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Plant isoprenoids are derived from two biosynthetic pathways, the cytoplasmic mevalonate (MVA) and the plastidial methylerythritol phosphate (MEP) pathway. In this study their respective contributions toward formation of dolichols in Coluria geoides hairy root culture were estimated using in vivo labeling with 13 C-labeled glucose as a general precursor. NMR and mass spectrometry showed that both the MVA and MEP pathways were the sources of isopentenyl diphosphate incorporated into polyisoprenoid chains. The involvement of the MEP pathway was found to be substantial at the initiation stage of dolichol chain synthesis, but it was virtually nil at the terminal steps; statistically, 6 -8 isoprene units within the dolichol molecule (i.e. 40 -50% of the total) were derived from the MEP pathway. These results were further verified by incorporation of Polyisoprenoid alcohols together with sterols and quinone side chains constitute three main branches of terpene products originating from farnesyl diphosphate (FPP) 4 (1). These linear five-carbon unit polymers are divided into two groups, i.e. polyprenols and dolichols, according to the hydrogenation status of the ␣-terminal isoprene unit (dolichol structure is shown in Fig. 1). In cells, polyprenols and dolichols are always found as mixtures of prenologues, and data collected so far show polyprenols to be typical for bacteria and plants, whereas dolichols are generally attributed to animals and yeast (2). Nevertheless, it should be remembered that dolichols are the predominant form in some plant organs like roots (3). Data on the occurrence and functions of polyisoprenoids are summarized in recently published reviews (4, 5). The formation of the polyisoprenoid chain, starting from the -end of the molecule (Fig. 1), proceeds in a biphasic manner with farnesyl-diphosphate synthase responsible for the synthesis of the all-trans-FPP (three isoprene units of -t 2 structure, t stands for trans-isoprene unit), and its further elongation by cis-prenyltransferase. The latter enzyme, cloned from several prokaryotic and eukaryotic organisms (see Refs. 6, 7 and references therein), including Arabidopsis thaliana (8,9) and Hevea brasiliensis (10), utilizes isopentenyl diphosphate (IPP) for elongation of FPP up to the desired chain length, thus producing a family of polyprenyl diphosphates (n isoprene units of -t 2 -c n-3 structure, c stands for cis-isoprene unit), which are subsequently converted to polyprenols or dolichols according to the "tissue-specific requirements" by a still unknown mechanism.In plant cells two pathways are known to produce IPP utilized by numerous enzymes to finally give more than 50,000 different isoprenoid structures, the mevalonate pathway (MVA) and the mevalonate-independent methylerythritol phosphate pathway (MEP) (for reviews, see Refs. 11-13). Both pathways are compartmentalized as follows: the MVA in the cytoplasm to provide sterols, the many sesquiterpenes, and the prenyl chains of ubiquinones, and the MEP one in the plastids Tables 1 and 2

Polyisoprenoid alcohols of the plant Coluria geoides were isolated and analyzed by HPLC with UV detection to determine the nature of the polyprenol and dolichol mixture in the organs studied. In roots, a family of dolichols (Dol-15 to Dol-23, with Dol-16 dominating, where Dol-n is dolichol composed of n isoprene units) was accompanied by traces of polyprenols of similar chain lengths, whereas in hairy roots grown in vitro, identical patterns with a slightly broader chain-length range were found. Conversely, in leaves and seeds polyprenols were the dominant form, and their pattern was shifted toward longer chains (maximal content of Pren-19, where Pren-n is polyprenol composed of n isoprene units). Interestingly, the pattern of dolichols in seeds and leaves (in which Dol-17 dominated) was similar to that found in roots. Structures of the dolichols and polyprenols isolated were confirmed by the application of a new HPLC/electrospray ionization-MS method, which also offers a much higher sensitivity in detection of these compounds compared to a UV detector. The highest sensitivity was obtained when the [M + Na]+ ions of polyprenols and dolichols were recorded in the selected ion monitoring mode and a small amount of sodium acetate solution was added post-column to enhance the formation of these ions in an electrospray ion source.

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This article is the first report describing a new validated method to determine the content of HupA in Huperzia selago (Huperziaceae) from wild population and obtained in in vitro culture using the chaotropic mobile phase. An aqueous-organic (acetonitrile) mobile phase with an added chaotropic salt (NaPF 6 ) was used. The system of mobile phases ensured very high selectivity and efficiency at up to N = 6683 ± 963 theoretical plates calculated for isocratic mode. A Hypercosil GOLD column, C18 250 × 4.6 mm, and a Hypercosil GOLD precolumn, 5UM 10 × 4 mm, were employed for detection at four wavelengths, 230 nm being analytical. The regression coefficient (R 2 ) of the calibration was 0.9993 over the range 25-1252 μg mL -1 . The recovery rates were 98.36-105.1% with RSD <2.9%. The intra-and inter-day precisions, expressed as RSD, ranged from 1.2% to 2.7%. LOD for HupA was 14 ng mL -1 for a signal-to-noise ratio of 3:1. The limit of quantification was 140 ng mL -1 . The huperzine A (HupA) content of the plant material ranged from 0.65 mg g -1 dry weight (d.w.) to 1.59 mg g -1 d.w. (material from wild plants) and from 0.44 to 1.10 mg g -1 d.w. (material from in vitro cultures). Interestingly, in our study, plants of H. selago derived from wild population had one of the highest HupA concentrations recorded for a club moss (1.59 mg g -1 d.w.). The findings demonstrate that H. selago, found in Europe and North America, is an alternative source of HupA, richer than H. serrata. In order to confirm that HupA was present in the alkaloid extracts, HPLC-ESI-MS/MS analyses of the patterns were performed in the positive ion mode. The fragmentation quasi-molecular ion of the standard HupA (m/z = 243, [M+H] + ) and the ion with m/z = 243 found in the samples were identical, confirming the compound as HupA.