This work focuses on the membrane perturbation, solubilisation and thermotropic phase transition process of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) MLVs induced by a glucose-triazole-hydrogenated cardanol conjugate (GTHCC). GTHCC is a recently introduced non toxic sugar derivative. Differential scanning calorimetry (DSC) and fluorescence molecular probe based techniques have been used to understand the concentration dependent membrane perturbation, solubilisation and thermotropic phase transition process of DPPC MLVs. The phase transition temperature of DPPC MLVs decreases with increase in mol% of GTHCC. At higher concentration above 10 mol%, GTHCC was significantly perturbed the membrane organization. The intrinsic fluorescence of GTHCC is also found to be sensitive towards phase behaviour and changes in membrane organization of DPPC MLVs. © 2014 Elsevier B.V. All rights reserved.

Ashok Kumar Mishra

Department Of Chemistry

Mani Kamalraj

Differential scanning calorimetry

Fluorescence

glucose

Hydrogenation

Lipid bilayers

Nitrogen compounds

solubility

1 ,2-DIPALMITOYL-SN-GLYCERO-3-PHOSPHOCHOLINE

CARDANOLS

Concentration-dependent

fluorescence anisotropy

FLUORESCENCE MOLECULAR

LIPID BILAYER MEMBRANES

SOLUBILISATION

THERMOTROPIC PHASE TRANSITION

Membranes

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Molecular Structure

The synthesis and gelation properties of a structurally simple, renewable-resource-based glucose-triazole-hydrogenated cardanol conjugate (GTHCC) are reported. The conjugation of hydrogenated cardanol and glucose was done using a triazole linker employing copper(i) mediated acetylene azide cycloaddition 'click' chemistry in the key step. The GTHCC was found to form four different classes of gels; namely, (i) hydrogel from aqueous-protic solvents, (ii) organogel from non-polar solvents, (iii) gel from vegetable oil and (iv) gel from petroleum oil. In a water-methanol (1:1) mixture, the conjugate acted as a stable thermoreversible supergelator, even at a very low gelator concentration of 0.03% w/v. Unlike glycoside-based gels derived from hydrogenated cardanol and glucose, the GTHCC is stable under acidic as well as basic conditions, owing to the covalent linkages in the tether. The intrinsic fluorescence of the hydrogel was found to be sensitive towards a gel-sol transition. © 2014 The Royal Society of Chemistry.

RSC Advances

Characterization and phase transition study of a versatile molecular gel from a glucose-triazole-hydrogenated cardanol conjugate

This work focuses on the molecular level understanding of interaction between FTY720 (Fingolimod hydrochloride) and dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLVs) as a drug molecule carrier by investigating the structural changes, solubilisation effect and thermotropic phase behaviour. Three different techniques like dynamic light scattering (DLS), differential scanning calorimetry (DSC) and fluorescent molecular probe based techniques were used to study the effect of FTY720 on DMPC MLVs. DLS studies showed that FTY720 induces a marked change in the DMPC MLVs' structure and solubilises the lipid membrane with the increase in concentration of FTY720. DSC and temperature dependent fluorescence intensity studies of 1-naphthol showed that FTY720 broadens and shifts the phase transition temperature of the DMPC MLVs to a lower temperature. This is in contrast to the effect of the sphingosine which is a structural analogous to FTY720. Fluorescence anisotropy study of 1,6-diphenyl-1,3,5-hexatriene (DPH) also revealed the above phenomena. Fluorescence lifetime decay analysis of 1-naphthol suggested that incorporation of FTY720 causes a redistribution of 1-naphthol molecules between the core and interfacial regions of the membrane. © 2014 the Partner Organisations.

A molecular level understanding of interaction between FTY720 (Fingolimod hydrochloride) and DMPC multilamellar vesicles

This work focuses on the study of aqueous phase aggregation of the recently FDA approved oral drug molecule FTY720 (fingolimod hydrochloride) and its effect on dimyristoylphosphatidylcholine (DMPC) liposomes using different fluorescent molecular probes and fluorescence parameters. The variation of the steady state fluorescence intensity of 8-anilino-1-naphthalene sulfonic acid (ANS) with FTY720 in water shows an efficient micellar aggregation with the critical micellar concentration (CMC) at ∼75 μM. The aggregation number calculation from steady state fluorescence quenching of pyrene shows the formation of small micellar aggregates in aqueous solution having an aggregation number of 42 ± 3 with the free energy of micellization ∼-23 kJ mol-1. Fluorescence intensity and lifetime decay analysis of the molecular probe 1-naphthol indicate that the interaction of FTY720 with the DMPC lipid bilayer membrane prevents partitioning of small molecules such as 1-naphthol to the membrane in both solid gel (SG) and liquid crystalline (LC) phases. Temperature dependent fluorescence intensity studies of 1-naphthol and fluorescence anisotropy measurements of 1,6-diphenyl-1,3,5-hexatriene (DPH) have shown that above the CMC of FTY720, the SG to LC main phase transition temperature (TM) of the lipid bilayer membrane decreases from 23°C to 21°C in the aqueous medium. © 2013 the Owner Societies.

Physical Chemistry Chemical Physics

Study of aqueous phase aggregation of FTY720 (fingolimod hydrochloride) and its effect on DMPC liposomes using fluorescent molecular probes

The interaction of submicellar concentrations of various physiologically important unconjugated [sodium deoxycholate (NaDC), sodium cholate (NaC)] and conjugated [sodium glycodeoxycholate (NaGDC), sodium glycocholate (NaGC), sodium taurodeoxycholate (NaTDC), sodium taurocholate (NaTC)] bile salts with dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) small unilamellar vesicles in solid gel (SG) and liquid crystalline (LC) phases was investigated using the excited-state prototropism of 1-naphthol. Steady-state and time-resolved fluorescence of the two excited-state prototropic forms of 1-naphthol indicate that submicellar bile salt concentration induces hydration of the lipid bilayer membrane into the core region. This hydration effect is a general phenomenon of the bile salts studied. The bilayer hydration efficiency of the bile salt follows the order NaDC > NaC > NaGDC > NaTDC > NaGC > NaTC for both DPPC and DMPC vesicles in their SG and LC phases. © 2011 American Chemical Society.

Langmuir

Effect of submicellar concentrations of conjugated and unconjugated bile salts on the lipid bilayer membrane

Effects of two bile salts, namely sodium deoxycholate (NaDC) and sodium cholate (NaC), on DPPC small unilamellar vesicles have been investigated using the steady-state fluorescence anisotropy (rss) of diphenylhexatriene (DPH) as a tool. It was found that the variation of rss is sensitive enough to monitor different stages of interaction of bile salts with DPPC vesicles. NaDC induced significant changes in the membrane well below its CMC (6 mM). Even at 4 mM, which is still lower than the CMC, the phospholipids were completely solubilised by the NaDC micelles. The effect of NaC on DPPC vesicles, however, was much less significant, especially in the sub-micellar concentration regime. Being more hydrophilic NaC does not interact with the membrane efficiently. Complete solubilisation of phospholipids took place only when the concentration of NaC was above its CMC (16 mM). The experiments also showed that the bile salt-induced changes of vesicle structure were strongly dependent on the concentration of the bile salt and not on the molar ratio of lipid and bile salt. © Indian Academy of Sciences.

Fulltext

Journal of Chemical Sciences

Effect of sodium deoxycholate and sodium cholate on DPPC vesicles: A fluorescence anisotropy study with diphenylhexatriene

Effect of a glucose-triazole-hydrogenated cardanol conjugate on lipid bilayer membrane organization and thermotropic phase transition

Journal	Data powered by TypesetJournal of Molecular Structure
Publisher	Data powered by TypesetElsevier
ISSN	00222860
Open Access	No