The role of dietary fats for preventing cardiovascular disease. A review.

At the present, there is a pandemic of chronic non-communicable disease (NCD) affecting most countries of the world. The World Health Organisation (WHO) has identified the main contributing determinants to be cardiovascular disease (CVD), diabetes, malignant cancer and chronic disease of the respiratory system. Unhealthy nutrition, as well as other adverse lifestyle health behaviour are recognised to be part of the prime factors responsible. According to WHO guidelines, a healthy lifestyle should include substituting saturated fatty acids (SFAs) with polyunsaturated fatty acids (PUFAs) together with eliminating trans-fatty acids from the diet and limiting the intake of refined carbohydrates in conjunction with increasing the consumption of fruit, vegetables, nuts and wholegrain cereal products. Recent studies on the relations between CVD prevention and dietary fats have been however unclear. The present study thus aims to provide a review of current evidence and opinion on the type of dietary fat most appropriate for preventing arteriosclerosis. The adoption of dated recommendations on the need to increase dietary PUFA in both Northern Europe and America has led to n-6 PUFAs being predominant in diets as compared to n-3 PUFAs. This disproportion may have caused mortality to rise, due to CVD, as a result of arteriosclerosis in these countries. In contrast, a traditional Mediterranean diet yields a PUFA n-6/n-3 ratio of 2:1, which is much lower than for the aforementioned northern countries. Some authors however consider that assessing this ratio is irrelevant and that decreasing n-6 PUFA may be harmful. Such differences of opinion leads to confusion in adopting an effective approach for arteriosclerosis management regarding dietary n-6/n-3 ratios. Moreover, recent studies have added much controversy to the notion that the characteristics of SFAs are responsible for arteriosclerosis. These found that replacing dietary SFAs with carbohydrates did not reduce the risk of ishaemic heart disease (IHD). Furthermore, changing to monounsaturated fatty acids (MUFAs) gave equivocal findings, but only changing to PUFAs reduced the risk of IHD. This last statement however requires qualification in that dietary n-6 PUFAs increases the risk of IHD. It is only the n-3 PUFAs that are beneficial. Up till now these controversies remain unsolved. It is however noteworthy that adopting a Mediterranean diet reduces IHD mortality. This is explained by a low consumption of SFAs but high intake of unsaturated fatty acids including n-3 PUFAs, and is linked to choosing the right vegetable fats. Oils that contain alpha-linoleic acid (ALA) are to be preferred in the diets of northern countries.

Effectiveness and safety of PCSK9 inhibitor therapy in patients with familial hypercholesterolemia within a therapeutic program in Poland: Preliminary multicenter data.

BACKGROUND: In Poland, treatment with proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors has become available free of charge in a therapeutic program. Assessed herein, is the efficacy and safety of alirocumab and evolocumab in patients with heterozygous familial hypercholesterolemia (FH). METHODS: Data of 55 adult FH patients who participated in the program were analyzed upon meeting the criteria established by the Ministry of Health (low density lipoprotein cholesterol [LDL-C] above 160 mg/dL on max. tolerated statin dose and ezetimib). The efficacy of PCSK9 inhibitors in reducing LDL-C with drug administration every 2 weeks was assessed after 3 months and 1 year of therapy. A safety profile evaluation was performed at each visit. 48 patients completed the 3-month and 21 for the 1-year observation periods (34 patients treated with alirokumab and 14 with evolocumab). RESULTS: The mean concentration of direct-measured LDL-C decreased from the initial level of 215.1 ± 74.5 mg/dL to 75.3 ± 64.1 mg/dL, i.e., by 65 ± 14% following 3 months of treatment. This effect was stable in 1-year observation (77.7 ± 72.8 mg/dL). Adverse effects were flu-like symptoms (13.0%), injection site reactions (11.1%), fatigue (5.6%) and musculoskeletal symptoms (5.6%). Seven patients failed to complete the 3-month treatment period due to side effects or non-compliance, and 1 patient failed to complete the 1-year treatment due to myalgia. CONCLUSIONS: This study confirmed high effectiveness of PCSK9 inhibitors in reducing LDL-C levels in patients with FH. Due to restrictive inclusion criteria with LDL-C threshold level > 160 mg/dL (> 4.1 mmol/L) required for participation in the therapeutic program, a relatively small number of FH patients were eligible for treatment.

Hypolipaemic nutraceutics: red yeast rice and Armolipid, berberine and bergamot.

INTRODUCTION: Increased serum cholesterol levels constitute one of the main risk factors for cardiovascular diseases. Statins are a major method for reducing the levels which also lower the risk of cardiovascular events. However, these valuable drugs cannot be used in all patients who need them due to contraindications and intolerance. In such cases, help can be sought from nutraceutics that reduce the serum cholesterol concentration. Since there are numerous products of this type available at drugstores, registered as supplements, there seems to be a need to demonstrate their effectiveness in preventing cardiovascular diseases induced by atherosclerosis. In literature, increasingly more attention is drawn to red yeast rice, Armolipid, berberine and bergamot. BRIEF DESCRIPTION: This article presents knowledge about these nutraceutics based on clinical studies and expert statements relating to their use. The results of clinical studies and metaanalyses have shown that nutraceutics with cholesterol lowering properties, red yeast rice and Armolipid are the most favourable for reducing cardiovascular events. However, the evidence of benefits of berberine and bergamot is not so conclusive. CONCLUSIONS: Red yeast rice products and Armolipid may be used as an alternative treatment in statin intolerant patients, especially in combination with ezetimibe. These nutraceutics can be also considered, as an adjunct to diet therapy in primary prevention of cardiovascular diseases in patients with mild and moderate hypercholesterolaemia. The opinion of experts on berberine and bergamot is ambiguous.

How much should LDL cholesterol be lowered in secondary prevention? Clinical efficacy and safety in the era of PCSK9 inhibitors.

There is a strong evidence that more marked lowering of low-density lipoprotein cholesterol (LDL-C) leads to progressively lower risk of cardiovascular disease (CVD) events. The evidence on validity of this hypothesis comes from epidemiological, genetic and clinical studies. The hypothesis "the lower the better" has been recently strongly supported by the results of secondary prevention trials with PCSK9 inhibitors. The combination of PCSK9 inhibitors and statins has resulted in achieving extremely low LDL-C levels with additional reduction of CVD events in secondary prevention. However, despite large clinical benefits, the safety of aggressive LDL-C lowering should be always taken into consideration, and there is still an ongoing discussion on whether very low LDL-C might result in some non-CVD adverse events. However, based on the available knowledge, so far the serious adverse events associated with achieving of very low LDL-C levels or intensive drug therapy have not been noted. These positive clinical effects were reflected in current ESC/EAS Guidelines (2019) for dyslipidaemia management. The experts strongly recommended the LDL-C lowering to levels that have been achieved in trials of PCSK9 inhibitors. In this state of the art review, we aimed to finally justify the critical need for LDL-C reduction to very low levels in secondary prevention patients in order to be as low as possible, as early as possible, and preferably lifelong.

Current state-of-the-art knowledge on the role of omega-3 fatty acids in the prevention of cardiovascular disease.

INTRODUCTION: Polyunsaturated n-3 fatty acid preparations containing eicosapentaenoic acid (EPA) and docosahexanaenoic acid (DHA), or EPA only, have long been recommended in the management of hypertriglyceridaemia, especially when severe (triglyceride levels ≥500 mg/dL), at the dose of 2-4 g/d, mostly for the prevention of acute pancreatitis. MATERIAL AND METHODS: The presented article reviews clinical trials and their metaanalyses which evaluated the effect of n-3 fatty acids on cardiovascular disease risk, and regulatory agencies' and cardiac societies' positions regarding their use. RESULTS: The findings indicate that only EPA is effective. Particular clinical benefit (25% reduction of cardiovascular events) was observed in the recently published REDUCE-IT trial which evaluated EPA (icosapent ethyl) at the dose of 4 g/d for 4.9 years (median), compared to placebo, in hypertriglycerydaemic patients at high or very high cardiovascular risk. This positive effect has been reflected in the expert opinions which recommend eicosapent ethyl (4 g/d) in patients similar to those participating in the REDUCE-IT trial. Additional data in favour of the above position have been provided by the EVAPORATE trial results which showed reduced progression of coronary atherosclerosis with EPA at the dose of 4 g/d. CONCLUSIONS: The clinical studies and metaanalyses strongly point out that only EPA (icosapent ethyl), especially at dose of 4 g/d, is effective in reducing cardiovascular events in very high and high risk patients with hypertriglyceridemia. The use of EPA + DHA preparations in doses up to 1 g/d does not prevent recurrent cardiovascular events.

What do we know about the role of lipoprotein(a) in atherogenesis 57 years after its discovery?

Elevated circulating concentrations of lipoprotein(a) [Lp(a)] is strongly associated with increased risk of atherosclerotic cardiovascular disease (CVD) and degenerative aortic stenosis. This relationship was first observed in prospective observational studies, and the causal relationship was confirmed in genetic studies. Everybody should have their Lp(a) concentration measured once in their lifetime. CVD risk is elevated when Lp(a) concentrations are high i.e. > 50 mg/dL (≥100 mmol/L). Extremely high Lp(a) levels >180 mg/dL (≥430 mmol/L) are associated with CVD risk similar to that conferred by familial hypercholesterolemia. Elevated Lp(a) level was previously treated with niacin, which exerts a potent Lp(a)-lowering effect. However, niacin is currently not recommended because, despite the improvement in lipid profile, no improvements on clinical outcomes have been observed. Furthermore, niacin use has been associated with severe adverse effects. Post hoc analyses of clinical trials with proprotein convertase subtilisin/kexin type-9 (PCSK9) inhibitors have shown that these drugs exert clinical benefits by lowering Lp(a), independent of their potent reduction of low-density lipoprotein cholesterol (LDL-C). It is not yet known whether PCSK9 inhibitors will be of clinical use in patients with elevated Lp(a). Apheresis is a very effective approach to Lp(a) reduction, which reduces CVD risk but is invasive and time-consuming and is thus reserved for patients with very high Lp(a) levels and progressive CVD. Studies are ongoing on the practical application of genetic approaches to therapy, including antisense oligonucleotides against apolipoprotein(a) and small interfering RNA (siRNA) technology, to reduce the synthesis of Lp(a).

Landmark studies in coronary heart disease epidemiology. The Framingham Heart Study after 70 years and the Seven Countries Study after 60 years.

This year we celebrate anniversaries of two prospective studies that have contributed most to our understanding of the epi-demiology of coronary heart disease (CHD): the Framingham Heart Study (FHS) and the Seven Countries Study (SCS). The FHS was initiated 70 years ago and is continued in the subsequent generations using new research opportunities, including evaluation of the risk factors for chronic non-cardiovascular diseases. The SCS is now finished because the original study population are mostly deceased, and the study did not continue in the children and grandchildren of the participants. The FHS allowed identification of factors predisposing to CHD, which were referred to as "risk factors" for the first time. Based on the FHS findings, a multivariate model of the 10-year CHD risk was developed, known as the Framingham Heart Score. In addition, criteria of heart failure and risk factors for atrial fibrillation were defined. The SCS provided the first evidence for an association between nutrition and CHD and laid the foundations for recommending the Mediterranean diet for cardio-vascular disease prevention.

How do we know that statins are diabetogenic, and why? Is it an important issue in the clinical practice?

There is no doubt nowadays that statins exert a diabetogenic action. The evidence comes from observational studies, ran-domised trials, and meta-analyses. The relationship between statin use and new-onset type 2 diabetes is associated with statin potency and dose. It seems also to be stronger if the lowering effect is stronger and the low-density lipoprotein cholesterol level achieved is lower. The mechanisms underlying the development of diabetes in statin-treated patients are not completely understood. Generally, the increased insulin resistance and decreased insulin secretion are taken into account. However, it should be kept in mind that the cardiovascular risk reduction effect of statins outweighs the harm related to diabetes induc-tion. The patients at risk of diabetes development should be monitored with regard to the parameters of glucose metabolism. The introduction of preventive lifestyle modifications to prevent diabetes is recommended. New-onset diabetes should be managed according to the guidelines.

Clinical management of heterozygous familial hypercholesterolemia in a Polish outpatient metabolic clinic: a retrospective observational study.

INTRODUCTION: There are currently no reports available from a Polish clinical practice on heterozygous familial hypercholesterolemia (HeFH) management. The aim of this study was to test the efficacy of HeFH hypolipidemic treatment in a Polish outpatient metabolic clinic according to treatment targets outlined in the European Atherosclerosis Society (EAS) and European Society of Cardiology (ESC) guidelines. MATERIAL AND METHODS: This retrospective, observational study was performed on HeFH patients who attended their routine follow-up visits in the metabolic outpatient clinic in the period between April and September 2016. According to EAS/ESC guidelines, the goal and intensity of therapy were assigned individually for every patient based on cardiovascular (CV) risk (high or very high). The treatment target was achievement of low-density lipoprotein cholesterol (LDL-C) levels < 1.8 mmol/l for very high CV risk patients and < 2.6 mmol/l for high CV risk patients. A ≥ 50% decrease in LDL-C over the observation period was an additional outcome measure. RESULTS: In the overall group of 222 HeFH patients (mean age: 55.2 ±16.2 years, 72% women), LDL-C levels decreased on average by 52.6% (p < 0.001). More than half of the patients were treated with the maximum tolerated dose of statins. A total of 25.2% of patients attained target levels of LDL-C and 55.9% attained a ≥ 50% reduction in its concentration. Despite therapy, significantly elevated post-follow-up levels of LDL-C (> 4.1 mmol/l) remained in 14% of all patients. CONCLUSIONS: Hypolipidemic therapy according to EAS/ESC guidelines was suboptimal for a significant number of HeFH patients. Additional clinical management should be considered.

Prevalence, diagnosis, and treatment of familial hypercholesterolaemia in outpatient practices in Poland.

BACKGROUND: Familial hypercholesterolaemia (FH) is the most common genetic disease leading to premature atherosclerosis. AIM: The aim of the study was to evaluate the prevalence, diagnosis, and treatment of FH in outpatient practices in Poland. METHODS: The study included a representative sample of 147 primary care physicians, cardiologists, and diabetologists caring for 2812 adult patients with hypercholesterolaemia and low-density lipoprotein cholesterol (LDL-C) level > 1.8 mmol/L, who were treated with statins or did not receive statins due to intolerance or contraindications. The physicians declared whether they diagnosed FH in the study group. In addition, we evaluated the Dutch Lipid Clinic Network (DLCN) diagnostic criteria for FH in all patients. The results were weighted and extrapolated to the general outpatient population in Poland. Treatment and its effectiveness were also evaluated. RESULTS: FH6+ score by the DLCN criteria was found in 3.6% of the study group, which translates by extrapolation to 136,300 adult patients with FH in Poland. Among patients with FH6+, this diagnosis was correctly made by physicians in 25% of cases and was not established in 75% of cases. Only 32.8% of patients received high statin doses. High LDL-C levels were found in a large proportion of patients, including levels ≥ 5.0 mmol/L in 42.7% of patients and ≥ 4.1 mmol/L in 59.7% of patients. CONCLUSIONS: Familial hypercholesterolaemia is inadequately diagnosed and treated in Poland, which calls for a radical im-provement of pre- and postgraduate education in this regard.

The mechanism of overcoming multidrug resistance (MDR) of fungi by amphotericin B and its derivatives.

Comparative studies were performed to determine the activity and cytotoxicity of amphotericin B (AmB) and its derivatives on standard strain of Saccharomyces cerevisiae and its transformants with cloned genes from Candida albicans encoding multidrug resistance (MDR) pumps of ATP-binding cassette and major facilitator superfamilies. The AmB derivatives: amphotericin B 3-dimethylaminopropyl amide and N-methyl-N-D-fructopyranosylamphotericin B methyl ester were shown to be fungistatic and fungicidal towards MDR strains, by membrane permeabilization mechanism. Antibiotic-cell interaction monitored by energy transfer method indicates similar membrane affinity in parent strain and its MDR transformants. Experiments with fungal cells loaded with rhodamine 6G point to lack of competition between this dye and AmB and its derivatives for efflux driven by CDR2p. It can be thus assumed that AmB and its derivatives overcome fungal MDR by not being substrates of the multidrug exporting pumps, presumably due to their large molecular volumes.

Prevalence of lipid abnormalities in Poland. The NATPOL 2011 survey.

BACKGROUND: Poland represents a country of high cardiovascular (CV) risk. The association between lipid abnormalities and increased CV risk is well established. Therefore, it is important to monitor the prevalence and control of dyslipidaemia. AIM: To evaluate serum lipids concentrations as well as the prevalence, awareness, and control of lipid abnormalities in a representative sample of adults in Poland. METHODS: In 2011, in a national cross-sectional survey blood samples were collected from 1168 males and 1245 females, aged 18-79 years, for measurement of total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), and triglycerides (TG) in blood serum. Low density lipoprotein cholesterol (LDL-C) was calculated using Friedewald's formula. RESULTS: Mean serum TC concentration was 197.1 mg/dL (95% CI 193.8-200.4) in males (M) and 198.6 mg/dL (95% CI 195.7-201.5) in females (F). Levels of LDL-C were 123.6 mg/dL (120.9-126.2) and 123.7 mg/dL (121.4-126.1), HDL-C - 45.8 mg/dL (44.7-47.0) and 54.1 mg/dL (53.1-55.1), TG - 140.9 mg/dL (133.0-148.8) and 104.0 mg/dL (99.8-108.2) for males and females, respectively. TC ≥ 190 mg/dL was found in 54.3% subjects (M 54.3%; F 54.4%). After adding patients on lipid-lowering treatment, hypercholesterolaemia was present in 61.1% of adults (M 60.8%; F 61.3%). LDL-C ≥ 115 mg/dL was detected in 57.8% of all subjects (M 58.3%; F 57.3%), while HDL-C < 40 mg/dL in 35.2% of males and < 45 mg/dL in 22% of females TG ≥ 150 mg/dL was found in 21.1% of subjects (M 28.4%; F 14.0%). The highest prevalence of elevated TC and LDL-C levels was present in the age group of 40-59-year-olds. Of those with hypercholesterolaemia 58.7% (M 61.5%, F 56.0%) were not aware of the condition; 22.0% (M 21.0%, F 24.5%) were aware but were not being treated; 8.1% (M 7.7%, F 8.5%) were treated but with TC ≥ 190 mg/dL; and only 10.9% (M 10.7%, F 11.0%) were being treated with TC < 190 mg/dL. CONCLUSIONS: The prevalence of dyslipidaemia in Poland continues to be high--over 60% of adults have hypercholesterolaemia, and control remains poor. The results of the NATPOL 2011 survey call for urgent preventive measures.

[Severe hypercholesterolaemia--when to use the proprotein convertase subtilisin-kexin type 9 protease inhibitors (PCSK9 inhibitors)? Polish Society of Cardiology experts' group statement]. / Ciezka hipercholesterolemia - kiedy stosowac inhibitory proproteinowej konwertazy subtilizyny/kexiny 9 (inhibitory PCSK9)? Stanowisko grupy ekspertów Polskiego Towarzystwa Kardiologicznego.

The severe hypercholesterolaemia can be recognised when low density lipoprotein cholesterol (LDL-C) serum levels are equal to or above 5 mmol/L (≥ 190 mg/dL). The prevalence of LDL-C ≥ 5 mmol/L is 3.8% in Polish population aged 18-79 years. Among these adults there are patients with familial hypercholesterolaemia (FH). According to meta-analysis of 6 Polish population surveys prevalence of heterozygous FH (HeFH) diagnosed using Dutch Lipid Clinic criteria is 0.4% (95% Cl 0.28-0.53%) in men and women aged 20-74 years, i.e. one in every 250 people. As HeFH is a wellknown cause of premature coronary heart disease the rigorous treatment targets for LDL-C have been established in clinical guidelines. Their achievements, even with a high dose of high efficacy statin therapy is difficult or even impossible. New strong hypolipidaemic drugs i.e. PCSK9 inhibitors have been initiated against this chalange. Both drugs, evolocumab and alirocumab, have been extensively studied in numerous phase 2 and phase 3 trials. Fewer studies with bococizumab are available until now. The PCSK9 inhibitors, as monotherapy as well in combination with statins were associated with mean LDL-C reduction about 60%. It means that the majority of patients (70-90%) with severe hypercholesterolaemia (including HeFH), treated with statins, after addition of PCSK9 inhibitors were able to achieve an LDL-C < 2.5 mmol/L (< 100 mg/dL) or < 1.8 mmol/L (< 70 mg/dL) level. Another group of patients who may benefit from PCSK9 inhibitors include those who need lipid lowering therapy, but who are statin intolerant, especially because of statin-associated muscle symptoms (SAMS). In our statement we have accepted the diagnosis of SAMS proposed recently by European Atherosclerosis Society. Today the longest clinical trial with evolocumab (11 months) was the open OSLER study, and with alirocumab ODYSSEY LONG TERM (78 weeks). In the first one the reduction of cardiovascular events by 53% (95% Cl 22-72%) was observed, and in the second one by 48% (10-69%). Neurocognitive events were reported more frequently with both drugs than with placebo. This adverse effect will be the subject of observation in ongoing studies. We still await the results of 4 ongoing large placebo controlled phase 3 trials investigating whether PCSK9 inhibitors on background of statin therapy reduce cardiovascular events. Meanwhile evolocumab, as well as alirocumab have been accepted to use in clinical practice by European Medicine Agency. In this situation the experts of Polish Society of Cardiology have prepared the statement on the use PCSK9 inhibitors with indication in the first place for HeFH patients, statin intolerant and those at high risk who are not able to reach LDL-C target level with a high potent high dose statin.

Comparative in vitro studies on liposomal formulations of amphotericin B and its derivative, N-methyl-N-D-fructosyl amphotericin B methyl ester (MFAME).

N-Methyl-N-D-fructosyl amphotericin B methyl ester (MFAME) is a semisynthetic derivative of the antifungal antibiotic amphotericin B (AMB). In contrast to the parent antibiotic, the derivative is characterised by low toxicity to mammalian cells and good solubility in water of its salts. Comparative studies on biological properties of free MFAME, AMB and their liposomal formulations were performed. To obtain liposomal forms, the antibiotics were incorporated into small unilamellar vesicles composed of dimyristoyl phosphatidylcholine (DMPC) and DMPC:cholesterol or ergosterol, 8:2 molar ratio. The effectivity of the liposomal and free forms of AMB and MFAME were compared by determination of fungistatic and fungicidal activity against Candida albicans ATCC 10261, potassium release from erythrocytes, and haemolysis. The results obtained indicate that in contrast to AMB, incorporation of MFAME into liposomes did not further improve its selective toxicity. Studies on the antagonistic effect of ergosterol and cholesterol on the antifungal activity of the antibiotics indicated that sterol interference was definitely less pronounced in the case of MFAME than in the case of AMB.

Facilitated diffusion of glucosamine-6-phosphate synthase inhibitors enhances their antifungal activity.

N3-(4-Methoxyfumaroyl)-L-2,3-diaminopropanoic acid (FMDP) and 2-amino-2-deoxy-D-glucitol-6-phosphate (ADGP) are strong inhibitors of the essential fungal enzyme, glucosamine-6-phosphate synthase, but their antifungal activity is poor, due to slow penetration of these agents through the cytoplasmic membrane. In the present studies we have exploited the possibility of enhancement of ADGP and FMDP antifungal activity by improving their transport properties. It has been found that membrane-permeabilising polyene macrolides amphotericin B (AMB) and its N-methyl-N-fructosyl methyl ester derivative (MF-AME), at subinhibitory concentrations, facilitate diffusion of ADGP through the fungal cell membrane, thus allowing a decrease of its minimal inhibitory concentration (MIC). Synergistic effects have been observed for combinations of ADGP with AMB or MF-AME. Fractional inhibitory concentration (FIC) indexes, determined against a number of Candida spp., have been in the 0.18-0.81 range. Weak antifungal synergistic effects have been found for combinations of FMDP with AMB or MF-AME. ADGP can be easily encapsulated into unilamellar lipid vesicles. Liposomal preparations of ADGP demonstrated stronger antifungal activity against some fungal strains than free ADGP.

Studies of the effects of antifungal cationic derivatives of amphotericin B on human erythrocytes.

The novel group of amphotericin B (AmB) cationic derivatives has been examined in terms of relationship between self-association and selective toxicity. In all determinations AmB has been used as reference compound. In vitro toxic effects of the compounds on human erythrocytes were determined by measuring leakage of intracellular potassium ions and hemolysis. Antifungal effects were determined as MIC and intracellular potassium loss. The compounds self-association was followed by UV-Vis spectroscopy. The results suggested that: i) unlike AmB the monomer/self-associated species ratio is not an essential in governing the selective toxicity of the derivatives studied; ii) the presence of a bulky substituent in the AmB molecule, preferably located at the amino group of mycosamine moiety is the structural factor essential for the selective toxicity improvement.

Interaction of amphotericin B and its low toxic derivative, N-methyl-N-D-fructosyl amphotericin B methyl ester, with fungal, mammalian and bacterial cells measured by the energy transfer method.

Amphotericin B (AMB) derivative, N-methyl-N-D-fructosyl amphotericin B methyl ester (MFAME) retains the broad antifungal spectrum and potency of the parent antibiotic, whereas its toxicity towards mammalian cells is reduced by about two orders of magnitude. The purpose of this work was to find out whether the differences observed in the toxicity of MFAME and native AMB are due to the differential drugs affinity to fungal and mammalian cell membranes. Comparative studies on AMB and MFAME biological activity and their affinity to fungal, mammalian and bacterial cells were performed. The interaction of AMB and MFAME with cells have been studied by fluorescence method based on the energy transfer between membrane fluorescent probe (donor) and the polyenic chromophore of the antibiotic (acceptor) simultaneously present in the cell membrane. The amount of the antibiotic bound to cells was indicated by the extent of fluorescence quenching of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) or 1,6-diphenyl-1,3,5-hexatriene (DPH) by polyenic chromophore of the antibiotic. The results obtained indicate that binding extent and characteristics for both antibiotics are comparable in the three types of cells studied. Dramatically lower toxicity of MFAME as compared to AMB towards mammalian cells is not related to the antibiotic-cell affinity, but rather to different consequences of these interactions for cells, reflected in membrane permeabilization. MFAME is definitely less effective than parent AMB in the permeabilizing species formation in mammalian cell membrane.