Curcumin Accelerates the Lateral Motion of DPPC Membranes

Abstract

Curcumin, the main ingredient in turmeric, has attracted attention due to its potential anti-inflammatory, anticancer, wound-healing, and antioxidant properties. Though curcumin efficacy is related to its interaction with biomembranes, there are few reports on the effects of curcumin on the lateral motion of lipids, a fundamental process in the cell membrane. Employing the quasielastic neutron scattering technique, we explore the effects of curcumin on the lateral diffusion of the dipalmotylphosphatidylcholine (DPPC) membrane. Our investigation is also supported by Fourier transform infrared spectroscopy, dynamic light scattering, and calorimetry to understand the interaction between curcumin and the DPPC membrane. It is found that curcumin significantly modulates the packing arrangement and conformations of DPPC lipid, leading to enhanced membrane dynamics. In particular, we find that the presence of curcumin substantially accelerates the DPPC lateral motion in both ordered and fluid phases. The effects are more pronounced in the ordered phase where the lateral diffusion coefficient increases by 23% in comparison to 9% in the fluid phase. Our measurements provide critical insights into molecular mechanisms underlying increased lateral diffusion. In contrast, the localized internal motions of DPPC are barely altered, except for a marginal enhancement observed in the ordered phase. In essence, these findings indicate that curcumin is favorably located at the membrane interface rather than in a transbilayer configuration. Further, the unambiguous evidence that curcumin modulates the membrane dynamics at a molecular level supports a possible action mechanism in which curcumin can act as an allosteric regulator of membrane functionality.

Modulation of Phase Behavior and Microscopic Dynamics in Cationic Vesicles by 1-Decyl-3-methylimidazolium Bromide

“…This type of motion has been characterized by various models, including ballistic flow-like motion, 43 Fickian diffusion, 44 subdiffusion, 58 and localized diffusion. 59 It is found that Fickian diffusion is valid at least for distances greater than the molecular diameter, [5][6][7]11 which is the case for the length scale accessible by the present QENS experiment. Hence, we have used the Fickian diffusion model, and the scattering law for the lateral motion can be written as 41,42…”

“…This type of motion has been characterized by various models, including ballistic flow-like motion, Fickian diffusion, subdiffusion, and localized diffusion . It is found that Fickian diffusion is valid at least for distances greater than the molecular diameter, − , which is the case for the length scale accessible by the present QENS experiment. Hence, we have used the Fickian diffusion model, and the scattering law for the lateral motion can be written as , S lat ( Q , E ) = L lat ( normalΓ lat , E ) = 1 π normalΓ lat false( E / ℏ false) 2 + Γ lat 2 where Γ lat is the half-width at half-maxima (HWHM) of the Lorentzian function corresponding to the lateral motion of the lipid molecules.…”

“…Cationic lipids with small head groups show complex phase behavior due to the intricate interplay between Coulombic and hydrophobic interactions, which are governed by the nature of the head group and alkyl tail. − A large hysteresis in heating and cooling cycles, the formation of intermediate phases, and the non-synchronous ordering between the polar head and non-polar tails are the peculiar features observed in these systems. , Moreover, not only the phase transition temperature but also the nature of the phase transition changes with varying chain length. This is in contrast with zwitterionic lipid membranes ,,− where nature of the phase transition remains unaltered and only phase transition temperatures shift with different chain lengths.…”

“…bilayer solution solvent (7) In the above eq, ϕ represents the volume fraction of the D 2 O in the vesicle solution. The terms I solution (Q, E) and I solvent (Q, E) refer to the scattering signals obtained from the solution of vesicles and D 2 O solvent, respectively.…”

Probing the Hydrophobic Region of a Lipid Bilayer at Specific Depths Using Vibrational Spectroscopy

“…Vibrational spectroscopy can offer small probes and high temporal resolution. C–H stretching modes of methylene groups were found to be useful to probe lipid conformations in lipids, allowing to discriminate between gauche- and anti-conformations. − However, atomic assignment using CH stretching modes is difficult due to vibrational coupling of different methylene groups along the chain. Two-dimensional infrared (2DIR) spectroscopy has emerged as a tool for elucidating molecular interactions and structural dynamics, including those of the lipid bilayers. − Molecular motions of a cell membrane, including the motions on an ultrafast scale, are essential for the cell to conduct its biological function.…”