Abstract
The radioactive compound sodium $acetate-U-C^{14}$ (C-14 acetate) was administered to two- and four-year-old July and September American ginseng (Panax quinquefolium L.) plants and cuttings. The C-14 acetate uptake was approximately $99\%.$ The autoradiochromatograms suggest that the saponins(panaquilins) isolated by preparative thin-layer chromatography contained impurities, especially those isolated from the leaf and stem extracts. The root and fruit methanol extracts yielded relatively pure saponins. The large amounts of panaquilin B and its proximity to panaquilin C on preparative thin-layer plates resulted in some admixing. The average concentration $(\%$ plant dry weight) of semipurified saponins were high in the leaves $(13.8\%),$ compared to fruits $(9.8\%),\;stems\;(7.9\%)\;and\;roots\;(6.3\%).$ The average percentage of C-14 acetate incorporation into panaquilins was $4.8\%.$ The average percentage of C-14 acetate incorporation into panaquilins B and C was higher $(1.40\%\;and\;1.13\%,$ respectively) than that into panaquilin C, (d), G-1 and G-2 $(0.75\%,\;0.65\%,\;0.13\%\;and\;0.53\%,$ respectively). Panaquilin synthesis may be depending upon the part collection period and age of the plant. The average percentage of C-14 acetate incorporation into panaquilin B is high in roots $(0.58\%)\;and\;stems\;(0.48\%);$ that into panaquilins C and (d) high in leaves $(0.40\%\;and\;0.45\%,$ respectively); and that into panaquilin E high in roots and leaves $(0.55\%\and\;0.50\%,$ respectively). Panaquilin G-2 was synthesized in all parts of plants. The panaquilins appear to be biosynthesized more actively in July than September (exception-panaquilin G-l). Panaquilins B, C and G-1 may be biosynthesized more actively in four-year-old plants and panaquilins (d) and E more actively in two-year-old plants. The results from expectance with cuttings suggest that the panaquilins are synthesized de novo in the above-ground parts of ginseng plants, and that panaquilin G-l may be synthesized de novo in the leaf. It is known from the tissue culture studies that panaquilins are produced by leaf, stem and root callus tissues and callus-root cultures of American and Korean ginseng plants. Panaquilins may actively be synthesized de novo in most any cell or organ of the ginseng plants. It was verified that C-14 acetate was incorporated into the panaxadiol portions of the panaquilins of two-year-old plants (sp. act., 0.56 $m{\mu}Ci/mg$) and four-year-old plants (sp. act., 0.54 $m{\mu}Ci/mg$).