Garlic allyl derivatives interact with membrane lipids to modify the membrane fluidity

Area of Science:

• Biochemistry
• Cell Biology
• Pharmacology

Background:

• Garlic (Allium sativum) possesses various medicinal properties.
• The precise mechanisms of action for garlic's therapeutic effects are not fully understood.
• Interactions with cell membranes are a potential pathway for bioactive compounds.

Purpose of the Study:

• To investigate the interaction of garlic constituents with model cell membranes.
• To determine how these interactions affect membrane fluidity and rigidity.
• To correlate membrane effects with known biological activities of garlic compounds.

Main Methods:

• Comparative study of allyl sulfides (diallyl trisulfide, diallyl disulfide, diallyl sulfide) and their precursor (alliin).
• Use of model membranes composed of phospholipids, cholesterol, and ergosterol.
• Assessment of membrane rigidification at varying concentrations (20-500 µM).
• Correlation of membrane effects with antiproliferative, antiplatelet, and antimicrobial activities.

Main Results:

• Allyl sulfides, especially diallyl trisulfide (DATS) and diallyl disulfide (DADS), rigidified tumor and platelet model membranes by interacting with lipid bilayers.
• DADS showed greater potency than DATS in rigidifying fungal (Candida) cell membranes containing ergosterol.
• Allyl sulfides did not affect bacterial membranes lacking ergosterol, and the precursor alliin was inactive.
• The potency and selectivity of membrane rigidification mirrored antiproliferative, antiplatelet, and antimicrobial effects.
• Membrane-active allyl sulfides inhibited tumor cell growth in culture, with DATS > DADS potency.

Conclusions:

• Interactions of diallyl sulfides with membrane lipids, leading to rigidification, represent a key mechanism for garlic's medicinal actions.
• The specific lipid composition of the membrane (e.g., presence of cholesterol or ergosterol) influences the efficacy of different allyl sulfides.
• The observed membrane effects provide a mechanistic basis for garlic's diverse biological activities, including anti-cancer, anti-platelet, and antimicrobial properties.