Development of an efficient callus proliferation system for Rheum coreanum Nakai, a rare medicinal plant growing in Democratic People's Republic of Korea.

A clonal mass propagation to obtain mountainous sources of Rheum coreanum Nakai, a rare medicinal plant in Democratic People's Republic of Korea was established by rhizome tissue culture. Whole plants were selected and collected as a vigorous individual free from blights and harmful insects among wild plants of R. coreanum grown on the top of Mt. Langrim (1.540 m above the sea) situated at the northern extremity of Democratic People's Republic of Korea. Induction of the callus was determined using four organs separated from the whole plant and different plant growth regulators. The callus was successfully induced from rhizome explant on MS medium containing 2.4-D (0.2-0.3 mg/l). In the MS medium supplemented with a combination of BAP (2 mg/l) and NAA (0.2 mg/l), single NAA (0.5 mg/l), or IBA (0.5 mg/l), a higher number of shoot, root and plantlets was achieved. The survival rate on the mountainous region of the plantlets successfully acclimatized (100%) in greenhouse reached 95%, and yields of crude drug and contents of active principles were higher than those obtained by sexual and vegetative propagation. This first report of R. coreanum tissue culture provides an opportunity to control extinction threats and an efficient callus proliferation system for growing resources rapidly on a large scale.

Dynamics of phytoestrogen, isoflavonoids, and its isolation from stems of Pueraria lobata (Willd.) Ohwi growing in Democratic People's Republic of Korea.

Four isoflavonoids were isolated from stems of Pueraria lobata (Willd.) Ohwi growing in Democratic People's Republic of Korea and identified as daidzein (1), genistin (2), daidzin (3), and puerarin (4), structures, which were elucidated by means of spectroscopic analysis. Isoflavonoids were isolated using silica gel chromatography and purified with organic solvents. Isoflavonoid contents in P. lobata were determined using reliable high-performance liquid chromatography. The results indicated that the contents of puerarin and genistin in the roots are higher than those in the stems (6.19% and 0.04% vs. 1.15% and 0.02%), whereas the stems have higher contents of daidzin and daidzein than the roots (3.17% and 0.06% vs. 1.72% and 0.05%). Accordingly, the root part of the plant is useful for the isolation of puerarin and the stem part for daidzin. This study suggests that the stem of P. lobata is useful as an alternative source of puerarin, daidzin, genistin, and daidzein. In addition, collection of the stem will not sacrifice the plant and thus is beneficial to the natural ecosystems.