Asymbiotic germination of immature seeds, plantlet development and ex vitro establishment of plants of Dendrobium tosaense Makino - A medicinally important orchid

Shi-hu (Dendrobium spp. or Dendrobii Herba) is one of the important traditional Chinese medicines. The commercially available crude drug in the traditional medicine market is composed mainly of three species: Dendrobium tosaense, D. nobile, and D. moniliforme. An efficient method of propagation has been developed via asymbiotic germination of seeds in vitro for the medicinally important D. tosaense. Seeds from capsules of D. tosaense collected 8-14 wk after artificial pollination germinated after being cultured on full-strength or half-strength Murashige and Skoog (MS) medium devoid of plant growth regulators and with 3% sucrose. Germination of seeds varied with the medium type and seed maturity. Germinated seedlings after transfer to MS medium with 1.5% sucrose and 8% banana homogenate or potato juice or coconut water and 20 wk of incubation developed into healthy plantlets. Well-developed plantlets were transplanted to moss or moss and tree fern or tree fern as substrates in plastic trays and transferred to a greenhouse for hardening. All plants survived, attained maturity, and developed normal flower and capsule after one and a half years. This protocol of successful plant regeneration by asymbiotic seed germination should permit rapid propagation and conservation of this medicinally important Dendrobium species

High-pressure rheological analysis of CO2-induced melting point depression and viscosity reduction of poly(ε-caprolactone)

High-pressure rheology has been used to assess the effects of supercritical carbon dioxide (scCO2) on the melting point (Tm) and viscosity of poly (ε-caprolactone) (PCL) over a range of temperatures and pressures up to 300 bar over a wide range of shear rates. Plots of the storage and loss moduli against temperature show a significant shift of Tm to lower temperatures in the presence of CO2, indicating that the polymer crystals melt at temperatures much lower than the ambient pressure Tm. Furthermore, a significant decrease in the viscosity of two PCL grades with different molecular weight (Mn ~ 10 kDa and 80 kDa) was also detected upon increasing the CO2 pressure to 300 bar. Experimental viscosity data were fitted to the Carreau model to quantify the extent of the plasticising effects on the zero-shear viscosity and relaxation time under different conditions. Similar analyses were conducted under high-pressure nitrogen, to compare the effects obtained in the presence of a non-plasticising gas

Micropropagation of Polygonum multiflorum THUNB and quantitative analysis of the anthraquinones emodin and physcion formed in in vitro propagated shoots and plants

An efficient and rapid protocol for in vitro induction and complete plant regeneration of Polygonum multiflorum THUNB has been developed. Nodal explants were grown in vitro on Murashige and Skoog's (MS) basal medium containing different concentrations of a-naphthaleneacetic acid (NAA) and benzyladenine (BA). The nodal explants (97%) produced multiple shoots (4.7 shoots per explant) on MS basal medium supplemented with 0.2 mg/l NAA and 2.0 mg/l BA after 6 weeks of culture. Eighty-eight percent to 100% of the shoots (1.0 cm in length) elongated (about 3.02-4.28 cm) and rooted on MS basal medium supplemented with NAA or indole-3-butyric acid (IBA). All the rooted shoots were transferred to pots containing autoclaved soil, vermiculite, and peat moss (1 : 1 : 1). The plantlets were successfully acclimatized under greenhouse conditions with high humidity before transferring to the field. The anthraquinone contents were determined using HPLC. Analysis revealed that the contents of the major medicinal compounds-emodin and physcion in the 6 weeks old in vitro grown shoots and three month old in vitro propagated plants grown in greenhouse were higher than those of the marketed crude drug (processed underground or stem parts of R multiflorum)

Isolation and quantitative analysis of cryptotanshinone, an active quinoid diterpene formed in callus of Salvia miltiorrhiza BUNGE

Effect of N-6-benzyladenine (BA) on tanshinone formation in callus cultures of Salvia miltiorrhiza was examined in an attempt to increase the productivity of the medicinal compound, cryptotanshinone. Primary callus was induced by culturing leaf explants on Murashige and Skoog's (MS) basal medium supplemented with 1.0 mg l(-1) of 2,4-dichlorophenoxyacetic acid (2,4-D) in darkness. The callus proliferated further on MS basal medium containing 1.0 mgl(-1) 2,4-D and 0.5 mg l(-1) BA and was analyzed for cryptotanshinone by high performance liquid chromatography (HPLC). The HPLC results indicated that it contained small amounts of cryptotanshinone (0.26+/-0.05 mg/g dry wt). Omission of 2,4-D from the medium resulted in a marked increase in the content of cryptotanshinone in callus. The HPLC analysis revealed that the content of cryptotanshinone in the callus cultured on the MS basal medium supplemented with 0.1, 0.2, 0.5, 1.0, and 2.0 mg l(-1) of BA was significantly higher than the marketed crude drug (processed underground parts of S. miltiorrhiza). Maximum yield of cryptotanshinone (4.59+/-0.09mg/g dry wt) was observed in the callus cultured on MS basal medium supplemented with 0.2 mg l(-1) BA for 60 d. Cryptotanshinone was isolated from callus through silica gel column chromatography followed by preparative TLC and characterized based on NMR and mass spectral data

Studies on the production of some important secondary metabolites from medicinal plants by plant tissue cultures

Plants are a tremendous source for the discovery of new products of medicinal value for drug development. Today several distinct chemicals derived from plants are important drugs currently used in one or more countries in the world. Many of the drugs sold today are simple synthetic modifications or copies of the naturally obtained substances. The evolving commercial importance of secondary metabolites has in recent years resulted in a great interest in secondary metabolism, particularly in the possibility of altering the production of bioactive plant metabolites by means of tissue culture technology. Plant cell culture technologies were introduced at the end of the 1960's as a possible toot for both studying and producing plant secondary metabolites. Different strategies, using an in vitro system, have been extensively studied to improve the production of plant chemicals. The focus of the present review is the application of tissue culture technology for the production of some important plant pharmaceuticals. Also, we describe the results of in vitro cultures and production of some important secondary metabolites obtained in our laboratory

In vitro propagation by asymbiotic seed germination and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity studies of tissue culture raised plants of three medicinally important species of Dendrobium

A simple and efficient plant propagation system has been developed by asymbiotic germination of seeds in three medicinally important Dendrobium species, namely, Dendrobium tosaense, Dendrobium moniliforme, and Dendrobium linawianum. Plants obtained from natural habitats were grown in the greenhouse. The flowers were hand pollinated. Seeds of the capsules derived after 12 weeks of hand-pollination germinated asymbiotically (50-74%) on half strength Murashige and Skoog's (MS) basal medium with 3% sucrose and solidified with 0.9% Difco agar. Active growth in the germinated seedlings was achieved by re-culturing on full strength MS basal medium supplemented with 8% banana homogenate, 8% potato homogenate, 8% coconut water, 1.5% sucrose and 0.9% Difco agar. Healthy plantlets, transferred to plastic trays containing moss or moss and tree fern, successfully acclimatized (84-100%) in the greenhouse. A marked varied response was observed in the free radical scavenging activity of methanolic extracts of in vitro propagated plants, on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical using a UV spectrophotometer assay. Methanolic extracts were prepared by dissolving the powdered plant material, obtained from six months old in vitro propagated plants, each about 5 g, in boiling methanol. The percentage of scavenging effect of D. tosaense extract was 95.9% at 0.4 mg/ml concentration, whereas D. monoliforme, and D. linawianum extracts scavenged 83.4% and 92.3%, respectively, at a concentration of 0.4 mg/ml. All the extracts scavenged DPPH radical significantly in a concentration dependent manner