Investigation of anti-inflammatory and antinociceptive activities of trans-dehydrocrotonin, a 19-nor-clerodane diterpene from Croton cajucara. Part 1

The drug likeness analysis of anti-inflammatory clerodane diterpenoids

Inflammation is an active defense response of the body against external stimuli. Long term low-grade inflammation has been considered as a deteriorated factor for aging, cancer, neurodegeneration and metabolic disorders. The clinically used glucocorticoids and non-steroidal anti-inflammatory drugs are not suitable for chronic inflammation. Therefore, it's urgent to discover and develop new effective and safe drugs to attenuate inflammation. Clerodane diterpenoids, a class of bicyclic diterpenoids, are widely distributed in plants of the Labiatae, Euphorbiaceae and Verbenaceae families, as well as fungi, bacteria, and marine sponges. Dozens of anti-inflammatory clerodane diterpenoids have been identified on different assays, both in vitro and in vivo. In the current review, the up-to-date research progresses of anti-inflammatory clerodane diterpenoids were summarized, and their druglikeness was analyzed, which provided the possibility for further development of anti-inflammatory drugs.

Characterization of Inhibitory Effectiveness in Hyperpolarization-Activated Cation Currents by a Group of ent-Kaurane-Type Diterpenoids from Croton tonkinensis

Croton is an extensive flowering plant genus in the spurge family, Euphorbiaceae. Three croton compounds with the common ent-kaurane skeleton have been purified from Croton tonkinensis. Methods: We examined any modifications of croton components (i.e., croton-01 [ent-18-acetoxy-7α-hydroxykaur-16-en-15-one], croton-02 [ent-7α,14β-dihydroxykaur-16-en-15-one] and croton-03 [ent-1β-acetoxy-7α,14β-dihydroxykaur-16-en-15-one] on either hyperpolarization-activated cation current (I_h) or erg-mediated K⁺ current identified in pituitary tumor (GH₃) cells and in rat insulin-secreting (INS-1) cells via patch-clamp methods. Results: Addition of croton-01, croton-02, or croton-03 effectively and differentially depressed I_h amplitude. Croton-03 (3 μM) shifted the activation curve of I_h to a more negative potential by approximately 11 mV. The voltage-dependent hysteresis of I_h was also diminished by croton-03 administration. Croton-03-induced depression of I_h could not be attenuated by SQ-22536 (10 μM), an inhibitor of adenylate cyclase, but indeed reversed by oxaliplatin (10 μM). The I_h in INS-1 cells was also depressed effectively by croton-03. Conclusion: Our study highlights the evidence that these ent-kaurane diterpenoids might conceivably perturb these ionic currents through which they have high influence on the functional activities of endocrine or neuroendocrine cells.

Clerodane Diterpenes from Croton Species: Distribution and a Compilation of their 13C NMR Spectral Data

The present work is a review of the literature of clerodane diterpenes from Croton species. It contains a compilation of 13C NMR data of 83 of these diterpenoids and their biological activities. This review covers a period from 1969 to October 2005 and 224 references are cited.

Pharmacological evaluation of 2-angeloyl ent-dihydrotucumanoic acid

CONTEXT

Gymnosperma glutinosum (Spreng.) Less. (Asteraceae) is a bush used for the empirical treatment of pain, fever, and cancer. An ent-neo-clerodane diterpene (2-angeloyl ent-dihydrotumanoic acid; ADTA) was isolated from G. glutinosum.

OBJECTIVE

This study evaluates the cytotoxic, anti-inflammatory, and antinociceptive effects of ADTA.

MATERIALS AND METHODS

The cytotoxic effects of ADTA (1-350 μM) were evaluated using the MTT assay with human tumorigenic (SW-620, MDA-MB231, SKLU1, SiHa, and PC-3), and non-tumorigenic (HaCaT) cells for 48 h. The in vitro anti-inflammatory effects of ADTA (0.23-460 μM) were assessed using murine peritoneal macrophages stimulated with LPS and estimating the levels of pro-inflammatory mediators for 48 h. The antinociceptive effects of ADTA (25-100 mg/kg p.o.) were evaluated using two in vivo models of chemical-induced nociception during 1 h.

RESULTS

ADTA lacked cytotoxic activity (IC₅₀> 100 μM) on tumorigenic cells. In non-tumorigenic cells (HaCaT), ADTA exerted low cytotoxic effects (IC₅₀=273 μM). ADTA, at concentrations of 115 μM or higher, decreased the release of pro-inflammatory mediators. The maximum antinociceptive effects of ADTA in the acetic acid-induced abdominal constrictions by ADTA was found at 100 mg/kg (63%), whereas in the formalin test at phase 1 and phase 2, ADTA (100 mg/kg) decreased the licking time by 47 and 71%, respectively.

CONCLUSION

The results indicate that ADTA, obtained from G. glutinosum, exerts moderate in vitro anti-inflammatory and in vivo antinociceptive effects, but lacks cytotoxic effects on human cancer cells.

Clerodane diterpenes: sources, structures, and biological activities

Covering: 1990 to 2015The clerodane diterpenoids are a widespread class of secondary metabolites and have been found in several hundreds of plant species from various families and in organisms from other taxonomic groups. These substances have attracted interest in recent years due to their notable biological activities, particularly insect antifeedant properties. In addition, the major active clerodanes of Salvia divinorum can be used as novel opioid receptor probes, allowing greater insight into opioid receptor-mediated phenomena, as well as opening additional areas for chemical investigation. This article provides extensive coverage of naturally occurring clerodane diterpenes discovered from 1990 until 2015, and follows up on the 1992 review by Merritt and Ley in this same journal. The distribution, chemotaxonomic significance, chemical structures, and biological activities of clerodane diterpenes are summarized. In the cases where sufficient information is available, structure activity relationship (SAR) correlations and mode of action of active clerodanes have been presented.

Antiulcer activity and subacute toxicity of trans-dehydrocrotonin from Croton cajucara

The antiulcerogenic activity of trans-dehydrocrotonin (DHC), a nor-clerodane diterpene isolated from Croton cajucara Benth. (Euphorbiaceae), and its subacute (35 days) toxicity were studied in mice and rats, respectively. For the antiulcerogenic tests, models of gastric ulcers induced in mice by ethanol/HCl or stress were used. In both models, an oral dose of DHC (100 mg/kg) significantly reduced (P <0.01) the formation of gastric lesions. DHC was also tested for its ability to scavenge free radicals, but no such action was observed in rat liver mitochondria. To assess the subacute toxicity, rats were treated orally with DHC (25, 50 and 100 mg/kg) for 5 weeks. A significant increase in liver weight was observed in male and female rats at highest doses, whereas a significant reduction in plasma alkaline phosphatase and cholesterol levels and an increase in gamma glutamyl transpeptidase were observed only at the highest dose (100 mg/kg) in female rats. DHC caused histopathological alterations in the liver that included a turbid tumefaction, microvacuolar degeneration and nuclear alterations. Despite the beneficial antiulcerogenic activity of DHC, our results suggest that the long-term use of this compound may induce liver damage.

Polyandric acid A, a clerodane diterpenoid from the Australian medicinal plant Dodonaea polyandra, attenuates pro-inflammatory cytokine secretion in vitro and in vivo

Dodonaea polyandra is a medicinal plant used traditionally by the Kuuku I'yu (Northern Kaanju) indigenous people of Cape York Peninsula, Australia. The most potent of the diterpenoids previously identified from this plant, polyandric acid A (1), has been examined for inhibition of pro-inflammatory cytokine production and other inflammatory mediators using well-established acute and chronic mouse ear edema models and in vitro cellular models. Topical application of 1 significantly inhibited interleukin-1β production in mouse ear tissue in an acute model. In a chronic skin inflammation model, a marked reduction in ear thickness, associated with significant reduction in myeloperoxidase accumulation, was observed. Treatment of primary neonatal human keratinocytes with 1 followed by activation with phorbol ester/ionomycin showed a significant reduction in IL-6 secretion. The present study provides evidence that the anti-inflammatory properties of 1 are due to inhibition of pro-inflammatory cytokines associated with skin inflammation and may be useful in applications for skin inflammatory conditions including psoriasis and dermatitis.

Anti-nociceptive and anti-inflammatory effects of Croton crassifolius ethanol extract

ETHNOPHARMACOLOGICAL RELEVANCE

Croton crassifolius has been used to treat snake bites, stomach ache, sternalgia, joint pain, as well as pharyngitis, jaundice, and rheumatoid arthritis in traditional Chinese medicine. However, there is no scientific evidence which supports the use in the literature.

AIM OF THE STUDY

To investigate the anti-nociceptive and anti-inflammatory effects of ethanol extract of C. crassifolius.

MATERIALS AND METHODS

Anti-nociceptive actions of C. crassifolius were assessed in mice using the hot-plate test, acetic acid-induced writhing test, and formalin test. Anti-inflammatory effects of C. crassifolius were determined in three animal models: acetic acid-induced capillary permeability accentuation in mice, carrageenan-induced edema of the hind paw in rats, and cotton pellet-induced granuloma formation in rats.

RESULTS

Ethanol extract of C. crassifolius showed no significant anti-nociceptive activity in the hot-plate test. However, extract at dosages of 45, 90 and 180 mg/kg significantly reduced acetic acid-induced writhing by 28.89% (P<0.05), 38.37% (P<0.05), and 56.53% (P<0.001), respectively. The extract also caused marked dose-related inhibition of formalin-induced pain in the second phase (P<0.05 for 45 mg/kg, P<0.001 for 90 and 180 mg/kg extract). C. crassifolius extract at dosages of 45, 90 and 180 mg/kg significantly reduced acetic acid-induced capillary permeability accentuation in mice by 26.18% (P<0.05), 65.70% (P<0.001), and 79.19% (P<0.001), and suppressed carrageenan-induced paw edema by 21.28% (P<0.05), 30.69% (P<0.01), and 49.17% (P<0.001) at 6 h after carrageenan injection, respectively. 180 mg/kg of the extract also showed significant activity against carrageenan-induced paw edema at 4 h. At 90 and 180 mg/kg, the extract inhibited cotton pellet-induced granuloma formation in rats.

CONCLUSIONS

These results collectively demonstrate that the ethanol extract of C. crassifolius possesses peripheral anti-nociceptive and anti-inflammatory effects, providing evidence to rationalize the traditional use of C. crassifolius for the treatment of pain and inflammation.

Involvement of glutathione, sulfhydryl compounds, nitric oxide, vasoactive intestinal peptide, and heat-shock protein-70 in the gastroprotective mechanism of Croton cajucara Benth. (Euphorbiaceae) essential oil

This study aimed to evaluate the gastroprotective mechanism of action of the essential oil of Croton cajucara Benth. (Euphorbiaceae) stem bark in ethanol-induced gastric ulcers and its in vitro anti-Helicobacter pylori activity. The involvement of heat-shock protein-70, vasoactive intestinal peptide, glutathione, nitric oxide, and nonprotein sulfhydryl compounds in the gastroprotective effect was determined in male Wistar rats. The minimum inhibitory concentration against H. pylori was determined in vitro. The results were analyzed by analysis of variance followed by the Dunnett test, and a P value less than 0.05 was considered to represent a statistically significant difference. C. cajucara decreased ethanol-induced ulcer area in 100% of ulcers and decreased the histologic lesions. In the C. cajucara group, the area marked by heat-shock protein-70 was significantly higher than the area in the control group; this finding was not seen for vasoactive intestinal peptide. C. cajucara could not maintain glutathione levels close to those in the sham group. The gastric ulcer area of rats treated with the sulfhydryl compound blocker was decreased, but the ulcer area of rats treated with nitric oxide synthase inhibitor showed no alteration. The minimum inhibitory concentration obtained for C. cajucara was 125 μg/mL. These findings suggest that sulfhydryl compounds and heat-shock protein-70, but not nitric oxide, glutathione, or vasoactive intestinal peptide, are involved in the C. cajucara gastroprotective effect against ethanol-induced gastric ulcers.

Effects of an aqueous extract of Croton bonplandianum Baill in rats

We have investigated the cytotoxic and biochemical effects of injecting aqueous phytoextract of Croton bonplandianum (Baill) leaves in male rats. Subchronic dosages of 3.25, 4.65 and 6.97mgphytoextractg(-1)b.wt.week(-1) were administered to rats. To test ameliorative effects, rats were injected with phytoextract mixed with 0.2mgg(-1)b.wt. of cyclophosphamide. Positive controls received only cyclophosphamide, while negative control groups were kept on normal diet and water. Our results demonstrate that phytoextract did not induce micronuclei formation in rats and shows insignificant amelioration (P<0.05). However, differences in serum LDH isoenzymes, ALP, SGOT, SGPT activities and bilirubin were remarkable and displayed dose as well as duration dependent variations. The most outstanding observation of this study was the release of cardiac TnI in sera of rats injected with 6.97mgg(-1)b.wt. of phytoextract for 21 days. Our findings suggest that at the highest concentrations used here phytoextract of C. bonplandianum is not clastogenic; instead it is cardio- and hepatotoxic.

Histologic evaluation of rats' liver after Croton cajucara Benth (sacaca) administration

PURPOSE: To evaluate the hepatic effect of Croton cajucara Benth (sacaca) herbal extract in rats. METHODS: 60 Wistar rats (Rattus novergicus albinus) were used, weighing between 250 and 350 g. The animals were distributed randomically in 2 groups: GS - animals which received daily 0,1 ml/ 100 g of sacaca herbal extract through gavage, and GA -animals which received daily 0,1 ml/100g of distilled water through gavage. These were distributed in 3 subgroups with 10 animals, according to theirs euthanasia dates, which were 14th, 28th and 56th day of treatment. RESULTS: Architectural alterations were not observed, however when it was analyzed the presence or absence of necrosis, it was observed in 50% of GS28 subgroup and 90% of subgroup. In 50% of the animals from GS28 subgroup and 90% of GS56 subgroup was observed vast degeneration areas and zonal necrosis, regarding center-lobular veins alterations, there were no alterations in any of the groups CONCLUSION: The Croton cajucara Benth (sacaca) herbal extract in this experiment caused degeneration and hepatic necrosis, suggesting dose-dependent action.

In search of cyclooxygenase inhibitors, anti-Mycobacterium tuberculosis and anti-malarial drugs from Thai flora and microbes

Malaria continues to be a major infectious disease of the developing world and the problem is compounded not only by the emergence of drug resistant strains but also from a lack of a vaccine. The situation for tuberculosis (TB) infection is equally problematic. Once considered a "treatable" disease for which eradication was predicted, TB has re-emerged as highly lethal, multi-drug resistant strains after the outbreak of AIDS. Worldwide, the disease causes millions of deaths annually. Similarly, treatments for chronic inflammatory diseases such as arthritis have been impeded due to the potentially lethal side effects of the new and widely prescribed non-steroidal anti-inflammatory compounds. Thais have utilized bioresources from plants and some microorganisms for medicine for thousands of years. Because of the need for new drugs to fight malaria and TB, with radically different chemical structures and mode of actions other than existing drugs, efforts have been directed towards searching for new drugs from bioresources. This is also true for anti-inflammatories. Although Thailand is considered species-rich, only a small number of potential bioresources has been investigated. This article briefly describes the pathogenesis of 2 infectious diseases, malaria and TB, and modern medicines employed in chemotherapy. Diversities of Thai flora and fungi and their chemical constituents with antagonistic properties against these 2 diseases are described in detail. Similarly, anti-inflammatory compounds, mostly cyclooxygenase (COX) inhibitors, are also described herein to demonstrate the potential of Thai bioresources to provide a wide array of compounds for treatment of diseases of a different nature.

Protective effect of DCTN (trans-dehydrocrotonin) against induction of micronuclei and apoptosis by different mutagenic agents in vitro

The use of medicinal plants to combat diseases has increased in the last years despite the little information available with regard to the possible health risks they represent. The aim of the present study was to determine in vitro the possible clastogenic, apoptotic and cytotoxic effects of the active principle of Croton cajucara, trans-dehydrocrotonin (DCTN), and determine its protective effect against three mutagenic agents using the micronucleus test (MN) and apoptosis index in CHO-K1 cells. Three DNA damage inducing agents were utilized in the clastogenicity and anticlastogenicity tests (methylmethane sulfonate (MMS), mitomycin C (MMC) and doxorubicin (DXR); a negative control (PBS) and solvent control were also included. DCTN at concentrations of 400, 320, 240, 160 and 80microM did not show clastogenic activity in cultured CHO-K1 cells in the micronucleus test, did not induce apoptosis and showed negligible cytotoxicity in all cases. DCTN at concentrations of 240 and 400microM was tested for protective activity using three treatment protocols in relation to positive controls: pre-treatment, simultaneous treatment and post-treatment. The micronucleus test showed a protective effect for DCTN which varied among the different treatment protocols and with regard to the different DNA damage inducing agents. In the apoptosis test, DCTN was seen to have a protective effect under the following conditions: (I) at both concentrations in relation to MMS, in all three treatment protocols; (II) at both concentrations against damage caused by MMC with pre-treatment and at the higher concentration with simultaneous treatment; (III) at both concentrations against DXR with simultaneous treatment. Therefore, DCTN itself is not a clastogenic or cytotoxic substance, and does not induce apoptosis the in vitro system used. These results together with findings reported for DCTN in vivo, support the indication of this active principle at these concentrations for therapeutic use.

The gastroprotective effect of the essential oil of Croton cajucara is different in normal rats than in malnourished rats

It has been shown previously that malnourished rats are resistant to acute gastric lesions but not to subchronic gastric ulceration. It also has been demonstrated that the essential oil obtained from the bark of Croton cajucara (Sacaca) has antiulcer properties. In the present study, the ability of this essential oil to prevent the formation of gastric ulcers in rats fed a diet with 17% protein (normoproteic rats) or 6% protein (malnourished rats) was investigated. At a dose of 100mg/kg body weight, orally, the essential oil significantly reduced the gastric injury caused by indomethacin (25% after 2h and 70% after 4h) only in normoproteic rats. In the pylorus ligature model, the essential oil increased the pH and gastric volume, but decreased the total acid concentration in both groups when compared to the respective control group. The essential oil significantly increased prostaglandin E2 production in glandular cells by 50% compared to the controls in both groups of rats. In addition, the amount of gastric mucus was two-fold higher in malnourished rats than in normoproteic rats. The present results show that the enhanced protective effect of essential oil in malnourished rats involved an increase in prostaglandin E2 production and mucus secretion, which are both factors that protect the gastric mucosa against damage. In agreement with this, malnourished rats always had a lower number of acute gastric ulcers.

Genotoxicity evaluation of kaurenoic acid, a bioactive diterpenoid present in Copaiba oil

Copaiba oil extracted from the Amazon traditional medicinal plant Copaifera langsdorffii is rich in kaurenoic acid (ent-kaur-16-en-19-oic acid), a diterpene that has been shown to exert anti-inflammatory, hypotensive, and diuretic effects in vivo and antimicrobial, smooth muscle relaxant and cytotoxic actions in vitro. This study evaluated its potential genotoxicity against Chinese hamster lung fibroblast (V79) cells in vitro, using the Comet and the micronucleus assays. Kaurenoic acid was tested at concentrations of 2.5, 5,10, 30 and 60 microg/mL. The positive control was the methylmethanesulfonate (MMS). The duration of the treatment of V79 cells with these agents was 3h. The results showed that unlike MMS, kaurenoic acid (2.5, 5, and 10 microg/mL) failed to induce significantly elevated cell DNA damage or the micronucleus frequencies in the studied tests. However, exposure of V79 cells to higher concentrations of kaurenoic acid (30 and 60 microg/mL) caused significant increases in cell damage index and frequency. The data obtained provide support to the view that the diterpene kaurenoic acid induces genotoxicity.

Synthesis, Anticonvulsant, and Anti-inflammatory Activities of Some New Benzofuran-Based Heterocycles

Treatment of 2-bromoacetylbenzofuran (2) with pyridine afforded its corresponding pyridinium bromide 3. The latter salt reacted with some activated alkenes and acetylenes to give the corresponding indolizine derivatives. Treatment of the salt 3 with benzylidenemalononitriles 9 afforded polysubstituted aniline derivatives, however with arylidenecyanothioacetamides 15 it gave the corresponding 4,5-dihydrothiophenes. Bromide 3 also coupled with p-chlorobenzenediazonium salt followed by ammonium acetate to give the corresponding 1,2,4,5-tetrazine derivative. The biological activity of the newly synthesized compounds was examined and some of them were found to possess anticonvulsant and anti-inflammatory activities.

Synthesis, anticonvulsant, and anti-inflammatory evaluation of some new benzotriazole and benzofuran-based heterocycles

Treatment of 2-bromoacetylbenzofuran with 1H-benzotriazole afforded 1-(benzofuran-2-yl)-2-(benzotriazol-1-yl)ethanone which reacted with phenylisothiocyanate to give the corresponding thioacetanilide derivatives. Treatment of the latter ethanone and thioacetanilide derivatives with hydrazonoyl chlorides afforded the corresponding pyrazole and 1,3,4-thiadiazole derivatives. The thioacetanilide derivative reacted with alpha-haloketones and alpha-halodiketones to afford thiophene and thiazole derivatives, respectively. The newly synthesized compounds were found to possess anticonvulsant and anti-inflammatory activities with the same mechanism of action of selective COX-2 inhibitors.

Biological activity of plant extracts: novel analgesic drugs

The plant-derived secondary metabolites have, over the years, greatly contributed to our current understanding of the important mechanisms related to the process of pain transmission and treatment. Furthermore, they have permitted us to characterise receptor types and identify endogenous ligands involved in the mechanism of nociception. In this review, we discuss the recent advances that have occurred regarding plant-derived substances in the process of development of new analgesic drugs. Plants, such as Papaver somniferum, Cannabis sativa and those of the Capsicum and Salix species, have greatly accounted for the development of clinically relevant drugs which are useful for the management of pain disorders. The recent advances in our understanding of the mechanisms of action of the above plant-derived substances, together with use of molecular biology techniques, have greatly accelerated attempts to identify promising targets for the discovery of new, safe and efficient analgesic drugs. Despite the great progress which has occurred in the elucidation of pain transmission and despite decades of use, leaving aside its known undesirable sides effects, morphine continues to be one of the most used drugs in clinical practice for the treatment of pain disorders. Thus, safer and more efficacious analgesic drugs are urgently needed. A search through the literature reveals that many potentially active antinociceptive plant-derived compounds have been identified. However, studies aiming to investigate their cellular and molecular mechanisms of action and well-controlled clinical trials to prove their efficacy in humans are still lacking. Nevertheless, natural or synthetic substances that bind to vanilloid or cannabinoid receptors, or even those that are capable of modulating the endogenous ligands which bind to these receptors, are expected to soon appear to assist in the treatment of several pain disorders, including those of neuropathic or neurogenic origin.

Cardiovascular effects of trans-dehydrocrotonin, a diterpene from Croton cajucara in rats

Previous studies have established the gastroprotective, hypoglycemic, and hypolipidemic effects of trans-dehydrocrotonin (t-DCTN), a major diterpene isolated from the Amazon medicinal plant Croton cajucara. This study aims to examine the potential effects of t-DCTN on hemodynamic parameters that include resting arterial blood pressure and heart rate in vivo, and on left atrial force, spontaneous beating atria, and aortic rings of rats in vitro. Intravenous bolus injections of t-DCTN (5, 10, or 15 mg/kg) to urethane anesthetized normotensive rats reduced the mean arterial pressure and heart rate in a dose-dependent manner. The hypotensive effect of t-DCTN (10 mg/kg) appears not mediated through effects on the muscarinic cholinergic receptor, beta-adrenoceptor, or ganglionic blockade, for it was not affected by atropine, propranolol, or hexamethonium but was abolished by N(w)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor. The diterpene t-DCTN showed no significant influence on inotropism. In isolated rat aortic rings with intact or denuded endothelium, t-DCTN relaxed the tonic contraction induced by phenylephrine (1 microM). Its vasorelaxant effect seen at smaller concentrations in endothelium intact preparations was, however, abolished in endothelium denuded or in l-NAME treated tissues. These data indicate the hypotensive and bradycardia effects of t-DCTN, possibly related in part to the release of nitric oxide and in part to direct effects on vascular smooth muscle, and cardiac pacemaker activity.

Antinociceptive and Anti-Inflammatory Effects of the Saponin and Sapogenins Obtained from the Stem of Akebia quinata

The stem of Akebia quinata Decasisne (Lardizabalaceae) has been used to treat urinary tract inflammatory disease. It has been reported that saponins in medicinal plants may act as bioactive components after biodegradation to sapogenins in the gastrointestinal tract. To find the active components, we obtained the methanol (MeOH) extract from A. quinata stems and fractionated this extract into CHCl(3), butanol (BuOH), and H(2)O fractions. A saponin-containing BuOH fraction was refluxed in an acidic solution to yield the hydrolyzed fraction. Silica gel column chromatography separated kalopanaxsaponin A (1) from the BuOH fraction, and oleanolic acid (2) and hederagenin (3) were obtained from the hydrolyzed fraction. The antinociceptive effect was tested by hot plate-writhing and tail-flicks methods using mice, and the anti-inflammatory effect was assayed using carrageenan-induced rat edema against the following samples: the MeOH extract of A. quinata stems, its fractions, the isolated saponin, kalopanaxsaponin A, and the sapogenins hederagenin and oleanolic acid. The MeOH extract exhibited antinociceptive/anti-inflammatory effects by oral administration of 100 and 250 mg/kg doses, indicating that the MeOH extract has an antinociceptive/anti-inflammatory activity. The BuOH fraction (crude saponin) also significantly exhibited those bioactivities. Treatments with 10 and 30 mg/kg perorally of these two sapogenins produced significant antinociceptive/ anti-inflammatory effects in the rat, suggesting that the sapogenins may act as resultant active compounds. Compounds 2 and 3 inhibited dye leakage into the peritoneal cavity induced by acetic acid, and the latter was more active than the former. The anti-inflammtory effects were further supported by the reduction of carrageenan-induced lipid peroxidation and hydroxy radical content in serum. These results suggest that the antinociceptive/anti-inflammatory properties of the stem of A. quinata can be attributed to the sapogenins oleanolic acid and hederagenin.

Anti-inflammatory and Anti-nociceptive Effects of the Methanol Extract of Fomes fomentarius

In an attempt to find bioactive natural products with an anti-inflammatory activity, we evaluated the effects of the methanol extract of Fomes fomentarius (MEFF) on in vivo anti-inflammatory and anti-nociceptive activities. MEFF (50, 100 mg/kg/d, p.o.) reduced acute paw edema induced by carrageenin in rats, and showed MEFF analgesic activity, as determined by an acetic acid-induced writhing test and a hot plate test in mice. To investigate the mechanism of the anti-inflammatory action of MEFF, we examined the effect of MEFF on lipopolysaccharide (LPS)-induced responses in murine macrophages cell line RAW 264.7. MEFF potently inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor-alpha (TNF-alpha) in LPS-stimulated RAW 264.7 macrophages. Consistent with these observations, inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) levels were reduced by MEFF in a dose-dependent manner. Furthermore, MEFF suppressed nuclear factor-kappaB (NF-kappaB) activation in LPS-stimulated RAW 264.7 macrophages. These findings suggest that the anti-inflammatory and anti-nociceptive properties of the methanol extract of MEFF may result from the inhibition of iNOS and COX-2 expression through the down-regulation of NF-kappaB binding activity.

Antileishmanial activity of a linalool-rich essential oil from Croton cajucara

The in vitro leishmanicidal effects of a linalool-rich essential oil from the leaves of Croton cajucara against Leishmania amazonensis were investigated. Morphological changes in L. amazonensis promastigotes treated with 15 ng of essential oil per ml were observed by transmission electron microscopy; leishmanial nuclear and kinetoplast chromatin destruction, followed by cell lysis, was observed within 1 h. Pretreatment of mouse peritoneal macrophages with 15 ng of essential oil per ml reduced by 50% the interaction between these macrophages and L. amazonensis, with a concomitant increase by 220% in the level of nitric oxide production by the infected macrophages. Treatment of preinfected macrophages with 15 ng of essential oil per ml reduced by 50% the interaction between these cells and the parasites, which led to a 60% increase in the amount of nitric oxide produced by the preinfected macrophages. These results provide new perspectives on the development of drugs with activities against Leishmania, as linalool-rich essential oil is a strikingly potent leishmanicidal plant extract (50% lethal doses, 8.3 ng/ml for promastigotes and 8.7 ng/ml for amastigotes) which inhibited the growth of L. amazonensis promastigotes at very low concentrations (MIC, 85.0 pg/ml) and which presented no cytotoxic effects against mammalian cells.

Antinociceptive and Antiinflammatory Effects of Niga-ichigoside F1 and 23-Hydroxytormentic Acid Obtained from Rubus coreanus

As an attempt to search for bioactive natural constituents exerting antinociceptive and antiinflammatory activities, we examined the potency of the extract of Rubus coreanus fruits by the activity-guided fractionation. The EtOAc- and BuOH fraction and those alkaline hydrolysates showed significant antinociceptive effects as assessed by writhing-, hot plate- and tail flicks tests in mice and rats as well as antiinflammatory effect in rats with carrageenan-induced edema. BuOH extract was subjected to column chromatography to obtain a large amount of niga-ichigoside F(1) (1,23-hydroxytormentic acid 28-O-glc), which was again hydrolyzed in NaOH solution to yield an aglycone 23-hydroxytormentic acid (1a). The aglycone, 23-hydroxytormentic acid, was much more potent in both antinociceptive and antiinflammatory tests than the glycoside, niga-ichigoside F(1). The antiinflammatory effects of these compounds were further supported by the reduction of carrageenan-induced lipid peroxidation and hydroxyl radical in serum. These results suggested that 23-hydroxytormentic acid might be an active moiety of niga-ichigoside F(1) present in R. coreanus.

Effect of essential oil obtained from Croton cajucara Benth. on gastric ulcer healing and protective factors of the gastric mucosa

The bark of Croton cajucara Benth. (Euphorbiaceae) is used widely in Amazonian folk medicine for the treatment of a wide range of gastrointestinal symptoms. Infusions of C. cajucara bark contain dehydrocrotonin (DHC), the furan diterpene, and an essential oil, a rich mixture of sesquiterpenes. Although the antiulcerogenic activity of the essential oil has been studied in different gastric ulcer models in mice and rats, its mechanism remains unclear. In this work, we examined the ability of this essential oil to increase PGE2 release from mucus cells, as well as its effects on the amount of gastric mucus and on the healing of acetic acid-induced gastric ulcers. The essential oil (100 mg/kg body wt., p.o), significantly increased PGE2 production by glandular cells (by 102% as compared to control) and the amount of Alcian blue binding to the gastric mucus. In chronic gastric ulcers, a single daily oral dose of essential oil (100 mg/kg body wt.) for 14 consecutive days accelerated ulcer healing to an extent similar to that seen with an equal dose of cimetidine. Thus, the protective and healing actions of the essential oil from C. cajucara bark on gastric lesions resulted mainly from an increase in PGE2 release and gastric mucus formation which would protect the gastric mucosa.

Blood glucose- and triglyceride-lowering effect of trans-dehydrocrotonin, a diterpene from Croton cajucara Benth., in rats

AIM

The objective of this study was to assess in rats the antidiabetic effects (i.e. reduction of hyperglycaemia and hypertriglyceridaemia) of trans-dehydrocrotonin (t-DCTN), a bioactive diterpene isolated from the popular medicinal plant Croton cajucara.

METHODS

Hyperglycaemia was induced by intraperitoneal injection of streptozotocin (STZ) and hypertriglyceridaemia by oral administration of ethanol in rats. The blood glucose levels were measured by the glucose oxidase method using commercially available enzyme kits.

RESULTS

Treating rats with t-DCTN (50 mg/kg) significantly reduced STZ-induced increases in blood glucose levels as well as ethanol-induced increases in blood triglycerides.

CONCLUSION

The results suggest that t-DCTN has an antidiabetic potential that warrants further research on its mechanism and clinical significance.

Effects of Ferula gummosa Boiss. fractions on morphine dependence in mice

Activity-guided fractionation of methanol-chloroform (1:1) extract of Ferula gummosa was carried out to investigate the isolation of the active component(s) responsible for the alleviation of morphine withdrawal syndrome induced by naloxone. Dependence was induced using subcutaneous (s.c.) injections of morphine daily for three days. On day 4, morphine was injected 0.5 h before the interaperitoneal (i.p.) injections of fractions or diazepam (5 mg/kg, i.p.) as positive control. Naloxone was injected (5 mg/kg, s.c.) 2 h after the final dose of morphine. The number of episodes of jumping during 30 min after the injection of naloxone was considered as the intensity of the withdrawal syndrome. The methanol-chloroform (1:1) extract of the aerial parts of plant was prepared and partitioned between water and chloroform. The active chloroform layer was concentrated and partitioned between methanol-water (9:1) and n-hexane. Activity was observed in the hydroalcoholic layer. This layer was concentrated and partitioned further between methanol-water (3:2) and chloroform. The chloroform layer showed a dose-dependent and significant activity. For all fractions the activity was observed at 470 mg/kg. Further purification on silica gel column chromatography gave a pure compound, which was 10 times as effective as the crude extract. The results of this study indicated that the plant extract contained component(s) that could be useful for the alleviation of morphine withdrawal syndrome.

The lipid-lowering effect of trans-dehydrocrotonin, a clerodane diterpene from Croton cajucara Benth. in mice fed on high-fat diet

The clerodane diterpene trans-dehydrocrotonin extracted and isolated from the stem bark of Croton cajucara Benth. was investigated for its lipid-lowering effect in mice fed on a high-fat diet. Mice fed on a high-fat diet for a two-week period demonstrated significantly increased blood levels of total cholesterol and triglycerides, compared with normal controls. Oral treatment with trans-dehydrocrotonin at a dose of 25 or 50 mg kg(-1) daily markedly suppressed the high-fat-diet associated rise in total cholesterol and triglyceride levels. The hypocholesterolaemic effect of trans-dehydrocrotonin was more prominent at the dose of 50 mg kg(-1) with significant decreases in high-density lipoprotein, very-low-density lipoprotein and low-density lipoprotein cholesterol levels. The lower atherogenic index of the trans-dehydrocrotonin-treated groups suggests the hypolipidaemic potential of this plant-based drug. These results indicate that orally administered trans-dehydrocrotonin is effective in suppressing high-fat-diet-induced hyperlipidaemia in mice and suggest its likely beneficial use as anti-atherogenic agent.

Effect of Boschniakia rossica on expression of GST-P, p53 and p21ras proteins in early stage of chemical hepatocarcinogenesis and its anti-inflammatory activities in rats

AIM: To investigate the effect of Boschniakia rossica (BR) extract on expression of GST-P, p53 and p21^ras proteins in early stage of chemical hepatocarcinogenesis in rats and its anti-inflammatory activities.

METHODS: The expression of tumor marker-placental form glutathione S-transferase (GST-P), p53 and p21^ras proteins were investigated by immunohistochemical techniques and ABC method. Anti-inflammatory activities of BR were studied by xylene and croton oil-induced mouse ear edema, carrageenin, histamine and hot scald-induced rat pow edema, adjuvant-induced rat arthritis and cotton pellet-induced mouse granuloma formation methods.

RESULTS: The 500 mg/kg of BR-H₂O extract fractionated from BR-Methanol extract had inhibitory effect on the formation of DEN-induced GST-P-positive foci in rat liver (GST-P staining was 78% positive in DEN+AAF group vs 20% positive in DEN+AAF+BR group, P < 0.05) and the expression of mutant p53 and p21^ras protein was lower than that of hepatic preneoplastic lesions (33% and 22% positive respectively in DEN+AAF group vs negative in DEN+AAF+BR group). Both CH₂Cl₂ and H₂O extracts from BR had anti-inflamatory effect in xylene and croton oil-induced mouse ear edema (inhibitory rates were 26%-29% and 35%-59%, respectively). BR-H₂O extract exhibited inhibitory effect in carrageenin, histamine and hot scald-induced hind paw edema and adjuvant-induced arthritis in rats and cotton pellet-induced granuloma formation in mice.

CONCLUSION: BR extract exhibited inhibitory effect on formation of preneoplastic hepatic foci in early stage of rat chemical-hepato-carcinogenesis. Both CH₂Cl₂ and H₂O extracts from BR exerted anti-inflammatory effect in rats and mice.

Naturally occurring antinociceptive substances from plants

Despite the progress that has occurred in recent years in the development of therapy, there is still a need for effective and potent analgesics, especially for the treatment of chronic pain. One of the most important analgesic drugs employed in clinical practice today continues to be the alkaloid morphine. In this review, emphasis will be given to the important contribution and the history of Papaver somniferum, Salix species, Capsicum species and Cannabis sativa in the development of new analgesics and their importance in the understanding of the complex pathways related to electrophysiological and molecular mechanisms associated with pain transmission. Recently discovered antinociceptive substances include alkaloids, terpenoids and flavonoid. Plant-derived substances have, and will certainly continue to have, a relevant place in the process of drug discovery, particularly in the development of new analgesic drugs.

Ethnopharmacology, phytochemistry and pharmacology: a successful combination in the study of Croton cajucara

Phytochemical and pharmacological studies of Croton cajucara were oriented by traditional medicine. The stem bark of the mature plant is a rich source of clerodane-type diterpenes: trans-dehydrocrotonin (DCTN), trans-crotonin (CTN), cis-cajucarin B, cajucarin A, cajucarinolide and two novel clerodanes, trans-cajucarin B and sacacarin. In young (18-month-old) plants, the triterpene acetyl aleuritolic acid (AAA) was the major stem bark component and in these the diterpene DCTN was not present. The highest concentration of DCTN (1.4% of dry bark) was detected in 4-6 year-old plants, while 3-year-old plants contained only 0.26% of this diterpene. Three steroids (beta-sitosterol, stigmasterol and sitosterol-3-O-beta-glucoside), two flavonoids (kaempferol 3,4', 7-trimethyl ether and 3,7-dimethyl ether) and one diterpene (cajucarinolide) were isolated from the leaves of this Croton. The main pharmacological activity was correlated with DCTN. This clerodane produced anti-inflammatory and antinociceptive effects and a significant hypoglycemia in alloxan-induced diabetic rats. The compound also reduced the index of gastric lesions induced by restraint-in-cold. Dose-related DCTN and CTN inhibited in vivo the basal acid secretion in pylorus-ligature rats and oxyntic glands isolated from rabbit gastric mucosa, DCTN, CTN or AAA decreased in vitro uptake basal acid secretion induced by histamine and measured with the 14C-aminopyrine uptake method. Uniquely DCTN inhibited 14C-AP uptake induced by bethanechol. The terpenoids, DCTN and AAA, and the chloroform extract of 6-month-old plants reduced gastrointestinal transit in mice. The effects of DCTN and CTN on the survival of mice bearing Sarcoma 180 and Ehrlich carcinoma ascitic tumors, on the proliferation of cultured cells and TNFalpha were determined. DCTN was also evaluated for a possible antioestrogenic activity using the immature rat as a model system for bioassay of oestrogen and for an anti-implantation effect in regularly cycling rats. The biological experiments, using the plant extracts and the terpenoids DCTN, CTN and AAA, are herein discussed.

Investigation of genotoxic activity of trans-dehydrocrotonin, a clerodane diterpene from Croton cajucara

The genotoxic action of three doses of trans-dehydrocrotonin (t-DCTN), an active ingredient obtained from the bark extracts of an Amazon native plant, Croton cajucara, were examined in Swiss mouse bone marrow cells in vivo, submitted to acute intraperitoneal treatment, by micronucleus (MN) and chromosomal aberration (CA) tests. The statistical tests (Anova and Tukey) made to compare the results obtained in each of the three doses of t-DCTN with the negative-control group showed that the frequencies of MN and mitotic index were equal to the negative-control and that the frequencies of CA were lower than that observed in the negative-control. Therefore, based on our results it can be said that t-DCTN is not genotoxic nor cytotoxic to mouse bone marrow cells, submitted to acute intraperitoneal treatment in vivo. Teratogenesis Carcinog. Mutagen. 19:377-384, 1999.

Anti-inflammatory and antinociceptive effects in rodents of the essential oil of Croton cajucara Benth

The plant Croton cajucara Benth. (Euphorbiaceae) is widely used in Amazonian folk medicine for the treatment of a wide range of illnesses. In this investigation the analgesic and anti-inflammatory properties of the essential oil from the bark of C. cajucara Benth., administered orally, were determined in several standard rodent models of pain and inflammation. We observed that pretreatment with essential oil significantly reduced the latency of sleeping time evoked by pentobarbital compared with the control group (P < 0.001). Doses of 100 or 1000 mg kg(-1) also increased the sleeping time induced by pentobarbital (30.9 +/- 3.91 and 52.1 +/- 15.6 min, respectively) compared with the negative control (12.4 +/- 4.27 min). We investigated the antinociceptive effect of the essential oil in chemical (acetic acid) and thermal (hot-plate) models of nociception in mice. Dipyrone (200 mg kg(-1)) and the highest doses of the essential oil (1000 mg kg(-1)) significantly inhibited acetic acid-induced abdominal constriction in mice (5.00 +/- 1.38 and 6.8 +/- 2.1 constrictions, respectively) compared with the negative control (33.1 +/- 2). The same dose of essential oil also raised the pain thresholds of mice in the hot-plate test and significantly (P < 0.05) increased the latency at all observation times. In acetic acid-induced abdominal constriction in mice pretreatment of the animals with naloxone (5 mg kg(-1)) significantly reversed the analgesic effect of morphine and of the essential oil at the highest dose (1000 mg kg(-1)). The essential oil of C. cajucara was also investigated for its anti-inflammatory properties. At the lowest dose (100 mg kg(-1)) the essential oil had anti-inflammatory effects in animal models of acute (carrageenin-induced paw oedema in mice) and chronic (cotton pellet granuloma) inflammation. The essential oil at doses of 50, 100 and 200 mg kg(-1) significantly and dose-dependently inhibited carrageenan-induced oedema (49 +/- 5; 37 +/- 5; 34 +/- 8 mg, respectively) compared with the negative control (74 +/- 8 mg). The essential oil (100 mg kg(-1)) also inhibited chronic inflammation by 38% whereas diclofenac inhibited it by 36%. However, the essential oil did not inhibit the migration of neutrophils into the peritoneal cavity. These data show that the essential oil from C. cajucara contains compounds that had a significant antinociceptive effect when the oil was administered at the highest dose. This effect seems to be related to interaction with the opioid system. The essential oil also had a significant anti-inflammatory effect in acute and chronic inflammation models when administered at lower doses. This effect seems to be related to cyclooxygenase inhibition.

Antioestrogenic effect of trans-dehydrocrotonin, a nor-clerodane diterpene from Croton cajucara Benth. in rats

This study examined trans-dehydrocrotonin (t-DCTN), a nor-clerodane diterpene isolated from the Brazilian medicinal plant Croton cajucara Benth., for a possible antioestrogenic activity using immature rats as a model system for bioassay of oestrogen, and for an antiimplantation effect in regularly cycling rats of proven fertility. In the antioestrogen test, t-DCTN (25 and 50 mg/kg) effectively prevented oestrogen-induced increases of uterine wet weights. In addition, the vaginal openings provoked by oestrogen were completely prevented by t-DCTN. However, blastocyst-implantation was only insignificantly affected in t-DCTN pretreated animals. These results suggest that t-DCTN may be an antioestrogen and warrants further studies with regard to its mechanism of action.

Proteins of rat serum IV. Time-course of acute-phase protein expression and its modulation by indomethacine

Changes in the concentration of major serum proteins were monitored from day 0 to day 4 in three experimental groups: rats injected with turpentine, rats receiving the turpentine shot and daily doses of indomethacine, and rats given indomethacine alone. In inflamed animals, peak changes for acute-phase reactants, evaluated by two-dimensional electrophoresis (2-DE), were usually observed between 48 and 72 h after the phlogistic stimulus. By itself, indomethacine was found to affect the synthesis of most proteins (except one of the thiostatin variants and ceruloplasmin); the changes in serum levels, whether positive or negative, were the same as upon inflammation (except for kallikrein-binding protein), but their extent and/or timing usually differed. When inflamed animals were given indomethacine, a clear-cut difference in the concentration of some proteins was observed versus inflamed rats not given medication, at 24 h after the start of the treatments. Proteins mainly affected were alpha2-macroglobulin, alpha2-HS-glycoprotein, C-reactive protein and kallikrein-binding protein.