Mode of stabilizing action of non-steroid anti-inflammatory drugs on erythrocyte membrane

Novel Derivatives of Eugenol as a New Class of PPARγ Agonists in Treating Inflammation: Design, Synthesis, SAR Analysis and In Vitro Anti-Inflammatory Activity

The main objective of this research was to develop novel compounds from readily accessed natural products especially eugenol with potential biological activity. Eugenol, the principal chemical constituent of clove (Eugenia caryophyllata) from the family Myrtaceae is renowned for its pharmacological properties, which include analgesic, antidiabetic, antioxidant, anticancer, and anti-inflammatory effects. According to reports, PPARγ regulates inflammatory reactions. The synthesized compounds were structurally analyzed using FT-IR, ¹HNMR, ¹³CNMR, and mass spectroscopy techniques. Molecular docking was performed to analyze binding free energy and important amino acids involved in the interaction between synthesized derivatives and the target protein. The development of the structure-activity relationship is based on computational studies. Additionally, the stability of the best-docked protein-ligand complexes was assessed using molecular dynamic modeling. The in-vitro PPARγ competitive binding Lanthascreen TR-FRET assay was used to confirm the affinity of compounds to the target protein. All the synthesized derivatives were evaluated for an in vitro anti-inflammatory activity using an albumin denaturation assay and HRBC membrane stabilization at varying concentrations from 6.25 to 400 µM. In this background, with the aid of computational research, we were able to design six novel derivatives of eugenol synthesized, analyzed, and utilized TR-FRET competitive binding assay to screen them for their ability to bind PPARγ. Anti-inflammatory activity evaluation through in vitro albumin denaturation and HRBC method revealed that 1f exhibits maximum inhibition of heat-induced albumin denaturation at 50% and 85% protection against HRBC lysis at 200 and 400 µM, respectively. Overall, we found novel derivatives of eugenol that could potentially reduce inflammation by PPARγ agonism.

Mechanism of the protective effects of sumac gall extract and gallic acid on the progression of CCl4-induced acute liver injury in rats

To examine the mechanism of the preventive effect of tannins on the progression of carbon tetrachloride (CCl4)-induced acute liver injury in rats, sumac gall (SG) extract and gallic acid (GA) were used as substitutes for crude tannins, because SG is a kind of Chinese traditional medicinal herb containing large amounts of various tannins, and GA is one of the major constituents of SG. The protective effect of oral (p.o.) and intraperitoneal (i.p.) administration of each substance on progression of CCl4-induced hepatitis was investigated in rats. Speculating that the superoxide dismutase (SOD)-like activities (O2 radical-scavenging activities) and/or protective effects of these substances on cell membranes might play a key role in the mechanism opposing the progression of CCl4-induced hepatitis, the O2 radical-scavenging activities in liver cells and serum in rats were monitored. Both substances significantly prevented the progression of acute liver injury with both p.o. and i.p. administration. These findings suggest that the mechanism for this prevention might be due mainly to the protective effect of these substances on cell membranes rather than O2 radical-scavenging activities.

Inhibition of colon cancer precursors in the rat by sulindac sulphone is not dependent on inhibition of prostaglandin synthesis

The non-steroidal anti-inflammatory drug, sulindac, inhibits the growth of colorectal tumours in animal models of colon cancer and causes regression of polyps in patients with familial adenomatous polyposis. The mechanism by which sulindac exerts this inhibitory effect is not known, but it has been postulated to be via the inhibition of prostaglandin synthesis. However, two recent studies have indicated that sulindac sulphone, the non-prostaglandin inhibiting metabolite of sulindac, may be important in tumour inhibition. In the present study, we examined the effect of sulindac sulphone on the formation of aberrant crypt foci, the earliest identifiable lesions in the development of colorectal cancer, in the rat colon. We have previously shown that sulindac causes a dose dependent inhibition of aberrant crypt formation in this model. Aberrant crypt foci were induced with two oral doses of 1,2-dimethyl hydrazine at 25 mg/kg per dose. Treatment with sulindac sulphone at either 10 mg/kg b.d., or 20 mg/kg, b.d., was started on the day following administration of the first carcinogen dose and was continued for 3 weeks. Colons were then removed and examined for aberrant crypt foci. Colonic crypts were visualized by staining the unsectioned colon in 0.2% methylene blue solution. There was a significant reduction in the number of aberrant foci in rats treated with sulindac sulphone at 20 mg/kg, b.d. (ANOVA, P = 0.0054). The mechanism by which non-steroidal anti-inflammatory drugs inhibit formation of aberrant crypt foci is not clear; however, these data suggest that it is not due to the inhibition of prostaglandin synthesis.

In vitro effects of oestradiol and indomethacin on rabbit erythrocyte fragility characteristics

An in vitro study was conducted to determine whether indomethacin (IN) and oestradiol (E(2)) induced decreases in rabbit haematocrit may be related to their effect on erythrocyte fragility (EF). Aliquots of treated rabbit whole blood were assayed as control, IN (9.6 mug/ml), E(2) (500 pg/ml) and IN + E(2), for changes in EF. Osmotic (OF) and mechanical (MF) fragility in eight experimental replicates were evaluated under approximate physiological conditions by measurement of haemoglobin release. Samples were assayed immediately after drug addition and again 4 hr after incubation at 39.5 degrees C. OF results showed a significant increase in 50% haemolysis between final IN and IN + E(2) values when compared with their initial values and with controls. OF haemolysis dispersion was increased over time by IN and IN + E(2). MF increased with IN, E(2) and IN + E(2) versus their initial values and the controls. Although the increase in MF from IN was greater than that from E(2), the MF from IN + E(2) was not greater than that from IN alone. The IN induced increases in both OF and MF indicate a difference in degree of interaction with the erythrocyte from that of E(2), which affected only MF and the effect of which was neither additive nor synergistic with that of IN.

Effect of picumast on histamine release from rat cardiac and peritoneal mast cells

Compound 48/80-induced histamine release (HR) from the isolated perfused rat heart was markedly and significantly inhibited by picumast (PIC), possibly by acting as a calmodulin antagonist (CMA) or membrane stabilizer. Trifluoperazine (TFP, another CMA in clinical use) had a similar effect. However, an action as CMA being the basis of inhibition of HR could not be confirmed in another 'allergy' model, namely HR from rat peritoneal mast cells (RPMC). PIC, TFP and two other CMA, W7 and N-(4-aminobutyl)-5-chloro-1-naphthalenesulfonamide) failed consistently to inhibit 48/80-induced HR from RPMC, and when used on their own at high concentration these compounds caused HR. PIC and TFP also potentiated the heat-induced haemolysis of rat erythrocytes, i.e. lacked membrane stabilizing effect in this model.

The inhibitory action of zinc sulphate on the contractile activity of guinea-pig ileum

The present study examines the inhibitory action of zinc sulphate (ZnSO4) on the contractile response of various agonists on guinea-pig isolated ileum. Different doses of agonists were selected to produce similar contractile activity, in order to compare the degree of inhibition produced by ZnSO4. Preincubation of ileum with ZnSO4 1 x 10(-3) or 3 x 10(-3) M for 10 min dose-dependently and significantly prevented the contraction induced by acetylcholine (1.7 x 10(-8) M), 5-HT (2.4 x 10(-6) M), histamine (5.4 x 10(-7) M) and nicotine (1.7 x 10(-6) M) but not by prostaglandin E2 (PGE2, 8.5 x 10(-9) M). The same doses of ZnSO4 reduced the twitch contraction produced by electrical field stimulation. These findings indicate that the contractile activity of PGE2 is mediated by a mechanism different from that of other agonists and of electrical field stimulation. It is likely that the contractile activity of PGE2 is acting through the receptors on the ileal muscle which are not blocked by ZnSO4 pretreatment.

Mechanisms responsible for long-term survival of adult rat hepatocytes in the presence of phenobarbital in primary culture

The mechanisms, by which phenobarbital (PB) supports the survival of adult rat hepatocytes in primary culture, were investigated. PB altered the shape of rat erythrocytes to produce cup-formed cells and protected them from hypotonic hemolysis. Anesthetics (ketamine, lidocaine, mepivacaine, and bupivacaine) and an anti-inflammatory agent (indomethacin), which are also known to protect erythrocytes from hypotonic hemolysis by stabilizing their membranes, efficiently supported the survival of hepatocytes in primary culture. Furthermore, the well-known biological membrane stabilizers, such as cholesterol and vitamin E, also showed the maintenance effect on primary cultured hepatocytes. PB effectively reduced the leakage of lactate dehydrogenase from hepatocytes caused by chenodeoxycholic acid in primary culture. Rotenone and amobarbital, which act repressively on the PB-sensitive site in the respiratory chain and are known to inhibit the mitochondrial formation of active oxygen species with NAD-linked substances, effectively prolonged the hepatocyte survival in primary culture. Elevation of oxygen tension in primary culture remarkably decreased the hepatocyte survival rate, which was preserved by addition of antioxidant substances, such as vitamin C, vitamin E, bifemelane, selenite, and superoxide dismutase. On the other hand, in the presence of PB, the hepatocyte survival rate hardly changed with the elevation of oxygen tension. From these findings, it seems that PB stabilizes the hepatocyte membranes and reduces the mitochondrial formation of active oxygen species and that the stabilized functions of membrane and the reduction of oxidative stress result in the prolonged survival of hepatocytes in primary culture.

The protective effect of a new antiallergic agent, KP-136 on mast cell activation: a comparison with disodium cromoglycate

The protective effects on mast cell activation were compared between a new antiallergic agent, KP-136 and disodium cromoglycate (DSCG), both of which inhibited the immunological degranulation of rat peritoneal mast cells. The IC50 was 0.03 micrograms/ml for KP-136 and 4.7 micrograms/ml for DSCG. KP-136 predominantly acted on the early stage of mast cell activation processes and inhibited the immunological increase in 45Ca uptake. KP-136 also inhibited A23187- and heat-induced degranulation and heat-induced hemolysis. In addition, KP-136 was effective on phospholipase A2-induced degranulation, although the compound did not directly affect the enzyme activity. In all tests for comparison, KP-136 and DSCG had similar profiles of action and the parallel experiments indicated that KP-136 was a more potent inhibitor of mast cell activation than DSCG, having a DSCG-like membrane stabilizing activity.

Effect of various barbituric acid derivatives on survival of functional hepatocytes from adult rats in primary culture

Eighteen barbituric acid (BA) derivatives and three structurally related chemicals (non-BA-derivatives) were tested for their potency in supporting survival of functional hepatocytes from adult rats in primary culture. Of the 18 BA derivatives, nine drugs showed excellent maintenance effect on hepatocyte survival and function. Although four BA derivatives were also effective, their potency was relatively lower. The remaining five BA derivatives and three structurally related chemicals exhibited no maintenance effect. Thus, a correlation was found between the BA derivative structure and the potency for supporting hepatocyte survival in primary culture. The dose response curves of hepatocyte survival were generally biphasic in shape, as a function of BA derivative concentration. The optimum concentrations for observing the morphological and biochemical effects of the BA derivatives differed from each other. The maintenance of hepatocytes was attained only in the continuous presence of the BA derivatives in the medium. The nine excellent BA derivatives efficiently prevented hepatocytes from morphological degeneration which was observed in the control cultures. The surviving hepatocytes in the presence of these BA derivatives showed higher albumin secretion and retained higher basal levels of tyrosine aminotransferase (TAT) activity for at least 2 weeks in primary culture, as compared with control. Furthermore, the addition of dexamethasone (10 microM) caused a 2- to 4-fold induction of TAT activity for at least 2-weeks in primary culture.

Synthesis of barbituric acid derivatives and their effect on survival of functional hepatocytes from adult rats in primary culture

Ten barbituric acid (BA) derivatives were synthesized and tested for their potency for supporting survival of functional hepatocytes from adult rats in primary culture. Of the 10 BA derivatives, 7 compounds (C-2, 3, 4, 5, 6, 9, and 10) efficiently supported hepatocyte survival for at least 2 wks in primary culture. Especially C-5, 6, and 9 showed excellent efficiency for such action. The optimum concentrations of the BA derivatives for observing the morphological and biochemical effects differed from each other. The maintenance of hepatocytes was attained only in the continuous presence of the BA derivatives in the medium. The morphologic features of hepatocytes surviving in the presence of the BA derivatives resembled those of hepatocytes 24 h after inoculation. The surviving hepatocytes secreted remarkably large amounts of albumin into the culture media. Tyrosine aminotransferase (TAT) activity was higher in the 1-wk-old cultures treated with C-5, 6, and 9 than in the freshly isolated hepatocytes. The addition of dexamethasone (10 microM) caused a 1.7 to 2.1-fold induction in TAT activity. The basal levels of TAT activity and the induction rates increased in the cultures treated with C-5 and 6 from Week 1 to 2 of primary culture.

Effects of aspirin, indomethacin, and sodium salicylate on human erythrocyte membranes as detected with electron spin resonance spectroscopy

Electron spin resonance spectroscopy of probed samples was used to determine the structural changes in human erythrocyte membranes prior to and at intervals following ingestion of either 10 grains acetylsalicylic acid, 10 grains sodium salicylate, or 50 mg indomethacin by both male and female subjects. Analysis of erythrocytes from female subjects indicated a time-dependent disordering of the membrane over the eight hour period following aspirin ingestion while the cells of male subjects showed a slight membrane ordering over the same time period. Erythrocytes drawn from females at the beginning of the menstrual cycle showed the greatest amount of membrane disordering at one hour following aspirin ingestion, but by eight hours, the membrane structure had returned to that of control. The time dependent disordering in membrane structure of cells from females in the middle of the menstrual cycle was biphasic. Ingestion of indomethacin induced only slight membrane changes in both male and female subjects over the times examined. Ingestion of sodium salicylate by either men or women did not induce significant changes in erythrocyte membrane order. Washed erythrocytes when mixed with salicylate, aspirin, or indomethacin were either identical to control cells or slightly more ordered. This study suggests that aspirin-induced alterations in membrane structure may depend upon steroid hormone levels.

Long-term survival of functional hepatocytes from adult rat in the presence of phenobarbital in primary culture

In the presence of phenobarbital (PB) at 3 mM, hepatocytes isolated from adult rats by a collagenase-perfusion technique survived well on plastic dishes for at least 49 days after initiation of primary culture. PB at concentrations less than 3 mM was ineffective for the maintenance of hepatocytes, and the maintenance of them was attained only in the continuous presence of 3 mM PB. The hepatocytes surviving in the presence of 3 mM PB were morphologically indistinguishable from the hepatocytes after 1-day attachment period, except for the presence of prominent nucleoli in the former. Although both the albumin secretion and tyrosine aminotransferase (TAT) activities of the cells decreased gradually up to day 7 with time in culture, both were thereafter maintained at relatively high levels at least up to day 35 of primary culture. The addition of 10 microM dexamethasone caused a 3-5-fold induction in TAT activity, and the cells were capable of responding to the hormone in this manner at least up to day 28 of primary culture. Furthermore, the cells also had glucose-6-phosphatase activity, even though the level of this enzyme activity was relatively low as compared with that of TAT activity. Survival of hepatocytes in the presence of 3 mM PB was further enhanced by simultaneous addition of dexamethasone (10 microM) and insulin (10 micrograms/ml). The sensitivity of hepatocytes to 3'-methyl-4-dimethylaminoazobenzene (0.24 mM) was remarkably reduced by treatment with PB at 3 mM. PB treatment decreased efficiently the falling rate of total cytochrome P-450 content, but did not induce P-450PB, which is the specific form of cytochrome P-450 induced by PB, in primary cultured hepatocytes. On the other hand, 3-methylcholanthrene (MC, 10 microM) caused an increase of both contents of total cytochrome P-450 and P-450MC, which is the specific form of cytochrome P-450 induced by MC, in primary cultured hepatocytes. However, MC was ineffective for the maintenance of hepatocytes in primary culture. The possible biological actions of PB on primary cultured hepatocytes are discussed on the basis of the experimental data obtained.

Erythrocyte membrane stabilization by plant saponins and sapogenins

Effects of saponins extracted from Bupleuri Radix (saikosaponin) and the corresponding aglycones on hypotonic or hyperthermic hemolysis were investigated. Low concentrations of saikosaponins protect or stabilize rat erythrocytes against both hypotonic and heat-induced hemolysis. Minor modifications of the aglyconic part of the saikosaponin have enormous effects on the membrane stabilizing potency. Saikogenins also protect erythrocytes from hypotonic hemolysis but do not show any prevention of heat-induced hemolysis. It is suggested that saikogenins react with erythrocyte membranes in a quite different manner from saponins and that the existence of the sugar moiety plays an important role in the reaction with membranes as does a slight modification of the molecular structure in the aglyconic part.

The modification of human erythrocyte membrane structure by membrane stabilizers: an electron spin resonance study

Membrane structure in intact human erythrocytes was analyzed by electron-spin-resonance (ESR) spectroscopy. The spin probes 5-doxyl stearate and 5-doxyl stearate methyl ester revealed thermally-induced structural transitions in the membrane at 37 degree C and 15 degree C. The addition of propranolol, diazepam, chlorpromazine, or Pluronic F68 all caused a decrease in the temperature of the upper transition, but did not markedly alter the temperature of the lower transition. In addition, diazepam caused a significant decrease in the ordering or packing of the membrane-lipid acyl chains. It is proposed here that the protection from hypotonic hemolysis that has been reported in the presence of these drugs is mediated by a structural rearrangement in the erythrocyte membrane involving a change in protein-lipid interactions.

Effects of various drugs on the osmotic lysis of rat mast cells

1. Rat mast cells were exposed to low osmotic pressures to produce a 'non-specific' disruption of the mast cell, with release of histamine along with other intracellular contents. 2. The effect of non-steroidal anti-inflammaotry drugs and various other drugs upon osmotically induced histamine release was examined. 3. Representative non-steroidal anti-inflammatory drugs indomethacin, phenylbutazone and flufenamic acid, the acidic compounds ethacrynic acid, iopanoic acid and probenecid, and the local anaesthetic lignocaine, all caused a dose-dependent facilitation of osmotically induced histamine release compared to controls. All drugs were active at 0.1 mmol/l. 4. The previously observed inhibition of compound 48/80 and the antigen-induced histamine release from rat mast cells by similar concentrations of the drugs used in the present study are unlikely to be due to mast cell plasma membrane stabilization.

About some common biochemical and pharmacological properties of bile salts and non steroidal anti-inflammatory drugs

Glyco- and tauro-deoxycholate, -chenodeoxycholate, -dehydrocholate and -cholate uncouple the mitochondrial oxidative phosphorylation in this order of potency. They also induce pseudo-energized mitochondrial swelling and lymphocyte swelling in the same order of potency. Similar swelling properties were observed for glyco- and tauro-lithocholate. Glyco- and tauro-deoxycholate induce alkalinization of the intra-mitochondrial space as determined on bromothymol blue pre-loaded mitochondria. These two bile salts conjugates also increase the amount of -SH groups available on lymphocyte membranes for sulfhydryl-disulfide interchange reactions. All these biochemical properties have been described for non-steroidal anti-inflammatory drugs. They could thus be implicated in the jaundice remission observed in various inflammatory states.

Effects of nonsteroidal anti-inflammatory drugs on the uptake of various cations by lymphoid cells

Several acidic nonsteroidal anti-inflammatory drugs (NSAID) as well as their corresponding alcohol molecules which are known to induce swelling of isolated lymphocytes by changing cell membrane permeability to water, are demonstrated also to induce changes of membrane permeability of lymphoid cells to one divalent cation, calcium, and to three monovalent cations, rubidium, cesium and sodium. According to the cells ionic environment, they increase or decrease the cellular uptake of cation which is itself also closely dependent on the ionic composition of the incubation medium. This drug-effect is very rapid, directly related to the medium NSAID concentration and almost totally reversible except to the most potent drugs such as flufenamic acid. Changes in intracellular ionic balance could have important catalytic effects on the metabolism of normal as well as of pathological cells. This fact could explain side-effects of these drugs as well as some of their therapeutic effects.

Inhibiting effects of morphine, chloroquine, nonsteroidal and steroidal anti-inflammatory drugs on electrically-induced contractions of guinea-pig ileum and the reversing effect of prostaglandins

Twelve different non steroidal antiinflammatory drugs (NSAID), five steroidal antinflammatory drugs, morphine and chloroquine have been added at various concentrations to in vitro electrically-stimulated preparations of guinea-pig ileum. They all inhibit the electrically-induced contractions. Prostaglandins E as well as nicotine reverse this inhibition. These reversing effects are less evident on totally inhibiting drug concentrations than on partially inhibiting drug concentrations. It is suggested that this inhibiting effect could be due mostly to nervous as well as muscular membrane permeability changes induced by these drugs and not to inhibition of prostaglandin synthesis which could be only proposed as partial explanation for NSAID effects. The reversing action of nicotine could be related to a release of acetylcholine while a sensitization of guinea-pig ileum smooth muscle to acetylcholine could explain the reversing properties of prostaglandins.

Effects of crude and pure cholera toxin on prostaglandin

Investigations were made into the effects of crude and pure preparations of cholera toxin on the release of prostaglandin-like substances (PLS) from rabbit ileum. Perfusion of ileal loops in vivo with buffer containing crude toxin was followed by a release of PLS into the perfusate, in amounts up to 37.5 ng/30 min (PGE2 equivalents). In contrast, no detectable PLS was released when ileal loops were perfused with pure toxin. Similarly, pieces of ileum opened longitudinally released PLS in amounts up to 107 ng PGE2/g tissue when incubated with crude toxin for 1-4 hr, but no release of PLS was detected in the presence of pure toxin under comparable conditions. Treatment of rabbits with indomethacin, 1.6 mg/kg p.o., had no effect on the accumulation of fluid in ileal sacs injected with crude or pure cholera toxin. These results support the view that prostaglandins do not play an essential role in the action of cholera toxin.

About some possible anti-inflammatory properties of various membrane permeant agents

Non steroidal anti-inflammatory drugs uncouple mitochondrial oxidative phosphorylation. They are membrane permeant agents. They also inhibit nucleic acids synthesis in lymphoid cells. Three antibiotics (valinomycin, gramicidin A, alamethicin) and one cyclic polyether (dibenzo-18-crown-6) which are potent membrane permeant agents and good uncouplers are demonstrated to inhibit such a nucleic acids synthesis. This inhibition is largely dependent on the ionic composition of the incubation medium. It is suggested on the basis of some preliminary results that these drugs, which are non-acidic molecules, should be further investigated for potential anti-inflammatory properties.