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PubMed1978

On the occurrence of the contact allergen primin and other quinoid compounds in species of the family of primulaceae.

82 different species of the Primulacea family have been investigated by a screening test. In 16 Primula species and 4 species of other genera the strong contact allergen primin could be detected by the Craven-test. Extracts of only 12 plants gave no color reaction. In the remaining species other quinoid components were detectable. From 4 species new quinoid substances were isolated. Primin itself was obtained from Primula elatior and from the petals (corollas) of Primula obconica. The results indicate that the presence of primin and other quinones is determined by their origin and seasonal variations. It is supposed that some of the detected quinones may function as allergens and therefore may be responsible for the contact dermatitis described in the literature due to several Primula species and some other species of the same family. Some indications point to the suspicion that primin occurs in the plant as a glycoside which is separated by extraction treatment to give its quinole and an unknown substance. The quinole oxidizes then to the quinhydrone and finally to primin itself.

Allergens↗
PubMed1999

Metabolism of D-glycero-D-manno-heptitol, volemitol, in polyanthus. Discovery Of a novel ketose reductase1

Volemitol (D-glycero-D-manno-heptitol, alpha-sedoheptitol) is an unusual seven-carbon sugar alcohol that fulfills several important physiological functions in certain species of the genus Primula. Using the horticultural hybrid polyanthus (Primula x polyantha) as our model plant, we found that volemitol is the major nonstructural carbohydrate in leaves of all stages of development, with concentrations of up to 50 mg/g fresh weight in source leaves (about 25% of the dry weight), followed by sedoheptulose (D-altro-2-heptulose, 36 mg/g fresh weight), and sucrose (4 mg/g fresh weight). Volemitol was shown by the ethylenediaminetetraacetate-exudation technique to be a prominent phloem-mobile carbohydrate. It accounted for about 24% (mol/mol) of the phloem sap carbohydrates, surpassed only by sucrose (63%). Preliminary 14CO2 pulse-chase radiolabeling experiments showed that volemitol was a major photosynthetic product, preceded by the structurally related ketose sedoheptulose. Finally, we present evidence for a novel NADPH-dependent ketose reductase, tentatively called sedoheptulose reductase, in volemitol-containing Primula species, and propose it as responsible for the biosynthesis of volemitol in planta. Using enzyme extracts from polyanthus leaves, we determined that sedoheptulose reductase has a pH optimum between 7.0 and 8.0, a very high substrate specificity, and displays saturable concentration dependence for both sedoheptulose (apparent Km = 21 mM) and NADPH (apparent Km = 0.4 mM). Our results suggest that volemitol is important in certain Primula species as a photosynthetic product, phloem translocate, and storage carbohydrate.

Journal Article↗