BIOPHYSICAL INVESTIGATION OF MOLECULAR INTERACTIONS BETWEEN ALLIIN AND ANIONIC DMPG MODEL MEMBRANE: AN FTIR STUDY

Garlic, which contains bioactive compound alliin, is a medicinal herb that has been traditionally utilized for its therapeutic properties against a range of illnesses. Our aim is to investigate the interactions between alliin and anionic dimyristoyl phosphatidylglycerol (DMPG) multilamellar vesicles (MLVs) at various temperatures and alliin concentrations (1, 3, 6 and 9 mol%) using Fourier transform infrared (FTIR) spectroscopy. The PerkinElmer Frontier spectrometer was used to collect spectra within the region of 4000-1000 cm-1. The specimens were subjected to scanning within a temperature range of 0 to 40 °C using the Specac temperature control device. The analyses were conducted utilizing the Spectrum v10.3.7 program. By introducing both low and high concentrations of alliin to DMPG MLVs, the wavenumber values of the CH2 antisymmetric stretching band decreased, while the bandwidth values increased, both in the gel and liquid crystal phases. During the gel phase, the presence of alliin resulted in a downward shift of the C=O stretching bands' wavenumber values. Opposite evidence occurred in the liquid crystal phase. The wavenumber values of the PO2- antisymmetric stretching band exhibited a shift towards lower values both in the gel and liquid crystal phases. In the present study, we investigated the biophysical effects of alliin on DMPG model membranes using parameters such as lipid order, dynamics and hydrogen bonding ability. The addition of alliin altered the physical characteristics of the DMPG MLVs by ordering the system, enhancing its dynamics, and promoting hydrogen bond interactions between the phosphate group of DMPG and alliin or water molecules, both in the gel and liquid crystalline phases. Moreover, alliin enhanced the strength of hydrogen bonding in proximity to carbonyl groups in the gel phase.