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Cajucarinolide and isocajucarinolide, two new clerodane diterpenes, have been isolated from the cortices of Croton cajucara (Euphorbiaceae). These compounds possess anti-inflammatory activity and inhibit bee venom phospholipase A2 in vitro.
Sangre de Grado extract used by Peruvian natives as a cicatrizant agent, was collected from trees of the species Croton lechleri growing in the Peruvian jungle. The Sangre de Grado was found to contain one alkaloid identified as taspine and which was shown to be the active cicatrizant principle by an in vivo test in mice. This alkaloid exhibited a dose-related cicatrizant effect and an ED50 of 0.375 mg/kg. Experiments with taspine hydrochloride in order to study its mechanism of action in cell culture systems showed that the alkaloid was non-toxic to human foreskin fibroblasts at concentrations below 150 ng/ml and that it had no effect on cell proliferation. On the other hand, taspine hydrochloride was found to increase the migration of human foreskin fibroblasts. This effect on the migration of fibroblasts is probably the mechanism by which Sangre de Grado and taspine hydrochloride accelerate the wound healing process. Using the two-stage mouse skin carcinogenesis system, we have been able to show that neither Sangre de Grado nor taspine hydrochloride had carcinogenic or tumour promoter activity after 17 months of treatment.
The synthesis and crystal structures of three new yttrium crotonate (crot) compounds, associated with three different nitrogenous bases, namely 1,10-phenanthroline (phen), 4-methyl-1,10-phenanthroline (mphen) and 2,2'-bipyridylamine (bpa), are presented. All three compounds organize as centrosymmetric dimers, to give tetra-micro-crotonato-bis[crotonato(1,10-phenanthroline)yttrium(III)] dihydrate, [Y(2)(C(4)H(5)O(2))(6)(C(12)H(8)N(2))(2)].2H(2)O or [Y(crot)(3)(phen)](2).2H(2)O, (I), tetra-micro-crotonato-bis[crotonato(4-methyl-1,10-phenanthroline)yttrium(III)] dihydrate, [Y(2)(C(4)H(5)O(2))(6)(C(13)H(10)N(2))(2)].2H(2)O or [Y(crot)(3)(mphen)](2).2H(2)O, (II), and tetra-micro-crotonato-bis[diaqua(crotonato)yttrium(III)] 2,2'-bipyridylamine tetrasolvate, [Y(2)(C(4)H(5)O(2))(6)(H(2)O)(4)].4C(10)H(9)N(3) or [Y(crot)(3)(aq)(2)](2).4(bpa), (III). Complexes (I) and (II) are isomorphous, with the bases acting as chelating ligands. In complex (III), the coordination sphere is built up of carboxylate and aqua ligands, with the non-coordinated diimine acting as included solvent.
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.
Croton cajucara Benth. (Euphorbiaceae) is widely used in Amazonian folk medicine for the treatment of a wide range of gastrointestinal symptoms. The essential oil from its bark was investigated for acute toxicity in mice and for its ability to prevent the formation of ulceration of the gastric mucosa in different models of experimentally induced gastric ulcer in mice and rats. When previously administered orally at a dose of 100 mg kg(-1), the essential oil significantly reduced (P < 0.01) the gastric injury induced by hypothermic restraint stress (48%), indomethacin (47%), ethanol (86%) and pylorus ligature models (87%) in rats. In the HCl/ethanol-induced gastric ulcer model in mice, at oral doses of 100 and 200 mg kg(-1), the essential oil from C. cajucara significantly reduced (P < 0.01) the formation of gastric lesions by 52% and 67%, respectively, when compared with the control group. In rats submitted to pylorus ligature, the essential oil given orally increased the volume of gastric juice when compared with the control group (P < 0.01). When the essential oil (100 mg kg(-1)) was administered intraduodenally to mice, significant modifications were found in gastric parameters such as pH and total acid content after oil treatment. We observed significant changes (P < 0.01) in gastric juice parameters such as an increase in volume and a decrease in gastric acidity (pH and total acid content). The acute toxicologic effects of the essential oil from C. cajucara were assessed in mice. The LD50 values were 9.3 g kg(-1) by the oral route and 680 mg kg(-1) by the intraperitoneal route. The good yield of essential oil obtained from dried C. cajucara bark (1%) as well as its anti-ulcerogenic activity and low toxicity suggest that pharmacological studies of this substance as a potential new anti-ulcerogenic drug are warranted.
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.
cDNAs encoding geranylgeranyl diphosphate synthase (GGPPS) of two diterpene producing plants, Scoparia dulcis and Croton sublyratus, were isolated using the homology-based polymerase chain reaction method. Both cloned genes showed high amino acid sequence homology (60-70%) to other plant GGPPSs and contained highly conserved aspartate-rich motifs. The obtained clones were functionally expressed in Escherichia coli and showed sufficient GGPPS activity to catalyze the condensation of farnesyl diphosphate (FPP) and isopentenyl diphosphate to form geranylgeranyl diphosphate. To investigate the factor determining the product chain length of plant GGPPSs, S. dulcis GGPPS mutants in which either the small amino acids at the fourth and fifth positions before the first aspartate-rich motif (FARM) were replaced with aromatic amino acids or in which two additional amino acids in FARM were deleted were constructed. Both mutants behaved like FPPS-like enzymes and almost exclusively produced FPP when dimethylallyl diphosphate was used as a primer substrate, and failed to accept FPP as a primer substrate. These results indicate that both small amino acids at the fourth and fifth positions before FARM and the amino acid insertion in FARM play essential roles in product length determination in plant GGPPSs.
cDNAs encoding geranylgeranyl diphosphate synthase (GGPPS) of two diterpene-producing plants, Scoparia dulcis and Croton sublyratus, have been isolated using the homology-based polymerase chain reaction (PCR) method. Both clones contained highly conserved aspartate-rich motifs (DDXX(XX)D) and their N-terminal residues exhibited the characteristics of chloroplast targeting sequence. When expressed in Escherichia coli, both the full-length and truncated proteins in which the putative targeting sequence was deleted catalyzed the condensation of farnesyl diphosphate and isopentenyl diphosphate to produce geranylgeranyl diphosphate (GGPP). The structural factors determining the product length in plant GGPPSs were investigated by constructing S. dulcis GGPPS mutants on the basis of sequence comparison with the first aspartate-rich motif (FARM) of plant farnesyl diphosphate synthase. The result indicated that in plant GGPPSs small amino acids, Met and Ser, at the fourth and fifth positions before FARM and Pro and Cys insertion in FARM play essential roles in determination of product length. Further, when a chimeric gene comprised of the putative transit peptide of the S. dulcis GGPPS gene and a green fluorescent protein was introduced into Arabidopsis leaves by particle gun bombardment, the chimeric protein was localized in chloroplasts, indicating that the cloned S. dulcis GGPPS is a chloroplast protein.
Croton nepetaefolius Baill., is an aromatic plant native to the northeast of Brazil where it is extensively used in folk medicine as a sedative, orexigen and antispasmodic agent. In the present study the antinociceptive effects of the essential oil of C. nepetaefolius (EOCn), administered orally, were evaluated in male Swiss mice (20-25 g). In the acetic acid-induced writhing test, EOCn (100 and 300 mg/kg; N = 14 and N = 12, respectively) was effective at the highest dose. In the hot-plate test, EOCn at 30 and 300 mg/kg, but not at 3 mg/kg, significantly increased the latency at all observation times up to the 180th min (N = 12 for each dose). In the formalin test, EOCn significantly reduced paw licking in the second phase of the test at 100 mg/kg (N = 12), but decreased it in both phases at 300 mg/kg (N = 12). At 30 mg/kg, the effect of EOCn did not differ from control values in either phase of the formalin test (N = 6). Pretreatment with naloxone (5 mg/kg, ip) significantly reversed the analgesic effect of morphine (5 mg/kg, sc) on both phases, but not that of EOCn at 300 mg/kg (N = 6) on both phases of the formalin test. The data show that orally administered EOCn promotes a dose-dependent antinociceptive effect whose mechanisms remain to be elucidated.
Albino mice (8-10 wks) weighing between 14 and 25 g were divided into 2 groups and dosed orally once per week with 2 doses (7 mg/kg and 21 mg/kg) of the gut-stimulating principle in Croton penduliflorus seeds (CP crystals) for 12 weeks. Some mice (3-4) from each group were killed at 10 days intervals for the first 6 wks of the experiment and at 20 days intervals for the last 6 weeks. Gross and histopathological changes in the brain, heart, liver, kidney, adrenal, spleen, testis, lung and various segments of the gastrointestinal tract including the stomach, duodenum, ileum and colon were observed. The relative weights of the visceral organs were also recorded. Significant weight change in the spleen was evident. The congestion of the lung was the most common gross pathological observation made. Other observations were splenomegaly, enlarged heart, swollen uterine horns, etc. Histopathological changes observed included haemorrhages in the lungs, myocardium, liver, kidney, testis, brain etc. Goblet cell hyperplasia with mucin present in the lumen were observed in the jejunum, ileum and colon. In conclusion, CP crystals produced severe lesions in the visceral organs and the brain after chronic oral administration at low and high dosage levels which should indicate caution in administering the extract to humans.
At Arapaho Prairie, in the sandhills of western Nebraska, the dioecious annual Croton texensis (Euphorbiaceae) exhibits biased sex ratios. Moreover, the direction of bias changes from year to year: in 1994 the study population was significantly female biased, in 1995 and 1996 it was significantly male biased, and in 1997 and 1998 the sex ratio did not differ from 1 : 1. Such variation in the observed sex ratio in plants is frequently attributed to environmental sex determination (ESD), which is favored by natural selection if the rate of fitness gain across an environmental gradient is greater for one sex than the other. We performed experiments to determine: (1) whether variation in the sex ratio is correlated with environmental conditions, as would be expected if ESD is operating, and (2) whether ESD, if present, would be favored by natural selection. In a common garden experiment in which water and fertilizer were manipulated the sex ratio was marginally male biased in treatments in which water was added, but not different from 1 : 1 in other treatments. In field plots into which seeds were planted none of several soil characteristics, nor overall plot quality for C. texensis (measured as average plant biomass) were correlated with plot sex ratio. However, plots in which a large number of planted seeds emerged tended to be female biased. These results provide very weak evidence for sex ratio bias across an environmental gradient, and thus provide little evidence for ESD. Moreover, sex-by-environment interactions for fitness, which are required for the evolution of ESD, were absent for all measured variables. Thus, ESD does not appear to be favored by natural selection in this population. Instead, these biases may have been caused by differences between the sexes in germination and/or early mortality.
Croton draco (Euphorbiaceae) from Guadalupe, San José, Costa Rica was collected in July 1992 and phytochemically studied (leaves, seeds, wood, bark, sap and flowers separately). Commonly known compounds such as 1-hydroxyjunenol, p-hydroxybenzaldehyde, p-methoxybenzoic acid, 3,4,5-trimethoxycinnamyl alcohol, the coumarin scopoletin, the nor-terpenoids 9-dehydrovomifoliol and 2,3-dihydrovomifoliol were obtained. Taspine, two aporphinic alkaloids, the diterpenes 9(11)-dehydrokaurenic acid, hardwikiic acid, the corresponding new 12-oxo derivative as well as five clerodanes and a phorbol ester were also isolated. Three clerodanes were not previously described and their NMR spectroscopical data and MS fragmentation patterns are reported.
In this paper the authors present the first report concerning the biological effects of a diterpene isolated from Croton aff. argyrophylloides Muell. Arg (Euphorbiaceae). Some biological and physiochemical properties of the antibiotic, named argyrophillic acid, were appreciated in comparison with those presented by cunabic acid, an antibiotic isolated from Icthyothere cunabi. The authors still show the microbial action of the abietic acid and confront it with that of the argyrophilic acid, the new antibiotic here reported.
L-3,4-(3-3,4-Dimethoxyphene-ethylamino-2-hydroxypropoxy)-phenyl-++ +crotonic acid nitrile X HCl (Hoe 224) has beta 1-blocking action. In the isolated left atrium of the guinea pig, the ED50 necessary to counteract the positive inotropic action of 2 ng/ml isoprenaline (isoproterenol) was determined as 10.3 ng/ml in comparison to the ED50 of propranolol 2.7 ng/ml. On the isolated right atrium of the same animal, the ED50 for inhibition of increased heart rate brought about by 2 ng/ml isoprenaline was 29.5 ng/ml in comparison to the ED50 of propranolol 13.5 ng/ml. On the isolated tracheal chain of the guinea pig 40 micrograms Hoe 224/ml also inhibited relaxation induced by 50 ng isoprenaline/ml only by 31%. The ED50 for propranolol in this experiment was 1.2 ng/ml. Therefore, Hoe 224 is a very specific beta 1-blocker. In the dog anaesthetized with pentobarbital the ED50 of Hoe 224 for depression of dp/dt increase by 0.1 mg isoprenaline/kg i.v. was determined as 85 micrograms/kg i.v. Under the same conditions, the ED50 for propranolol was 10 micrograms/kg i.v., for atenolol 17 micrograms/kg i.v., for practolol 56 micrograms/kg i.v. In the conscious dog, 1.6 mg Hoe 224/kg orally depressed the increase of dp/dt brought about by 0.1 microgram isoprenaline/kg i.v. by 50%. The beta 2-blocking effect of Hoe 224 intraarterially against vasodilating effect of 0.01 microgram isoprenaline/kg given intraarterially in the A. femoralis of anaesthetized dogs was very weak. 100 micrograms Hoe 224/kg reduced the effect of isoprenaline only by 23%, but 2 micrograms propranolol/kg intraarterially reduced this effect by 61%.(ABSTRACT TRUNCATED AT 250 WORDS)
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