Effect of triterpene glycosides on the plasma membrane permeability for amino acids in Saccharomyces carlsbergensis yeast cells

The effect of triterpen glycosides, such as cauloside C from Caulophyllum robustum, stichoposide A from Stichopus japonicus S and the asaponine from Thea sinensis L on permeability of the plasmic membranes for amino acids was studied. It was shown that the glycosides induced higher levels of liberation of the amino acids with positively or negatively charged molecules from the cells of Saccharomyces carlsbergensis as compared to the control. The transport of the non-polar amino acids was least affected by addition of the saponines to the incubation medium.     

Chemical structure and antifungal activity of a number of triterpenoids

Antifungal activity was tested in 49 pentacyclic triterpenoids and their glycosides, of plant and semisynthetic origin. Several of these compounds inhibited the multiplication of the yeast Saccharomyces carlsbergensis. The highest antifungal activity was found in the triterpene glycosides oleanolic acid and hederagenin, which have a free carboxyl group at C 28(27). Triterpenes of the meristotropic acid, macedonic acid, and lupan types had no fungistatic activity at concentrations up to 100 microgram/ml.     

Antimicrobial action spectrum of triterpene and steroid glycosides]

Antimicrobial activity of 9 triterpene glycosides of the plant and animal origin was studied. It was found that saponins inhibited the fungal growth to different extents and had no activity against grampositive and gramnegative bacteria. Triterpene glycosides of the animal origin, i.e. holoturins A and B, stichoposids A and C had the most pronounced antifungal activity as compared to the saponins isolated from plants. Changes in the length of the carbon chain from 2 to 6 monosugars had no significant effect on the activity of the triterpeneglycosides studied.     

Triterpene glycosides and the structural-functional properties of membranes

Triterpene glycosides have been found in many plant species and some marine animals. Many of these compounds are physiologically active and possess a broad range of medico-biological action. The physiological activity of triterpene glycosides is based on their ability to interact with the components of biological systems, primarily with sterols comprising the structure of biomembranes. The interaction of glycosides with sterols causes disturbance of selective permeability in plasmic membranes. Triterpene glycosides affect the liposome ionic permeability and flat bilayer lipid membranes. The rate of glycoside effect depends on quantitative and qualitative sterol level in the membrane. These compounds are used by organisms in the struggle for life and in maintaining the biological equilibrium in the antagonistic interactions of biological systems and ensure plant immunity against fungal diseases. Triterpene glycosides as substances of exogenous origin exhibit physiological activity towards warm-blooded animals. They affect the metabolism, the functional state of the organs and the organism as a whole.     

Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism

Avenacin, the resistance factor ioat roots against Ophiobolus graminisi ν graminis, and a related triterpeneglycoside, aescin, inhibited growth of various fungi, while the growth of a few fungi was unaffected. The triterpenoidal saponins tested seemed to be fungicidal, as the mycelia did not grow after exposure to the inhibitors. The fungicidal effect, however, depended on the medium used. The inhibitors did not seem to act primarily on the endogenous respiration, since the oxygen uptake, although much reduced, continued after the time required to destroy the growth capacity. The leakage of UV-absorbing substances from fungi, sensitive to the inhibitors, and the decrease of UV-absorbing substances in the transient pool of the cells indicate a change in the cell membrane.     

Multiple defensive roles for triterpene glycosides from two Caribbean sponges

Despite their high nutritional value and a lack of physical defenses, most marine sponges appear to be minimally affected by predators, competitors, and fouling organisms, possibly due to sponge chemical defenses. In the last 15 years, several triterpene glycosides have been isolated from sponges, but their ecological or physiological roles are largely unknown. We tested triterpene glycosides from Erylus formosus and Ectyoplasia ferox, Caribbean sponges belonging to two different orders, in field and laboratory assays for effects on fish feeding, attachment by potential biofilm-forming bacteria, fouling by invertebrates and algae, and overgrowth by neighboring sponges. Formoside and other triterpene glycosides from Erylus formosus deterred predation, microbial attachment, and fouling by invertebrates and algae. Triterpene glycosides from Ectyoplasia ferox were found to be antipredatory and allelopathic. Thus, triterpene glycosides in these sponges appear to have multiple ecological functions. Tests with different triterpene glycosides at several concentrations indicated that small differences in molecular structure affect ecological activity. In order to establish whether triterpene glycosides could be involved in water-borne versus surface-mediated interactions, the presence of triterpene glycosides in the seawater surrounding live sponges was measured using two in situ sampling methods followed by HPLC and NMR spectral analysis. Water-borne triterpene glycosides were below detection limits for both species. However, top sponge layers and swabs of the surfaces of both sponges contained sufficiently high concentrations of triterpene glycosides to deter bacterial settlement and fouling of Erylus formosus surfaces and overgrowth of Ectyoplasia ferox by neighboring sponges. Enemies of these sponges appear to be deterred by surface contact of triterpene glycosides rather than by water-borne interactions. The dual strategy of employing one group of compounds for multiple purposes and minimizing the loss of compounds into seawater suggests that these organisms utilize chemical defenses with efficiency.     

Study of the mechanism of permeabilization of lecithin liposomes and rat liver mitochondria by the antimicrobial drug triclosan

The effect of the antimicrobial compound triclosan (5-chloro-2′-(2,4-dichlorophenoxy)phenol) on the permeability of lecithin liposomes and rat liver mitochondria was studied. It was found that triclosan was able to increase nonspecific permeability of liposomes in a dose-dependent manner, which was detected by the release of the fluorescent probe sulforhodamine B (SRB) from vesicles. A partial release of SRB occurs instantly at the moment of triclosan addition, which is followed by a slow leakage of the dye. The triclosan-induced release of SRB from liposomes grew as pH of the medium was decreased from 9.5 to 7.5. As revealed by the laurdan generalized polarization (GP) technique, triclosan increased laurdan GP in lecithin liposomes, indicating a decrease in membrane fluidity. Measurements of GP as a function of fluorescence excitation wavelength gave an ascending line for triclosan-containing liposomes, which can be interpreted as phase heterogeneity of the lipid/triclosan system. Dynamic light scattering experiments also showed that at a high triclosan-to-lipid molar ratio (~ 0.5), a population of smaller light-scattering particles (~ 0.4 of the size of liposomes) appear in the system. Experiments with rat liver mitochondria demonstrated that triclosan (10–70 μM) induced a high-amplitude cyclosporin А-insensitive swelling of the organelles accompanied the release of cytochrome c. On the basis of the results obtained, possible mechanisms of the toxic effect of triclosan in eukaryotic cells are discussed.     

Factors that influence the permeability assay of the outer membrane of Pseudomonas aeruginosa

Brief exposure of Pseudomonas aeruginosa to a temperature of 10 degrees C or lower caused a significant leakage of the periplasmic beta-lactamase into the medium. The extent of leakage increased as the incubation temperature was lowered to 4 degrees C and reached a maximum at 0 degrees C. Cells grown in the presence of beta-lactamase inducers were unsuitable for the permeability assay. It was found that the diffusion rates of beta-lactams through the outer membrane of P. aeruginosa were much lower than those previously reported, as assayed under refined conditions. The diffusion rates of beta-lactams in one of the mutants tested were an order of magnitude lower than those of the other strains, despite the fact that the outer membrane protein profile of the strain appeared to be indistinguishable from those of the others. These results suggest that beta-lactam antibiotics diffuse through the outer membrane of P. aeruginosa, at least partly, through a non-porin pathway.     

Source of nitrogen as a factor limiting saponin production by hairy root and suspension cultures of <Emphasis Type="Italic">Calendula officinalis</Emphasis> L.

Triterpenic saponins represented in Calendula officinalis L. by oleanolic acid (OA) glycosides are pentacyclic triterpene compounds with a wide range of biological and medicinal properties. This report demonstrates nitrogen source impact on growth, saponin accumulation, and secretion in hairy root and suspension cultures of marigold. Hairy roots preferred nitrate as a mineral source of nitrogen, but its impact on growth, OA glycosides accumulation, and secretion were line-dependent. The best productivity of OA glycosides was found in CC16 line (74.86 mg flask^?1) in ½ MS medium modified by 2.5× KNO₃ and ammonium elimination with 2.5 g l^?1 peptone. Organic nitrogen source at 27.5-g l^?1 impairs the growth rate of hairy roots. Its effect on saponin accumulation and secretion to the surrounding medium depended on line and media composition. Nitrate:ammonium ratio of 4:2 for CC16 resulted in 5.7-fold increment of saponin secretion comparing to the standard medium. Embryo roots, apical bud, and hypocotyls explants were crucial for induction of suspension culture synthesizing saponins; however, effect of mineral form of nitrogen in cultivating medium had to be considered. The highest OA glycosides level (171.97 μg g^?1 of dry weight) was recorded in the root derived culture with nitrate as a sole mineral form of nitrogen. Peptone from lactalbumin decidedly inhibited the saponin formation; however, it was essential for culture initiation, proliferation, and organ differentiation.     

Effect of the initial pH value of the medium on the growth of Streptococcus lactis and the biosynthesis of nisin]

The effect of the initial pH value of the medium within 4.0 to 6.6 on the growth of Str. lactis and biosynthesis of nicin was studied. It was found that at the initial pH 4.0--4.5 of the medium the growth of the culture was poor, i.e. 11--14% of the control (initiral pH 6.6). With an increase in the value of the initial pH at least to 5.0 the growth of Str. lactis also increased. At the initial pH 4.0 no biosynthesis of nicin was observed. Under the experimental conditions the antibiotic synthesis by tr. lactic started at the initial pH being equal to 4.5 and reached its maximum at pH 6.6.     

Effects of pH and Ethephon on Betacyanin Leakage from Beet Root Discs

Betacyanin leakage from beet root discs was found to increase with decreasing pH of the incubation medium. Although 10 millimolar Ca²⁺ reduced pigment leakage at pH 3.5, it was ineffective at pH 2.3. Leakage was also stimulated by 100 micrograms per milliliter (2-chloroethyl)-phosphonic acid (pH 3.1), but when the solution was neutralized, this leakage was eliminated. Bubbling C₂H₄ through a neutral medium containing beet discs had no effect on pigment leakage; it appears that the effect of Ethephon solutions on this process is a function of their low pH.     

Flavonoids in translucent bracts of the Himalayan<Emphasis Type="Italic"> Rheum nobile</Emphasis> (Polygonaceae) as ultraviolet shields

UV-absorbing substances were isolated from the translucent bracts of Rheum nobile, which grows in the alpine zone of the eastern Himalayas. Nine kinds of the UV-absorbing substances were found by high performance liquid chromatography (HPLC) and paper chromatography (PC) surveys. All of the five major compounds are flavonoids, and were identified as quercetin 3-O-glucoside, quercetin 3-O-galactoside, quercetin 3-O-rutinoside, quercetin 3-O-arabinoside and quercetin 3-O-[6-(3-hydroxy-3-methylglutaroyl)-glucoside] by UV, ¹H and ¹³C NMR, mass spectra, and acid hydrolysis of the original glycosides, and direct PC and HPLC comparisons with authentic specimens. The four minor compounds were characterised as quercetin itself, quercetin 7-O-glycoside, kaempferol glycoside and feruloyl ester. Of those compounds, quercetin 3-O-[6-(3-hydroxy-3-methylglutaroyl)-glucoside] was found in nature for the first time. The translucent bracts of R. nobile accumulate a substantial quantity of flavonoids (3.3–5 mg per g dry material for the major compounds). Moreover, it was clarified by quantitative HPLC survey that much more of the UV-absorbing substances is present in the bracts than in rosulate leaves. Although the flavonoid compounds have been presumed to be the important UV shields in higher plants, there has been little characterisation of these compounds. In this paper, the UV-absorbing substances of the Himalayan R. nobile were characterised as flavonol glycosides based on quercetin.     

Effect of the products of the vital activity of yeast-like fungi on levorin synthesis

The effect on levorin synthesis of the cells and fermentation broth filtrates of Candida tropicalis after their cultivation in the fermentation medium was studied. It was found that the yeast-like fungi belonging to Candida excreted during their development some products capable of stimulating the synthesis of levorin by 40--60 per cent. When the actinomycete producing levorin was grown on the medium containing 80 per cent of the filtrate the level of levorin synthesis was the same as that observed with mixed cultivation of the actinomycete and C. tropicalis. The study on the conditions providing accumulation of the stimulating substances showed the following: production of the stimulating substances started during the first hours of the yeast growth and reached its maximum by the 48th hour, these substances being consumed by the actinomycete during the fermentation process. Aeration is required for production of the stimulating substances but its high levels are not necessary.     

Production of sakacin P by Lactobacillus sakei in a completely defined medium

In order to investigate factors influencing the production of the bacteriocin, sakacin P, Lactobacillus sakei CCUG 42687 was grown in a completely defined medium (DML-B) with 33 components. Although the maximum sakacin P concentration obtained was higher on a complex medium due to higher cell mass, the production per cell mass was higher in DML-B. Sakacin P was produced at 4-30 degrees C, with the highest specific production at low temperatures. More sakacin P was produced at uncontrolled pH compared with cultivation at pH 6.3. Tween-80 had a positive effect on sakacin P production, while addition of sodium chloride and trace metals had negative effects. The decrease in sakacin P concentration during the late growth and stationary phases was shown to be cell-independent and promoted at high temperature and pH. Some differences in production levels of sakacin P were found among six strains of Lactobacillus sakei tested.     

Effect of cryoprotectors on the structural state of liposomes cooled to minus 25 degrees C

Cryoprotectors (propylene glycol), ethylene glycol, polyethylene glycol-1500 and dimethyl sulphoxide) are studied for their effect on permeability of liposomes for incorporated molecules of 5,5-dithiobis-2-nitrobenzoic acid (DTNB) under cooling within a temperature range from 0 degree C to -25 degrees C. A similarity is found in the way of ethylene glycol and propylene glycol, dimethyl sulphoxide and polyethylene glycol-1500 effect on the liposome permeability way. Cooling in the presence of ethylene glycol and propylene glycol causes changes in liposome permeability with a local maximum at -18 degrees C. In the medium with 2M NaCl and ethylene glycol, liposomes were resistant to cooling. Dimethyl sulphoxide and polyethylene glycol-1500 induced a two-phase kinetics of changes in liposome permeability, the first phase being within the 0 = -9 degrees C and the second--within -9--25 degrees C temperature ranges. The found differences are supposed to be associated with the effect of the cryoprotective compounds on the lipid crystallization in a lower-temperatures range.     

Nisin adsorption on silica adsorbents

It has been shown that silica adsorbents can be used for adsorption of nizin from solutions obtained after centrifugation of the fermentation broth. The optimal structure of the adsorbent pores has been determined. Silica with pores 50 to 75 nm in size provided the highest adsorption rates. The value of silica adsorption of nizin depended on the medium pH. The maximum adsorption rates were observed at pH 6.5--7. At pH 3.5 the level of nizin adsorption was low.     

Antitrypanosomal activity of some pregnane glycosides isolated from Caralluma species

Pregnane glycosides previously isolated from genus Caralluma (C. Penicillata, C. tuberculata and C. russelliana) were tested for their antitrypanosomal activity. Penicilloside E showed the highest antitrypanosomal activity (IC₅₀ 1.01 μg/ml) followed by caratuberside C (IC₅₀ 1.85 μg/ml), which exhibited the highest selectivity index (SI 12.04). It was noticed that acylation is required for the antitrypanosomal activity while glycosylation at C-20 has no significant effect on the activity.     

Membranotropic effect of some triterpene glycosides possessing immunostimulating properties

The peculiarities of the interaction between cell membrane lipids and triterpene glycosides from holothurians Apostichopus japonicus S. and Cucumaria japonica (holotoxin A1 and cucumarioside A2-2, respectively) were studied in comparison with plant saponins from Quillaja saponaria, known as hemolytic, adjuvant, and structure-forming components of immunostimulating complexes. Similar to Quillaja saponins, the sea glycosides, holotoxin A1 and cucumarioside A2-2 were shown to possess a high hemolytic activity (2.6 and 3 microg/ml, respectively) and sterol-depending membranotropic effect mediated by the formation of nonbilayer sterol-lipid-glycoside complexes. At the same time, cucumarioside A2-2 bound exogenic cholesterol only in the presence of membrane lipids, such as phosphatidylcholine or monogalactosyldiacylglycerol, in contrast to Quillaja saponins and holotoxin A1, which bound cholesterol in the molar ratios 1:2 and 1:8, respectively. Moreover, in all cases, tree-component complexes containing cholesterol, lipid, and glycoside exhibited a lower hemolytic activity compared with two-component sterol-glycoside complexes. It was concluded that the hydrophobic medium of cell membranes performs a potentiative role in the effective interaction between triterpene glycosides and "sterol receptors". A method for decreasing the toxicity of membranotropic holothurian glycosides possessing the immunomodulating properties was suggested.     

Induction of lipid synthesis in mammary organ cultures from mature virgin and pregnant goats.

The hormones needed to induce lipogenesis in mammary organ cultures from mature virgin and pregnant goats were studied. In tissues from both mature virgin goats and goats at week 10 of pregnancy, cultivated in Waymouth medium without hormones, the rate of the incorporation of (1-(14C))-acetate into the lipids was low and decreased throughout culture. In the presence of insulin, the rate of acetate incorporation was maintained at a higher level. Cortisol acted synergistically with insulin, to produce a rate of lipid synthesis higher than that using insulin alone. The further addition of prolactin had little effect on the incorporation of acetate into the lipids of mammary explants from mature virgin goats, but markedly stimulated it in tissue from animals at weeks 9--10 of pregnancy. The maximum increase in the rate of lipid synthesis was achieved in the presence of 0.5 microgram prolactin/ml, whereas with growth hormone 50 microgram/ml was needed for the maximum effect. The initial rate of acetate incorporation into mammary explants from goats at weeks 13 and 18 of pregnancy was high. It was not stimulated by the hormones during culture, however, and decreased more rapidly in the absence of hormones than in their presence. The rate of acetate incorporation into the lipids was in agreement with the histological evaluation of the secretory response of the mammary explants after cultivation. The secretory response to prolactin and the rate of the incorporation of acetate into the lipids were highest in goats at weeks 9--10 of pregnancy while in tissues from goats at weeks 13 and 18 were not stimulated and decreased during culture.     

The effect of pH and ATP on the transport of oleanolic acid monoglycosides into isolated vacuoles of Calendula officialis leaves.

The transport of oleanolic acid and its glycosides (3-O-monoglucuronide F and 3-O-monoglucoside I) into the vacuoles of C. officinalis leaves was studied. It was found that these monoglycosides are transported into the vacuolar space whereas free oleanolic acid only binds with the tonoplast. The transport of monoglycosides depends on pH of the medium, the optimum pH for monoglucoside I and monoglucuronide F being 6.0 and 7.0, respectively. Moreover, it was demonstrated that the transport of monoglucoside I, in contrast to that of monoglucuronide F, depends on ATP at 0.5-2.0 mM concentrations. The presented results indicate that different mechanisms underlie the transport of these two compounds into vacuoles.