Isolation and characterization of a calendic acid producing (8,11)-linoleoyl desaturase. (1/22)

For the biosynthesis of calendic acid a (8,11)-linoleoyl desaturase activity has been proposed. To isolate this desaturase, PCR-based cloning was used. The open reading frame of the isolated full-length cDNA is a 1131 bp sequence encoding a protein of 377 amino acids. For functional identification the cDNA was expressed in Saccharomyces cerevisiae, and formation of calendic acid was analyzed by RP-HPLC. The expression of the heterologous enzyme resulted in a significant amount of calendic acid presumably esterified within phospholipids. The results presented here identify a gene encoding a new type of (1,4)-acyl lipid desaturase.  (+info)

Formation of conjugated delta8,delta10-double bonds by delta12-oleic-acid desaturase-related enzymes: biosynthetic origin of calendic acid. (2/22)

Divergent forms of the plant Delta(12)-oleic-acid desaturase (FAD2) have previously been shown to catalyze the formation of acetylenic bonds, epoxy groups, and conjugated Delta(11),Delta(13)-double bonds by modification of an existing Delta(12)-double bond in C(18) fatty acids. Here, we report a class of FAD2-related enzymes that modifies a Delta(9)-double bond to produce the conjugated trans-Delta(8),trans-Delta(10)-double bonds found in calendic acid (18:3Delta(8trans,10trans,12cis)), the major component of the seed oil of Calendula officinalis. Using an expressed sequence tag approach, cDNAs for two closely related FAD2-like enzymes, designated CoFADX-1 and CoFADX-2, were identified from a C. officinalis developing seed cDNA library. The deduced amino acid sequences of these polypeptides share 40-50% identity with those of other FAD2 and FAD2-related enzymes. Expression of either CoFADX-1 or CoFADX-2 in somatic soybean embryos resulted in the production of calendic acid. In embryos expressing CoFADX-2, calendic acid accumulated to as high as 22% (w/w) of the total fatty acids. In addition, expression of CoFADX-1 and CoFADX-2 in Saccharomyces cerevisiae was accompanied by calendic acid accumulation when induced cells were supplied exogenous linoleic acid (18:2Delta(9cis,12cis)). These results are thus consistent with a route of calendic acid synthesis involving modification of the Delta(9)-double bond of linoleic acid. Regiospecificity for Delta(9)-double bonds is unprecedented among FAD2-related enzymes and further expands the functional diversity found in this family of enzymes.  (+info)

Identification and analysis of a gene from Calendula officinalis encoding a fatty acid conjugase. (3/22)

Two homologous cDNAs, CoFad2 and CoFac2, were isolated from a Calendula officinalis developing seed by a polymerase chain reaction-based cloning strategy. Both sequences share similarity to FAD2 desaturases and FAD2-related enzymes. In C. officinalis plants CoFad2 was expressed in all tissues tested, whereas CoFac2 expression was specific to developing seeds. Expression of CoFad2 cDNA in yeast (Saccharomyces cerevisiae) indicated it encodes a Delta12 desaturase that introduces a double bond at the 12 position of 16:1(9Z) and 18:1(9Z). Expression of CoFac2 in yeast revealed that the encoded enzyme acts as a fatty acid conjugase converting 18:2(9Z, 12Z) to calendic acid 18:3(8E, 10E, 12Z). The enzyme also has weak activity on the mono-unsaturates 16:1(9Z) and 18:1(9Z) producing compounds with the properties of 8,10 conjugated dienes.  (+info)

Medicinal flowers. III. Marigold. (1): hypoglycemic, gastric emptying inhibitory, and gastroprotective principles and new oleanane-type triterpene oligoglycosides, calendasaponins A, B, C, and D, from Egyptian Calendula officinalis. (4/22)

The methanolic extract and its 1-butanol-soluble fraction from the flowers of Calendula officinalis were found to show a hypoglycemic effect, inhibitory activity of gastric emptying, and gastroprotective effect. From the 1-butanol-soluble fraction, four new triterpene oligoglycosides, calendasaponins A, B, C, and D, were isolated, together with eight known saponins, seven known flavonol glycosides, and a known sesquiterpene glucoside. Their structures were elucidated on the basis of chemical and physicochemical evidence. The principal saponin constituents, glycosides A, B, C, D, and F, exhibited potent inhibitory effects on an increase in serum glucose levels in glucose-loaded rats, gastric emptying in mice, and ethanol- and indomethacin-induced gastric lesions in rats. Some structure-activity relationships are discussed.  (+info)

Medicinal flowers. IV. Marigold. (2): Structures of new ionone and sesquiterpene glycosides from Egyptian Calendula officinalis. (5/22)

Following the characterization of hypoglycemic, gastric emptying inhibitory, and gastroprotective principles and the structure elucidation of calendasaponins A, B, C, and D, two new ionone glucosides (officinosides A and B), and two sesquiterpene oligoglycosides (officinosides C and D), were isolated from the flowers of Egyptian Calendula officinalis. The structures of the officinosides were elucidated on the basis of chemical and physicochemical evidence.  (+info)

Mechanism of 1,4-dehydrogenation catalyzed by a fatty acid (1,4)-desaturase of Calendula officinalis. (6/22)

The mechanism by which the fatty acid (1,4)-desaturase of Calendula officinalis produces calendic acid from linoleic acid has been probed through the use of kinetic isotope effect (KIE) measurements. This was accomplished by incubating appropriate mixtures of linoleate and regiospecifically dideuterated isotopomers with a strain of Saccharomyces cerevisiae expressing a functional (1,4)-desaturase. GC-MS analysis of methyl calendate obtained in these experiments showed that the oxidation of linoleate occurs in two discrete steps since the cleavage of the C11-H bond is very sensitive to isotopic substitution (kH/kD = 5.7 +/- 1.0) while no isotope effect (kH/kD = 1.0 +/- 0.1) was observed for the C8-H bond breaking step. These data indicate that calendic acid is produced via initial H-atom abstraction at C11 of a linoleoyl substrate and supports the hypothesis that this transformation represents a regiochemical variation of the more common C12-initiated Delta12 desaturation process.  (+info)

Dimorphecolic acid is synthesized by the coordinate activities of two divergent Delta12-oleic acid desaturases. (7/22)

Dimorphecolic acid (9-OH-18:2Delta(10)(trans)(,12)(trans)) is the major fatty acid of seeds of Dimorphotheca species. This fatty acid contains structural features that are not typically found in plant fatty acids, including a C-9 hydroxyl group, Delta(10),Delta(12)-conjugated double bonds, and trans-Delta(12) unsaturation. Expressed sequence tag analysis was conducted to determine the biosynthetic origin of dimorphecolic acid. cDNAs for two divergent forms of Delta(12)-oleic acid desaturase, designated DsFAD2-1 and Ds-FAD2-2, were identified among expressed sequence tags generated from developing Dimorphotheca sinuata seeds. Expression of DsFAD2-1 in Saccharomyces cerevisiae and soybean somatic embryos resulted in the accumulation of the trans-Delta(12) isomer of linoleic acid (18: 2Delta(9)(cis)(,12)(trans)) rather than the more typical cis-Delta(12) isomer. When co-expressed with DsFAD2-1 in soybean embryos or yeast, DsFAD2-2 converted 18:2Delta(9)(cis)(,12)(trans) into dimorphecolic acid. When DsFAD2-2 was expressed alone in soybean embryos or together with a typical cis-Delta(12)-oleic acid desaturase in yeast, trace amounts of the cis-Delta(12) isomer of dimorphecolic acid (9-OH-18:2Delta(10)(trans,)(12)(cis)) were formed from DsFAD2-2 activity with cis-Delta(12)-linoleic acid [corrected]. These results indicate that DsFAD2-2 catalyzes the conversion of the Delta(9) double bond of linoleic acid into a C-9 hydroxyl group and Delta(10)(trans) double bond and displays a substrate preference for the trans-Delta(12), rather than the cis-Delta(12), isomer of linoleic acid. Overall these data are consistent with a biosynthetic pathway of dimorphecolic acid involving the concerted activities of DsFAD2-1 and DsFAD2-2. The evolution of two divergent Delta(12)-oleic acid desaturases for the biosynthesis of an unusual fatty acid is unprecedented in plants.  (+info)

Phase III randomized trial of Calendula officinalis compared with trolamine for the prevention of acute dermatitis during irradiation for breast cancer. (8/22)

PURPOSE: The effectiveness of nonsteroid topical agents for the prevention of acute dermatitis during adjuvant radiotherapy for breast carcinoma has not been demonstrated. The goal of this study was to compare the effectiveness of calendula (Pommade au Calendula par Digestion; Boiron Ltd, Levallois-Perret, France) with that of trolamine (Biafine; Genmedix Ltd, France), which is considered in many institutions to be the reference topical agent. PATIENTS AND METHODS: Between July 1999 and June 2001, 254 patients who had been operated on for breast cancer and who were to receive postoperative radiation therapy were randomly allocated to application of either trolamine (128 patients) or calendula (126 patients) on the irradiated fields after each session. The primary end point was the occurrence of acute dermatitis of grade 2 or higher. Prognostic factors, including treatment modalities and patient characteristics, were also investigated. Secondary end points were the occurrence of pain, the quantity of topical agent used, and patient satisfaction. RESULTS: The occurrence of acute dermatitis of grade 2 or higher was significantly lower (41% v 63%; P <.001) with the use of calendula than with trolamine. Moreover, patients receiving calendula had less frequent interruption of radiotherapy and significantly reduced radiation-induced pain. Calendula was considered to be more difficult to apply, but self-assessed satisfaction was greater. Body mass index and adjuvant chemotherapy before radiotherapy after lumpectomy were significant prognostic factors for acute dermatitis. CONCLUSION: Calendula is highly effective for the prevention of acute dermatitis of grade 2 or higher and should be proposed for patients undergoing postoperative irradiation for breast cancer.  (+info)

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