Wajid Husain Ansari

Solubilization of polycyclic aromatic hydrocarbons by novel biodegradable cationic gemini surfactant ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride and its binary mixtures with conventional surfactants

The aqueous solubility enhancement of the polycyclic aromatic hydrocarbons (PAHs) anthracene and pyrene was investigated by means of micellar solubilization. The solubilization capacity of equimolar binary mixed surfactant solutions of a biodegradable ester-bonded cationic gemini surfactant ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy)dichloride (C16H33(CH3)2N+(CH2COOCH2)2N+(CH3)2C16H33·2Cl−, 16-E2-16) with cationic cetylpyridinium chloride (CPC) and hexadecyltrimethylammonium chloride (CTAC); anionic sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS); nonionic polyoxyethylene (20) cetyl ether (Brij 58) and Triton X-100 (TX-100) towards the PAHs were studied spectrophotometrically. The solubilization capabilities have been discussed in terms of molar solubilization ratio (MSR), micelle–water partition coefficient (Km) and free energy of solubilization (ΔG0S) of the PAHs. While studying the surface and micellar properties of the single/mixed equimolar gemini–conventional surfactant systems by conductometric, tensiometric and fluorescence quenching methods, synergism between the component surfactants in the mixed micellar solutions was observed. The gemini–anionic surfactant mixtures show better solubilization capacity than the gemini–cationic and gemini–nonionic surfactant mixtures.

Biflavonyls of the araucariales

Abstract TLC examination of complex mixtures of biflavonyls from the leaf extracts of Araucaria bidwilli A. cookii, A. cunninghamii, Agathis alba and A. palmerstoni has been carried out. Chromatographically homogeneous mixtures of natural biflavonyls including minor components have been identified after complete methylation. Attention is drawn to aspects of chemotaxonomical significance.

Interaction between Zwitterionic Surfactants and Amphiphilic Drug: A Tensiometric Study

Abstract The physicochemical properties, viz, critical micelle concentration (cmc), surface excess concentration (Γmax), minimum area per head group (Amin) of zwitterionic surfactants (designated as n(−)-2-m(+); n = 8, 10, 12 and m = 12, 14, 16) and their mixtures with amphiphilic antidepressant drug amitriptyline hydrochloride (AMT) were determined by using surface tension measurements. The cmc and ideal cmc (cmcid) values along with interaction parameters, βm and βσ (calculated using Rubinghs and Rosens models), suggest attractive interactions among the components. The Krafft temperature measurements also indicate strong attractive interactions. Γmax (or Amin) increases (or decreases) with the addition of gemini surfactant; the values being closer to that of the drug. These values and micellar mole fraction (X1m-calculated from Rubinghs model and X1Moto-calculated from Motomuras model) indicate larger contribution of gemini surfactants in mixed micelles and smaller contribution at air/solution interface (as mole fraction values at interface, X1σ, are slightly smaller than X1m). The standard Gibbs energy of micellization (Δ Gmicº) and adsorption (Δ Gadº) as well as excess energy of mixing (Δ Gexm) are all negative. All these results suggest higher stability of the mixed systems. UV absorbance results also suggest that the mixed micelles are stable for several days.

Experimental and theoretical approach to cationic drug-anionic gemini surfactant systems in aqueous medium.

Herein the results of surface tension measurements on the mixed systems of an amphiphilic drug amitriptyline hydrochloride (AMT) and three anionic bisphosphodiester gemini surfactants having different hydrophobic tails (8, 10, and 12 carbon) are presented. The experimental and ideal critical micelle concentration (cmc and cmcid) values suggest synergism in mixed systems of AMT and 8-2-8/10-2-10 and attractive interaction in AMT-12-2-12 systems. Other parameters evaluated from the data also suggest mixed micellization among the components with almost 50% contribution of surfactants (micellar mole fraction, X1(m), close to 0.5). The X1 values evaluated from Rubinghs model (X1(m)) and Motomuras model (X1(M)) as well as X1(id) values increase with increasing content of surfactants in solution. Adsorption behavior too indicates that the mixed monolayers experience attractive interaction (β(σ)) which vary in the order: AMT-12-2-12<AMT-8-2-8<AMT-10-2-10. Interaction in mixed micelles (β(m)) follows the same trend. The results suggest that mixed systems of AMT-10-2-10 are the most stable one. Probably the difference in length of hydrophobic parts of AMT and gemini is most compatible in this system.

Phenolic glycosides from Salix babylonica

Abstract From the leaves of Salix babylonica, the new naturally occurring benzyl ester of gentisic acid 2′-O-acetyl β- d -glucoside has been isolated along with the known compounds-trichocarpin, salicin, kaempferol 7-O-glucoside, apigenin 7-O-galactoside, luteolin 4′-O-glucoside and an ester of terephthalic acid.

flavonol glycosides from Callitris Glauca

Abstract From the leaves of Callistris glauca myricetin 7-arabinoside, quercitrin, kaempferol 5-rhamnoside, a quercetin arabinoside, quercetin, kaempferol, galangin and shikimic acid were isolated. The natural occurrence of myricetin 7-arabinoside has not previously been reported.