Degraded and undegraded carrageenans and antipeptic activity

The antipeptic activities of a series of undegraded κ- and Λ-carrageenans and degraded carrageenans have been examined by two methods. The activities differ quantitatively. Compared with the κ-carrageenans, the Λ-carrageenans, as a group, have greater activity and this is associated with low 3,6-anhydro-d -galactose and high ester sulphate content. Within the series of undegraded carrageenans, both κ and Λ, differences in antipeptic activity are significantly and positively related to differences in sulphate content. In addition to the effect of sulphate, 3,6-anhydrogalactose content appears to be inversely related to activity but in the Λ-series only; differences in viscosity are without effect. Initial degradation without loss of sulphate resulted in loss of activity but further degradation, also without loss of sulphate did not reduce activity further. Antipeptic activity appears to depend on a combination of structural features of which the differences between κ-Λ carrageenans, molecular size and polyanionic properties are aspects.     

Carrageenans and the proteolytic activity of human gastric secretion

The inhibition of the peptic activity of human gastric secretion by undegraded and degraded carrageenans of similar sulphate content has been examined over the pH range 1.5–3.75. Inhibition by degraded carrageenan is constant throughout this range, but inhibition by undegraded carrageenan decreases between pH 2.5 and 3.25, when a lower level is established. The inhibition by both types of carrageenan is caused by substrate-inhibitor interaction. The differences in degree of inhibition and the effect of pH on the inhibition by undegraded carrageenan appear to originate in the differing natures of the substrate-inhibitor complexes formed by degraded and undegraded carrageenans.     

The water binding behavior of κ-Carrageenan determined by three different methods

κ-Carrageenan is a biopolymer extracted from red seaweeds which has been in the focus of pharmaceutical development for many years. Most applications make use of the large water binding capacity of κ-carrageenan. The primary limitation of κ-carrageenan is the variation in the substance quality. Therefore, the water binding capacity of different κ-carrageenan products was investigated by dynamic vapor adsorption, freezing and non-freezing bound water and water retention value. The κ-carrageenans were observed to have a higher water binding capacity than microcrystalline cellulose (MCC) in all three methods. The amount of adsorbed water is similar for all carrageenans. Differences between the carrageenan types (κ, ι, and λ) were remarkable for the freezing bound water and centrifugation bound water as well as between the κ-carrageenans of different suppliers.     

The Behavior of Different Carrageenans in Pelletization by Extrusion/Spheronization

κ-Carrageenan is known as a novel pelletization aid in manufacturing of pellets by extrusion/spheronization. The implentation of κ-carrageenan as a pelletization aid can overcome several disadvantages of commonly used microcrystalline cellulose (MCC) such as lacking disintegration and adsorption of several actives. The aim of this study was to compare different types of carrageenans from different suppliers: one ι-, five κ-, and one λ-carrageenan. The κ-carrageenans had the best pelletization behavior. Four of the five tested κ-carrageenans resulted in pellets with acceptable shapes, sizes, and size distributions using a high drug load of 80% hydrochlorothiazide. These pellets have similar properties over a wide range of water contents ranging from 90 to 105%. The filler, dicalcium phosphate, affected the pelletization process and the pellet properties of all investigated κ-carrageenans.     

Gastroretentive drug delivery systems with L-dopa based on carrageenans and hydroxypropylmethylcellulose

A comprehensive study was conducted to investigate the effects of carrageenans, and hydroxypropylmethylcellulose (HPMC) on the properties of hydrodynamically balanced systems (HBS) containing L-dopa as a model drug. The novel integrated approach included measurements of: solvent uptake, erosion, apparent density and changes in the internal structure of dosage forms during dissolution test by means of a USP4 compatible MRI. Differences in water ingress into the matrices with pure carrageenans (ι, κ, λ) or low viscous HPMC, were detected by non-invasive magnetic resonance imaging. Matrices based on carrageenans subjected to rapid hydration and erosion, were not able to maintain satisfactory floating properties for a sufficiently long period of time. The application of carrageenans in mixtures with HMC promoted water uptake by HBS formulations. The effect produced by varying the polymer blend's composition on release of the L-dopa was also studied. Dissolution data was fitted to Korsmeyer-Peppas equation. For matrices containing mixtures of carrageenan and HPMC, the linear increase in the releasing rate constant, K, with the carrageenan content in the matrix was observed.     

Mast cell amines and the oedema induced by zymosan and carrageenans in rats

Cimetidine and metiamide suppressed the paw swelling induced in rats by low doses of histamine while these H2 antagonists had little effect on the oedema induced by 100 micrograms of histamine and inhibited by mepyramine. When administered 0.5 h before the inflammagens, H2 antagonists reduced the oedema induced by zymosan and iota carrageenan; they had a slight effect on the oedema induced by lambda and kappa carrageenans and no effect on the oedema induced by compound 48/80. When administered 18 h before the inflammagens, cimetidine greatly increased zymosan oedema and slightly increased lambda carrageenan oedema. Mepyramine, methysergide or depletion of the 5-hydroxytryptamine stores in mast cells by pretreatment with reserpine inhibited the oedema induced by compound 48/80 and zymosan but did not affect the oedema induced by lambda and kappa carrageenans. Histamine may play a dual role in inflammatory reactions. Mast cell amines take a part in the development of zymosan oedema though they play a minor role in the oedema induced by the carrageenans.     

The effects of carrageenan on drug-metabolizing enzyme system activities in the guinea-pig

Carrageenans are seaweed extracts comprising high molecular weight sulphated polygalactosides. They are used in foods at concentrations of up to 2.5% as thickening and gelling agents. When degraded to lower molecular weight forms, they have been shown to induce ulcerative colitis and colon cancer in laboratory animals. Furthermore, undegraded carrageenan (CG) has been shown to promote azoxymethane and methylnitrosourea initiated carcinogenesis, but the promotion mechanism is unclear. To determine if this mechanism involves alterations of tissue drug-metabolizing enzyme system (DMES) activities, six groups of five guinea-pigs each were administered 0.2% κ undegraded, 0.2% ι undegraded, 1% κ degraded or 1% ι degraded CG, or control solutions in the drinking-water for 8 wk. Microsomal and cytosolic DMES activities of the liver, small intestine and colon were determined. The κ undegraded CG group exhibited significant (P < 0.05) increases in small intestine cytochrome P-450 levels and benzo[a]pyrene hydroxylase activities. These data suggest that undegraded CG may selectively induce DMES activities in the small intestine mucosa.     

A critical review of the toxicological effects of carrageenan and processed eucheuma seaweed on the gastrointestinal tract

Carrageenan is a high-molecular-weight, strongly anionic polymer derived from several species of red seaweed that is used for the textural stabilization of foods. Processed Eucheuma Seaweed (PES) is a form of carrageenan with a higher cellulose content. Food-grade carrageenan has a weight average molecular weight greater than 100,000 Da, with a low percentage of smaller fragments. Carrageenan is not degraded to any extent in the gastrointestinal tract and is not absorbed from it in species examined, such as rodents, dogs, and non-human primates. Systemically administered carrageenan has been reported to have a variety of effects, particularly on the immune system, but these are not pertinent to orally administered carrageenan. The substance poligeenan (formerly referred to as degraded carrageenan) is not a food additive. It exhibits toxicological properties at high doses that do not occur with the food additive carrageenan. In-long term bioassays, carrageenan has not been found to be carcinogenic, and there is no credible evidence supporting a carcinogenic effect or a tumor-promoting effect on the colon in rodents. Also, like many dietary fibers, there is significant cecal enlargement in rodents when it is administered at high doses, but this does not appear to be associated with any toxicological consequences to the rodent. Many toxicological studies on carrageenan have involved administration at doses in excess of today's standards for dietary feeding levels in bioassays, and they are orders of magnitude in excess of those to which humans are exposed. Previous reviews of carrageenan and PES by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) have recommended a group allowable daily intake (ADI) of "not specified". The lack of carcinogenic, genotoxic, or tumor-promoting activity with carrageenan strongly supports continuing such an ADI, and JECFA, during its most recent review in 2001, continued this recommendation. The various toxicological studies related to orally administered food-grade carrageenan are summarized along with a brief discussion of critical factors in intestinal carcinogenesis.     

Effect of orally administered food-grade carrageenans on antibody-mediated and cell-mediated immunity in the inbred rat

Experiments were performed to investigate the immunological consequences associated with the persorption of poorly degradable carregeenans from the diet. Using an inbred strain of rat it was demonstrated histochemically, by the carrageenan-specific Alcian blue staining technique, that small quantities of food-grade carrageenans given at 0.5% in drinking-water for 90 days could penetrate the intestinal barrier of adult animals. This apparently occurred via an intact mucosa in the absence of inflammatory or pathological lesions. The carrageenan was demonstrated in macrophage-like cells present within the villi and lamina propria of the small intestine. The oral administration of κ, λ or ? food-grade carrageenans did not affect local (biliary) or systemic antibody responses to gut commensal microorganisms, or to orally-administered sheep erythrocytes. However, when sheep red blood cells were administered parenterally the ensuing anti-sheep red blood cell haemagglutinating antibody response was temporarily suppressed in carrageenan-fed rats. λ-Carrageenan and ?-carrageenan both significantly (P ? 0.01 and P ? 0.05, respectively) reduced the mid-phase (14–28 days) haemagglutinin response; κ-carrageenan (L100) was less effective but caused significant depression at day 21 (P ? 0.01). Individual responses were, however, within the control range 35 days after sheep erythrocyte administration, thus indicating the temporary nature of this effect. Although carrageenan administration depressed the anti-sheep erythrocyte antibody response, it did not affect T-cell immune competence as measured by the popliteal lymph node assay for graft-versus-host reactivity.     

Effect of low molecular lambda-carrageenan from Chondrus ocellatus on antitumor H-22 activity of 5-Fu.

λ-Carrageenan is a kind of sulfated galactan isolated from some red algae and reported to have more biological activities than other types, such as K-type [Güven KC, özsoy Y, Ulutin ON. Anticoagulant, fibrinolytic and antiaggregant activity of carrageenans and alginic acid. Bot Mar 1991; 34: 429–432]. The molecular weight (MW) of λ-carrageenan reaches up to 600–700 kDa, the high MW decreased their solubility and limited their bioactivities. At the same time, the production and applications of λ-carrageenan are limited for its some characteristics, such as the high viscosity, and the experiments of antitumor and immunomodulation also indicated that MW of polysaccharides had notably effect on the activities [Zhou G, Sun YP, Xin H, Zhang Y, Li Z, Xu Z. In vivo antitumor and immunomodulation activities of different molecular weight lambda-carrageenans from Chondrus ocellatus. Pharmacol Res 2004; 50(1) 47–53, Zhou G, Xin H, Sheng W, Sun Y, Li Z, Xu Z. In vivo growth-inhibition of S180 tumor by mixture of 5-Fu and low molecular λ-carrageenans from C. ocellatus. Pharmacol Res 2005; 51(2) 153–157].In this research, λ-carrageenan was extracted from C. ocellatus, an important economic alga in China. Then some small MW samples of 650, 240, 140, 15 and 9.3 kDa are obtained by the method of microwave degradation, respectively. The tumor inhibiting activities of the low MW λ-carrageenan and mixture of it and 5-Fu on transplanted H-22 tumor mice were investigated. The weight of immune organ, proliferation ratio of lymphocyte and concentration of Tumor Necrosis Factor-α (TNF-α) and histopathology of tumor from transplanted H-22 tumor mice were also determined. The results indicated that the degraded λ-carrageenan could add the antitumor activities of 5-Fu and improve the immunocompetence damaged by 5-Fu.     

Sucralfate: antipeptic, antiulcer activities and antagonism of gastric emptying.

The antiulcerogenic and antipeptic activities of sucralfate (Ulcerlmin), a basic aluminum sucrose sulfate complex, were investigated. In rats, sucralfate inhibited the formation of ulcers induced by pyloric ligation, indometacin and cysteamine. In doses antagonizing forestomach ulcer formation, sucralfate increased the pH of the gastric juice in a dose-related manner. In vitro, at pH 1.9, sucralfate inhibited rat, dog and hog pepsin in a concentration-related manner and also the peptic activity in human gastric juice. Sucralfate may act as an inhibitor of pepsin by precipitating the enzyme or by binding with it reversibly. The antipeptic activity appears to be directly related to the amount of sucralfate in suspension rather than that in solution. In the gastrointestinal tract, the basic nature of sucralfate may enhance the antipeptic activity of the sucralfate molecule. In rats, sucralfate decreases the rate of gastric emptying.     

Ecabet sodium, a novel locally-acting anti-ulcer agent, protects the integrity of the gastric mucosal gel layer from pepsin-induced disruption in the rat

BACKGROUND: Ecabet sodium, a novel non-systemic anti-ulcer agent, possesses high affinity to gastric adherent mucus, which plays an important role in the protection of the gastric epithelium against acid and pepsin. AIM: To assess the effect of ecabet on pepsin-induced degradation of the structure of the mucus gel layer. METHODS: Everted sacs of rat stomach were incubated in HCl solution containing pepsin with or without ecabet. Pepsin-induced release of the cleaved peptides and hexosamine from the sacs was determined. Changes in the molecular size of glycoproteins in the adherent mucus (using gel filtration methods) and in the morphology of the epithelium (using both light and scanning electron microscopy) were also examined. RESULTS: Ecabet reduced the pepsin-induced release of peptides and hexosamine, depending on its content in the adherent mucus. Pepsin treatment partially lowered the molecular weight of native glycoproteins in the adherent mucus, caused exfoliation of the epithelial cells, and degraded the network-like ultrastructure of the mucus layer, giving it a lumpy, globular appearance. Ecabet prevented both the pepsin-induced molecular size shift in mucus glycoproteins, and morphological alteration of the epithelium, including ultrastructural derangement of the mucus gel layer. CONCLUSION: Ecabet protects the polymeric structure of mucus glycoproteins from proteolytic degradation by pepsin, and thus maintains integrity of the gastric mucus gel layer.     

Preparation and In Vivo. Antitumor Activity of κ-Carrageenan Oligosaccharides

Abstract

Carrageenan oligosaccharides were produced from the final products of commercial extractions of gelling carrageenan and thickening carrageenan, which were specifically depolymerized by κ-carrageenase extracted from the marine bacterium Cytophaga. MCA-2. The weight-average molecular weights of the two oligosaccharides produced were 681 and 798 Da. The sulfate contents were assayed as 17.2% and 21.8%. Antitumor activities of the oligosaccharides were tested on Sarcoma 180 tumor transplanted in mice. The carrageenan oligosaccharide from the thickening carrageenan product showed much higher tumor inhibition (70.8%) and catalase activity at a dosage of 100 mg kg^?1 compared with the control group. The gelling and thickening carrageenan oligosaccarides could also significantly increase the weight of immune organs such as the thymus, which suggests that the antitumor mechanism of the carrageenan oligosaccharides may be initiated via organ-mediated defense reactions.     

Peptic inhibition by macroanions

Heparin, dextran sulphate, dextran phosphate, chondroitin sulphate and degraded Λ-carrageenan inhibit peptic activity by substrate occlusion or depletion. This holds for various substrates and enzyme preparations, but the amount of inhibition observed varies with method and inhibitor used. The most active inhibitors of the series are disulphated on at least alternate sugar residues and in addition to disulphation high molecular weight confers, in certain conditions, greatest activity. High and low molecular weight macroanions have different inhibition characteristics and it is concluded that activity may depend upon the structure of the substrate-inhibitor complexes formed. Inhibition is not observed when substrate-inhibitor interaction does not occur, as when pepsin or N-acetyl-L-phenylalanine-L-diiodotyrosine (APDT) are used as substrate.     

Controlled-release tablets from carrageenans: effect of formulation, storage and dissolution factors.

The purpose of this study was to investigate the potential of two carrageenans, iota-carrageenan and lambda-carrageenan for the preparation of controlled-release tablets. Tablets were compressed on a Carver press and the effect of formulation factors, moisture, and storage on the release of theophylline was studied. The effect of sodium chloride in the tablet formulation and a change in the ionic strength of the dissolution media was studied on the release of three model drugs. The release rate increased both with an increase in tablet diameter and increase in drug to carrageenan ratio in the tablets. The two lubricants studied had a negligible effect on the rate of drug release at their commonly used concentrations. Moisture content of carrageenans, storage of tablets at 37 degrees C/75% RH for 3 months, and incorporation of 10% sodium chloride in the tablets did not have any significant effect on the release rate. The change in ionic strength of simulated gastric fluid altered the release rate whereas the ionic strength of simulated intestinal fluid did not have a significant effect on the release rate. Carrageenan tablets were relatively insensitive to small changes in formulation parameters and dissolution conditions.     

The role of carrageenan in complement activation

A study has been made of the nature of the interaction between complement and carrageenan, which has been widely reported to inhibit haemolytic complement activity both in vivo and in vitro. Using modified haemolytic complement-fixation tests, the degree of complement consumption by various forms of carrageenan was measured in whole human and rat sera. The median effective concentrations of the carrageenans studied were found to lie in the range 3-300 micrograms/ml for the classical pathway and 500-7800 micrograms/ml for the alternative pathway and were unrelated to sulphate content, as determined by energy dispersive X-ray analysis. It was also found that carrageenan-coated sheep erythrocytes were lysed by complement. This activity was suppressed by ethylene glycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, which inhibits the classical, but not the alternative pathway, providing conclusive evidence that carrageenan preferentially activates the classical pathway. This finding may help in elucidating the inflammatory reaction induced by carrageenan.     

Biochemical studies on camomile components/III. In vitro studies about the antipeptic activity of (--)-alpha-bisabolol (author's transl)]

(--)-alpha-Bisabolol has a primary antipeptic action depending on dosage, which is not caused by an alteration of the pH-value. The proteolytic activity of pepsin is reduced by 50 percent through addition of bisabolol in the ratio of 1/0.5. The antipeptic action of bisabolol only occurs in case of direct contact. In case of a previous contact with the substrate, the inhibiting effect is lost.     

Effect of D-002 on the Pre-ulcerative Phase of Carrageenan-induced Colonic Ulceration in the Guinea-pig

D-002 is a natural mixture of higher aliphatic primary alcohols, isolated and purified from beeswax which has anti-inflammatory properties, reduces leukotrienes (LTB₄) and thromboxane B₂ (TXB₂) in exudated carrageenan-induced pleurisy, and has anti-ulcer activity in different experimental models. This study was conducted to determine the effect of D-002 on the pre-ulcerative phase of carrageenan-induced colonic ulceration in guinea-pigs. Animals were randomly distributed among a negative control, a positive control group treated with the vehicle Tween 20 in H₂O and two experimental groups receiving D-002 at 25 and 50 mg kg^?1. All treated animals received degraded carrageenan for three days for induction of colonic ulceration. Significant reductions in wet weight, wall thickness, counts of infiltrating polymorphonuclear neutrophils and of macrophages, and histological index were observed in colonic mucosa of D-002-treated animals compared with controls. It is concluded that D-002 has a protective effect on the pre-ulcerative phase of carrageenan-induced colonic ulceration in the guinea-pig.     

In vitro inhibitory effect of carrageenan oligosaccharide on influenza A H1N1 virus

Carrageenan polysaccharide has been reported to be able to inhibit the infection and replication of many different kinds of viruses. Here, we demonstrated that a 2 kDa κ-carrageenan oligosaccharide (CO-1) derived from the carrageenan polysaccharide, effectively inhibited influenza A (H1N1) virus replication in MDCK cells (selectivity index >25.0). Moreover, the 2 kDa CO-1 inhibited influenza A virus (IAV) replication better than that of 3 kDa and 5 kDa κ-carrageenan oligosaccharides (CO-2 and CO-3). IAV multiplication was suppressed by carrageenan oligosaccharide treatment in a dose-dependent manner. Carrageenan oligosaccharide CO-1 did not bind to the cell surface of MDCK cells but inactivated virus particles after pretreatment. Different to the actions of carrageenan polysaccharide, CO-1 could enter into MDCK cells and did not interfere with IAV adsorption. CO-1 also inhibited IAV mRNA and protein expression after its internalization into cells. Moreover, carrageenan oligosaccharide CO-1 had an antiviral effect on IAV replication subsequent to viral internalization but prior to virus release in one replication cycle. Therefore, inhibition of IAV intracellular replication by carrageenan oligosaccharide might be an alternative approach for anti-influenza A virus therapy.     

Trimipramine and other antipsychotics inhibit Campylobacter pylori in vitro

A series of conventional anti-ulcer drugs, tricyclic antidepressants and neuroleptics (and some CNS non-active isomers) were tested in vitro for possible inhibition of Campylobacter pylori. These bacteria are claimed to play an etiological role in peptic ulcer disease, at least in gastritis B. While cimetidine, famotidine, ranitidine and pirenzepine were inactive, all the antipsychotic agents and their isomeric derivatives were active to various degrees with IC50 of 26-59 microM. Of special interest is trimipramine (Surmontil) that has been demonstrated to be effective against duodenal ulcers in some trials. The activity of the non-neuroleptic stereo-isomers of clopenthixol and chlorprothixene may lead to investigation in patients with peptic ulcer disease of this kind of agents. However, a firm connection between the antimicrobial activity of these compounds, their possible anti-ulcer effect and the etiological role of Campylobacter pylori in peptic ulcer disease must first be established.