The Characteristics of Atropine Metabolism in Cultured Tissues and Seedlings of Duboisia

The intact plant has communication between organs with respect to transport and metabolism of secondary products, but isolated organs do not. In fact, it is well established that tropane alkaloid hyoscyamine is biosynthesized in the root of tropane alkaloid-producing plants and then transported to and accumulated in the aerial parts (1,2). Study with cultured tissues of Duboisia clarified that conversion of hyoscyamine into scopolamine occurs in the shoots as well as in the roots (3). Previously, we showed that transport and metabolism of atropine (dl-hyoscyamine) were much more dynamic in the intact Duboisia plants than in the cultured tissues. Atropine was transported not only from root to leaf but also from leaf to root, through the xylem and phloem, respectively (4,5). Furthermore, atropine was hydrolyzed to tropine and tropic acid by atropine esterase in the roots of intact plants but not in the cultured roots which are able to produce atropine, suggesting that the intact plant roots decompose atropine which is transported back to the roots from the aerial parts (6).