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Sulfation of wheat straw soda lignin by the sulfamic acid–urea mixture in different solvents has been investigated for the first time. The effect of a catalyst used in the lignin sulfation process on the yield of the lignin sulfates and sulfur content in them has been explored. It has been found that the optimal medium for the lignin sulfation with sulfamic acid is dioxane and, in the presence of a catalyst, urea. Although the sulfated lignins obtained using the reaction in dimethyl sulfoxide and diglyme have the maximum sulfur contents (11.2% and 9.9%, respectively), these products are difficult to isolate and purify, which complicates the use of these solvents. Sulfated lignin obtained in the dioxane medium has a high (10.1%) sulfur content and is easy to isolate and purify. The incorporation of sulfate groups into the lignin structure has been confirmed by the infrared and nuclear magnetic resonance spectroscopy investigations. In the infrared spectra of sulfated lignin, characteristic absorption bands at 800–860 and 1260–1200 cm−1 appear. The dominant substitution of aliphatic hydroxyl groups has been confirmed by the nuclear magnetic resonance spectroscopy study. It has been found that, during the modification and purification of lignin, the latter is fractionated, which results in the redistribution of molecular weights toward the high molecular-weight region, as well as the removal of some low-molecular-weight components, which is reflected in a decrease in the number of signals in the nuclear magnetic resonance spectra.

The review discusses the results of recent studies in the promising field of integrated processing of lignocellulosic biomass – the reductive catalytic fractionation (RCF). The effect of catalysts, cocatalysts, solvents, hydrogen sources and features of lignocellulosic feedstock on the selectivity of monomeric products formation from lignin is considered. RCF processes are performed mostly with the heterogeneous catalysts, which allow implementing the reductive depolymerization of lignin to obtain low-molecular compounds and preserve carbohydrate components of biomass. Among the studied catalysts based on platinum group metals and transition metals, the highest activity is observed for the catalysts containing Pd, Pt, Ru and Ni. Features of the metal also affect the composition of the resulting products. Thus, ruthenium catalysts make it possible to obtain 4-propylguaiacol as the main product, while Ni and Pd – 4-propanolguaiacol. Mo-containing catalysts, owing to their lower hydrogenating activity, can be used to obtain monolignols or their etherified derivatives with the preservation of carbohydrate components of lignocellulosic biomass. However, most efficient in RCF processes are the bifunctional catalysts, which have both the acidic and metallic active sites. Acidic sites promote the cleavage of the ether β-O-4 bonds, whereas metallic sites – the reduction of the formed intermediate compounds. An important aspect of choosing the appropriate catalysts for RCF process is the possibility of their repeated application. The use of a ferromagnetic catalyst or a catalyst basket allows separating the catalyst from the products.

Lignin is a large-scale waste product of hydrolysis and the pulp-and-paper industries. The problem of lignin utilization is addressed by developing techniques for the comprehensive processing of wood biomass that are based on preliminary catalytic fractionation into its key components, which are subsequently used for obtaining target products. Hemicelluloses of larch wood are known to undergo effective depolymerization (~95 wt %) in ethanol at 250°C. Using hydrogen in combination with a catalyst enables us to increase the lignin conversion to 61 wt %, with 47 wt % of the cellulose left in the solid residue. The highest lignin conversion (67 wt %) is achieved using formic acid, but there is undesirable cellulose depolymerization (conversion, 66 wt %) under these conditions. The main monomer products of the catalytic conversion of lignin are 4-propenylguaiacol and 4-propylguaiacol. The content of 4-propenylguaiacol among the liquid products obtained using ethanol and formic acid as reducing agents can be as high as 36 and 33 rel %, respectively. The content of 4-propylguaiacol among the liquid products obtained using hydrogen grows to 33 rel % when a catalyst is used. This work describes the first study of the catalytic fractionation of larch wood in supercritical ethanol in the presence of the bifunctional 3%Ru/C catalyst containing acidic groups. The aim is to identify the effect of the catalyst and the nature of the hydrogen donor (ethanol, H2, or formic acid) on the yield and composition of the product.

The regularities of thermocatalytic transformation of pine ethanol lignin in supercritical ethanol in the presence of catalysts NiCu/SiO₂ and NiCuMo/SiO2 in the temperature range 250–400 °C were established. The composition and structure of ethanol lignin, liquid and solid products of its conversion were studied by methods of elemental analysis and gel-permeating chromatography (GPC). The composition of gaseous products – by method of gas chromatography. At the process temperature of 250 °C the catalysts do not have a significant effect on conversion of ethanol lignin. The maximal yield of liquid products (83.5 wt. %) was obtained at temperature 300 °C in the presence of catalyst NiCuMo/SiO₂ containing 8.8 wt. % of molybdenum. At temperature 350 °C NiCu/SiO₂ and NiCuMo/SiO2 catalysts contribute to the almost complete conversion of ethanol lignin into liquid and gaseous products, and the yield of solid products does not exceed 1 wt. %. In liquid products of catalytic conversion there is a decrease in the atomic ratio of O/C and the increase of H/C atomic ratio as compared to initial ethanol lignin due to catalytic intensification of reactions of deoxygenation and hydrogenation of lignin and products of its depolymerization. According to GPC data on the curves of molecular mass distribution (MMD) of liquid products of thermocatalytic conversion of ethanol lignin at 300 °C there are peaks with highs at 160 and 380 Da, probably related to guiacyle monomers and dimmers, respectively. From the comparison of MMD of liquid products obtained by ethanol lignin depolymerization at 300 °C over catalysts NiCu/SiO₂ and NiCuMo/SiO₂ it follows, that the introduction of molybdenum in the catalyst promotes the formation of monomeric guaiacyl products

Lignin is a bulky waste of the hydrolysis and paper-pulp industry. To solve the problem of its utilization, approaches to deep processing of wood biomass are being developed; they are based on a preliminary catalytic fractionation of wood biomass into main components, which are processed into target products. For the first time, the reductive catalytic fractionation of larch was studied in a supercritical ethanol medium in the presence of 3%Ru/С bifunctional catalyst containing acid groups. The goal of the study was to reveal the effect of the catalyst and features of a hydrogen donor (ethanol, H2, formic acid) on the yields and composition of the products. It was shown that wood hemicelluloses efficiently (ca. 95 wt.%) depolymerize to ethanol at 250 °С. The use of hydrogen in the presence of the catalyst makes it possible to increase the conversion of lignin to 61 wt.% with retaining 47 wt.% cellulose in a solid residue. The maximum conversion of lignin equal to 67 wt.% was obtained in the presence of formic acid; however, the indicated conditions lead to undesirable depolymerization of cellulose (the conversion of 66 wt.%). The main monomeric products of lignin conversion on the catalyst are propenylguaiacol and propylguaiacol. In the liquid products obtained with ethanol and formic acid as the reductants, the content of propenylguaiacol reaches 36 and 33 rel.%, respectively. In the products obtained with hydrogen, the content of propylguaiacol increases to 33 rel.% in the presence of the catalyst.

The effect of bifunctional catalyst Pt/ZrO₂ on the yield and composition of products of abies wood and ethanol lignin hydrogenation in supercritical ethanol at temperature of 250 °C was established. In the process of abies wood hydrogenation, the catalyst Pt/ZrO₂ increases the degree of conversion of wood from 52.0 to 65.7 wt.%, the yield of liquid products from 31.0 to 38.1 wt.%,.%, and also increases the content of monomeric compounds in the liquid products. In the presence of catalyst, the cellulose content in the solid product of wood catalytic hydrogenation reaches to 77.1 wt.%, and the content of lignin and hemicelluloses decreases to 21.2 wt.% and 1.7 wt.%, respectively. In the process of ethanol lignin hydrogenation the catalyst Pt/ZrO₂ increases the degree of lignin conversion from 86.0 to 99.4 wt.%, the yield of liquid products from 75.0 to 90.0 wt.%, and also reduces the yield of solid residue from 14.0 to 0.6 wt.% and the yield of gases from 4.7 to 3.3 wt.%. Thus, the polysaccharides of wood biomass complicate the reductive depolymerization of native lignin in comparison with the depolymerization of isolated ethanol lignin. The use of the catalyst Pt/ZrO₂ makes it possible to fractionate the abies wood in supercritical ethanol at 250 °C on solid product with a high content of cellulose, as well as liquid and gaseous products from lignin and hemicelluloses

Xanthan is an important polysaccharide with many beneficial properties. Sulfated xanthan derivatives have anticoagulant and antithrombotic activity. This work proposes a new method for the synthesis of xanthan sulfates using sulfamic acid. Various N-substituted ureas have been investigated as process activators. It was found that urea has the greatest activating ability. BBD of xanthan sulfation process with sulfamic acid in 1,4-dioxane has been carried out. It was shown that the optimal conditions for the sulfation of xanthan (13.1 wt% sulfur content) are: the amount of sulfating complex per 1 g of xanthan is 3.5 mmol, temperature 90 °C, duration 2.3 h. Sulfated xanthan with the maximum sulfur content was analyzed by physicochemical methods. Thus, in the FTIR spectrum of xanthan sulfate, in comparison with the initial xanthanum, absorption bands appear at 1247 cm−1, which corresponds to the vibrations of the sulfate group. It was shown by GPC chromatography that the starting xanthan gum has a bimodal molecular weight distribution of particles, including a high molecular weight fraction with Mw &gt, 1000 kDa and an LMW fraction with Mw &lt, 600 kDa. It was found that the Mw of sulfated xanthan gum has a lower value (~612 kDa) in comparison with the original xanthan gum, and a narrower molecular weight distribution and is characterized by lower PD values. It was shown by thermal analysis that the main decomposition of xanthan sulfate, in contrast to the initial xanthan, occurs in two stages. The DTG curve has two pronounced peaks, with maxima at 226 and 286 °C.

Thermal conversion of flax shives was studied in sub- and supercritical ethanol medium at 225 and 250 °C in the presence of the bifunctional catalyst 3% Ru/C. The use of 3% Ru/C catalyst in the process of thermal conversion of flax shives in supercritical ethanol was found to increase the conversion of the shives by 27% and the yield of liquid products by 10%. The use of 3% Ru/C catalyst in sub- and supercritical ethanol led to the destruction of both lignin and cellulose. The degree of delignification in the non-catalytic thermal conversion increased upon transition from subcritical (225 °C) to supercritical (250 °C) conditions. Main monomeric products of the thermal conversion process were guaiacylpropene or guaiacylpropane depending on the process temperature. In the presence of Ru/C catalyst, the molecular weight distribution was shifted towards an increase in the content of monomeric compounds in the liquid products.

fff; International audience; Catalytic hydrogenolysis in the medium of supercritical organic solvents is a promising way of wood lignins depolymerization into liquid products.In this study, for the first time, the catalytic properties of bifunctional catalysts Ru/C, Pt/ZrO2, NiCuMo/SiO2, containing nanosized metal particles on acidic groups are compared in the processes of aspen wood and ethanol lignin hydrogenolysis in supercritical ethanol.The most active catalysts are Ru/C and Pt/ZrO2 which provide the high conversion of wood (to 78.0 wt%), significant yield of liquid products (to 50.6 wt%) and low yield of solid rest (to 22.0 wt%) at temperature 250 °C and H2 pressure 9.0 MPa. These catalysts increase the yield of monomeric compounds in liquid products from 10.5 % to 50.4 % on mass of lignin.GC–MS analysis shows that alkyl derivatives of methoxyphenols (mainly propyl syringol and propyl guaiacol) are dominated in liquid products. Solid products of aspen wood catalytic hydrogenolysis contain mainly cellulose (to 82.2 wt%). Therefore, the catalytic hydrogenolysis in supercritical ethanol in the presence of by functional catalysts Ru/C and Pt/ZrO2 allows to fractionate the aspen wood biomass on cellulose and liquid products enriched with propyl syringol and propyl guaiacol.In catalytic hydrogenolysis of ethanol lignin the yield of alkyl derivatives of methoxyphenols is lower compared to wood. This is probably due to the reduced content of reactive β-O-4 bonds in the structure of ethanol lignin compared to native lignin of aspen wood. As follows from the results obtained, native lignin of wood is easier depolymerized to monomeric compounds in the process of catalytic hydrogenolysis than ethanol lignin, isolated from wood.According to GPC data, the catalysts shift to the region of lower molecular mass the molecular mass distribution of liquid products of aspen wood and ethanol lignin hydrogenolysis.

Background Recent studies have focused on the potential role of epicardial adipose tissue (EAT) in the development of coronary artery disease (CAD). ABCA1 and ABCG1 transporters regulate cell cholesterol content and reverse cholesterol transport. We aimed to determine whether DNA methylation and mRNA levels of the ABCA1 and ABCG1 genes in EAT and subcutaneous adipose tissue (SAT) were associated with CAD. Methods Paired EAT and SAT samples were collected from 82 patients undergoing elective cardiac surgery either for coronary artery bypass grafting (CAD group, N = 66) or valve surgery (NCAD group, N = 16). ABCA1 and ABCG1 mRNA levels in EAT and SAT samples were analyzed using real time polymerase chain reaction, ABCA1 protein levels in EAT samples were assessed by western blotting. ABCA1 and ABCG1 DNA methylation analysis was performed in 24 samples from the CAD group and 9 samples from the NCAD group via pyrosequencing. Results DNA methylation levels in the ABCA1 promoter and ABCG1 cg27243685 and cg06500161 CpG sites were higher in EAT samples from patients with CAD compared with NCAD (21.92% vs 10.81%, p = 0.003; 71.51% vs 68.42%, p = 0.024; 46.11% vs 37.79%, p = 0.016, respectively). In patients with CAD, ABCA1 and ABCG1 DNA methylation levels were higher in EAT than in SAT samples (p ABCA1 mRNA levels in EAT samples were reduced in the subgroup of patients with CAD and concomitant carotid artery disease or peripheral artery disease compared with the NCAD group (p = 0.024). ABCA1 protein levels in EAT samples tended to be lower in CAD patients than in the NCAD group (p = 0.053). DNA methylation levels at the ABCG1 cg27243685 site positively correlated with plasma triglyceride concentration (r = 0.510, p = 0.008), body mass index (r = 0.556, p = 0.013) and waist-to-hip ratio (r = 0.504, p = 0.012) in SAT samples. Conclusion CAD is associated with ABCA1 and ABCG1 DNA hypermethylation in EAT. CAD with concomitant carotid artery disease or peripheral artery disease is accompanied by decreased ABCA1 gene expression in EAT. DNA methylation levels at the ABCG1 cg27243685 locus in SAT are associated with hypertriglyceridemia and obesity.

For the first time, the fractionation of birch wood into microcrystalline cellulose, xylose and methoxyphenols is suggested based on the integration of alkali-acid pretreatments and hydrogenation in ethanol over a bifunctional Ru/C catalyst. It is established that removal of hemicelluloses during pretreatments of birch wood influences the yields of the liquid, gaseous and solid products of the non-catalytic and catalytic hydrogenation of pretreated samples in ethanol at 225 °C. The bifunctional Ru/carbon catalyst affects in different ways the conversion and yields of products of hydrogenation of the initial and acid- and alkali-pretreated birch wood. The most noticeable influence is characteristic of the hydrogenation of the acid-pretreated wood, where in contrast to the non-catalytic hydrogenation, the wood conversion and the yields of liquid products increase but the yields of the solid and gaseous products decrease. GC-MS, gel permeation chromatography and elemental analysis were used for characterization of the liquid product composition. The molecular mass distribution of the liquid products of hydrogenation of the initial and pretreated wood shifts towards the low-molecular range in the presence of the catalyst. From the GC-MS data, the contents of monomer compounds, predominantly 4-propylsyringol and 4-propanolsyringol, increase in the presence of the ruthenium catalyst. The solid products of catalytic hydrogenation of the pretreated wood contain up to 95 wt% of cellulose with the structure, similar to that of microcrystalline cellulose.

The process of sulfation of arabinogalactan—a natural polysaccharide from Larix sibirica Ledeb.—with sulfamic acid in 1,4-dioxane using different activators has been studied for the first time. The dynamics of the molecular weight of sulfated arabinogalactan upon variation in the temperature and time of sulfation of arabinogalactan with sulfamic acid in 1,4-dioxane has been investigated. It has been found that, as the sulfation time increases from 10 to 90 min, the molecular weights of the reaction products grow due to the introduction of sulfate groups without significant destruction of the initial polymer and sulfation products. Sulfation at 95 °C for 20 min yields the products with a higher molecular weight than in the case of sulfation at 85 °C, which is related to an increase in the sulfation rate, however, during the further process occurring under these conditions, sulfation is accompanied by the destruction and the molecular weight of the sulfated polymer decreases. The numerical optimization of arabinogalactan sulfation process has been performed. It has been shown that the optimal parameters for obtaining a product with a high sulfur content are a sulfamic acid amount of 20 mmol per 1 g of arabinogalactan, a process temperature of 85 °C, and a process time of 2.5 h.

Sulfated polysaccharides, due to the presence of anionic groups, are able to form complexes with positively charged molecules. This work presents the results of obtaining complexes of the sulfated polysaccharide arabinogalactan with tetramethylammonium bromide. The resulting complex was shown to be soluble in water and methylene chloride. The introduction of tetramethylammonium bromide into the molecule of sulfated arabinogalactan has been proven by elemental analysis and FTIR spectroscopy.

Flax shive is the main waste (up to 70 wt %) in the production of flax fiber. It represents the lignified parts of the flax stem mainly in the form of small straws. Complex processing of such wastes is a significant problem due to the heterogeneity of the chemical structure of lignin. This article presents the results of reductive catalytic fractionation (RCF) of flax shive in ethanol and isopropanol at elevated temperatures (225&ndash, 250 &deg, C) in the presence of a bifunctional catalyst (Ru/C) and molecular hydrogen. This provides solvolytic depolymerization of lignin and hemicelluloses presented in flax shive. Catalytic hydrogenation effectively stabilizes the formed lignin intermediates and prevents repolymerization reactions producing the lignin fraction with a high degree of depolymerization. RCF of flax shive produces solid products with a high cellulose content and liquid products consisting mainly of monophenolic compounds. Furthermore, the effect of different characteristics (the ruthenium content, particle size, and support acidity) of the bifunctional catalysts containing ruthenium nanoparticles supported on mesoporous, graphite-like carbon material Sibunit&reg, 4 on the yield and composition of the products of hydrogenation of flax shive in sub- and super-critical ethanol has been studied. Bifunctional catalysts Ru/C used in the RCF of flax shive increase its conversion from 44 to 56 wt % and the yield of monophenols from 1.1 to 10.2 wt % (based on the weight of lignin in the sample). Using the best Ru/C catalyst containing 3% of Ru on oxidized at 400 &deg, C carbon support, the high degree of delignification (up to 79.0%), cellulose yield (up to 67.2 wt %), and monophenols yield (up to 9.5 wt %) have been obtained.

Tissue specific expression of genes encoding the cholesterol transporters ABCA1 and ABCG1 as well as genes encoding the most important transcriptional regulators of adipogenesis (LXRα, LXRβ, PPARγ and RORα) has been investigated in intraabdominal adipose tissue (IAT) samples from obese patients and patients without overweight. A direct correlation between the content of ABCA1 and ABCG1 proteins and the RORα protein level (r = 0.480, p < 0.05; r = 0.435, p < 0.05, respectively) suggests involvement of the transcription factor RORα in the regulation of ABCA1 and ABCG1 protein levels in IAT. ABCA1 and ABCG1 gene expression positively correlated with such obesity indicators as body mass index (BMI) (r = 0.522, p = 0.004; r = 0.594, p = 0.001, respectively) and waist circumference (r = 0.403, p = 0.033; r = 0.474, p = 0.013, respectively). The development of obesity is also associated with decreased IAT levels of RORα and LXRβ mRNA (p = 0.016 and p = 0.002, respectively). This suggest that the nuclear factor RORα can play a significant role in the regulation of cholesterol metabolism and control IAT expression of ABCA1 and ABCG1 genes, while the level of IAT LXRβ gene expression may be an important factor associated with the development of obesity.

Atherosclerosis is one of the most common causes of death worldwide. Epidemiology studies firmly established an inverse relationship between atherogenesis and distorted lipid metabolism, in particular, higher levels of total cholesterol, an accumulation of CH-laden macrophages (foam cells), and lower plasma levels of antiatherogenic high density lipoprotein (HDL). It is believed that the reverse cholesterol transport, a process that removes excess cholesterol from peripheral tissues/cells including macrophages to circulating HDL, is one of the main mechanisms responsible for anti-atherogenic properties of HDL. The key proteins of reverse cholesterol transport-ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1)-mediate the cholesterol efflux from macrophages and prevent their transformation into foam cells. This review focuses on the role of ABC transporters A1 and G1 in the pathogenesis of atherosclerosis.

The antiatherogenic role of high-density lipoproteins (HDL) was demonstrated by numerous experimental, clinical and epidemiological studies. The mechanism underlying the antiatherogenic potential of HDL is based on their involvement in reverse cholesterol transport (RCT) from peripheral tissues into the liver. Transmembrane transporter ABCG1 is a key RCT protein. Its function is to remove cholesterol from cells and transfer it to HDL. The role of ABCG1 transporter in the development of atherosclerosis in humans remains unexplored. The goal of our study was to investigate the expression of ABCG1 gene in patients with atherosclerosis. Real-time PCR was applied to study ABCG1 mRNA content in leukocytes, monocytes, and macrophages activated with macrophage colony-stimulating factor (M-CSF) from patients with atherosclerosis and healthy people. The amount of ABCG1 protein in monocytes and macrophages of patients and healthy donors was assayed by immunoblotting. It was found that the level of ABCG1 mRNA (p < 0.001) and ABCG1 protein (p < 0.05) was lower in macrophages of patients with atherosclerosis. The level of ABCG1 mRNA in monocytes of patients with artery occlusion was lower than in patients with features of lesser stenosis and the control group (p < 0.05). No correlation was found between ABCG1 gene expression and total and HDL cholesterol levels in the blood plasma. It can be concluded that reduced ABCG1 gene expression in monocytes and macrophages may be critical for the atherosclerosis progression.

ABCA1 transporter is one of the key factors defining the level of antiatherogenic HDL in plasma. It is involved in cholesterol removal from peripheral tissues by reverse cholesterol transport. However, the influence of ABCA1 mRNA and ABCA1 protein levels in macrophages on atherosclerosis remains unexplored. Using real-time PCR, we determined the ABCA1 mRNA level in macrophages cultured for 5 days with macrophage colony-stimulating factor (M-CSF). The ABCA1 mRNA level in macrophages from patients with arterial stenosis was increased compared to the control group, p = 0.04. Western-blot assayed ABCA1 protein content in macrophages from patients was significantly lower than in the control group, p = 0.01. Our results suggest that ABCA1 mRNA and ABCA1 protein levels in macrophages may be important factors in the development of atherosclerosis.

Apolipoprotein A-I is a key structure protein of antiatherogenic high density lipoproteins (HDL). The aim of the study was to investigate the relationship between (-75)G/A and 83C/T polymorphic variants of apolipoprotein A-I gene (APOA1) and the plasma lipid profile in the population of Saint-Petersburg. Allele T83 of APOA1 gene was found to be associated with the reduced risk of atherosclerosis development among Saint-Petersburg inhabitants. The study demonstrates that allele T83 of APOA1 gene is associated with higher plasma HDL cholesterol levels (p

Amodiaquine (AQ) and tebuquine are 4-aminoquinoline antimalarials with Mannich base side chain and are highly effective against chloroquine (CQ)-resistant strains of Plasmodium falciparum. Clinical use of AQ has been severely restricted due to hepatoxicity and agranulocytosis side effects associated with its long term use. Lysosomal accumulation and bioactivation to generate reactive quinoneimine metabolite are implicated to be the cause of the observed AQ toxicities. To avoid the quinoneimine formation and thus the toxicity, a series of isotebuquine analogues and their Nomega-oxides with hydroxy group meta to the amino rather than in para position of the aniline moiety were prepared. The new Mannich bases are highly active against both CQ-sensitive (D6) and -resistant (W2 and TM91C235) clones of P. falciparum with IC50 in the range of 0.3-120 ng/mL. New compounds are1000-fold less toxic (IC50 = 0.7-6 microg/mL) to mouse macrophage cell line than to parasite cell lines. Mono-Mannich bases are more active than bis-Mannich bases. Mono-Mannich base 1a (IC50 = 0.3 ng/mL) is 20-fold more active than the corresponding trifluoromethyl analogue 1b. No appreciable difference in either toxicity or efficacy were observed between the new Mannich bases (m-hydroxyaniline derivatives) 1a or 2a and the corresponding p-hydroxyaniline derivatives.

A variety of semisynthetic derivatives of natural antibacterial glycopeptide antibiotics such as vancomycin, eremomycin, ristocetin A, teicoplanin A(2)-2, DA-40926, their aglycons, and also the products of their partial degradation with a destroyed or modified peptide core show marked anti-retroviral activity in cell culture. In particular, aglycon antibiotic derivatives containing various substituents of a preferably hydrophobic nature displayed activity against human immunodeficiency virus type 1 (HIV-1), HIV-2, and Moloney murine sarcoma virus at a 50% inhibitory concentration in the lower micromolar (1-5 microM) concentration range while not being cytostatic against human lymphocytic cells at 250 microM or higher. The mode of anti-HIV action of the antibiotic aglycon derivatives could be ascribed to inhibition of the viral entry process.