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PubMed1992

Phosphoenolpyruvate carboxylase activity and concentration in the endosperm of developing and germinating castor oil seeds.

Monospecific polyclonal antibodies against maize leaf phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) were utilized to examine the subunit composition and developmental profile of endosperm PEPC in developing and germinating castor oil seeds (Ricinus communis L. cv Baker 296). PEPC from developing endosperm consists of a single type of 100-kilodalton subunit, whereas the enzyme from 2- to 5-day germinated endosperm appears to contain equal proportions of immunologically related 103- and 108-kilodalton subunits. The maximal activity of PEPC in developing endosperms (2.67 micromoles oxaloacetate produced per minute per gram fresh weight) is approximately 20-fold and threefold greater than that of fully mature (dry seed) and germinating endosperms, respectively. The most significant increase in the activity and concentration of endosperm PEPC occurs during the middle cotyledon to full cotyledon stage of seed development; this period coincides with the most active phase of storage oil accumulation by ripening castor oil seeds. The data are compatible with the recent proposal (RG Smith, DA Gauthier, DT Dennis, DH Turpin [1992] Plant Physiol 1233-1238) that PEPC plays a fundamental role in vivo in the cytosolic production of an important substrate (malate) for fatty acid biosynthesis by developing castor oil seed leucoplasts. Immediately following seed imbibition, PEPC activity and concentration increase in parallel, with the greatest levels attained by the third day of germination. It is suggested that during this early phase of seed germination PEPC has a critical function to build up cellular dicarboxylic acid pools required to initiate significant activities of both the tricarboxylic acid and glyoxylate cycles.

Journal Article↗
PubMed1997

Role of tachykinins in castor oil diarrhoea in rats.

1. We set out to ascertain the role of tachykinins, neurokinin A and substance P, in castor oil-induced diarrhoea in rats as disclosed by the inhibitory effect of the non-peptide NK1- and NK2-receptor antagonists. SR 140333 and SR 48968, respectively. 2. SR 48968 (0.02 to 20 micrograms kg-1, s.c. or p.o.), and the opioid receptor agonist loperamide (1-10 mg kg-1, p.o.), dose-dependently prevented castor oil effects: % inhibition vs castor oil, diarrhoea 0 to 100, increase in faecal mass 7 to 90 and water content 16 to 90. SR 140333 (0.02 to 20 micrograms kg-1, s.c.) and the platelet activating factor antagonist SR 27417 (5 to 500 micrograms kg-1, p.o.) did not prevent the increase in faecal water content, but reduced faecal mass (35 to 66%) and diarrhoea (0 to 57%). 3. The R-enantiomers of tachykinin NK1 and NK2 receptor antagonists, SR 140603 and SR 48605 (both at 2 or 20 micrograms kg-1, s.c.) had no effect other than reducing faecal mass at the highest dose tested. 4. SR 48968 (20 micrograms kg-1, p.o.) but not loperamide (10 mg kg-1, p.o.) given 24 h before castor oil, still slightly but significantly reduced by 30% the increase of faecal mass output; both treatments significantly reduced (30 to 70%) the effect of castor oil on faecal water content, although the incidence of diarrhoea was only slightly less than in controls. 5. In castor oil-treated rats, naloxone (2 mg kg-1, s.c.) completely blocked the antidiarrhoeal action of loperamide (10 mg kg-1, p.o.) but not of SR 48968 (20 micrograms kg-1, p.o.): a similar result was obtained on faecal mass and water content. 6. Castor oil strongly increased the occurrence of manometrically recorded propulsive giant contractions (500 to 1000% over control values) of transverse and distal colon, this effect being significantly prevented (80 to 100%) by SR 48968 and loperamide and partially by SR 140333 (35% distal colon, 70% transverse colon). 7. In castor oil free rats, loperamide but not SR 48968 or SR 140333 significantly reduced by 50% the gastrointestinal transit of a charcoal test meal, as well as 24 h faecal mass output. Consistently, loperamide, unlike the tachykinin receptor antagonists, had a dramatic effect on manometric recordings of intestinal motility, reducing all kinds of colonic contractions. 8. Our findings suggest that castor oil diarrhoea in rats entails activation of NK1 and NK2 receptors by endogenous tachykinins, whose antagonists may have a potential as antidiarrhoeal agents free from the constipating action of opioids.

Animals↗
PubMed2003

Determination of the disproportionation products of limonene used for the catalytic hydrogenation of castor oil.

The direct determination by GC-MS analysis of the products from the limonene disproportionation obtained from the catalytic hydrogenation of castor oil is not possible since a transesterification of the oil is required before injection. Therefore, a method for the determination of those products is proposed here: a solid-phase microextraction (SPME) followed by GC-MS. With the optimization of SPME it was possible to isolate a great number of products of the disproportionation of limonene used as hydrogen donor in the catalytic hydrogenation of castor oil by Pd/C. This system also proved to be appropriate to monitor castor oil hydrogenation by following and identifying the limonene disproportionated products.

Castor Oil↗
PubMed1989

Molecular and immunological characterization of plastid and cytosolic pyruvate kinase isozymes from castor-oil-plant endosperm and leaf.

1. Monospecific antiserum was raised in rabbits to homogeneous cytosolic pyruvate kinase isolated from 5-day-old germinating endosperm of the castor oil plant, Ricinus communis. An earlier study demonstrated that the purified enzyme is putatively heterotetrameric, composed of two subunits which migrate as 57-kDa and 56-kDa proteins upon sodium dodecyl sulfate/polyacrylamide gel electrophoresis [Plaxton, W. C. (1988) Plant Physiol. (Bethesda) 86, 1065-1069]. Both proteins were detected on Western blots of extracts prepared under denaturing conditions from 4-8-day-old, but not 0-3-day-old, germinating-endosperm tissue. This suggests that both subunits exist in vivo, and that the large increase in pyruvate kinase activity which occurs around the fourth day of germination is due to an increase in pyruvate kinase concentration. 2. The cytosolic and plastidic pyruvate kinase isozymes (termed PKc and PKp, respectively) from castor-oil-plant developing endosperm and expanding leaf tissue were separated by anion-exchange chromatography on Q-Sepharose. The antigenic reaction of the partially purified enzyme preparations to rabbit polyclonal antibodies raised against homogeneous germinating-castor-bean PKc was tested by immunoprecipitation and Western blotting. Although developing-endosperm and leaf PKc appeared to be antigenically very similar to germinating-endosperm PKc, they differed from the heterotetrameric germinating-endosperm enzyme by being composed of a single type of subunit with a molecular mass of about 56 kDa. No cross-reactivity of the PKc antibodies was observed with either developing-endosperm or leaf PKp, nor with rabbit muscle or Bacillus stearothermophilus pyruvate kinase. Conversely, none of the castor-oil-plant pyruvate kinase preparations showed significant cross-reactivity with antibodies raised against purified yeast or rabbit muscle pyruvate kinases. 3. To investigate the structural relationship between the two germinating-endosperm-PKc subunits, each polypeptide was characterized by amino acid composition analysis and peptide mapping by CNBr fragmentation. The amino acid compositions and CNBr cleavage patterns of the two subunits were similar, but not identical, suggesting that these polypeptides are related, but distinct, proteins. Mild tryptic attack of native enzyme led to an approximate 6-kDa reduction in the apparent molecular mass of both subunits, further indicating sequence similarity between the two polypeptides. 4. Native molecular masses of the various castor-oil-plant pyruvate kinases were estimated by Superose-6 gel-filtration chromatography.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗
PubMed1989

Castor-oil induced diarrhoea in ponies: a model for acute colitis.

A reproducible, reversible model of colitis induced in ponies by administering castor oil (2.5 ml/kg bodyweight [bwt] per os) was characterised by abdominal pain, fever, watery diarrhoea, dehydration, hypovolaemia, toxaemia, leucopenia, decreased serum Cl, Na and K levels and metabolic acidosis. The signs were most severe between 24 and 48 h post induction, stabilisation was frequently observed after 72 h, although diarrhoea could persist beyond 96 h. Morphological and in vitro transport studies (right ventral colon) were conducted on tissues from animals destroyed at 24, 48 and 72 h. In the caecum and colon, surface epithelial disruption and exfoliation from the basement membrane occurred between 24 and 48 h. Early signs of recovery were evident by replenishment of denuded areas with columnar epithelium at 72 h. The crypt epithelium was unaffected throughout the intestinal tract. In vitro transport studies were consistent with the morphological findings. Decreased Na-Cl absorption and normal Cl secretion indicated an impaired surface epithelium coincident with an undamaged cryptal epithelium. Increased mucosal permeability was demonstrated by high ionic conductance and large unidirectional isotopic fluxes. Tissue conductance improved during in vitro incubation suggesting epithelial repair after removal of castor oil. Changes in the population and proportion of bacteria in the faeces as diarrhoea ensued were confirmed at necropsy with a predominance of E. coli and Enterobacter/Klebsiella sp in the large bowel. The experimental induction of castor oil colitis showed many similarities to intestinal endotoxaemia and the secretory type diarrhoea encountered in naturally occurring acute colitis syndromes in horses. The model could prove applicable in studying the pathophysiological mechanisms precipitating such life-threatening disorders.

Acidosis↗
PubMed2004

Optimization of a supercritical fluid extraction/reaction methodology for the analysis of castor oil using experimental design.

The aim of this work was to optimize a supercritical fluid extraction (SFE)/enzymatic reaction process for the determination of the fatty acid composition of castor seeds. A lipase from Candida antarctica (Novozyme 435) was used to catalyze the methanolysis reaction in supercritical carbon dioxide (SC-CO(2)). A Box-Behnken statistical design was used to evaluate effects of various values of pressure (200-400 bar), temperature (40-80 degrees C), methanol concentration (1-5 vol %), and water concentration (0.02-0.18 vol %) on the yield of methylated castor oil. Response surfaces were plotted, and these together with results from some additional experiments produced optimal extraction/reaction conditions for SC-CO(2) at 300 bar and 80 degrees C, with 7 vol % methanol and 0.02 vol % water. These conditions were used for the determination of the castor oil content expressed as fatty acid methyl esters (FAMEs) in castor seeds. The results obtained were similar to those obtained using conventional methodology based on solvent extraction followed by chemical transmethylation. It was concluded that the methodology developed could be used for the determination of castor oil content as well as composition of individual FAMEs in castor seeds.

Ricinus communis↗
PubMed1997

[Involvement of nitric oxide, which was synthesized by constitutive nitric oxide synthase, and prostaglandin on diarrhea induced by castor oil in rats].

To clarify the mechanism of castor oil-induced diarrhea, this study was performed by using rats in relation to nitric oxide (NO) and prostaglandin (PG). Castor oil induced diarrhea in all rats within 3 hr in the control group. The pretreatment of NG-nitro-L-arginine methyl ester prevented the diarrhea, and this effect was attenuated by the combined treatment of L-arginine. Amino-guanidine inhibiting inducible NO synthase had no effect on the diarrhea, but dexamethasone, an inhibitor of both inducible NO synthase and phospholipase A2 that synthesizes PGs, significantly prevented it. Indomethacin, an inhibitor of cyclooxygenase that synthesizes PGs, also significantly prevented diarrhea. Therefore, the mechanism of the preventive effect by dexamethazone on diarrhea was suggested to be the inhibition of PGs generation. From the above results, it became clear that PG and NO, especially that synthesized by constitutive NO synthase, are involved in the mechanism of diarrhea induction by castor oil in rats.

Animals↗
PubMed2003

Synthesis, physical properties and preliminary investigation of hemocompatibility of polyurethanes from aliphatic resources with castor oil participation.

The synthesis of polyurethanes (PURs) from oligoetherdiol, two low molecular diols, castor oil and 4,4'-Methylenebis(cyclohexylisocyanate) is described. These polymers are characterized by measurements of the mechanical bulk and surface properties, preliminary investigation of compatibility with human blood and calcification in static conditions. The critical surface energy of synthesized PURs is similar to the critical surface energy of natural surfaces. Material-induced hemolysis and the changes of platelet counts in blood samples after contact with PURs are very low. Static seven-weeks-calcification testing in a synthetic calcification fluid did not indicate calcification by optical density measurements and by visual inspection and computer image processing of the X-ray films for PURs with and without castor oil.

Biocompatible Materials↗
PubMed1996

Purification and characterization of cytosolic pyruvate kinase from leaves of the castor oil plant.

Cytosolic pyruvate kinase (PKc) from leaves of the castor oil plant (Ricinus communis L.) has been purified 3900-fold to apparent homogeneity and a final specific activity of 51 mumol of pyruvate produced/min/mg protein. PAGE, immunoblot, and gel filtration analyses of the final preparation indicated that this enzyme is an alpha 2 beta 2 heterotetramer of about 250 kDa that is composed of an equivalent ratio of 57- and 56-kDa subunits. The enzyme was relatively heat-stable and displayed a broad pH optimum of approximately 6.5. However, optimal efficiency in substrate utilization [in terms of Vmax/Km for phosphoenolpyruvate (PEP) or ADP] occurred at pH 7.5. Enzyme activity was absolutely dependent upon the simultaneous presence of bivalent and a univalent metal cation, with Mg2+ and K+ fulfilling this requirement. Hyperbolic saturation kinetics were observed with PEP, ADP, and K+, whereas Mg2+ binding exhibited positive cooperativity. Mg2 citrate, oxalate, and glutamate were the most effective inhibitors at pH 7.5. Inhibition by these compounds was more pronounced at pH 7.5 than at pH 6.5 and they yielded additive inhibition when tested in pairs. Aspartate functioned as an activator by facilitating the binding of PEP and relieving the inhibition of PKc by glutamate. The in vivo activity of leaf PKc is probably regulated by the relative cytosolic levels of citrate, glutamate, and aspartate. This provides a possible rationale for the known activation of leaf PKc that occurs during periods of enhanced ammonia assimilation. Together with our previous studies, the results also indicate that castor oil plant PKc exists as tissue-specific isoforms that demonstrate substantial differences in their respective physical and/or kinetic and regulatory properties.

Animals↗
PubMed2006

Comparison between polyurethanes containing castor oil (soft segment) and cancellous bone autograft in the treatment of segmental bone defect induced in rabbits.

The aim of this study is to compare polyurethanes containing castor oil (soft segment) in granular form compared to cancellous bone autograft applied to a segmental bone defect. Norfolk adult female rabbits - approximately 13 months of age with a mean body weight of 4.5 kg - are used. In both radial diaphyses, 1 cm osteoperiosteal segmental defects are created. The defect in the left radius is filled with the castor-oil-based polyurethane, and the right one, filled with cancellous bone autograft, collected from the left proximal humerus. The rabbits are euthanazed at 15, 30, 60, and 120 days postsurgery (5 animals/ period), for histological analyses. By radiographic analyses, at these time points, the bone regeneration is more evident and accelerated in the bone defects treated with the cancellous bone autograft. At 120 days postsurgery, the segmental bone defects treated with the cancellous bone autograft are totally reconstituted and remodeled, while the bone defects treated with polyurethane polymer have bone formation of 79%. Histological study shows that the polyurethane acts as a space filler, minimizing the local production of fibrous tissue. No granule degradation, resorption or any inflammatory reaction is detected. Thus, it is possible to conclude that the castor-oil-plant-based polyurethane - in the granule presentation - is biocompatible and osteointegrated, but does not show the same bone regeneration capacity as the cancellous bone autograft.

Animals↗
PubMed1978

[Pharmacological studies of loperamide, an anti-diarrheal agent. I. Effects on diarrhea induced by castor oil and prostaglandin E. (author's transl)].

Effects of loperamide on diarrhea induced by castor oil and prostaglandin E1 were investigated in rats and mice and compared with those of narcotic analgesics, atropine, mecamylamine and local anesthetics. The following results were obtained. Loperamide markedly suppressed the appearance of diarrhea induced by oral administration of castor oil in rats and the ED50 values for 1 and 2 hr protection was 0.082 and 0.42 mg/kg p.o., respectively. Loperamide markedly suppressed the appearance of diarrhea induced by i.v. administration of prostaglandin E1 and the ED50 value for 2 hr protection was 0.24 mg/kg p.o. in rats. The ID120 min value of loperamide which was calculated on the basis of the dose producing a 20% or more inhibition of the charcoal transport in the small intestine for 120 min was 0.8 mg/kg p.o. in mice and this activity was 9.2 times more potent than that of morphine. The analgesic ED50 value (Haffner's method) and LD50 value of loperamide was 149 and 249 mg/kg p.o., respectively. These results suggest that loperamide has a potent anti-diarrheal activity and specificity to the gastrointestinal tract and inhibits the effect of prostaglandin E1 and ricinoleic acid on the intestinal tract in rats.

Analgesics↗
PubMed2002

Molecular species of PC and PE formed during castor oil biosynthesis.

As part of a program to elucidate castor oil biosynthesis, we have identified 36 molecular species of PC and 35 molecular species of PE isolated from castor microsomes after incubations with [14C]-labeled FA. The six [14C]FA studied were ricinoleate, stearate, oleate, linoleate, linolenate, and palmitate, which were the only FA identified in castor microsomal incubations. The incorporation of each of the six FA into PC was better than that into PE. The [14C]FA were incorporated almost exclusively into the sn-2 position of both PC and PE. The incorporation of [14C]stearate and [14C]palmitate into 2-acyl-PC was slower compared to the other four [14C]FA. The incorporation does not show any selectivity for the various lysoPC molecular species. The level of incorporation of [14C]FA in PC was in the order of: oleate > linolenate > palmitate > linoleate > stearate > ricinoleate, and in PE: linoleate > linolenate > oleate > palmitate > stearate > ricinoleate. In general, at the sn-1 position of both PC and PE, linoleate was the most abundant FA, palmitate was the next, and oleate, linolenate, stearate, and ricinoleate were minor FA. The activities of oleoyl-12-hydroxylase, oleoyl-12-desaturase seem unaffected by the FA at the sn-1 position of 2-oleoyl-PC. The FA in the sn-1 position of PC does not significantly affect the activity of phospholipase A2, whereas ricinoleate is preferentially removed from the sn-2 position of PC. The results show that (i) [14C]oleate is most actively incorporated to form 2-oleoyl-PC, the immediate substrate of oleoyl-12-hydroxylase; (ii) 2-ricinoleoyl-PC is formed mostly by the hydroxylation of 2-oleoyl-PC, not from the incorporation of ricinoleate into 2-ricinoleoyl-PC; and (iii) 2-oleoyl-PE is less actively formed than 2-oleoyl-PC.

Carbon Radioisotopes↗
PubMed1989

Castor oil increases intestinal formation of platelet-activating factor and acid phosphatase release in the rat.

1. When castor oil was administered by gavage to rats, the duodenum and jejunum but not ileum and colon produced large amounts (5-6 fold greater than control) of platelet activating factor (Paf). 2. Intraluminal release of acid phosphatase (AP) was also markedly increased (5-6 fold greater than control) in the duodenum and jejunum of castor oil-treated rats and there was a correlation between the elevated release of AP and intestinal hyperaemia. 3. These findings support a role for Paf as a mediator of intestinal damage induced by castor oil.

Acid Phosphatase↗
PubMedDate not supplied

Characterisation of castor oil by on-line and off-line non-aqueous reverse-phase high-performance liquid chromatography-mass spectrometry (APCI and UV/MALDI).

A non-aqueous reverse-phase HPLC method, based on two columns in series, has been used to separate the major triacylglycerols (TAGs) from commercial castor oil and to perform either on-line negative ion atmospheric pressure chemical ionisation (APCI), or off-line positive ion matrix-assisted laser desorption ionisation (MALDI)/MS. The resulting Mass Spectra showed chloride-attached TAG molecules [M + CI]- in the case of negative-ion APCI, and sodium-attached TAG molecules [M + Na]+ in the case of positive-ion MALDI. For MALDI time-of-flight (TOF)/MS, a liquid binary matrix system consisting of sodium ferrocyanide and glycerol was applied, resulting in excellent TAG sensitivity, which was necessary for the determination of trace amounts of TAGs in castor oil. Both techniques allowed unambiguous molecular mass determination of the intact TAG molecules with no thermal degradation. Furthermore, seamless post source decay (PSD) fragment ion analysis by means of a curved field reflector TOF mass spectrometer allowed the determination of the fatty acid composition of each individual TAG. Castor oil contained eight different TAGs which were successfully determined by both APCI and MALDI techniques. In each TAG, at least two units of 12-hydroxy-9-octadecenoic acid (ricinoleic acid) were present. The following fatty acids were determined by seamless PSD fragment ion analysis and APCI/MALDI molecular mass determination as TAG substructures: ricinoleic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, dihydroxy stearic acid and eicosenoic acid. Triricinolein was the dominating TAG.

Castor Oil↗
PubMed1994

Mutagenicity tests of polyoxyethylene hydrogenated castor oil 60 (HCO-60).

The genotoxicity of polyoxyethylene hydrogenated castor oil 60 (HCO-60) was examined in reverse mutation test in bacteria, chromosome aberration test in vitro and micronucleus test in mice. The in vitro tests were done with and without metabolic activation using rat liver microsomal fraction. HCO-60 did induce neither reverse mutation in Salmonella typhimurium TA100, TA98, TA1535, and TA1537 and in Escherichia coli WP2uvrA, nor chromosome aberrations in Chinese hamster V79 cells. In addition, no increase in micronucleated polychromatic erythrocytes was elicited in the bone marrow of BDF1 male and female mice. It is concluded that HCO-60 was not genotoxic in these in vitro and in vivo assays.

Animals↗