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At least 217 records · Page 12Linked to original sources
PubMed1997

Effects of Sangre de Drago from Croton lechleri Muell.-Arg. on the production of active oxygen radicals.

The total reactive antioxidant potential (TRAP) of 'Sangre de Drago' from Croton lechleri (Euphorbiaceae) was determined by monitoring the intensity of luminol enhanced chemiluminescence enhanced by peroxyl radicals derived from thermolysis of 2,2'-azo-bis(2-amidinopropane). The TRAP index was calculated as 935.4 +/- 141 microM, measured as equivalents of Trolox concentration. On the other hand, the additive incorporation of lower concentrations yielded an instantaneous increase in chemiluminescence, suggesting a prooxidant activity at these levels. DNA sugar damage induced by Fe(II) salts was also used to determine the capacity of the latex to suppress hydroxyl radical-mediated degradation of DNA. As in the case of luminol enhanced chemiluminescence, Sangre de Drago was highly effective in reducing oxidation of DNA at higher concentrations, but showed an increase in the production of TBARS at lower doses, as compared to the control. Finally, antioxidant activity was tested using hydroperoxide-initiated chemiluminescence in rat liver homogenates, and the latex showed an increase in light emission, suggesting the presence of prooxidant compounds.

Animals↗
PubMed2000

Gastroprotective effect of essential oil from Croton cajucara Benth. (Euphorbiaceae).

The gastroprotective activity of the essential oil from the bark of Croton cajucara Benth (Euphorbiaceae) was assessed in three different models of experimentally induced gastric ulcer in mice. At oral dose of 100 mg/kg the essential oil reduced gastric lesions induced by hypothermic restraint stress and HCl/ethanol significantly. In the HCl/ethanol model a dose-dependent gastroprotective effect was found. Moreover, significant changes in gastric parameters such as pH, secretion rate and total gastric acid were found after intraduodenal administration of essential oil under ligated pylorus (Shay) conditions. The acute toxicity of essential oil was assessed in mice. The LD50 values were 9.3 and 680 mg/kg for oral and intraperitoneal administrations, respectively. The cytotoxicity of essential oil was studied also. A dose-dependent cell viability inhibition was found in V79 fibroblast cell cultures with an IC50 of 22.9 microg/ml. Our results support the pharmacological study of this essential oil.

Animals↗
PubMed2001

Reaction of cyclohexanone benzylimines with ethylidenemalonate diesters. Diphenyl 2-ethylidenemalonate: a highly electrophilic synthetic equivalent of crotonic esters.

The diastereoselective Michael alkylation of alpha-substituted and alpha,alpha'-disubstituted cyclohexanone benzylimines with ethylidenemalonate diesters was carried out for mechanistic and synthetic purposes. In the first case, an inverse regioselectivity occurred in comparison with what is generally observed since the Michael adducts resulted from alkylation of the non substituted enamine tautomer. With alpha,alpha'-disubstituted imines, in all cases, the stereochemistry of the major diastereomer was the one anticipated from a mechanism including a chairlike complex approach with a preferred exo position for the beta-methyl group of the ethylidenemalonic acid diesters. Furthermore, diphenyl 2-ethylidenemalonate 4 was found to be a highly electrophilic synthetic equivalent of crotonic esters.

Journal Article↗
PubMedDate not supplied

Dereplication of phorbol bioactives: Lyngbya majuscula and Croton cuneatus.

Lyngbya majuscula and Croton cuneatus were used as prototypes for the dereplication of phorbol ester receptor binding activity using a combination of hplc-uv and online phorbol dibutyrate (PDBu) receptor binding and batch fractionation over either Si gel or diolbonded Si gel. Debromoaplysiatoxin was responsible for the bioactivity of Lyngbya, whereas a complex of potent phorbol esters was detected in C. cuneatus.

Binding, Competitive↗
PubMed1998

Croton ruizianus: platelet proaggregating activity of two new pregnane glycosides.

The MeOH extract of the aerial parts of Croton ruizianus afforded two new pregnane glycosides 1 and 2, together with the morphinandienone alkaloids flavinantine (3) and O-methylflavinantine (4). Their structures were elucidated by NMR experiments including 1H-1H (1D TOCSY and 2D DQF-COSY) and 1H-13C (HSQC, HMBC) spectroscopy. The proaggregating activity of the MeOH extract and the isolates were evaluated. Although the MeOH extract and pregnane glycosides (at different doses) were found to promote platelet aggregation, flavinantine (3) and O-methylflavinantine (4) showed only slight activity. The ability of the MeOH extract and the four compounds to act synergistically with thrombin was also evaluated. All the tested compounds were successful in augmenting the aggregating effect of thrombin, although to different degrees.

Blood Platelets↗
PubMed1998

Two new cembranoids from croton oblongifolius

Two new cembranoids, crotocembraneic acid (1) and neocrotocembraneic acid (2), were isolated from the stem bark of Croton oblongifolius. Their structures were established on the basis of spectroscopic analysis.

Journal Article↗
PubMed1999

Neocrotocembranal from Croton oblongifolius.

A new cembranoid diterpene, neocrotocembranal (3), was isolated from the stem bark of Croton oblongifolius. Its structure was established on the basis of spectroscopic analysis. This compound inhibited platelet aggregation induced by thrombin, with an IC50 value of 47.21 microg/mL, and exhibited cytotoxicity against P-388 cells in vitro, with an IC(50) value of 6.48 microg/mL.

Animals↗
PubMed2003

Raman spectroscopic analysis of dragon's blood resins-basis for distinguishing between Dracaena(Convallariaceae), Daemonorops(Palmae) and Croton(Euphorbiaceae).

"Dragon[prime or minute]s blood" is the name applied to the deep-red coloured resin obtained from various plants. The original source in Roman times, used by many cultures and esteemed for its depth of colour and mystical association, was the dragon tree Dracaena cinnabari(Convallariaceae), found only on the Indian Ocean island of Socotra, (Yemen). Additional sources emerged later, including another species of Dracaena, D. draco, from the Canary Islands and Madeira, and species in the genera Daemonorops(Palmae) from South East Asia and Croton(Euphorbiaceae) from tropical parts of both the New and Old Worlds. In this study, examples of dragon's blood resins from the Economic Botany Collections at the Royal Botanic Gardens, Kew, dating from 1851 to 1993, have been analysed non-destructively using Raman spectroscopy. The Raman spectra of well-documented, provenanced specimens have been used to establish the source of specimens of questionable or unknown origin. It has also been possible from the Raman spectra to indicate whether processing of the resins has been undertaken in the preparation of the specimens before their deposition at Kew.

Dracaena↗
PubMed1999

Antiulcerogenic mechanisms of dehydrocrotonin, a diterpene lactone obtained from Croton cajucara.

The bark of Croton cajucara Benth, is used in Brazilian folk medicine as an infusion to treat gastrointestinal disorders. The aim of the present study was to assess the mechanisms involved in the antiulcerogenic activity of dehydrocrotonin (DHC), a diterpene isolated from C. cajucara bark. We studied the effects of DHC on pylorus ligature (Shay) in mice treated with the drug (100 mg/kg) by the intraduodenal route. DHC did not induce any alteration in gastric volume in Shay mice but modified the pH and total acid concentration of gastric juice. Incubation of gastric juice with DHC did not reduce gastric acidity compared to control. We also investigated the effects of DHC on the response to histamine of right atria isolated from guinea pigs and on the response to carbachol of stomach fundus strips from rats. The concentration-response curves for the chronotropic effect of histamine in guinea pig right atria were shifted to the right, with a significant decrease in the maximum response, in the presence of DHC. Similar results were obtained with DHC (30 microM) for the concentration-response curves to carbachol in the isolated rat stomach. The ability of DHC to increase PGE2 release from rat stomach mucous cells was also studied. We observed that DHC induced a significant increase in PGE2 production (60% compared to control). In addition, the effects of DHC on the healing of acetic acid-induced gastric ulcer in rats were evaluated 14 days after acid injection. Oral administration of DHC (100 mg/kg per day) for 14 consecutive days had no effect on gastric ulcer healing in rats. Thus, the protective effect of DHC on induced gastric lesions could be due to synergistic effects, e.g., an increase in PGE2 release and non-competitive antagonism of H2-receptors and of muscarinic receptors. Whereas the former result represents an increase in the protective factors, the latter one shows a decrease in the aggressive factors against the gastric mucosa.

Animals↗
PubMed1999

Cytotoxicity of trans-dehydrocrotonin from Croton cajucara on V79 cells and rat hepatocytes.

The cytotoxicity of trans-dehydrocrotonin (DHC), an antiulcerogenic diterpene from Croton cajucara (Euphorbiaceae), was assessed on a V79 fibroblast cell line and on rat hepatocytes. Three independent endpoints for cytotoxicity were evaluated: DNA content, MTT reduction and neutral red uptake (NRU). For the V79 cells IC50 values of 253 and 360 microM were obtained for the NRU and MTT tests. The cytotoxic effect of DHC was time exposure dependent and no ability to recover after treatment was observed. For the rat hepatocytes IC50 values of 8, 300 and 400 microM for the MTT, DNA and NRU assays were obtained. The greater toxicity observed for the MTT test was inhibited when the experiment was performed using non-fresh hepatocytes in an age-dependent fashion. The treatment of V79 cells with the conditioned medium resulting after hepatocyte incubation with DHC showed an enhancement of MTT reduction without any evident toxic effects on fibroblasts. These results suggest that DHC has basal cytotoxic effects as observed on V79 fibroblasts and expresses a selective cytotoxicity after its metabolization by the hepatocytes. The bioactivation of DHC is mediated by cytochrome P450 and could generate metabolites that have no toxicity for V79 fibroblasts.

Animals↗
PubMed1999

Cardiovascular effects of the essential oil of Croton nepetaefolius in rats: role of the autonomic nervous system.

Cardiovascular effects of intravenous (i.v.) treatment with the essential oil of Croton nepetaefolius (EOCN) were investigated in rats. Additionally, this study examined the importance of the autonomic nervous system in mediation of the EOCN-induced changes in mean aortic pressure (MAP) and heart rate (HR). In both pentobarbitone-anaesthetised and conscious rats, i.v. bolus injections of EOCN (1 to 50 mg/kg) elicited dose-dependent decreases in MAP and HR. Both decreases were of the same order of magnitude or duration, irrespective of whether the animal was under general anaesthesia. Pretreatment of anaesthetised rats with bilateral vagotomy reduced the magnitude of EOCN-induced bradycardia without affecting hypotension. Likewise, i.v. pretreatment of conscious rats with either methylatropine (1 mg/kg) or hexamethonium (30 mg/kg) significantly decreased the bradycardic effects of EOCN by the same order of magnitude. Neither compound influenced the hypotensive effects elicited by EOCN. This is the first physiological evidence that i.v. treatment with EOCN in either anaesthetised or conscious rats elicits hypotension and bradycardia. EOCN-induced bradycardia appears dependent upon the presence of an intact and functional parasympathetic nerve drive to the heart. However, EOCN-induced hypotension appears independent of the presence of an operational sympathetic nervous system. This suggests that EOCN may be a direct vasorelaxant agent.

Animals↗
PubMed1999

Anti-tumour activity of two 19-nor-clerodane diterpenes, trans-dehydrocrotonin and trans-crotonin, from Croton cajucara.

The effects of two nor-diterpenes, trans-dehydrocrotonin (DCTN) and trans-crotonin (CTN) from Croton cajucara (Euphorbiaceae), on the survival of mice bearing Sarcoma 180 and Ehrlich carcinoma ascitic tumours, on the proliferation of cultured Ehrlich cells and TNF alpha activity were determined. When the mice were treated with 80 and 120 mg/kg of DCTN or 38 mg/kg of 5-FU a significant anti-tumour activity was obtained (%T/C of 128-140). The cytotoxicity against Ehrlich carcinoma was 16 microM for DCTN and CTN whereas the flavonoid quercetin was cytotoxic at 44 microM in 48 h cell culture. No apoptosis was seen on in vitro electrophoresis of DNA extracted from the tumour cells treated with DCTN and CTN. A significant TNF alpha activity was detected in Ehrlich tumour-bearing mice treated with DCTN suggesting an enhanced immune function.

Animals↗
PubMed2000

Essential oil of Croton nepetaefolius decreases blood pressure through an action upon vascular smooth muscle: studies in DOCA-salt hypertensive rats.

Experiments tested the hypothesis that hypotensive effects of intravenous (i.v.) treatment with the essential oil of Croton nepetaefolius (EOCN) result from its vasodilatory effects directly upon vascular smooth muscle. In both deoxycorticosterone-acetate (DOCA)-salt hypertensive and uninephrectomised control, conscious rats, i.v. bolus injections of EOCN (1 to 50 mg/kg) decreased mean aortic pressure (MAP) and heart rate (HR) in a dose-related manner. Treatment with DOCA-salt significantly enhanced EOCN-induced decreases in MAP without affecting bradycardia. Likewise, both maximal percent and absolute decreases in MAP elicited by i.v. hexamethonium (30 mg/kg), a ganglion blocker, were significantly greater in DOCA-salt hypertensive than in control rats. In DOCA-salt hypertensive rats, i.v. pretreatment with hexamethonium (30 mg/kg) reduced the bradycardia elicited by EOCN (50 mg/kg) without affecting the enhancement of EOCN-induced hypotension. In isolated thoracic aorta preparations from DOCA-salt hypertensive rats, EOCN (1-300 micrograms/ml) induced a concentration-dependent reduction of phenylephrine-induced contraction. Arteries from DOCA rats showed increased sensitivity to EOCN, as evidenced by the significant decrease in the IC50 for EOCN-induced reduction of phenylephrine-induced contraction (16.4 +/- 3.6 vs. 112.9 +/- 23.4 micrograms/ml in uninephrectomized controls). These results show that i.v. treatment with EOCN dose-dependently decreases blood pressure in conscious DOCA-salt hypertensive rats, and this action is enhanced when compared with uninephrectomized controls. This enhancement appears to be related mainly to an increase in EOCN-induced vascular smooth muscle relaxation rather than to enhanced sympathetic nervous system activity in this hypertensive model. Thus, the hypothesis that EOCN may be a direct vasorelaxant agent is supported by the results of the present study.

Animals↗
PubMed1998

Antiulcerogenic activity of trans-dehydrocrotonin from Croton cajucara.

trans-Dehydrocrotonin (DHC), the major diterpene isolated from Croton cajucara Benth, was assayed for antiulcerogenic activity in four induced gastric ulcer models in the rat. At an oral dose of 100 mg/kg DHC showed a significant antiulcerogenic effect on ulcers induced by hypothermic restraint stress, ethanol, and pylorus ligature. No significant changes in indomethacin-induced gastric lesions or modifications in gastric parameters such as wall mucus, secretion rate, pH, and total acid content were found after DHC treatment. The acute toxicological effects of DHC were assessed in mice. The LD50 values were 876 mg/kg and 47.2 mg/kg for oral and intraperitoneal administrations, respectively. The cytotoxicity of DHC was also studied. A dose-dependent inhibition of cell viability was observed in V-79 fibroblast cell cultures with an IC50 of 240 microM. The high yields of DHC obtained from dried C. cajucara barks as well as its good antiulcerogenic activity and low toxicity support the pharmacological study of this compound as a potential new antiulcerogenic drug.

Animals↗
PubMed1997

Hypoglycemic effect of trans-dehydrocrotonin, a nor-clerodane diterpene from Croton cajucara.

trans-Dehydrocrotonin (t-DCTN), a 19-nor-clerodane diterpene isolated from the bark of Croton cajucara Benth. (Euphorbiaceae) demonstrated a significant hypoglycemic activity in alloxan-induced diabetic rats but not in normal rats, at oral doses of 25 and 50 mg/kg body weight. The drug also effectively lowered the blood sugar levels in glucose fed normal rats. The hypoglycemic effect of t-DCTN was almost comparable to that produced by glibenclamide (2 mg/kg), a clinically useful drug. The results indicate the antihyperglycemic potential of t-DCTN.

Animals↗
PubMed1996

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

The anti-inflammatory and antinociceptive effects of trans-dehydrocrotonin, isolated from the bark of Croton cajucara (Euphorbiaceae), were investigated using several animal models. The trans-dehydrocrotonin produced a significant inhibition of carrageenin-induced paw edema and cotton pellet granuloma in rats. It also inhibited the writhings in mice induced by acetic acid, but did not show a significant effect in the hot-plate test in mice. The LD50 of t-DCTN was 555.0 mg/kg (p.o.) for mice.

Analgesics↗