Parasorbic acid

Other methods include ring opening of parasorbic acid [108-54-3] (5-lactone of 5-hydroxy-2-hexenoic acid) in hydrochloric acid or in alkaline solutions (43,44), the ring opening of y-vinyl- y-butyrolactone in various catalysts (45,46), or isomerization of 2,5-hexadienoic acid esters (47,48). Other methods are described in thehterature (6,49,50). 

Lactones. Physiologically active lactones such as parasorbic acid, coumarin, scopoletin, and protoanemonin occur in many plant families (Figure 2). The lactones may perform a regulatory function in the plant, and have been shown to inhibit germination and to repress root growth [reviewed in detail by Hemberg 61), Evenari 36,37), and Borner 12)]. 

Parasorbic acid (Figure 2) was isolated from fruits of Sorbus aucuparia. Germination of mustard seed Sinapis alba) was affected adversely by parasorbic acid at 3.5 X 10-3 M and growth of excised tomato roots was inhibited at approximately 8.5 X 10 4 M (25). The acid also antagonized indoleacetic acid (IAA) in the Avena assay. Cornman 29,30) reported that parasorbic acid slowed down mitosis. Metaphase stages were observed to accumulate, but abnormalities were not detected. 

In addition to effects on biochemical reactions, the inhibitors may influence the permeability of the various cellular membranes and through physical and chemical effects may alter the structure of other subcellular structures such as proteins, nucleic acid, and spindle fibers. Unfortunately, few definite examples can be listed. The action of colchicine and podophyllin in interfering with cell division is well known. The effect of various lactones (coumarin, parasorbic acid, and protoanemonin) on mitotic activity was discussed above. Disturbances to cytoplasmic and vacuolar structure, and the morphology of mitochondria imposed by protoanemonin, were also mentioned. Interference with protein configuration and loss of biological activity was attributed to incorporation of azetidine-2-carboxylic acid into mung bean protein in place of proline. 

Sorbic acid has been prepared from crotonaldehyde 1 5 or aldol6 and malonic acid in pyridine solution by hydrogen peroxide oxidation of the condensation product of crotonaldehyde and pyruvic acid 7 and by the action of alkali on 3-hydroxy-4-hexenoic acid,8 9 /3,5-disulfo-w-caproic acid,10 and parasorbic acid.1112... 

In the case of nonracemic homopropargylic ether 17, hydrozirconation/carbonylation was followed by exposure of the intermediate to molecular iodine (Scheme 4.12) [39]. The ( )- and (Z)-forms of the acyl iodide presumed to be formed in situ were seemingly in equilibrium under the reaction conditions and intramolecular attack followed by dealkylation afforded (S)-(+)-parasorbic acid. 

A simple lactone, parasorbic acid, from the fruit of mountain ash, inhibits seed germination and also has antibacterial action (75). Another such compound, patulin, is produced by several fungi, including Penicillium urticae, which produced large amounts of the substance when growing on wheat straw (76). 

An extract of leaves of the American cranberry plant, Vaccinium macrocarpon, was examined for growth inhibitors. No free parasorbic acid, a known growth inhibitor from cranberry leaves, could be isolated in the absence of a preliminary acid or base treatment. 

The parasorbic acid was isolated from the extract in the form of its glucoside. It was shown that this glucoside could only account for a portion of the growth inhibition of the leaf extract. 

We prepared a sample of parasorbic acid by the method of Stafford (2) This allowed us to develop an analytical glc technique to determine the acid or its precursor in the leaf extract. 

Since parasorbic acid was previously isolated by steam distillation of the juice of mountain ash berries (.S), we steam distilled a sample of the cranberry leaf extract, but obtained little 2. The literature reports that before the ash berry juice was distilled, it was treated with calcium hydroxide to precipitate malic acid. Tschesche later showed that such treatment followed by acidification converted the glucoside of parasorbic acid, into the free acid (lactone), 2, (9). This base treatment effects a B-ellmination of the glucose fragment. In the absence of this base treatment, no free parasorbic acid was liberated from the berries. 

Hence we sought to determine whether we simply were observing the effect of parasorbic acid, a known plant growth inhibitor, or its glucoside in our tests. 

When the cranberry leaf extract was treated with calcium hydroxide followed by acidification and extraction with ether, parasorbic acid was indeed isolated. It was identified from the IR and HMR spectra of the crude extract and by identical retention time on two glc columns with an authentic sample of parasorbic acid. We then analyzed samples of the cranberry leaf extract by glc before and after treatment with calcium hydroxide (followed by acidification), samples of parasorbic acid alone, and extract plus parasorbic acid (in the presence of calcium hydroxide followed by acidification). Our results (Table I) show that parasorbic acid from the extract was obtained only upon calcium hydroxide treatment. This result agrees with Tschesche s observations on mountain ash berries. 

Table I. Parasorbic Acid Found After Calcium Hydroxide Treatment...

Sample Added Parasorbic Acid Ca(0H)2 Treatment Parasorbic Acid Found... 

Table II. Proton NMR Shifts (ppm) of Parasorbic Acid Glucoside, 3, and its Aglycone, 4...

Having the glucoside, we could now determine its concentration in the leaves. Extract samples of varying sizes were subjected to calcium hydroxide treatment, acidification, extraction, and glc quantitation. The amounts of parasorbic acid obtained from the samples are shown in Figure 1 to be proportional to sample size. 

Recovery of Parasorbic Acid from Cranberry Leaf Extract... 

Although the bioassay of racemic parasorbic acid showed good activity (wheat seed root growth was 50% inhibited with 0.25 mg/mL), the conclusion that little of the growth-retardant activity in cranberry leaves can be accounted for by parasorbic acid was confirmed by examination of Devlin s extract. In this case neither parasorbic acid nor its glucoside was present. Subsequent work by Hussain (12) has resulted in the isolation of two plant growth inhibitors identified as cinnamyl alcohol and 3-pheny1-1-propanol (hydrocinnamyl alcohol). 

Cyclization of methyl cis-2,5-hexadienoate (106) with polyphosphoric acid gives47 2,3,4,6-tetradeoxy-DL-g/(/cero-hex-2-enono-1,5-lactone (107 DL-parasorbic acid). Epoxidation of 107 with 40% hydrogen per-... 

Sorbus alnifolia (Sieb. Zucc.) K. Koch S. alnifolia (Sieb. Zucc.) K. Koch var. lobulata Rehd. S. amurensis Koehne S. pohuashanensis (Hance) Hedl. var. manshuriensis (Kitag.) Y. C. Chu. Shui Yu (stem, bark, fruit) Fatty acids, starch, essential oils, flavonoids, isochlorogenic acid, parasorbic acid.48 For stomach infection and ache, swellings, cough, vitamin deficiencies. 

China Sorbus alnifolia (Sieb. Zucc.) K. Koch Fatty acids, starch, essential oils, flavonoids, isochlorogenic acid, parasorbic acid.48 For stomach infection and ache, swellings, cough, vitamin deficiencies. 

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