ◽  
...  
Keyword(s):  
Double Bond ◽  
Amphotericin B ◽  
Leishmania Major ◽  
Pathogenic Fungi ◽  
New Drugs ◽  
Sterol Synthesis ◽  
Null Mutant ◽  
Biologically Relevant ◽  
Membrane Components ◽  
Triton X

ABSTRACTLathosterol oxidase (LSO) catalyzes the formation of C5-C6 double bond in the synthesis of various types of sterols in mammals, fungi, plants and protozoa. In Leishmania parasites, mutations in LSO or other sterol biosynthetic genes are associated with amphotericin B resistance. To investigate the biological roles of sterol C5-C6 desaturation, we generated a LSO-null mutant line (lso–) in Leishmania major, the causative agent for cutaneous leishmaniasis. Lso– parasites lacked the ergostane-based sterols commonly found in wild type L. major and instead accumulated equivalent sterol species without the C5-C6 double bond. These mutant parasites were replicative in culture and displayed heightened resistance to amphotericin B. However, they survived poorly after reaching the maximal density and were highly vulnerable to the membrane-disrupting detergent Triton X-100. In addition, lso– mutants showed defects in regulating intracellular pH and were hypersensitive to acidic conditions. They also had potential alteration in the carbohydrate composition of lipophosphoglycan, a membrane-bound virulence factor in Leishmania. All these defects in lso– were corrected upon the restoration of LSO expression. Together, these findings suggest that the C5-C6 double bond is vital for the structure of sterol core, and while the loss of LSO can lead to amphotericin B resistance, it also makes Leishmania parasites vulnerable to biologically relevant stress.IMPORTANCESterols are essential membrane components in eukaryotes and sterol synthesis inhibitors can have potent effects against pathogenic fungi and trypanosomatids. Understanding the roles of sterols will facilitate the development of new drugs and counter drug resistance. Lathosterol oxidase (aka sterol C5-desaturase) is required for the formation of C5-C6 double bond in the sterol core structure in mammals, fungi, protozoans, plants and algae. Functions of this C5-C6 double bond are not well understood. In this study, we generated and characterized a lathosterol oxidase-null mutant in Leishmania major. Our data suggest that the C5-C6 double bond is vital for the structure and membrane-stabilizing functions of leishmanial sterols. In addition, our results imply that while mutations in lathosterol oxidase can confer resistance to amphotericin B, an important antifungal and antiprotozoal agent, the alteration in sterol structure leads to significant defects in stress response that could be exploited for drug development.

scholarly journals Lathosterol Oxidase (Sterol C-5 Desaturase) Deletion Confers Resistance to Amphotericin B and Sensitivity to Acidic Stress in Leishmania major

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Yu Ning ◽  
Cheryl Frankfater ◽  
Fong-Fu Hsu ◽  
Rodrigo P. Soares ◽  
Camila A. Cardoso ◽  
...  
Keyword(s):  
Double Bond ◽  
Amphotericin B ◽  
Leishmania Major ◽  
Pathogenic Fungi ◽  
New Drugs ◽  
Sterol Synthesis ◽  
Null Mutant ◽  
Content Type ◽  
Biologically Relevant ◽  
Membrane Components

ABSTRACT Lathosterol oxidase (LSO) catalyzes the formation of the C-5–C-6 double bond in the synthesis of various types of sterols in mammals, fungi, plants, and protozoa. In Leishmania parasites, mutations in LSO or other sterol biosynthetic genes are associated with amphotericin B resistance. To investigate the biological roles of sterol C-5–C-6 desaturation, we generated an LSO-null mutant line (lso−) in Leishmania major, the causative agent for cutaneous leishmaniasis. lso− parasites lacked the ergostane-based sterols commonly found in wild-type L. major and instead accumulated equivalent sterol species without the C-5–C-6 double bond. These mutant parasites were replicative in culture and displayed heightened resistance to amphotericin B. However, they survived poorly after reaching the maximal density and were highly vulnerable to the membrane-disrupting detergent Triton X-100. In addition, lso− mutants showed defects in regulating intracellular pH and were hypersensitive to acidic conditions. They also had potential alterations in the carbohydrate composition of lipophosphoglycan, a membrane-bound virulence factor in Leishmania. All these defects in lso− were corrected upon the restoration of LSO expression. Together, these findings suggest that the C-5–C-6 double bond is vital for the structure of the sterol core, and while the loss of LSO can lead to amphotericin B resistance, it also makes Leishmania parasites vulnerable to biologically relevant stress. IMPORTANCE Sterols are essential membrane components in eukaryotes, and sterol synthesis inhibitors can have potent effects against pathogenic fungi and trypanosomatids. Understanding the roles of sterols will facilitate the development of new drugs and counter drug resistance. LSO is required for the formation of the C-5–C-6 double bond in the sterol core structure in mammals, fungi, protozoans, plants, and algae. Functions of this C-5–C-6 double bond are not well understood. In this study, we generated and characterized a lathosterol oxidase-null mutant in Leishmania major. Our data suggest that LSO is vital for the structure and membrane-stabilizing functions of leishmanial sterols. In addition, our results imply that while mutations in lathosterol oxidase can confer resistance to amphotericin B, an important antifungal and antiprotozoal agent, the alteration in sterol structure leads to significant defects in stress response that could be exploited for drug development.

scholarly journals ANTI-CANDIDA ALBICANS ACTIVITY OF THE ASSOCIATION OF CITRONELAL WITH ANFOTERICIN B OR WITH CETOCONAZOLE

2019 ◽  
Vol 16 (31) ◽  
pp. 250-257
Author(s):  
Patrícia Duarte Costa SILVA ◽  
Brenda Lavínia Calixto dos SANTOS ◽  
Gustavo Lima SOARES ◽  
Wylly Araújo de OLIVEIRA
Keyword(s):  
Candida Albicans ◽  
Antifungal Activity ◽  
Amphotericin B ◽  
Inhibitory Concentration ◽  
Fungal Infections ◽  
Pathogenic Fungi ◽  
Mortality Rates ◽  
New Drugs ◽  
High Morbidity ◽  
Isolated Species

Fungal infections caused by species of the genus Candida are responsible for high morbidity and mortality rates, mainly affecting immunocompromised individuals. Among fungi, Candida albicans is the most frequently isolated species of clinical specimens. A problem associated with increased resistance of pathogenic fungi to the agents used in the therapeutic regimen and the limited number of drugs to cure these infections. As a result, the search for new drugs with antifungal activity has become increasingly important. The aim of this study is to study the antifungal activity of citronellal alone and in combination with amphotericin B or ketoconazole. The Minimal Inhibitory Concentration of citronellal, amphotericin B and ketoconazole against strains of Candida albicans were evaluated by the microdilution technique, and the Minimum Fungicide Concentration of citronellal against the same strains was also performed. Through the checkerboard methodology the effect of the combination of citronelal with amphotericin B or with ketoconazole was determined. This study showed that the association of citronellal with ketoconazole was shown to be an additive against one of the strains of C. albicans and indifferent to another strain. While the combined activity of citronellal and amphotericin B demonstrated an indifferent effect on the strains tested.

Novel nano-sized chitosan amphotericin B formulation with considerable improvement against Leishmania major

Nanomedicine ◽  
2018 ◽  
Vol 13 (24) ◽  
pp. 3129-3147 ◽  
Author(s):  
Tahereh Zadeh Mehrizi ◽  
Mehdi Shafiee Ardestani ◽  
Mostafa Haji Molla Hoseini ◽  
Ali Khamesipour ◽  
Nariman Mosaffa ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Leishmania Major ◽  
Considerable Improvement

scholarly journals Leishmanicidal Activity of Isoselenocyanate Derivatives

2018 ◽  
Vol 63 (2) ◽  
pp. e00904-18 ◽  
Author(s):  
Celia Fernández-Rubio ◽  
Esther Larrea ◽  
José Peña Guerrero ◽  
Eduardo Sesma Herrero ◽  
Iñigo Gamboa ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Amphotericin B ◽  
Cell Cycle Progression ◽  
Leishmania Major ◽  
Antitumor Agents ◽  
Peritoneal Macrophages ◽  
Reference Drug ◽  
Content Type ◽  
Leishmanicidal Activity

ABSTRACTConventional chemotherapy against leishmaniasis includes agents exhibiting considerable toxicity. In addition, reports of drug resistance are not uncommon. Thus, safe and effective therapies are urgently needed. Isoselenocyanate compounds have recently been identified with potential antitumor activity. It is well known that some antitumor agents demonstrate effects againstLeishmania. In this study, thein vitroleishmanicidal activities of several organo-selenium and organo-sulfur compounds were tested againstLeishmania majorandLeishmania amazonensisparasites, using promastigotes and intracellular amastigote forms. The cytotoxicity of these agents was measured in murine peritoneal macrophages and their selectivity indexes were calculated. One of the tested compounds, the isoselenocyanate derivative NISC-6, showed selectivity indexes 2- and 10-fold higher than those of the reference drug amphotericin B when evaluated inL. amazonensisandL. major, respectively. The American strain (L. amazonensis) was less sensitive to NISC-6 thanL. major, showing a trend similar to that observed previously for amphotericin B. In addition, we also observed that NISC-6 significantly reduced the number of amastigotes per infected macrophage. On the other hand, we showed that NISC-6 decreases expression levels ofLeishmaniagenes involved in the cell cycle, such astopoisomerase-2(TOP-2),PCNA, andMCM4, therefore contributing to its leishmanicidal activity. The effect of this compound on cell cycle progression was confirmed by flow cytometry. We observed a significant increase of cells in the G1phase and a dramatic reduction of cells in the S phase compared to untreated cells. Altogether, our data suggest that the isoselenocyanate NISC-6 may be a promising candidate for new drug development against leishmaniasis.

scholarly journals Bright Side of Fusarium oxysporum: Secondary Metabolites Bioactivities and Industrial Relevance in Biotechnology and Nanotechnology

2021 ◽  
Vol 7 (11) ◽  
pp. 943
Author(s):  
Sabrin R. M. Ibrahim ◽  
Alaa Sirwi ◽  
Basma G. Eid ◽  
Shaimaa G. A. Mohamed ◽  
Gamal A. Mohamed
Keyword(s):  
Fusarium Oxysporum ◽  
Cyclic Peptides ◽  
Pathogenic Fungi ◽  
New Drugs ◽  
Biotechnological Applications ◽  
The World ◽  
Different Types ◽  
Bright Side ◽  
Reported Data ◽  
Industrial Relevance

Fungi have been assured to be one of the wealthiest pools of bio-metabolites with remarkable potential for discovering new drugs. The pathogenic fungi, Fusarium oxysporum affects many valuable trees and crops all over the world, producing wilt. This fungus is a source of different enzymes that have variable industrial and biotechnological applications. Additionally, it is widely employed for the synthesis of different types of metal nanoparticles with various biotechnological, pharmaceutical, industrial, and medicinal applications. Moreover, it possesses a mysterious capacity to produce a wide array of metabolites with a broad spectrum of bioactivities such as alkaloids, jasmonates, anthranilates, cyclic peptides, cyclic depsipeptides, xanthones, quinones, and terpenoids. Therefore, this review will cover the previously reported data on F. oxysporum, especially its metabolites and their bioactivities, as well as industrial relevance in biotechnology and nanotechnology in the period from 1967 to 2021. In this work, 180 metabolites have been listed and 203 references have been cited.

scholarly journals New Triazole NT-a9 Has Potent Antifungal Efficacy against Cryptococcus neoformans In Vitro and In Vivo

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
Ren-Yi Lu ◽  
Ting-Jun-Hong Ni ◽  
Jing Wu ◽  
Lan Yan ◽  
Quan-Zhen Lv ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Pathogenic Fungi ◽  
Control Group ◽  
Survival Times ◽  
Content Type ◽  
Fungal Burden ◽  
Wide Range

ABSTRACT In the past decades, the incidence of cryptococcosis has increased dramatically, which poses a new threat to human health. However, only a few drugs are available for the treatment of cryptococcosis. Here, we described a leading compound, NT-a9, an analogue of isavuconazole, that showed strong antifungal activities in vitro and in vivo. NT-a9 showed a wide range of activities against several pathogenic fungi in vitro, including Cryptococcus neoformans, Cryptococcus gattii, Candida albicans, Candida krusei, Candida tropicalis, Candida glabrata, and Candida parapsilosis, with MICs ranging from 0.002 to 1 μg/ml. In particular, NT-a9 exhibited excellent efficacy against C. neoformans, with a MIC as low as 0.002 μg/ml. NT-a9 treatment resulted in changes in the sterol contents in C. neoformans, similarly to fluconazole. In addition, NT-a9 possessed relatively low cytotoxicity and a high selectivity index. The in vivo efficacy of NT-a9 was assessed using a murine disseminated-cryptococcosis model. Mice were infected intravenously with 1.8 × 106 CFU of C. neoformans strain H99. In the survival study, NT-a9 significantly prolonged the survival times of mice compared with the survival times of the control group or the isavuconazole-, fluconazole-, or amphotericin B-treated groups. Of note, 4 and 8 mg/kg of body weight of NT-a9 rescued all the mice, with a survival rate of 100%. In the fungal-burden study, NT-a9 also significantly reduced the fungal burdens in brains and lungs, while fluconazole and amphotericin B only reduced the fungal burden in lungs. Taken together, these data suggested that NT-a9 is a promising antifungal candidate for the treatment of cryptococcosis infection.

Domino construction of a bullataketal core via double bond cleavage in activated dihydrofurans

2018 ◽  
Vol 5 (10) ◽  
pp. 1655-1663 ◽  
Author(s):  
Konstantin L. Ivanov ◽  
Ivan M. Vatsouro ◽  
Stanislav I. Bezzubov ◽  
Mikhail Ya. Melnikov ◽  
Ekaterina M. Budynina
Keyword(s):  
Double Bond ◽  
Bond Cleavage ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Biologically Relevant ◽  
Brönsted Acid

A new rapid approach to structurally challenging and biologically relevant methanobenzodioxepines was developed via a Brønsted acid-triggered domino transformation of 3-carbonyl-4,5-dihydrofurans, substituted with MOM-protected o-hydroxyaryls at the C4 atom.

scholarly journals Antileishmanial Potential of Propolis Essential Oil and Its Synergistic Combination With Amphotericin B

2020 ◽  
Vol 15 (1) ◽  
pp. 1934578X1989956 ◽  
Author(s):  
Ayari Jihene ◽  
Essid Rym ◽  
Karoui Jabri Ines ◽  
Hammami Majdi ◽  
Tabbene Olfa ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Essential Oil ◽  
Amphotericin B ◽  
Leishmania Major ◽  
Antileishmanial Activity ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Spectrometry Analysis ◽  
Low Cytotoxicity ◽  
Promising Source

The antileishmanial activity of Tunisian propolis essential oil (EO) and its combination with amphotericin B was investigated against 2 local clinical strains of Leishmania: Leishmania major and Leishmania infantum. The cytotoxic potential of this EO was evaluated against macrophage Raw264.7. Combination of propolis EO and amphotericin B was investigated using the checkerboard method. The propolis sample was collected from the region of Beni Khalled, a Tunisian city located west of Cape Bon (Nabeul). Its location is particular since it is near to sea with a steppe climate and the predominance of citrus trees. The EO was obtained by Clevenger-type apparatus. Its chemical composition was identified using gas chromatography with flame ionization detector and gas chromatography-mass spectrometry analysis. Our results demonstrate that Tunisian propolis EO exhibit good antileishmanial activity against L. major and L. infantum promastigotes (IC50 = 5.29 ± 0.31 and 3.67 ± 0.52 µg/mL, respectively) and amastigotes (IC50 = 7.38 ± 0.45 and 4.96 ± 0.24 µg/mL, respectively). Moreover, it reduced significantly the parasite proliferation on a dose-dependent response (95%) with low cytotoxicity (selectivity index = 16.18 and 23.33, respectively). Its combination with amphotericin B showed a synergistic potential (fractional inhibitory concentration = 0.37). Interestingly, the data suggest that propolis EO was involved in macrophage activation by hyperproduction of NO. A total of 51 compounds were identified in the propolis EO. The major compound identified was α-pinene (36.7% ± 2.36%) followed by α-cedrol (6.7% ± 0.10%), totarol (6.6% ± 0.09%), and dehydroabietane (5.2% ± 0.10%). Our findings suggest that Tunisian propolis might constitute a promising source for antileishmanial molecules.

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