In vitro rapid and mass multiplication of highly valuable medicinal plant Bacopa monnieri (L.) Wettst.

A protocol has been developed for micropropagation of Bacopa monnieri (L) Wettst, a medicinal plant of high commercial potential with legendary reputation as a memory vitalizer. Nodal segments containing axillary buds were surface sterilized with 0.1% solution of mercuric chloride for 5 min and were inoculated aseptically on culture medium, axillary bud break was achieved in 100% of cultures in semisolid MS medium supplemented with 0.2 mg/l BAP. These proliferated in vitro axillary shoots were excised and cut into groups of shoot clusters and subcultured on MS medium supplemented with 0.2 mg/l BAP for shoot multiplication. 100% in vitro rooting was obtained when shoot clusters were cultured on MS medium supplemented with 0.15 mg/l IBA. The rooted plantlets were hardened, acclimatized and successfully established in field.Key words: Bacopa monnieri, nodal segments, micropropagation, plant growth regulators

Organic dyes containing coplanar dihexyl-substituted dithienosilole groups for efficient dye-sensitised solar cells

peer-reviewedA chromophore containing a coplanar dihexyl-substituted dithienosilole (CL1) synthesised for use in dye-sensitised solar cells displayed an energy conversion efficiency of 6.90% under AM 1.5 sunlight irradiation. The new sensitiser showed a similar fill factor and open-circuit voltage when compared with N719. Impedance measurements showed that, in the dark, the charge-transfer resistance of a cell using CL1 in the intermediate-frequency region was higher compared to N719 (69.8 versus 41.3 Omega). Under illumination at AM 1.5G-simulated conditions, the charge-transfer resistances were comparable, indicative of similar recombination rates by the oxidised form of the redox couple. The dye showed instability in ethanol solution, but excellent stability when attached to TiO2. Classical molecular dynamics indicated that interactions between ethanol and the dye are likely to reduce the stability of CL1 in solution form. Time-dependent density functional theory studies were performed to ascertain the absorption spectrum of the dye and assess the contribution of various transitions to optical excitation, which showed good agreement with experimental results.PUBLISHEDpeer-reviewe

Electrochemical and spectroscopic characterization of dye-sensitized solar cell

Novel porphyrin and triphenylamine based organic dyes with different electron-donating moieties, π-bridging units and cyanoacetic acid as an acceptor (D-π-A) were characterised for use in dye-sensitized solar cells. The electrochemical and spectroscopic properties of the dyes were characterized by cyclic voltammetry, Raman, ATR-FTIR, UV-Vis, fluorescence and XPS. The UV-Vis spectra of all the dyes displayed maximum absorbances in the range 400-500 nm. ATR-FTIR and Raman spectra of all the adsorbed dyes showed asymmetric and symmetric carboxylate stretches which indicated that the dyes were adsorbed to the TiO2 surface via the carboxylate group. The HOMO energy levels of the dyes were in the range of ca. (1.0 – 1.4)V, more positive than the redox potential of the iodide/triiodide couple (0.4 V vs NHE). The LUMO levels of the dyes were more negative, ca. (- 0.6 to -1.5 V), than the conduction band edge (-0.5 V vs NHE) of TiO2. The results showed that all the dyes fulfil the criteria for use in DSSC. The current-voltage (I-V) characteristics of the dye-sensitized solar cells were used to determine the power conversion efficiency of the cells. Electrochemical impedance spectroscopy was used to study the kinetics of electrochemical and photo electrochemical processes in DSSCs under dark and illumination conditions. The charge transfer resistances and the electron lifetime in the mesoscopic film were obtained by using an appropriate equivalent circuit. Among all the dyes, the organic dye (CL1) based DSSC showed the highest efficiency, η ~ 4.3%, compared to C212D (η~2.4%) and L0 DSSC (η~1.9%). The best performance of the CL-DSSC was a result of reduced charge recombination confirmed by the electrochemical impedance data. The overall conversion efficiency of porphyrin dyes (PM1-5) were quite low, ranging from 0.1 to 1.1 %, compared to their counterpart organic dyes. PPy-co-PEDOT copolymers were successfully used as counter electrodes in dye-sensitized solar cells. Cells using PPy-co-PEDOT (at a ratio of 2:1) as a counter electrode exhibited an overall conversion efficiency of 4.6% compared to a value of 5.5% for a DSSC utilising platinum as the counter electrode. Impedance analysis of the response demonstrated that the PPy-co-PEDOT (2:1) counter electrode had enhanced catalytic activity to the reduction of triiodide in comparison to a Pt counter electrode. This study indicates that PPy-co-PEDOT coated FTO represent a good alternative for use as a counter electrode in DSSCs

2-HYDROXY-4-METHOXYBENZALDEHYDE, AN ASTOUNDING FOOD FLAVORING METABOLITE: A REVIEW

  Objective: Rich endowment of traditional knowledge plays a critical role in health care, food security, culture, environment and development. Traditional knowledge is also widely used by the aromatic, flavoring, food and health industries. Plant-based traditional medicine has often been used to identify and fast-track the development of modern food and drugs. Plants synthesize such wide array of secondary metabolites that includes alkaloids, glucosinolates, terpenoids and phenylpropanoids. This study is aimed to review on indigenous and exotic medicinal plants containing an astounding food flavoring metabolite; 2-hydroxy-4-methoxybenzaldehyde (HMB).Material and Method: The review focuses on the isomer of vanillin, 2-hydroxy-4-methoxybenzaldehyde, also called MBALD, HMB, or 2H4MB, a flavor compound that is generally found in the roots and rhizomes of medicinal plants. This food flavoring phenylpropenoid is one of the least investigated isomers of vanillin. HMB is known to exhibit a wide array of medicinal properties. Though the molecular role of these metabolites remains largely unknown, they are known to play a key role in plant-environment interactions/stress response/defence signaling and application in pharmaceutical and nutraceutical industries.Discussion and Conclusion: One of the key secondary metabolites is the group of phenylproponoids synthesized either through shikimic acid pathway or the malonate/acetate pathway. Phenylalanine ammonia lyase (PAL) is the enzyme involved in phenylpropanoid pathway catalysing the deamination of phenylalanine to synthesize cinnamic acid that subsequently synthesizes variety of phenylpropanoid products. Inspite of its medicinal importance, the regulatory molecular mechanism underlying the biosynthetic pathway is largely unknown

Design, Synthesis, and Pharmacological Evaluation of 5,6-Disubstituted Pyridin-2(1<i>H</i>)‑one Derivatives as Phosphodiesterase 10A (PDE10A) Antagonists

We report the design and synthesis of novel 5,6-diarylated pyridin-2­(1<i>H</i>)-one derivatives as pharmacophoric PDE10A inhibitors. This highly potent molecular scaffold was developed from an inactive diarylpyridine-2-amine derivative <b>3b</b> by extensive and systematic analogue synthesis and SAR analysis. Further optimization of the scaffold resulted in identification of pyridin-2­(1<i>H</i>)-one <b>18b</b> as a lead compound with good potency (IC₅₀ = 1.6 nM) and selectivity (>6000-fold) over other related PDEs but with a poor pharmacokinetic profile. Careful metabolite profiling of <b>18b</b> revealed that poor systemic exposure in rats (<i>C</i>_max = 44 ng/mL; AUC_0–<i>t</i> = 359 ng·h/mL) at 10 mg/kg was due to the formation of <i>O</i>-glucuronide conjugate by phase 2 metabolism. The structure of the glucuronide metabolite was confirmed by retention time and LC–MS/MS fragmentation matching with the synthetic glucuronide <b>26</b>. The problem of low exposure of <b>18b</b> was effectively addressed by its conversion to an acetate prodrug <b>25b</b>, which upon oral dosing resulted in an improved pharmacokinetic profile (<i>C</i>_max = 359 ng.h/mL; AUC_0–<i>t</i> = 2436 ng.h/mL) and a desirable brain to plasma ratio of 1.2. The prodrug <b>25b</b> showed good efficacy in selected rodent models of psychosis