Synthesis and antifungal activity of some new benzimidazole derivatives

Synthesis and antifungal evaluation of 5-ethoxycarbonyl-2-(substituted-benzyl or phenoxymethyl)benzimidazoles are reported. Structures of the compounds were elucidated with IR-, 1H-NMR-, 13C-NMR-, mass-spectra and elemental analysis. Preliminary results show that none of the synthesized benzimidazole derivatives has antifungal activity at the concentration of 100 micrograms/ml against Candida parapsilosis, Candida stellatoidea, and Candida pseudotropicalis.     

Synthesis of 1,2,5(6)-Trisubstituted Benzimidazoles and Evaluation of Their Antimicrobial Activities

A series of 22 benzimidazoles, having several substituents on the azole and benzene nuclei, were prepared and evaluated in vitro for antimicrobial activity. At first 2-chloro or 2-chloromethyl-5(6)-substituted-1H-benzimidazoles were synthesized, which were then substituted at C-2 with several piperazine or piperidine derivatives. The antibacterial activity of these compounds against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa, and the antifungal activity against Candida albicans, Candida stellatoidea, Candida parapsilosis, and Candida pseudotropicalis were determined as the MIC values. Since compound 12 exhibits good activity, in order to clarify the effect of substituents at C-1 on the activity, benzimidazole derivatives having ethyl, allyl, benzyl, and p-fluorobenzyl substituents at C-1 were prepared, and slightly increased activity was seen.     

New heterocyclic derivatives of benzimidazole with germicidal activity. IV--In vivo anticandida activity of 5-fluoro-2-(5'-nitro-2'-furyl) benzimidazole (F-O-NO2)

We have studied the possible in vitro and in vivo antibacterial activity of 5-fluoro-2-(5'-nitro-2'-furyl)benzimidazole (F-O-NO2). Our data demonstrate that F-O-NO2 is able to inhibit the in vitro growth of different mycetes and bacteria, including Candida albicans and Cryptococcus neoformans. We also tested the possible in vivo activity against Candida albicans. The results clearly show that treatment with F-O-NO2 is able to significantly augment the survival of all treated animals; in particular, when injected i.p. at the dose of 120 mg/kg, 30' or 1 hr after Candida albicans challenge, it givens a MST (Medium Survival Time) longer than 60 days. These data demonstrate that F-O-NO2 has antibacterial and antimycotic activity.     

Fungicidal activity of human lactoferrin-derived peptides based on the antimicrobial αβ region

Owing to the increasing number of infections in hospitalised patients caused by resistant strains of fungi, there is a need to develop new therapeutic agents for these infections. Naturally occurring antimicrobial peptides may constitute models for developing such agents. A modified peptide sequence (CFQWKRAMRKVR; HLopt2) based on amino acid residues 20-31 of the N-terminal end of human lactoferrin (hLF) as well as a double-sized human lactoferricin-like peptide (amino acid residues 16-40; HLBD1) were investigated for their antifungal activities in vitro and in vivo. By in vitro assay, HLopt2 was fungicidal at concentrations of 12.5-25 μg/mL against Cryptococcus neoformans, Candida albicans, Candida krusei, Candida kefyr and Candida parapsilosis, but not against Candida glabrata. HLopt2 was demonstrated to have ≥ 16-fold greater killing activity than HLBD1. By inducing some helical formation caused by lactam bridges or by extending the assay time (from 2h to 20 h), HLBD1 became almost comparable with HLopt2 in its fungicidal activity. Killing of C. albicans yeast cells by HLopt2 was rapid and was accompanied by cytoplasmic and mitochondrial membrane permeabilisation as well as formation of deep pits on the yeast cell surface. In a murine C. albicans skin infection model, atopic treatment with the peptides resulted in significantly reduced yields of Candida from the infected skin areas. The antifungal activities of HLopt2 in vitro and in vivo suggest possible potential as a therapeutic agent against most Candida spp. and C. neoformans. The greatly improved antifungal effect of the lactam-modified HLBD1 indicates the importance of amphipathic helix formation for lethal activity.     

Antifungal Activity of Plant Extracts against Candida Species from Oral Lesions

Seventy five patients with oral lesions attending the different departments of Rajah Muthiah Medical College and Hospital, Annamalai University were screened for Candida. Forty six (61.3%) Candida strains were isolated from the oral lesions. Of the 46 Candida strains, Candida albicans accounted for 35 (76.08%), Candida glabrata for 5 (10.86%), Candida tropicalis and Candida krusei for 2 (4.34%) each and Candida parapsilosis and Candida guilliermondii for one (2.17%) each. Antifungal activity of ethanol extracts of five plant species that included Syzygium jambolanum, Cassia siamea, Odina wodier, Momordica charantia and Melia azedarach and two algal species, Sargassum wightii and Caulerpa scalpelliformis were tested against 25 isolated strains by disc diffusion method. Antifungal activity was observed at 100 mg/ml for Syzygium jambolanum, Cassia siamea and Caulerpa scalpelliformis and at 10 mg/ml for Sargassum wightii.     

Effects of subinhibitory concentrations of ciclopirox on the adherence of Candida albicans to human buccal and vaginal epithelial cells.

At present, only a limited number of studies of the effects of sub-inhibitory antifungal agents on the adherence of Candida to epithelial (buccal and vaginal) host cells are available. The adherence of Candida albicans to the epithelial cell surface is accepted as an important first step in persistent colonization and in the following symptomatic or asymptomatic infection of mucosal surface. Ciclopirox (ciclopiroxolamine, CAS 29342-05-0) is a substituted pyridone antimycotic drug, unrelated to the imidazole derivatives and its topical application ensures maximum local bioavailability. The present study was done to investigate the effects of sub-inhibitory concentrations of ciclopirox on the adherence of Candida albicans to human buccal and vaginal epithelial cells. The findings on the adherence of different strains of Candida indicate that the drug caused a significant reduction in the mean number of Candida adhering to both buccal and vaginal cells. This reduction was maximal at concentration of 1/2 MIC and still significant at 1/4, 1/8, 1/16 MIC, but with progressive return to mean control values at 1/32 MIC. Ciclopirox acts on fungi by inhibiting the intracellular uptake of essential substrates and ions and this probably acts on the Candida ability to express its adherence mechanisms.     

In vitro antifungal activity of itraconazole, a new triazole antifungal agent, against clinical isolates from patients with systemic mycoses]

The in vitro antifungal activity of itraconazole (ITZ), a new oral triazole antifungal agent, against clinical isolates from patients with systemic mycoses were compared with those of existing systemic antifungals, viz. ketoconazole (KCZ), miconazole or amphotericin B. The studies were performed with 65 isolates of pathogenic yeasts and 13 isolates of Aspergillus spp. using the agar dilution method on casitone agar. ITZ showed the most potent antifungal activities against isolates of pathogenic yeasts including several Candida spp. (Candida parapsilosis, Candida krusei, Candida guilliermondii), Cryptococcus neoformans, Trichosporon cutaneum (MIC less than or equal to 0.08 micrograms/ml) and Aspergillus spp. including Aspergillus fumigatus (MIC less than or equal to 5 micrograms/ml). On the other hand, activities of ITZ against isolates of other Candida spp. such as Candida albicans and Candida glabrata were lower than those of KCZ and other reference drugs. Some isolates of C. albicans and C. tropicalis were not completely inhibited by ITZ even at concentrations above 10 micrograms/ml on casitone agar. However, in the micro-broth dilution method using synthetic amino acid medium, fungal as the test medium, ITZ completely inhibited the growth of all these isolates at drug concentrations of less than or equal to 0.20 micrograms/ml.     

Preliminary evaluation of immunoadjuvant activity of an orally administered glucan extracted from Candida albicans.

The immunoadjuvant activity of an orally administered glucan (Glucanil, Gluimmun) was investigated in mice. Glucan was extracted from Candida albicans ATCC 20955 and purified by an alkali-acid and detergent treatment. In this study the chronic intravenous infection with Candida albicans (treated or not with amphotericin B) or Staphylococcus aureus was the experimental model. Moreover the production of interleukin-2 was evaluated in treated animals. Oral treatment with glucan at 1 mg/mouse/day repeated doses, starting from 10 days before the experimental infection, significantly increased polymorphonuclear leukocytes and peripheral monocytes number. A significant increase in number and in vitro candidacidal activity was also observed for alveolar macrophages. The resistance towards systemic infection with Candida albicans or Staphylococcus aureus increased, significantly reducing the growth of microorganisms in the kidneys of infected animals. Glucan significantly increased the candidacidal spleen cells activity and synergized with amphotericin B chemotherapeutic action. Higher doses (eg. 2 or 5 mg/mouse) were not effective. A 10 days oral treatment with 1 mg/mouse/d significantly increased the interleukin-2 production. Toxicological studies showed that glucan is highly tolerated.     

Synthesis and antimicrobial activity of some 5-[2-(morpholin-4-yl)acetamido] and/or 5-[2-(4-substituted piperazin-1-yl)acetamido]-2-(p-substituted phenyl)benzoxazoles

In this study, a series of twelve novel 5-[2-(morpholin-4-yl)acetamido] and/or 5-[2-(4-substituted pip-erazine-1-yl)acetamido]-2-(p-substituted phenyl]benzoxazole derivatives have been synthesized and their structures were confirmed by IR, (1)H NMR, and mass spectral data. These compounds were prepared by reacting 5-(2-chloroacetamido)-2-(4-p-substituted-phenyl)benzoxazoles, which were obtained by using 5-amino-2-[p-substituted-phenyl]benzoxazoles with chloroacetyl chloride, in the presence of morpholine or 1-substituted piperazines. All synthesized compounds 3-14 were tested by using the method of twofold serial dilution technique for in vitro activities against certain strains of Gram-positive, Gram-negative bacteria as well as the yeasts Candida albicans, Candida krusei, and Candida glabrata in comparison with standard drugs. Microbiological results showed that the newly synthesized compounds possessed a broad spectrum of activity, showing MIC values of 3.12-50 mug/mL against the Candida species.     

深部感染真菌对常用抗真菌药物的耐药性

目的:调查北京医院2003年4月～10月期间真菌感染的菌种分布及耐药性,指导临床合理用药.方法:采用显色培养基对真菌进行鉴定,用药敏纸片法测定真菌对氟康唑、伊曲康唑和两性霉素B的敏感性.结果:共分离到285株真菌,主要来源于呼吸道、泌尿道和消化道,其中检出最多的是白色假丝酵母133株(46.7%)、光滑假丝酵母66株(23.2%)和热带假丝酵母54株(18.9%).三种抗真菌药物对285株深部感染真菌总的耐药率分别为氟康唑10.9%、伊曲康唑7.7%和两性霉素B0%.对氟康唑耐药的有光滑假丝酵母26株、克柔假丝酵母1株、季也蒙假丝酵母2株和白色假丝酵母2株;对伊曲康唑耐药性较高有克柔假丝酵母1株、季也蒙假丝酵母2株、热带假丝酵母5株、光滑假丝酵母12株和白色假丝酵母2株.结论:定期开展真菌的耐药监测,有助于合理应用抗真菌药物.     

Echinocandin antifungal drugs in fungal infections: a comparison

This review compares the pharmacology, spectrum of antifungal activity, pharmacokinetic and pharmacodynamic properties, safety and clinical efficacy of the three licensed echinocandins: caspofungin, micafungin and anidulafungin. Echinocandins inhibit the synthesis of 1,3-β-D-glucan, an essential component of the fungal cell wall, and represent a valuable treatment option for fungal infections. The echinocandins exhibit potent in vitro and in vivo fungicidal activity against Candida species, including azole-resistant pathogens. For all agents, strains with drug minimum inhibitory concentrations (MICs) of ≤ 2?μg/mL are considered susceptible; the MIC at which 90% of isolates tested were inhibited (MIC??) values are typically <2?μg/mL but 100-fold higher MIC?? values are seen with Candida parapsilosis (1-2?μg/mL) and Candida guilliermondii (1-4?μg/mL). Activity is comparable between the three agents, although limited data indicate that anidulafungin may have low MICs against C. parapsilosis and Candida glabrata strains that demonstrate elevated MICs to caspofungin and micafungin. All three drugs have good fungistatic activity against Aspergillus spp., although minimal effective concentrations of micafungin and anidulfungin are 2- to 10-fold lower than those for caspofungin. Synergistic/additive in vitro effects of echinocandins when combined with a polyene or azole have been observed. Clinical resistance to the echinocandins is rare despite case reports of caspofungin resistance in several Candida spp. Resistance has been attributed to mutations in the FKS1 gene within two hot spot regions, leading to amino acid substitutions, mostly at position 645 (serine), yet not all FKS1 mutants have caspofungin MICs of >2?μg/mL. Of the three echinocandins, the in vitro 'paradoxical effect' (increased growth at supra-MIC drug concentrations) is observed least often with anidulafungin. All echinocandins have low oral bioavailability, and distribute well into tissues, but poorly into the CNS and eye. Anidulafungin is unique in that it undergoes elimination by chemical degradation in bile rather than via hepatic metabolism, has a lower maximum concentration and smaller steady state under the concentration-time curve but longer half-life than caspofungin or micafungin. In children, dosing should be based on body surface area. Daily doses of caspofungin (but not micafungin and anidulafungin) should be decreased (from 50 to 35?mg) in moderate liver insufficiency. All echinocandins display concentration-dependent fungicidal (for Candida) or fungistatic (for Aspergillus) activity. The postantifungal effect is 0.9-20 hours against Candida and <0.5 hours against Aspergillus. The echinocandins are well tolerated with few serious drug-drug interactions since they are not appreciable substrates, inhibitors or inducers of the cytochrome P450 or P-glycoprotein systems. In parallel with the greater clinical experience with caspofungin, this agent has a slightly higher potential for adverse effects/drug-drug interactions, with the least potential observed for anidulafungin. Caspofungin (but not micafungin or anidulafungin) dosing should be increased if coadministered with rifampicin and there are modest interactions of caspofungin with calcineurin inhibitors. All three agents are approved for the treatment of oesophageal candidiasis, candidaemia and other select forms of invasive candidiasis. Only micafungin is licensed for antifungal prophylaxis in stem cell transplantation, whereas caspofungin is approved for empirical therapy of febrile neutropenia. Caspofungin has been evaluated in the salvage and primary therapy of invasive aspergillosis. Combination regimens incorporating an echinocandin showing promise in the treatment of aspergillosis. However, echinocandins remain expensive to use.     

人类免疫缺陷病毒相关性口腔念珠菌的药物敏感性分析

目的探讨HIV/AIDS病人口腔念珠菌对常用抗真菌药物的敏感性。方法采用微量液基稀释法,测定念珠菌对氟康唑、酮康唑、氟胞嘧啶和两性霉素B共4种常用抗真菌药物的敏感性(MIC值)。结果60株HIV相关性念珠菌对上述4种药物敏感性的几何均数分别为0.871、0.050、0.179和0.329 mg·L~(-1);耐药率分别为2%、5%、3%和5%;白色念珠菌和非白色念珠菌对氟康唑和两性霉素B的耐药率差异均具有显著性;有1株光滑念株菌对氟康唑、酮康唑和两性霉素B同时耐药。结论上述4种临床常用抗真菌药物可选作HIV/AIDS病人口腔念珠菌病的治疗,但应注意某些菌株的耐药和交叉耐药现象,尤其是非白色念珠菌。     

Biochemical studies in infective amosite pneumoconiosis

The effects of Candida albicans, of amosite dust, and of the 2 agents combined, on some biochemical parameters of the lung in male guine pigs were determined. Adult guinea pigs were intratracheally injected with 50 mg of amosite dust and 0.3 mg of viable suspension of mycelia of Candida albicans. The other groups received either dust or organism or none. Biochemical measurements done at 30, 60 and 90 days after infection showed that the superimposed state produced more rapid and drastic changes in pulmonary contents of collagen, mucopolysaccharides and phospholipids and activities of lactic dehydrogenase and succinate dehydrogenase. The levels of lactic acid and pyruvic acid were also more profoundly changed after amosite + Candida. These ersults indicate that Candida albicans which is commonly found in upper respiratory tract could aggrevate the lesions caused by exposure to asbestos.     

Synthesis of some hydroxamic acid derivatives of benzimidazole and their antibacterial and antifungal activities.

A number of 1H-benzimidazole-2-propanoic acid derivatives have been synthesized by Phillips method, and their antibacterial and antifungal activities have been tested. The chemical structures of the synthesized compounds were elucidated by spectroscopic (IR, NMR, mass) and elementary analysis. Investigation of antimicrobial activity of the compounds was done by agar dilution technique using bacteria (Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Mycobacterium smegmatis ATCC 607) and yeast-like fungi (Candida albicans, Candida tropicalis, Candida pseudotropicalis, Candida kruzei, Candida globrata). Among the compounds tested N-hydroxy-3-(1H-benzimidazol-2-yl)-propionamide (Compound 6) showed considerable activity against both Candida albicans and Candida tropicalis.     

The in vitro properties of a new hydroxypyridone antimycotic rilopirox, with special reference to its anti-Candida activity

In vitro properties of a new hydroxypyridone antimycotic rilopirox (RIL) with special reference to its anti-Candida activities were studied in comparison with the three reference drugs, ciclopirox olamine (CPO), oxiconazole nitrate (OCZ) and isoconazole nitrate (ICZ), using several strains of Candida albicans and Candida glabrata as the test organisms. RIL was potently fungicidal for growing cultures of these Candida strains, whereas all the three reference drugs were slightly fungicidal or fungistatic. Unlike OCZ and ICZ whose anti-Candida activity was decreased by lowering pH or adding serum to culture media, the activity of RIL was scarecely affected by change in pH or serum addition. However, RIL became less potent in the presence of Fe3+ at concentrations of 10(-5) mmol/ml or above. These findings suggest that RIL will be useful as a topical anti-Candida agent.     

不同抗真菌药治疗白念珠菌性阴道炎模型小鼠的疗效比较

目的 比较特比萘芬、氟康唑、伊曲康唑等抗真菌药治疗小鼠白念珠菌性阴道炎的疗效。方法构建ICR小鼠白念珠菌性阴道炎模型，应用特比萘芬、氟康唑、伊曲康唑灌服治疗，并在灌药后不同时间动态观察阴道灌洗液真菌载量。结果 特比萘芬组在不同时间点其小鼠阴道灌洗液真菌载量明显高于氟康唑组及伊曲康唑组（P＜0.01），连续灌药1周后其真菌载量仍处于较高水平。氟康唑组与伊曲康唑组从灌服药物后第2天开始其阴道灌洗液真菌载量明显减少，灌服药物后第3天开始阴道灌洗液真菌载量即处于极低水平，表明两组疗效显著，但两者之间疗效差异无显著性（P＞0.05）。结论 特比萘芬治疗小鼠白念珠菌性阴道炎的疗效欠佳，而氟康唑与伊曲康唑治疗小鼠白念珠菌性阴道炎疗效显著。     

A clinical evaluation of injectable fluconazole in the treatment of deep mycosis associated with hematological malignancy

The clinical efficacy and the safety of fluconazole as given at an intravenous dose of 100-400 mg daily were assessed in 7 patients with deep mycosis associated with hematological malignancy. Enrolled in the study were 1 patient with acute lymphatic leukemia, 1 with acute myelocytic leukemia, 2 with acute myelomonocytic leukemia, 2 with malignant lymphoma and 1 with myelodysplastic syndrome. Pathogens isolated from 4 patients were all Candida species including 2 Candida albicans, 1 Candida parapsilosis and 1 Candida krusei. Diagnoses of fungal infections of the patients were Candida pneumonia in 3 patients, candidemia in 1 and fungemia suggested in 3. Assessment of the clinical efficacy was made on 4 patients from whom pathogens were isolated. The global clinical improvement was good in 2 patients and fair in 1 with Candida pneumonia and good in 1 with candidemia. In the mycological assessment, pathogenic fungi were eradicated in 3 patients and decreased in 1 patient. No significant adverse reactions nor abnormality in clinical laboratory tests related with the dosing of fluconazole were observed in any of the patients.     

Susceptibility to miconazole (base) of isolates from the oral cavity and esophagus of patients with mycosis

An antifungal agent of the imidazole class, miconazole (MCZ) (base), was investigated for its in vitro antifungal activities against isolates from the oral cavity and esophagus of patients with mycosis, and the following findings were obtained: 1. Those yeast-like fungi which were presumed to be the causative agents were isolated from the oral cavity and esophagus of patients with mycosis, and identified. Candida albicans was the most frequently occurring species, accounting for 71.4% of all the isolates. Less frequently, several other Candida species, such as Candida krusei, Candida tropicalis, Candida lusitaniae and Candida lipolytica were also isolated mostly from patients with polymicrobial infections. 2. The MICs of MCZ against the isolates of Candida species which were obtained from materials from patients with oral and esophageal candidiasis as the presumable causative agent distributed through such a wide range as less than or equal to 0.04 to 20 micrograms/ml, and susceptibilities of these isolates to MCZ proved to be no less than those to amphotericin B, which was used as the control drug. The results suggest that an appropriate preparation of MCZ (base) will be effective in treating mycosis of the oral cavity and esophagus.     

Mycological and electron microscopic study of Solanum chrysotrichum saponin SC-2 antifungal activity on Candida species of medical significance

Solanum chrysotrichum is utilized in traditional Mexican medicine for the treatment of mycotic skin infections. Several microbiological studies have provided evidence of its antifungal activity against dermatophytes and yeasts. S. chrysotrichum saponins have been identified as a group of compounds with antifungal activity and saponin SC-2 has demonstrated to be the most active. Previous clinical studies have shown the therapeutic effectiveness of S. chrysotrichum-derived saponin-standardized herbal products in the treatment of Tinea pedis and Pityriasis capitis. There is no previous evidence of the activity of these saponins against Candida non-albicans species, or fluconazole- and ketoconazole-resistant Candida strains. The present study reports the biological activity of the SC-2 saponin (inhibitory concentration [IC (50)] and minimum fungicide concentration [MFC]), against 12 Candida strains of clinical significance ( C. albicans, five strains; C. glabrata and C. parapsilosis, two; C. krusei, C. lusitaniae and C. tropicalis, one), including some fluconazole (Fluco)- and ketoconazole (Keto)-resistant clinical isolates. In addition, SC-2-associated microstructural alterations were reported in four of the above-mentioned Candida species. Seven strains had IC (50) of 200 microg/mL for SC-2, 400 microg/mL was found in four strains, and 800 microg/mL for a sole C. glabrata strain. Susceptibility to SC-2 saponin was as follows: C. albicans = C. lusitaniae > C. krusei > C. glabrata. The MFC was 800 microg/mL for the majority of strains (nine), 400 microg/mL for C. albicans (two strains) and C. lusitaniae. The ultrastructural Candida changes originated by SC-2 included the following: 1) damage on cytoplasmic membrane and organelles; 2) changes in cell wall morphology and density, with separation of cytoplasmatic membrane from cell wall and disintegration of the latter; and 3) total degradation of cellular components and death. Changes were manifested from 6 h of incubation, reaching their maximum effect at 48 h. In conclusion, the saponin SC-2 possesses fungicide and fungistatic activity on different Candida albicans and non- albicans species (including some azole-resistant strains) with IC (50) values of 200 microg/mL (in Fluco-susceptible strains) and of 400 - 800 mug/mL (in Fluco-resistant strains). Additionally, we observed by transmission electron microscopy (TEM) that saponin SC-2 causes severe changes in all fungal cell membranes, and to a lesser degree on the cell wall.     

Clinical efficacy of fluconazole in urinary tract fungal infections

Fluconazole, a new antifungal agent was administered to 7 patients with complicated urinary tract fungal infections. Patients were 6 males and 1 female with ages of 29 to 83 years, with underlying conditions of bladder tumor (3 patients), neurogenic bladder (3 patients) and hydronephrosis (1 patient). Urinary fungi identified were Candida albicans in 5 patients and Candida tropicalis in 2 patients over 10(4) CFU/ml. These fungi were isolated at least twice in intervals of 5 to 7 days before treatment. Fluconazole was given either orally (4 patients) or intravenously (3 patients) in a dose of 50 mg per day. Clinical efficacies were excellent in 3 patients, moderate in 3 patients and poor in 1 patient, showing an efficacy rate of 85.7%. Mycologically, 6 Candida out of the 7 were eliminated. No side effects nor abnormal laboratory data were observed. In conclusion, fluconazole is effective and safe in the treatment of urinary tract fungal infections.