Stimulation of the production of hypericins by mannan in Hypericum perforatum shoot cultures

Shoot organ cultures were established from callus derived from anthers of Hypericum perforatum flowers and the effect of elicitors on hypericin and pseudohypericin production in shoot organ cultures was investigated. Mannan stimulated pseudohypericin production up to four fold (0.82 mg/g dry wt) and hypericin production up to two fold (0.04 mg/g dry wt.) beta-1,3-glucan and pectin slightly stimulated pseudohypericin production (ca. two fold), but had no effect on hypericin production. On the other hand, yeast extract showed no stimulatory effect, on either hypericin or pseudohypericin production.     

The Effect of Cork Pieces on Pseudohypericin Production in Cells ofHypericum perforatumShoots

The stimulating effect of cork pieces on hypericin and pseudohypericin biosyntheses was studied in cells of shoots regenerated from the callus cultures of St. John's wort (Hypericum perforatumL.). The addition of the cork matrix slightly stimulated shoot growth and enhanced pseudohypericin biosynthesis about threefold (to 0.4 mg/g dry wt). Pseudohypericin production increased proportionally with the amount of cork material added (from 1 to 4 mg/ml of growth medium). Further increase in the amount of cork pieces inhibited both pseudohypericin production and shoot growth. Organic and aqueous extracts of cork pieces did not affect the production of these substances.     

Effect of Various Elicitors on Lignan Biosynthesis in Callus Cultures of Linum austriacum

Effects of elicitors (mannan, -1,3-glucan, and ancymidol) on the activity of several key enzymes participating in lignan biosynthesis were studied in Linum austriacum L. cell cultures. The activities of L-phenylalanine ammonia-lyase, polyphenoloxydase, tyrosine ammonia-lyase, soluble phenoloxidase, and membrane-bound and soluble oxidases were assayed. The elicitors under study affected various steps in the metabolic pathway of lignan biosynthesis. Elevated enzyme activity accompanied an elicitor-enhanced synthesis of podophyllotoxins and peltatins.     

Regulation of isoflavone production in hydroponically grown Pueraria montana (kudzu) by cork pieces, XAD-4, and methyl jasmonate

A mini-hydroponic growing system was employed for seedlings of kudzu vine (Pueraria montana) and contents of isoflavones (daidzein, genistein, daidzin, genistin, and puerarin) from shoot and root parts of seedlings were analyzed quantitatively. In addition, exogenous cork pieces, polymeric adsorbent, XAD-4, and universal elicitor, methyl jasmonate (MeJA), were used to regulate the production of these isoflavones. It was shown that cork pieces up-regulate the production of daidzein and genistein up to seven- and eight-fold greater than the levels obtained for control roots. In contrast, levels of glucosyl conjugates, daidzin and genistin, decrease up to five- and eight-fold, respectively. Cork treatment also induces the excretion of the root isoflavone constituents into the growth medium. Minimal levels of isoflavones are absorbed by the cork pieces. XAD-4 stimulates the production of glucosyl conjugates, daidzin and genistin, in root parts about 1.5-fold greater than that obtained in control roots. These are the highest amounts of daidzin and genistin that are observed (5.101 and 6.759 mg g⁻¹ dry weight, respectively). In contrast to these two adsorbents, MeJA increases the accumulation of isoflavones in shoot rather than in root parts of seedlings, about three- to four-fold over control levels, with the exception of genistein. These studies reveal new observations on the regulation of isoflavone production in hydroponically grown Pueraria montana plants by two adsorbents (cork pieces and XAD-4) and MeJA elicitor.     

The influence of some elicitors on growth and morphogenesis of Hypericum perforatum L. callus cultures

We studied the effects of elicitors, such as mannan, gβ-1,3-glucan, ancymidol, and cork crumbs, on morphogenetic and biosynthetic potencies of shoot cultures of Hypericum perforatum L. In the presence of these elicitors, different morphogenetic structures of H. perforatum callus cultures were formed. A correlation was found between the morphogenetic processes and induction of hypericin and pseudohypericin biosynthesis in the callus cultures.     

Differential accumulation of hyperforin and secohyperforin in Hypericum perforatum tissue cultures

Hyperforin is a pharmacologically active constituent of Hypericum perforatum (St. John's wort). In vitro cultures of this medicinal plant were found to contain hyperforin and three related polyprenylated acylphloroglucinol derivatives. The accumulation of these compounds was coupled to shoot regeneration, with secohyperforin being the major constituent in morphogenic cultures. The structure of secohyperforin was elucidated online by LC-DAD, -MS, and -NMR. In multiple shoot cultures, the ratio of hyperforin to secohyperforin was strongly influenced by the phytohormones N6-benzylaminopurine (BAP) and naphthalene-1-acetic acid (NAA). While increasing concentrations of BAP stimulated the formation of hyperforin, increasing concentrations of NAA elevated the level of secohyperforin. No differential stimulation was observed after elicitor treatment. Hyperforin and secohyperforin are proposed to arise from a branch point in the biosynthetic pathway.