Anti-malarial activities of Andrographis paniculata and Hedyotis corymbosa extracts and their combination with curcumin

<p>Abstract</p> <p>Background</p> <p>Herbal extracts of <it>Andrographis paniculata </it>(AP) and <it>Hedyotis corymbosa </it>(HC) are known as hepato-protective and fever-reducing drugs since ancient time and they have been used regularly by the people in the south Asian sub-continent. Methanolic extracts of these two plants were tested in vitro on choloroquine sensitive (MRC-pf-20) and resistant (MRC-pf-303) strains of <it>Plasmodium falciparum </it>for their anti-malarial activity.</p> <p>Methods</p> <p>Growth inhibition was determined using different concentrations of these plant extracts on synchronized <it>P. falciparum </it>cultures at the ring stage. The interactions between these two plant extracts and individually with curcumin were studied in vitro. The performance of these two herbal extracts in isolation and combination were further evaluated in vivo on Balb/c mice infected with <it>Plasmodium berghei </it>ANKA and their efficacy was compared with that of curcumin. The in vivo toxicity of the plant derived compounds as well as their parasite stage-specificity was studied.</p> <p>Results</p> <p>The 50% inhibitory concentration (IC₅₀) of AP (7.2 μg/ml) was found better than HC (10.8 μg/ml). Combination of these two herbal drugs showed substantial enhancement in their anti-malarial activity. Combinatorial effect of each of these with curcumin also revealed anti-malarial effect. Additive interaction between the plant extracts (AP + HC) and their individual synergism with curcumin (AP+CUR, HC+CUR) were evident from this study. Increased in vivo potency was also observed with the combination of plant extracts over the individual extracts and curcumin. Both the plant extracts were found to inhibit the ring stage of the parasite and did not show any in vivo toxicity, whether used in isolation or in combination.</p> <p>Conclusion</p> <p>Both these two plant extracts in combination with curcumin could be an effective, alternative source of herbal anti-malarial drugs.</p

Challenges and opportunities in mixed method data collection on mental health issues of health care workers during COVID-19 pandemic in India

Background: The present paper describes the key challenges and opportunities of mixed method telephonic data collection for mental health research using field notes and the experiences of the investigators in a multicenter study in ten sites of India. The study was conducted in public and private hospitals to understand the mental health status, social stigma and coping strategies of different healthcare personnel during the COVID-19 pandemic in India.Methods: Qualitative and quantitative interviews were conducted telephonically. The experiences of data collection were noted as a field notes/diary by the data collectors and principal investigators.Results: The interviewers reported challenges such as network issues, lack of transfer of visual cues and sensitive content of data. Although the telephonic interviews present various challenges in mixed method data collection, it can be used as an alternative to face-to-face data collection using available technology.Conclusions: It is important that the investigators are well trained keeping these challenges in mind so that their capacity is built to deal with these challenges and good quality data is obtained

Mn(VII) oxidation using cetyltrimethylammonium permanganate: Oxidation of alkyl cinnamates

662-666The kinetics and mechanism of Mn(VII) oxidation of substituted alkyl (E) cinnamates by cetyltrimethylammonium permanganate have been studied spectrophotometrically at 524 nm in chloroform medium. From the formation of aldehydes and Mn(III) a mechanism for the oxidation reaction has been proposed. The formation of cyclic manganate(V) diester intermediate is supported by a large negative entropy of activation. A negatively charged transition state is also supported by the Hammett plot

Classification of solvents on the basis of topology of the molecule

571-578Attempt has been made to classify the solvents on the basis of the topology of the molecule. The principal components of nine topological parameters for all the solvents have been determined. From the first principal component (PC1.) the solvents have been classified into positive and negative principal component class, where most of the nonpolar solvents have negative PC1 values and most of the polar solvents have positive PC1 values

Oxidation of phenylthioureas by cetyltrimethylammonium permanganate: A kinetic study

174-178<span style="font-size:9.0pt;mso-fareast-font-family:Calibri;mso-ansi-language: EN-IN;mso-fareast-language:EN-IN">Phenylthioureas have been subjected to oxidation in acetonitrile medium in neutral condition to investigate the oxidation behaviour of cetyltrimethylammonium permanganate on multifunctional groups. The oxidation product in each reaction is found to be the corresponding phenylurea. The rate of reaction is dependent on [CTAP], [phenylthiourea], [surfactant] and reaction temperature. A Michaelis-Menten type kinetics is observed with respect to the substrate. A reaction mechanism involving the formation of a cyclic intermediate in the slow step is proposed for the oxidation reaction. </span

Solvent effect on the photophysical behavior of some bischromophoric dyes

9-18Absorption and emission spectra of some bischromophoric dyes, having 4-(p-N,N-dimethylaminostyryl) pyridinium units flanked by spacers with 2, 3, 4 and 6 methylene units, in different organic solvents have been subjected to multiple regression analysis with twelve different solvent parameters. Optimization of multiparametric regression models has been achieved by successive exclusion of variable technique. The validity of the regression models has been established from the linearity of the calculated and observed transition energy relating to absorption spectra and Stokes shift. Variation in the trends in change of photophysical behavior of the dyes results in classification of the solvents into two distinct classes, viz., hydroxylic and dipolar aprotic solvents. A higher dipole moment of the excited state than of the ground state of all these dyes has been deduced from the Stokes shift. The study on quantitative Stokes shift-solvent parameter relationship reveals a significant change in the behavior of dyes with two methylene units as compared to the other dyes. To this effect different types of hydrogen bonding has been proposed

Correlation of critical micelle concentration of nonionic surfactants with molecular descriptors

113-118<span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">The critical micelle concentration (CMC) values of three sets. of fortysix nonionic surfactants with oxyethylene groups as the hydrophilic group have been subjected to quantitative structure-property relationships (QSPR) studies. The hydrophobic groups have varied number of carbon atoms with linear, octyl phenol and branched alkyl chain derivatives. Molecular descriptors derived from the chemical graphs have been used for the studies. A general regression model has been proposed to predict the CMC of non ionic surfactants. Plots related to principal components of molecular descriptors resulted in the ordination of non ionic surfactants.</span

Acid dissociation constants of N-alkyl <i>p/o-</i>hydroxy<i> </i>styryl pyridinium dyes in surfactant solutions

155-158Some N-alkyl p/o-hydroxy styryl pyridinium halides, the alkyl moieties being methyl, hexyl and decyl, have been synthesised and the acid dissociation constants of these compounds in aqueous and surfactant solutions have been determined using spectrophotometric method. The alkyl chain does not have any substantial effect on the pKa values in aqueous and cationic surfactant (cetyl trimethylammonium bromide: CTAB) system. However, with longer alkyl chain the pKa values increase in anionic surfactant (sodium dodecyl sulphate: SDS). These results have been attributed to the variation in solubilization sites of the surfactants

Oxidation of cis-olefinic double bonds by cetyltrimethylammonium permanganate

159-164The oxidation kinetics of cis-double bonds of cyclohexene, maleic anhydride and cholesterol have been investigated in chloroform medium by using cetyltrimethyl ammonium permanganate (CTAP). The products are found to be corresponding diols. Probable mechanism has been proposed for each case

On the HOMO-LUMO separation in the graph spectra of heterocyclobutadienes

370-372The characteristic polynomials of heterocyclobutadienes have been generated, and their graph spectra have been analysed. The molecular stability/reactivity and the electronic spectra have been discussed in the light of HOMO-LUMO separation in the graph spectrum. The presence of zero in the graph spectrum which leads to instability of the molecule has been reinvestigated. Triaza- and tetraza-cyclobutadienes having no zero in their graph spectra have been found to be more unstable than cyclobutadiene with two zeros in the corresponding graph spectrum