Comparative evaluation of antiinflammatory potential of fixed oil of different species of Ocimum and its possible mechanism of action.

Ocimum sanctum fixed oil and linolenic acid found to possess significant antiinflammatory activity against PGE2, leukotriene and arachidonic acid-induced paw edema. The other species of Ocimum, viz. O. basilicum and O. americanum also containing linolenic acid in varying proportions, also showed significant inhibition of edema against carrageenan, PGE2, leukotriene and arachidonic acid-induced paw edema. The fixed oil of O. basiliaum containing maximum percentage of linolenic acid showed higher protection. The results suggests that linolenic acid percent in the fixed oils of different species of Ocimum has the capacity to block both the cyclooxygenase and lipoxygenase pathways of arachidonate metabolism and could be responsible for the antiinflammatory activity.     

Evaluation of anti-inflammatory activity of plant lipids containing alpha-linolenic acid

Two groups of fatty acids are essential to the body, the omega6 (n6) series derived from linoleic acid (18:2, n-6) and the omega3 (n3) series derived from alpha-linolenic acid (18:3, n-3). Fatty acids provide energy, are an integral part of the cell membranes and are precursors of prostaglandins, thromboxanes and leukotrienes collectively known as eicosanoids. Eicosanoids participate in development and synthesis of immunological and inflammatory responses. The fixed oils (1, 2, 3 ml/kg) containing alpha-linolenic acid, obtained from the seeds of Linseed (Linum usitatissimum), Soyabean (Glycine max) and Holy basil (Ocimum sanctum) were screened for their antiinflammatory activity using carrageenan, leukotriene and arachidonic acid induced paw edema models in rats and the antiinflammatory effects were compared with the standard drug indomethacin. Significant inhibition of paw edema was produced by all the oils in the highest dose (3 ml/kg) in all the models. While O. sanctum oil produced the maximum percentage inhibition in leukotriene induced paw edema, L. usitatissimum oil produced maximum percentage inhibition in carrageenan and arachidonic acid induced paw edema models. The results show that oils with higher alpha-linolenic acid content (L. usitatissimum and O. sanctum) produced a greater inhibition of paw edema suggesting that modulation of the course of inflammatory disorders may be achieved by altering the eicosanoid precursor (i.e. poly unsaturated fatty acids: PUFA) availability through dietary manipulation.     

Evaluation of gastric anti-ulcer activity of fixed oil of Ocimum basilicum Linn. and its possible mechanism of action

Fixed oil of O. basilicum was found to possess significant antiulcer activity against aspirin, indomethacin, alcohol, histamine, reserpine, serotonin and stress-induced ulceration in experimental animal models. Significant inhibition was also observed in aspirin-induced gastric ulceration and secretion in pylorus ligated rats. The lipoxygenase inhibiting, histamine antagonistic and antisecretory effects of the oil could probably contribute towards antiulcer activity. O. basilicum fixed oil may be considered to be a drug of natural origin which possesses both antiinflammatory and anti-ulcer activity.     

Anti-inflammatory activity of tea (Camellia sinensis) root extract

Pharmacological studies were carried out with methanol-water (1:1) extract of dried tea (Camellia sinensis) root extract (TRE). TRE was found to possess anti-inflammatory, analgesic and antipyretic activities at 1/10th of its LD50 dose of 100 mg/kg i.p. It was found that TRE inhibited the arachidonic acid-induced paw oedema in rats which indicated that TRE produced the anti-inflammatory activity by inhibiting both the cyclooxygenase and lypooxygenase pathways of arachidonic acid metabolism. TRE also enhanced peritoneal cell count and the number of macrophages in normal mice. It is plausible that the saponins present in TRE may be responsible for these activities of TRE.     

Analgesic and anti-inflammatory activity of the proanthocyanidin shellegueain A from Polypodium feei METT.

Analgesic and antiinflammatory activity of proanthocyanidin isolated from Polypodium feei roots has been tested using acetic acid-induced writhing and carrageenan-induced paw edema methods, respectively. The compound at doses of 50 and 100 mg/kg significantly decreased writhing responses of mice induced by 0.7 % acetic acid along the 60 min test in a dose-dependent manner. The compound at a dose of 100 mg/kg gave the percent protection of 76.23 higher than that of acetylsalicylic acid (59.84 %) at a dose of 50 mg/kg. In the antiinflammatory test, this compound caused significant inhibition of the rats' plantar edema induced by 1 % of carrageenan, but this activity was observed only at a higher dose (200 mg/kg). These findings suggest that proanthocyanidin of P. feei roots might have analgesic and antiinflammatory activity, and its mechanism of action might be due to the inhibition of prostaglandin biosynthesis, because the proanthocyanidin fraction had an inhibitory effect on cyclooxygenase, but not on 5-lypoxygenase enzymes.     

Antiinflammatory activity of adrenomedullin in the acetic acid peritonitis in rats

The antiinflammatory effect of ADM was studied in different models of inflammation and compared to the one of CGRP. Peptides were active against acetic acid-induced peritonitis in the rats. ADM and CGRP exerted the antiinflammatory effect at different doses, 400 and 20 ng/kg respectively, but with different efficacy (ADM >CGRP). This effect was blocked by pretreatment with CGRP (8-37) fragment or with L-NAME. No antiinflammatory activity was evidenced against serotonin- or carrageenin-induced rat paw edema. Our data suggest that ADM exerts antiinflammatory activity in the model characterized by a vascular component. This effect involves CGRP receptors and appears to be mediated by nitric oxide system.     

Calotropis procera latex-induced inflammatory hyperalgesia--effect of antiinflammatory drugs

The milky white latex of plant Calotropis procera produces inflammation of the skin and mucous membranes on accidental exposure. It produces edema on local administration due to the release of histamine and prostaglandins and is associated with hyperalgesia. In the present study we have evaluated the antiedematous and analgesic activity of antiinflammatory drugs against inflammatory response induced by dried latex (DL) of C procera in rat paw edema model. An aqueous extract of DL of C procera was injected into the subplantar surface of the rat paw and the paw volume was measured by a plethysmometer at 0, 1, 2, 6, 12, and 24 hours. Concomitantly the hyperalgesic response was also evaluated by motility test, stair climbing ability test, dorsal flexion pain test, compression test, and observing the grooming behavior. The inhibitory effect of diclofenac and rofecoxib on edema formation and hyperalgesic response was compared with cyproheptadine (CPH). DL-induced edema formation was maximum at 2 hours that was associated with decreased pain threshold, functional impairment, and grooming. Treatment with antiinflammatory drugs and CPH significantly attenuated the edematous response and grooming, increased the pain threshold, and improved functional parameters. Both antiinflammatory and antiserotonergic drugs significantly inhibited the hyperalgesia associated with DL-induced paw edema. Rofecoxib was found to be superior than diclofenac and was as effective as CPH in ameliorating the hyperalgesia. However, it was found to be less effective than CPH in attenuating edema formation.     

Radical scavenging as the mechanism for stimulation of prostaglandin cyclooxygenase and depression of inflammation by lipoic acid and sodium iodide.

Certain radical-trapping reducing agents have been shown to stimulate prostaglandin biosynthesis in vitro (1--6) and to depress phorbol myristate acetate-induced mouse ear edema (16). The increased prostaglandin synthesis resulted from influences on the cyclooxygenase. To ascertain whether these alterations were due to direct interaction with the enzyme or to indirect scavenging of the oxidant released during PGG2 reduction, we report the effects of lipoic acid and sodium iodide. Both of these agents stimulated the enzymatic oxygenation of arachidonic acid, increased the reduction of PGG2 to PGH2, quenched the EPR signal induced by arachidonic acid and depressed mouse ear edema. In addition to discovering two unusual antiinflammatory agents, we have confirmed that materials with entirely different structures can have identical effects on the cyclooxygenase, suggesting indirect stimulation of this enzyme due to trapping of the oxidant.     

Pharmacological analysis of the antiinflammatory effects of low-intensity extremely-high-frequency electromagnetic radiation

The antiinflammatory effect of low-intensity extremely-high-frequency electromagnetic radiation (EHF EMR, 42.0 GHz, 0.1 mW/cm²) was studied in comparison to the effects of the antiinflammatory drug sodium diclofenac and the antihistamine clemastine in acute inflammatory reaction in mice of NMRI outbred stock. The local inflammatory reaction was induced by intraplantar injection of zymosan to the left hind paw. Intraperitoneal injections of 2, 3, 5, 10, and 20 mg/kg of sodium diclofenac or 0.02, 0.1, 0.2, 0.4, and 0.6 mg/kg of clemastine were made 30 min after the initiation of inflammation. An hour after the initiation of inflammation, animals were whole-body exposed to EHF EMR for 20 min. The inflammatory reaction was assessed 3–8 h after initiation by measuring the footpad edema and hyperthermia of the inflamed paw. Sodium diclofenac (5–20 mg/kg) reduced the exudative edema by ～26% compared to the control. Hyperthermia of the inflamed paw decreased by 60% with an increase in the diclofenac dose to 20 mg/kg. EHF EMR reduced both the footpad edema and hyperthermia by ～20%. This was comparable to the effect of a single therapeutic dose of diclofenac (3–5 mg/kg). The combination of diclofenac and exposure to EHF EMR produced a partial additive effect. Clemastine (0.02–0.4 mg/kg) did not affect the exudative edema, but at a dose of 0.6 mg/kg, edema was reduced by 14–22% five to eight hours after zymosan injection. Clemastine caused a dose-dependent increase in hyperthermia of inflamed paw at doses 0.02–0.2 mg/kg and did not affect the hyperthermia at doses 0.4 and 0.6 mg/kg. A combination of clemastine and EHF EMR exposure resulted in a dose-dependent abolishment of the antiinflammatory effect of EHF EMR. Our results suggest that both arachidonic acid metabolites and histamine are involved in the achievement of the antiinflammatory effects of low-intensity EHF EMR.     

Anti-inflammatory activity of a novel selective cyclooxygenase-2 inhibitor, FR140423, on type II collagen-induced arthritis in Lewis rats

The mechanism of action of FR140423 (3-(difluoromethyl)-1-(4-methoxyphenyl)-5-[4-(methylsulfinyl)-phenyl]pyrazole), a novel and selective cyclooxygenase (COX)-2 inhibitor, in rat type II collagen-induced arthritis was investigated and compared with that of indomethacin. We tested the inhibitory effects of FR140423 on paw edema and the formation of arachidonic acid metabolites in inflamed paws immunized with type II collagen. Oral administration of FR 140423 showed a dose-dependent anti-inflammatory effect and was two-fold more potent than indomethacin. The increase of prostaglandin (PG) E2 and thromboxane (TX) B2 but not leukotriene B4 in inflamed paws was associated with the development of paw edema. FR140423 and indomethacin dose-dependently suppressed the levels of PGE2 and TXB2 in arthritic rat paws. Unlike indomethacin, FR140423 did not induce gastric lesions in arthritic rats. These results suggest that FR140423 shows a potent anti-inflammatory effect mediated by inhibition of prostanoids produced by COX-2 in inflamed tissues immunized with type II collagen, with a greatly improved safety profile compared to indomethacin.     

Comparison of anti-inflammatory compounds in the carrageenan induced paw edema model and the reversed passive Arthus model utilizing the same animal

In order to better define antiinflammatory activity in new agents, a test was devised utilizing both carrageenan induced paw edema and the reversed passive Arthus reaction in the same animal. The model of carrageenan induced rat paw edema is a standard laboratory assay used to predict classical "aspirin-like" antiinflammatory molecules. The reversed passive cutaneous Arthus reaction involves precipitating antigen-antibody complexes, complement and infiltrating polymorphonuclear leukocytes (PMN's) and can be used to identify agents that affect one or more of these factors specifically. Antiinflammatory compounds were given orally one hour prior to the administration of carrageenan and goat anti-rat serum. Comparisons were made between several non-steroidal compounds and the steroid hydrocortisone. All of the compounds tested gave good carrageenan activity, but only hydrocortisone produced significant Arthus lesion inhibition in this assay.     

Radical scavenging as the mechanism for stimulation of prostaglandin cyclooxygenase and depression of inflammation by lipoic acid and sodium iodide

Certain radical-trapping reducing agents have been shown to stimulate prostaglandin biosynthesis (1–6) and to depress phorbol myristate acetate-induced mouse ear edema (16). The increased prostaglandin synthesis resulted from influences on the cyclooxygenase. To ascertain whether these alterations were due to direct interaction with the enzyme or to indirect scavenging of the oxidant released during PGG₂ reduction, we report the effects of lipoic acid and sodium iodide.Both of these agents stimulated the enzymatic oxygenation of arachidonic acid, increased the reduction of PGG₂ to PGH₂, quenched the EPR signal induced by arachidonic acid and depressed mouse ear edema. In addition to discovering two unusual antiinflammatory agents, we have confirmed that materials with entirely different structures can have identical effects on the cyclooxygenase, suggesting indirect stimulation of this enzyme due to trapping of the oxidant.     

The stimulation of arachidonic acid metabolism in human platelets by hydrodynamic stresses

Even though shear-induced platelet activation and aggregation have been studied for about 20 years, there remains some controversy concerning the arachidonic acid metabolites formed during stress activation and the role of thromboxane A2 in shear-induced platelet aggregation. In this study, platelets were labelled with [1-14C]arachidonic acid to follow the metabolism of arachidonic acid in stimulated platelets using HPLC and scintillation counting. Platelets activated by thrombin formed principally thromboxane A2, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE). In contrast, for platelets activated by shear--though arachidonic acid metabolism was stimulated--only 12-HETE was formed and essentially no cyclooxygenase metabolites were detected. This indicates that physical forces may initiate a different pathway for eicosanoid metabolism than most commonly used chemical stimuli and perhaps also implies that regulation of the cyclooxygenase activity may be a secondary level of regulation in eicosanoid metabolism.     

Antiinflammatory and chronic toxicity study of the leaves of Ageratum conyzoides L. in rats

The hydroalcoholic extract (HAE) of Ageratum conyzoides leaves was studied for its antiinflammatory effect on subacute (cotton pellet-induced granuloma) and chronic (formaldehyde-induced arthritis) models of inflammation in rats. The absence or presence of toxicity by prolonged use of HAE was also evaluated through biochemical and hematological analysis of rats blood samples using daily oral doses of 250 or 500 mg/kg body wt., during 90 days. The results showed that the group of rats treated with HAE (250 mg/kg body wt.; p.o.) had a 38.7% (p < 0.05) reduction in cotton-pellet granuloma. The development of chronically induced paw edema was also reduced significantly (p < 0.05) by the plant extract. The toxicity study did not show any treatment-related abnormalities in biochemical and hematological parameters. The biochemical analysis from blood samples drawn from group of rats treated orally with 500 mg/kg body wt. did, however, present 30.2% (p < 0.05) reduction of SGPT activity as compared to the corresponding control group. These results confirm the antiinflammatory properties of A. conyzoides, with no apparent hepatotoxicity.     

Preliminary studies on phospholipase A2-induced mouse paw edema as a model to evaluate antiinflammatory agents

Phospholipase A2 (PLA2) is a key component of the inflammatory process because of its role in the generation of eicosanoids and platelet-activating factor (PAF). Manipulation of PLA2 activity offers a novel therapeutic approach for the development of antiinflammatory agents; however, there is a need for a suitable in vivo model. Injection of 1 microgram of snake venom PLA2 (A. piscivorus piscivorus, D-49) into the mouse hind footpad produced a significant three- to four-fold rise in paw edema within 10 min, compared to the saline control. Edema formation depended on enzyme concentration and appeared specific for PLA2 since edema was negated by enzyme pretreatment with p-bromophenacyl bromide, a nonspecific PLA2 inhibitor. Moreover, injection of a protein such as bovine serum albumin did not result in significant edema. Coinjection of phenidone (lipoxygenase inhibitor, 50 micrograms), indomethacin (cyclooxygenase inhibitor, 50 micrograms), cyproheptadine (antihistamine/antiserotonin, 50 micrograms), aristolochic acid (putative PLA2 inhibitor, 100 micrograms), or kadsurenone (PAF antagonist, 50 micrograms) with PLA2 (1 microgram/paw) resulted in partial reduction (44.5, 34.2, 54.7, 64, and 50% inhibition, respectively) of edema formation. Oral administration of cyproheptadine (10 mg/kg), indomethacin (10 mg/kg), BW 755c (100 mg/kg), or dexamethasone (1 mg/kg) 1-3 h before challenge also decreased PLA2-induced edema (63.0, 30.1, 47.8, or 62.5% inhibition, respectively). The data suggest that mouse paw edema resulting from PLA2 injection is a multicomponent event, influenced by both autacoids and lipid mediators of inflammation.     

Effect of nutritional copper deficiency on carrageenin edema in the rat

The effects of nutritional copper deficiency on carrageenin edema in the rat were investigated with emphasis on studying the correlation between the degree of copper deficiency and the degree of edema. Carrageenin paw edema in both copper-sufficient and copper-deficient groups of rats was compared after either 20, 40, or 60 d on respective diets. The degree of copper deficiency was quantitated by analyzing total copper concentrations in a number of tissues. Other copper dependent parameters were also determined. Results indicated that: (1) although copper sufficient rats showed relatively little change in the degree of edema, copper-deficient rats showed a steady and significant increase in edema from d 20 to 40 to 60; (2) paw edema in copper-deficient animals was highly and negatively correlated to the concentrations of copper in the liver; the correlation with liver Cu,Zn-superoxide dismutase activity, however, was inconsistent; (3) paw edema was not correlated either to copper concentration in tissues other than liver or to plasma ceruloplasmin activity; and (4) aggravation of carrageenin edema in copper-deficient animals seemed to be mediated via an as yet unknown secondary effect of copper deficiency.     

Evaluation of anti-inflammatory activity of Alstonia macrophylla Wall ex A. DC. leaf extract.

Methanolic extract of dried leaves of Alstonia macrophylla Wall ex A. DC. and its fractions were investigated for its anti-inflammatory activity. The extract at a concentration of 200 mg kg(-1) and 400 mg kg(-1), p.o. and its fractions at 25 mg kg(-1) and 50 mg kg(-1), p.o. showed the significant dose dependent antiinflammatory activity in carrageenan and dextran-induced rats hind paw edema (acute models) as well as in cotton pellet-induced granuloma (chronic model) in rats. Anti-inflammatory activity of the tested extract and its fractions was comparable with that of the standard drug Indomethacin (10 mg kg(-1)).     

In vitro inhibition of prostaglandin production by azathioprine and 6-mercaptopurine

Although there are many data concerning the cytotoxic and immunosuppressive effects of antimetabolites such as azathioprine and 6-mercaptopurine, the mechanism of their antiinflammatory action has not been extensively investigated. In the present work, it is shown that azathioprine and 6-mercaptopurine (10-500 micrograms/ml) inhibit in a dose-dependent manner the production of PGE2, PGF2 alpha, 6-keto-PGF1 alpha and TXB2 by unseparated spleen cells as well as that of 6-keto-PGF1 alpha by adherent peritoneal macrophages. This inhibitory effect appears rapidly in vitro (within 15 min of incubation) and is observed in the presence of exogenous arachidonic acid (5 x 10(-6) M). The persistence of this effect in the presence of arachidonic acid, together with the fact that the production of four cyclooxygenase derivatives of acid arachidonic metabolism are inhibited, suggests that these drugs are acting at the cyclooxygenase level. The finding that cytotoxic and immunosuppressive agents, which act mainly by inhibiting RNA and DNA synthesis, can block prostaglandin production, may explain part of their antiinflammatory effects.     

Stimulation of histamine release and arachidonic acid metabolism in rat peritoneal mast cells by thapsigargin, a non-TPA-type tumor promoter

Thapsigargin, a non-TPA-type tumor promoter, releases histamine and stimulates arachidonic acid metabolism in rat peritoneal mast cells. In order to clarify the relationship between the histamine-releasing activity and the arachidonic acid metabolism-stimulating activity of thapsigargin in mast cells, the effects of cyclooxygenase inhibitors, indomethacin and ibuprofen, a lipoxygenase inhibitor, AA861, and dual inhibitors for cyclooxygenase and lipoxygenase, nordihydroguaiaretic acid and BW755C, on histamine release and arachidonic acid metabolism were examined. High-performance liquid chromatography analysis revealed that the peritoneal mast cells preferentially produce prostaglandin D2 by thapsigargin treatment. These inhibitors suppressed thapsigargin-induced prostaglandin D2 production in a dose-dependent manner, but failed to inhibit histamine release, suggesting that the mechanisms for stimulation of histamine release by thapsigargin is not dependent on increased arachidonic acid metabolism. Time-course experiments of histamine release and the release of radioactivity from [3H]arachidonic acid-labeled mast cells also provide evidence for a difference in mechanism.     

Evidence for the localization of hydrogen peroxide-stimulated cyclooxygenase activity in rat brain mitochondria: a possible coupling with monoamine oxidase

The distribution of basal and of H2O2-stimulated cyclooxygenase activity in the primary fractions of rat brain homogenates and in the subfractions of crude mitochondrial fraction was studied. For comparison, the localization of H2O2-generating monoamine oxidase (MAO) as well as that of the mitochondrial marker succinate dehydrogenase (SDH) was also examined. H2O2 was generated by MAO using 5 x 10(-4) M noradrenaline (NA) or 2 x 10(-4) M 2-phenylethylamine (PEA) as substrates, or by 25 micrograms glucose oxidase (GOD) per ml in the presence of 1 mM glucose. For nonstimulated (basal) cyclooxygenase, the relative specific activity (RSA) was high in microsomes (1.79) and in the free mitochondria-containing subfraction of the crude mitochondrial fraction (1.94). Parallel distribution of MAO and H2O2-stimulated cyclooxygenase was observed in all fractions studied in the presence of NA. The highest RSA was found in the purified mitochondria for both enzymes (1.85 for MAO and 1.97 for H2O2-stimulated cyclooxygenase). The enrichment of SDH (RSA = 2.21) indicated a high concentration of mitochondria in this fraction. The same distribution of H2O2-stimulated cyclooxygenase was obtained when, instead of the MAO-NA system, hydrogen peroxide was generated by GOD in the presence of glucose. H2O2 generated by deamination of NA or PEA by MAO, or during the enzymatic oxidation of glucose by GOD, caused a threefold increase in mitochondrial endoperoxide formation. Indomethacin (2 x 10(-4) M), catalase (50 micrograms/ml), and pargyline (2 x 10(-4) M) eliminated the MAO-dependent mitochondrial synthesis of PG endoperoxides. The GOD-dependent cyclooxygenase activity in this fraction was abolished by indomethacin or catalase, but not by pargyline. The results show the existence of a mitochondrial cyclooxygenase in brain tissue. The enzyme is sensitive to H2O2 and produces prostaglandin endoperoxides from an endogenous source of arachidonic acid. The identical localization of H2O2-producing MAO and H2O2-sensitive cyclooxygenase suggests a possible coupling between monoamine and arachidonic acid metabolism.