Cell line selection combined with jasmonic acid elicitation enhance camptothecin production in cell suspension cultures of Ophiorrhiza mungos L.

Ophiorrhiza mungos is a herbaceous medicinal plant which contains a quinoline alkaloid, camptothecin (CPT), an anticancer compound. A high-yielding cell line, O. mungos cell line-3 (OMC3) was selected from cell suspension cultures of O. mungos using cell aggregate cloning method and established cell suspension culture. OMC3 cell suspension produced significantly high biomass (9.25 ± 1.3 g/flask fresh weight (FW)) and CPT yield (0.095 ± 0.002 mg g-1 dry weight (DW)) compared with the original cell suspension. Inoculum size of OMC3 cell suspension culture was optimised as 14 g L-1. Media optimisation has shown that 5 % (w/v) sucrose and an increased ammonium/nitrate concentration of 40/20 mM favoured CPT production, whereas 3 % (w/v) sucrose, an ammonium/nitrate concentration of 20/40 mM and 1.25 mM of phosphate favoured biomass accumulation. Jasmonic acid, chitin and salicylic acid was used to elicit CPT production in the original cell suspension culture and achieved significantly high CPT production with jasmonic acid (JA) elicitation. Further, OMC3 cell suspension culture was elicited with JA (50 µM) and obtained 1.12 ± 0.08 mg g-1 DW CPT and 9.52 ± 1.4 g/flask FW (190.4 g L-1 FW). The combination of cell line selection and elicitation has produced 18.66-fold increases in CPT production together with significantly high biomass yield. The study is helpful in the scale-up studies of O. mungos cell suspension culture in suitable bioreactor systems for the production of CPT.

Unusually short chalcogen bonds involving organoselenium: insights into the Se-N bond cleavage mechanism of the antioxidant ebselen and analogues.

Structural studies on the polymorphs of the organoselenium antioxidant ebselen and its derivative show the potential of organic selenium to form unusually short Se⋅⋅⋅O chalcogen bonds that lead to conserved supramolecular recognition units. Se⋅⋅⋅O interactions observed in these polymorphs are the shortest such chalcogen bonds known for organoselenium compounds. The FTIR spectral evolution characteristics of this interaction from solution state to solid crystalline state further validates the robustness of this class of supramolecular recognition units. The strength and electronic nature of the Se⋅⋅⋅O chalcogen bonds were explored using high-resolution X-ray charge density analysis and atons-in-molecules (AIM) theoretical analysis. A charge density study unravels the strong electrostatic nature of Se⋅⋅⋅O chalcogen bonding and soft-metal-like behavior of organoselenium. An analysis of the charge density around Se-N and Se-C covalent bonds in conjunction with the Se⋅⋅⋅O chalcogen bonding modes in ebselen and its analogues provides insights into the mechanism of drug action in this class of organoselenium antioxidants. The potential role of the intermolecular Se⋅⋅⋅O chalcogen bonding in forming the intermediate supramolecular assembly that leads to the bond cleavage mechanism has been proposed in terms of electron density topological parameters in a series of molecular complexes of ebselen with reactive oxygen species (ROS).

Vivipary in Ophiorrhiza mungos L. - a rare phenomenon in angiosperms.

Vivipary, the precocious germination of seeds within the parent plant, is a specialised feature of evolutionary and biological importance that ensures survival of a plant. Reports on vivipary in angiosperms are rare, accounting for <0.1% of flowering plants. Here, we report a remarkable case of occurrence of vivipary in Ophiorrhiza mungos. A study was conducted to collect information on the morphology of the capsules that support vivipary, environmental factors that induce vivipary, survival mode and the survival of viviparous seedlings. The hydroscopic movement of the cup-shaped capsules of O. mungos was found to help in viviparous germination during the rainy season. Of the total seeds in a capsule, 70% showed viviparous germination. The seedlings remaining inside the capsule attain a height of 0.98 ± 0.4 cm and reach the ground when the capsule falls. On the ground, seedlings obtain easy anchorage to the substratum since they have already germinated. Vivipary appears to be an adaptation of O. mungos to the rainy season for ensuring viable offspring. This suggests that vivipary in this species might be artificially induced by continuous spraying with water to rescue seeds in all seasons for use in large-scale propagation to meet increasing market demand and conservation of this valuable anticancer medicinal herb.

Solvent microenvironments and copper binding alters the conformation and toxicity of a prion fragment.

The secondary structures of amyloidogenic proteins are largely influenced by various intra and extra cellular microenvironments and metal ions that govern cytotoxicity. The secondary structure of a prion fragment, PrP(111-126), was determined using circular dichroism (CD) spectroscopy in various microenvironments. The conformational preferences of the prion peptide fragment were examined by changing solvent conditions and pH, and by introducing external stress (sonication). These physical and chemical environments simulate various cellular components at the water-membrane interface, namely differing aqueous environments and metal chelating ions. The results show that PrP(111-126) adopts different conformations in assembled and non-assembled forms. Aging studies on the PrP(111-126) peptide fragment in aqueous buffer demonstrated a structural transition from random coil to a stable ß-sheet structure. A similar, but significantly accelerated structural transition was observed upon sonication in aqueous environment. With increasing TFE concentrations, the helical content of PrP(111-126) increased persistently during the structural transition process from random coil. In aqueous SDS solution, PrP(111-126) exhibited ß-sheet conformation with greater α-helical content. No significant conformational changes were observed under various pH conditions. Addition of Cu(2+) ions inhibited the structural transition and fibril formation of the peptide in a cell free in vitro system. The fact that Cu(2+) supplementation attenuates the fibrillar assemblies and cytotoxicity of PrP(111-126) was witnessed through structural morphology studies using AFM as well as cytotoxicity using MTT measurements. We observed negligible effects during both physical and chemical stimulation on conformation of the prion fragment in the presence of Cu(2+) ions. The toxicity of PrP(111-126) to cultured astrocytes was reduced following the addition of Cu(2+) ions, owing to binding affinity of copper towards histidine moiety present in the peptide.

A protocol for high frequency regeneration through nodal explant cultures and ex vitro rooting of Plumbago rosea L.

A rapid clonal multiplication scheme comprising direct multiple shoot initiation and downsizing of the node with buds proliferated upon during subculture was developed for Plumbago rosea. Sixty five per cent of the nodes (approximately 2.0 cm) dissected out of young shoots from field grown plants and cultured in MS agar medium containing 3% sucrose and 15.4 microM BAP remained contamination free and responded at 95% rate with callusing at basal cut end and axillary bud break in 5 days followed by the formation of 2.41 +/- 0.14 shoots of 0.87 +/- 0.14 cm length in 3 weeks. Though differences in frequency and number of buds formed between nodes of 1-5 positions from the young shoots was negligible, the shoots emanated from the youngest node were shorter (0.92 +/- 0.19 cm) than those (2.3 +/- 0.50 cm) of the mature 5th node. Synergistic influence of BAP and auxins on caulogenesis was absent. Bud emergence in shorter (approximately 0.5 cm) nodes was delayed up to 3 weeks and extensive callus proliferation from the cut basal end overlapped the 8.2 +/- 0.37 axillary shoots/buds formed after 7 weeks. Reduction in the size (downsized) of the 2.0 cm node with buds to 1.0 cm by dissecting out the basal internodal segment having the callus and subculture of them (approximately 1.0 cm) with buds in contact with the medium for 3 weeks contributed to maximum multiplication of 42.1 +/- 5.40 shoot buds. Division of the shoot cluster and transfer of 2-3 shoots (0.5-1.5 cm) in a clump to MS basal liquid medium induced elongation of the shoots to 4.1 +/- 0.18 cm in 2 weeks. Shoots of 3.0-4.2 cm length were rooted within 3 weeks at 100% efficiency in vitro or ex vitro without hardening. In vitro rhizogenesis in presence of 0.49 microM IBA is recommended for enhanced rooting and high yield of commercially important tuberous roots during cultivation in the field.

In vitro mass multiplication of Ophiorrhiza mungo Linn.

A protocol for in vitro mass multiplication of plants through seedling (shoot) cultures was established for Ophiorrhiza mungo. Maximum number of adventitious shoots per shoot culture (10.4 +/- 1.72) was initiated on MS solid medium supplemented with BAP (2.22 microM) after 3 weeks. Shoots were further multiplied (12.8 +/- 2.8) through subculture of intact shoots and reculture of nodal segments of aseptic shoots (6.5 +/- 0.94) in MS solid medium containing BAP (0.89 microM). Shoot elongation (1.27 +/- 0.12 cm) was achieved in the medium containing GA3 (1.44 microM) in two weeks. Rooting was favoured in basal agar medium supplemented with IBA (12.3 microM) plus NAA (1.07 microM). The plants were successfully established (100%) in the pots containing sand and top soil (1:1) mixture in a period of two weeks.

In vitro mass multiplication and production of roots in Plumbago rosea.

Mass multiplication of Plumbago rosea was achieved by indirect organogenesis in young stem, leaf and root explant cultures of 6-9-month-old plants. All the explants responded similarly in a hormonal regime of 2.5 mg/L BA and 1.5 mg/L NAA with the formation of nodular callus in 4 weeks; the callus was divided and subcultured at 4-week intervals in the presence of 3.0 mg/L BA to produce up to 23.5 +/- 1.6 shoots in 18 weeks and then at 2.0 mg/L BA to produce up to 79.6 +/- 1.5 shoots in 23 weeks. The shoots of 2.0-3.5 cm length were rooted easily in half-strength MS agar medium supplemented with 0.1 mg/L IBA and rooted plants established within 4 weeks at a 95-98 % rate without hardening. Eight weeks after establishment, the micropropagated plants were transferred to experimental plots and cultivated for 10 months to obtain a significantly higher number (18.0 +/- 0.5) of larger tuberous roots (137.4 +/- 3.4 g fw/plant) compared to conventional rooted cuttings (14.0 +/- 1.7, 47.9 +/- 1.6 g fw/plant). During this period, the concentration of the root-specific compound, plumbagin recorded per g dw (1.5 %), was higher than that of conventionally propagated plants (0.9-1.0 %). The early formation of plumbagin-rich tuberous roots holds significant potential for the commercial cultivation of the micropropagated plants.

In vitro multiplication of Nothapodites foetida (Wight.) Sleumer through seedling explant cultures.

In vitro multiplication of Nothapodites foetida (Wight.) Sleumer was achieved using axenic seedling explant cultures. Isolated nodes (1.0-1.2 cm) and shoot tips (1.0-1.5 cm) cultured in Murashige and Skoog's agar medium containing varying concentrations of TDZ, BA and combinations of 2iP and GA3. Single shoot (0.8-1.2 cm) was regenerated in each culture after 6 weeks. Axillary shoots were then excised and recultured for 8 weeks in medium containing TDZ (0.05 mgL-1) which formed shoots (about 4 in no.; 2 cm) from the basal node. Axillary branches (2) which formed on 60% of these shoots after 10-12 weeks of culture were separated and recultured in the same medium for 8 weeks. Three shoots (0.8-1.0 cm) per culture were regenerated. Shoots of 0.8-1.8 cm length were subcultured on a low cytokinin (0.01 mgL-1 TDZ) regime to induce shoot elongation (2.0-3.5 cm) in 4 weeks. Shoot cuttings were rooted (60%) in the medium containing IBA (1.5 mgL-1). Rooted plantlets established in pots (90%) after hardening resumed normal growth in 3 months.