Biosynthesis of sterols and triterpenes in Pelargonium hortorum |
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Authors: | AM Atallah RT Aexel RB Ramsey HJ Nicholas |
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Institution: | Institute of Medical Education and Research and Department of Biochemistry, St. Louis University School of Medicine, St. Louis, Missouri 63104, U.S.A. |
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Abstract: | Although all parts of the geranium plant (Pelargonium hortorum) are capable of synthesizing sterols and triterpenes and their esters in vitro from mevalonic acid-2-14C], the aerial portions are more active than other tissues. All plant parts were shown to incorporate mevalonic acid-2-14C] into isoprenoids for at least 3 days. The leaves and petioles had the greatest incorporation on a wet weight basis. Chopped preparations showed comparable incorporations of mevalonate whereby rootlets incorporated about one half as much as most parts; the flower petals incorporated five times the average amount. In leaves the principal sterol synthesized was sitosterol. Metabolic studies with isolated leaves indicated a fairly rapid conversion of free tetracyclic triterpenes to 4-desmethyl-sterols, while β-amyrin was synthesized at a different rate than α-amyrin. Esterified tetracyclic triterpenes exhibited only a slight amount of conversion to 4-desmethylsterols. |
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Keywords: | geranium sterol biosynthesis sitosterol stigmasterol α- and β-amyrin tetracyclic triterpenes |
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