Actions of flavonoids and the novel anti-inflammatory flavone, hypolaetin-8-glucoside, on prostaglandin biosynthesis and inactivation

The newly identified plant-derived flavone-glycoside hypolaetin-8-glucoside, which has anti-inflammatory and gastric ulcer protective properties, and its corresponding aglycone, hypolaetin, were tested for effects on prostaglandin biosynthesis and degradation. They were compared with four other flavonoids, viz. rutin and its corresponding aglycone, quercetin, and the aglycones isoscutellarein and kaempferol. Over the range 10-1000 microM the glycosides rutin and hypolaetin-8-glucoside stimulated prostaglandin formation by sheep seminal vesicle microsomes incubated with radiolabelled arachidonic acid; the other compounds were essentially inactive. Over 5-5000 microM rutin and hypolaetin-8-glucoside enhanced the release of prostacyclin (and other prostanoids) from fragments of rat caecum incubated in the absence of additional arachidonic acid; the four aglycones compounds did not stimulate prostacyclin release but some reduced it at 5000 microM. However, the glycosides did not affect the enzymatic inactivation of radiolabelled prostaglandin F2 alpha by semi-purified bovine lung prostaglandin 15-hydroxydehydrogenase (PGDH) or in 100,000 g supernatants prepared from homogenised rat stomach. Three of the four aglycones (quercetin, kaempferol, isoscutellarein, in descending order of potency) were inhibitory to PGDH with ID50 values in the range 130-2100 microM. The results show that the capacity of flavonoids to enhance prostaglandin formation is associated with the presence of glycosidic substitution, whereas PGDH inhibition requires its absence. The relevance of this biochemical profile of hypolaetin-8-glucoside to its anti-inflammatory gastroprotective effects in vivo is discussed.     

Effects of the new anti-ulcer agent KB-5492 on experimental gastric mucosal lesions and gastric mucosal defensive factors, as compared to those of teprenone and cimetidine.

Effects of KB-5492, a new anti-ulcer agent, on various experimental gastric mucosal lesions and mucosal defensive factors in rats were compared with those of teprenone and cimetidine. KB-5492 administered orally at 12.5-200 mg/kg inhibited water-immersion stress- and indomethacin-induced gastric mucosal lesions in a dose-dependent manner with ED50 values of 46 and 27 mg/kg, respectively, indicating that KB-5492 was more potent than teprenone but less potent than cimetidine. KB-5492, administered orally at 12.5-100 mg/kg, also inhibited ethanol-induced gastric mucosal lesions in a dose-dependent manner with an ED50 of 23 mg/kg, so KB-5492 was 3 times more potent than teprenone, whereas cimetidine produced no obvious inhibition. In addition, KB-5492, administered orally at 25 and 50 mg/kg twice daily for 10 consecutive days, significantly accelerated the healing of acetic acid-induced gastric ulcers more potently than teprenone and cimetidine. KB-5492 at anti-ulcer doses significantly increased gastric mucosal blood flow in normal anesthetized rats and inhibited the reduction of gastric mucosal hexosamine content induced by aspirin, but did not affect gastric acid secretion in pylorus-ligated rats. These results indicate that KB-5492 has potent and broad anti-ulcer properties, which are probably exerted by its enhancement of gastric mucosal defensive factors through increasing gastric mucosal blood flow and/or retaining gastric mucus, and not by its inhibition of gastric acid secretion.     

Selectivity of neutrophil 5-lipoxygenase and cyclo-oxygenase inhibition by an anti-inflammatory flavonoid glycoside and related aglycone flavonoids

A newly described plant-derived flavonoid, hypolaetin-8-glucoside, which has anti-inflammatory and gastroprotective actions in-vivo, and its corresponding aglycone, hypolaetin, have been compared with 14 other flavonoids for inhibition of eicosanoid generation via the 5-lipoxygenase and cyclo-oxygenase pathways in elicited rat peritoneal leukocytes stimulated with calcium ionophore. Comparable results for the inhibitory profiles of the compounds were obtained using either radioimmunoassay of released eicosanoids or radio-TLC of metabolites formed from labelled arachidonate, but there were differences in absolute potency of the inhibitors. Hypolaetin-8-glucoside was a weak but selective inhibitor of 5-lipoxygenase (IC50 56 microM vs 5-lipoxygenase; greater than 1000 microM vs cyclo-oxygenase), whereas the aglycone hypolaetin was a more potent and selective 5-lipoxygenase inhibitor (IC50 4.5 microM vs 70 microM). Results with three other glycoside/aglycone pairs confirmed that addition of sugar residues greatly reduces inhibitory potency whilst retaining selectivity against 5-lipoxygenase. Analysis of 12 aglycone flavonoids showed that inhibitory potency and selectivity against 5-lipoxygenase is conferred by the presence of 3'4'-vicinal diol (catechol) in ring B as part of a 3,4-dihydroxycinnamoyl structure as proposed by others and by incorporation of additional hydroxyl substituents. In contrast, "cross-over" of inhibitory selectivity is observed in compounds containing few hydroxyl substituents (with none in ring B) which are selective against cyclo-oxygenase. These results are discussed in relation to possible mechanisms of hypolaetin-8-glucoside's protective actions and the concept that these inhibitory effects of flavonoids cannot be ascribed to a unitary free radical scavenging action.     

Pharmacology of the potent new non-steroidal anti-inflammatory agent aceclofenac.

Aceclofenac (2-[(2,6-dichlorophenyl) amine]phenylacetoxyacetic acid; CAS 89796-99-6) is a new orally effective non-steroidal anti-inflammatory agent of the phenylacetic acid group which showed remarkable anti-inflammatory, analgesic, and antipyretic properties. Hence, aceclofenac possesses a potent inhibitory activity in several models of acute and chronic inflammation in rodents, and resembles indometacin and diclofenac in its pharmacodynamic profile, being superior to naproxen and phenylbutazone. In addition, aceclofenac was found to be highly active against sodium urate-induced synovitis in dogs and adjuvant-induced polyarthritis in rats, both prophylactically and therapeutically. The analgesic effect of aceclofenac on the pain elicited by chemical and mechanical stimuli was nearly equal to or slightly better than that of indometacin and diclofenac. Fever induced by brewer's yeast injection in rats was also markedly suppressed by aceclofenac. In contrast, the acute gastric ulcerogenic activity of aceclofenac was about 2, 4 and 7-fold lesser than that of naproxen, diclofenac, or indometacin, respectively. As a consequence of its high anti-inflammatory activity and lower potential for gastric damage aceclofenac exhibited the most favourable therapeutic ratio in comparison with indometacin, diclofenac, naproxen, and phenylbutazone. These data indicate that aceclofenac could be a potent anti-inflammatory and analgesic agent with a wide margin of safety in clinical practice.     

Pharmacological investigations of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M 73101), a new analgesic and anti-inflammatory drug

Analgesic, anti-inflammatory and other related actions of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101) were investigated in experimental animals, and the following results were obtained: Analgesic activity of M73101 was more potent than that of other anti-inflammatory drugs except for aminopyrine in phenylquinone test in mice. M73101 showed the most potent analgesic activity among the drugs tested in Randall-Selitto test in rats. The mode of analgesic action of M73101 resembled that of aminopyrine. M73101 possessed potent inhibitory activities on acute inflammatory edema and suppressed the permeability of capillary vessels. M73101 inhibited histamine release from isolated rat mast cells (in vitro) and rat skin (in vivo) by the condensation product of N-methyl-homoanisylamine formaldehyde (compound 48/80), and leucocyte emigration in carrageenin rat pleurisy. M73101 was much less active than phenylbutazone and other anti-inflammatory drugs in causing gastric lesion. Considering from therapeutic index, M73101 was found to be much superior to mepirizole, tiaramide, benzydamine, phenylbutazone and acetylsalicylic acid.     

Effects of the anti-ulcer agents ecabet sodium,cimetidine and sucralfate on acetylsalicylic acid-induced gastric mucosal damage deteriorated by renal failure in rats

Renal failure including post-renal transplantation increases the susceptibility of the upper gastrointestinal mucosa to injury. The aim of this study was to confirm the influence of renal failure on gastric mucosal barrier and the protective effect of various anti-ulcer agents in rats. Renal failure (RF) was induced by 45-min left renal artery clamping and right-uninephrectomy. Four days after surgery, gastric mucosal lesions were induced by intragastric administration of acetylsalicylic acid (ASA, CAS 50-78-2) (100 mg/kg). Anti-ulcer agents were given orally 30 min before ASA administration. RF induced moderate gastric mucosal damages, but significantly worsened the ASA-induced gastric lesions. Ecabet sodium (CAS 86408-72-2) and cimetidine (CAS 51481-61-9) significantly inhibited ASA-induced gastric lesions in RF rats, whereas sucralfate (CAS 54182-58-0) tended to inhibit it. ASA and all of these anti-ulcer agents had no effect on the serum creatinine and blood urea nitrogen levels increased by RF. The gastric mucosa of RF rats is more susceptible to damage induced by ASA. Ecabet and cimetidine potently inhibited gastric lesions in RF rats suggesting its utility for the gastric mucosal damage in patients with RF including post-renal transplant.     

Effect of mifentidine on mepirizole-induced duodenal ulcer in the rat

The H2-receptor antagonists mifentidine, famotidine, cimetidine and ranitidine were examined for their ability to prevent the duodenal ulcer caused by mepirizole (250 mg/kg p.o.), a non-steroidal anti-inflammatory agent, in the conscious rat. All the compounds exerted a dose-related protective effect and on the basis of their ED50s, the following rank order of potency was found: mifentidine = famotidine greater than ranitidine greater than cimetidine. The antiulcer activity displayed by the H2-receptor antagonists evaluated in this model reflects their potency in inhibiting basal and stimulated gastric acid secretion in rat. The results of these studies indicate mifentidine as a potent anti-ulcer agent.     

A new screening method for anti-ulcer agents: psychological stress produced by intraspecies emotional communication

Psychological stress produced by intraspecies emotional communication in a communication box was studied to see whether it could be applied to a new screening method for anti-ulcer agents. There were two groups of mice, the 'sender' mice that received electrical foot shocks and showed emotional responses such as piloerection, abnormal squealing and jumping, and the 'responder' mice that were affected by the sender's emotional responses without foot shock. The gastric lesions (erosions) produced by conditioned emotional stimuli were observed in both groups. The effects of the anti-ulcer drugs cetraxate, cimetidine and gefarnate were examined. In 'senders', the gastric lesions were significantly suppressed by the administration of cetraxate at a dose of 200 mg/kg (p.o.) or cimetidine at doses of 30 and 100 mg/kg (p.o.). The gastric lesions in 'responders' were significantly suppressed by two administrations of cetraxate at doses of 100 and 200 mg/kg (p.o.), cimetidine at doses of 10-100 mg/kg (p.o.) or gefarnate at a dose of 200 mg/kg (p.o.). The gastric lesions of 'responders' were more sensitive to anti-ulcer drugs. The present results indicate that the gastric erosions of 'responders' are useful for the evaluation of anti-ulcer agents.     

The effect of ranitidine on gastric acid secretory response curves to histamine, pentagastrin or bethanechol in the dog with a Heidenhain pouch

The H2-receptor antagonists ranitidine and cimetidine were tested against gastric secretory dose-response curves to histamine, pentagastrin and bethanechol in the Heidenhain-pouch dog. Histamine-induced gastric secretion was antagonized in a competitive manner by both ranitidine and cimetidine, but ranitidine was approximately 8 times more potent than cimetidine. Pentagastrin -induced secretion was markedly reduced by ranitidine and cimetidine but this antagonism was not competitive in nature. Bethanechol-induced gastric secretion was slightly reduced by both drugs. These findings are discussed in relation to the physiological control of gastric secretion.     

Pharmacological activity of FPP028 (2-phenylpyrazolo-4-ethyl-4,7-dihydro [1,5a]pyrimidin-7-one) a new non-steroid anti-inflammatory agent

The activity of 2-phenylpyrazolo-4-ethyl-4,7-dihydro [1,5a]pyrimidin-7-one (FPP028), a non-acidic, analgesic, antipyretic, and anti-inflammatory compound, was investigated in a number of pharmacological tests performed in rats. The anti-inflammatory properties of FPP028 were evaluated through the carrageenan induced paw edema and the cotton pellet induced granuloma and compared with the activity of indomethacin, phenylbutazone, and isoxicam; as a result, the activity of FPP028 was shown to be similar to that of the latter compounds. To assess the analgesic properties of FPP028 in comparison with indomethacin and phenylbutazone, the Randall and Sellitto and the mouse-writhing tests were used; in both tests, FPP028 demonstrated a significant analgesic activity. FPP028 was shown to possess antipyretic properties in the test of yeast-induced pyrexia. The gastro-erosive activity of phenylbutazone and FPP028 was studied in restraint-stressed rats; in such test the ulcerogenic activity of phenylbutazone appeared to be dose-related; conversely, FPP028 demonstrated a gastro-protective effect since the number of gastric lesions induced either by stress or phenylbutazone treatment was decreased bu FPP028. Our data show that FPP028 is endowed with most of the pharmacological properties of the classic antiinflammatory drugs. Further studies are however needed to more fully elucidate its mechanism of action because our in-vivo data indicate that FPP028 is not an inhibitor of prostaglandin biosynthesis.     

Pharmacological studies of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101). (2). Anti-inflammatory activity (author's transl)]

The anti-inflammatory activity and the mode of action of M73101, a new non-steroid analgesic anti-inflammatory agent, were investigated in experimental animals and compared with those of reference drugs. M73101 inhibited the increase in vascular permeability induced by acetic acid and its activity was more potent than that of phenylbutazone. M73101 showed a marked inhibitory effect against rat paw edema induced by various phlogistic agents (carrageenin, dextran, histamine, serotonin and bradykinin) and the activities were equal to or more potent than those of aminopyrine, mepirizole and tiaramide HCl. M73101 also inhibited the edema induced by mustard, scalding and anti-rat rabbit serum in rats. In addition, the anti-edematous effect of M73101 on carrageenin-induced rat paw edema was not influenced by spinalectomy or adrenalectomy, indicating that the anti-inflammatory action of M73101 was not mediated by the central nervous system and the adrenals. Local and oral administration of M73101 inhibited significantly the leucocyte migration into the fluid of CMC pouch in rats and the activity was more potent than phenylbutazone, suggesting that the anti-inflammatory effect of M73101 was due to the direct action at the inflamed site. On the other hand, M73101 did not show any marked activities on the experimental chronic inflammatory models. From these results, it is suggested that M73101 may be useful for clinical application as a basic analgesic, anti-inflammatory drug with remarkable anti-inflammatory activity in acute and subacute cases. The mechanism of the anti-inflammatory action of M73101 probably involves inhibition of an increase in vascular permeability and leucocyte migration.     

Comparison in rats of the anti-inflammatory and gastric irritant effects of etodolac with several clinically effective anti-inflammatory drugs

The anti-inflammatory and gastric effects of etodolac were compared in the rat with those of seven clinically established nonsteroidal anti-inflammatory drugs. The anti-inflammatory potency of etodolac was found to lie between that of sulindac and piroxicam. Etodolac was 2.8 times more active than sulindac and 2.2 times less active than piroxicam. Compared to phenylbutazone it was 12.5 times more potent. The irritation produced on the gastric mucosa was less than that of sulindac, although this difference did not reach statistical significance. However, etodolac was significantly (p less than 0.05) less irritant than piroxicam. Of the drugs studied, etodolac showed the highest ratio between the irritant ED50 and the dose which inhibited inflammation by 50%. From these results etodolac is predicted to be a potent anti-inflammatory drug with a high gastric tolerance. Clinical trials appear to confirm these predictions.     

Synthesis and analgesic and anti-inflammatory activities of 1,2-benzothiazine derivatives

Three 1,2-benzothiazine derivatives were synthesized, and their analgesic/anti-inflammatory efficacy and their effects on gastric irritation were evaluated. Among the three compounds, 39 exhibited the most potent analgesic action, but the effect was weaker than that of piroxicam. Nonetheless, the compound showed 4 times more potent analgesic action with less gastric damage than did ibuprofen. These compounds did not show anti-inflammatory effect at an oral dose of 5 mg/kg.     

The analgesic and antipyretic effects of a non-steroidal antiinflammatory agent, EB-382, in experimental animals

The analgesic and antipyretic effects of EB-382 as a new non-steroidal antiinflammatory agent were examined in mice and rats. EB-382 had an equipotent inhibition to ibuprofen on the writhing syndrome caused by acetic acid, phenylquinone and acetylcholine in mice, but phenylbutazone was less potent in these experiments. EB-382 had a much more potent inhibition on the pain by the Randall-Selitto method and silver nitrate-induced arthritic pain in rats than ibuprofen and phenylbutazone. EB-382 had no analgesic effect on the pain of non-treated foot by the Randall-Selitto method in rats and by the hot-plate method in mice. EB-382 had a much more potent inhibition on the yeast-induced chronic inflammatory and adjuvant arthritic pains in rats than ibuprofen and phenylbutazone. The antipyretic activity of EB-382 was almost equipotent to that of ibuprofen in rats. EB-382 had no effect on the normal body temperature in rats, which was different from aminopyrine. The above results suggest that EB-382 will be a useful analgesic agent with an antipyretic antiinflammatory activity in clinical studies.     

Some aspects of the inhibitory activity of hypolaetin-8-glucoside in acute inflammation

Hypolaetin-8-glucoside (H-8-G) has been examined for its mode of action in several models of acute inflammation. Its anti-inflammatory activity in carrageenan-induced inflammation of the rat hind-paw is not affected either by adrenalectomy or by phentolamine given with propranolol. H-8-G and its aglycone, hypolaetin, did not antagonize the actions of histamine, 5-hydroxytryptamine (5-HT), bradykinin or prostaglandin E2 (PGE2) on various smooth muscle preparations in-vitro, but protected erythrocytes from heat-induced lysis. The glycoside was more potent than troxerutin on capillary permeability increased by histamine and exerted inhibitory effects on protein exudation, leucocyte migration and beta-glucuronidase activity in the carrageenan air pouch, thereby showing some difference from indomethacin. These results are discussed in relation to the features of non-steroidal anti-inflammatory drugs (NSAID) and flavonoid anti-inflammatory actions.     

Famotidine. Pharmacodynamic and pharmacokinetic properties and a preliminary review of its therapeutic use in peptic ulcer disease and Zollinger-Ellison syndrome

Famotidine is a new histamine H2-receptor antagonist. On a weight basis, famotidine is 20 times more potent than cimetidine and 7.5 times more potent than ranitidine in inhibiting basal and pentagastrin-stimulated gastric acid secretion in humans. Therapeutic trials have shown that famotidine 20 mg twice daily or 40 mg at bedtime may be an effective alternative to standard doses of cimetidine for healing gastric ulcers and to standard doses of cimetidine and ranitidine for healing duodenal ulcers. When used prophylactically, a single 20 mg dose of famotidine at night decreases the incidence of duodenal ulcer recurrence (versus placebo). However, further study is needed to clarify the comparative efficacy of the H2-receptor antagonists, in particular as maintenance therapy for healed peptic ulcer. Preliminary results in a few patients with Zollinger-Ellison syndrome indicate that famotidine, alone or in combination with an anticholinergic agent, gives good control of gastric acid hyperacidity with no evidence of biochemical or haematological toxicity. Famotidine appears to be well tolerated. Unlike cimetidine, it does not have antiandrogenic effects or alter hepatic metabolism of drugs. However, wider clinical experience with famotidine is needed to accurately determine its relative tolerability compared with other anti-ulcer drugs. Thus, famotidine appears to be a suitable and well tolerated alternative to cimetidine and ranitidine for healing peptic ulcers, but wider clinical experience is needed to assess its relative efficacy and tolerability in the long term maintenance treatment of patients with healed ulcers as well as in patients with Zollinger-Ellison syndrome.     

Pharmacology of diferuloyl methane (curcumin), a non-steroidal anti-inflammatory agent

Some pharmacological actions of curcumin (diferuloyl methane) have been examined in rats, mice and cats. The compound possesses significant anti-inflammatory activity in acute as well as in chronic models of inflammation. It is as potent as phenylbutazone in the carrageenan oedema test but only half as potent in chronic tests. Curcumin possesses a much lower ulcerogenic index than phenylbutazone. It prevents the inflammation induced increase in SGOT and SGPT levels. It lacks analgesic and antipyretic activity. It has no other significant pharmacological effects. The oral LD50 in mice is more than 2m?0 g kg^?1.     

Inhibition of sheep platelet arachidonate metabolism by flavonoids from Spanish and Indian medicinal herbs

The influence of 22 flavonoids was studied on the arachidonic acid metabolism in sonicated sheep platelets. Flavones and flavonols possessing catechol groups inhibited 12-lipoxygenase. Sideritoflavone and quercetagetin-7-O-beta-D-glucoside were more selective than quercetin. Cirsiliol, hypolaetin, hypolaetin-8-O-beta-D-glucoside, gossypetin, gossypin, hibifolin and leucocyanidol were also 12-lipoxygenase inhibitors with some differences in potency and selectivity. Xanthomicrol was a weak cyclooxygenase inhibitor. These results suggest that lipoxygenase inhibition can play a role in the anti-inflammatory activity of hypolaetin-8-O-beta-D-glucoside, sideritoflavone, gossypin and hibifolin. On the other hand, the presence of sideritoflavone, hypolaetin-8-O-beta-D-glucoside, cirsiliol and xanthomicrol in several species of Sideritis may provide a basis for the use of such plants as anti-inflammatory agents.     

Fenbufen, a new anti-inflammatory analgesic: synthesis and structure-activity relationships of analogs.

One hundred analogs of fenbufen were prepared and tested using the carrageenan, polyarthritis, and UV erythema anti-inflammatory tests and the 2-phenyl-1,4-benzoquinone writhing and inflamed paw pressure analgesic tests. Only three retained the same full spectrum of activity as fenbufen: dl-4-(4-biphenylyl)-4-hydroxybutyric acid, dl-4-(4-biphenylyl)-1,4-butanediol, and 4-biphenylacetic acid. Fenbufen had the same spectrum of activity as aspirin, phenylbutazone, and indomethacin in the five tests. In addition, dose-response derived potencies show fenbufen more potent than aspirin and at least as potent as phenylbutazone in all five tests. Two related compounds were generally similar.     

Anti-ulcer and secretion-inhibitory properties of the tricyclic derivative doxepin in rats and dogs

The anti-ulcer and antisecretory properties of 3-(dibenz[b,e] oxepin - 11(6H)-ylidene)-N,N- dimethylpropylamine hydrochloride (doxepin) were investigated in a series of acute experiments in rats with gastric and duodenal ulcer. Acute gastric ulceration induced by immobilisation and stress (waterbath), and by non-steroidal anti-inflammatory agents, was reduced by doxepin to the same extent as by pirenzepine and cimetidine. Doxepin and cimetidine showed a weak but significant effect against serotonin-induced ulcers in the rat, but pirenzepine did not. Duodenal ulcer caused by increased acid production (pentagastrin plus carbachol induced) was suppressed by pirenzepine, doxepin and cimetidine. The inhibition of gastric secretion by doxepin was studied in anaesthetised rats and conscious dogs. In the Lai rat, doxepin decreased carbachol-induced secretion of hydrochloric acid more effectively than cimetidine. Doxepin was as ineffective as pirenzepine against histamine- or pentagastrin-induced secretion. In the dog with gastric fistula, doxepin inhibited the acid production induced by 2-desoxy-d-glucose more effectively, and for longer periods, than that induced by pentagastrin or histamine. In the dog with a Heidenhain pouch, doxepin reduced the acid secretion stimulated by pentagastrin and carbachol, and by histamine, less effectively and for a shorter time, than cimetidine. The antagonism of doxepin to the action of carbachol in the rat and that of 2-desoxy-d-glucose in the dog appears to be an important factor in its mode of action. To inhibit the secretion of saliva and to delay intestinal transport, a dose of doxepin 3-10 times greater than that required for anti-ulcerative and secretion-inhibitory effects was necessary.