Stable DOPG/Glycyrrhizin Vesicles with a Wide Range of Mixing Ratios: Structure and Stability as Seen by Scattering Experiments and Cryo-TEM.

Carina Dargel,Lionel Porcar,Pascal Fandrich,Yvonne Hannappel,Ramsia Geisler,Thomas Hellweg,Friederike Gräbitz-Bräuer

doi:10.3390/molecules26164959

Carina Dargel, Lionel Porcar + Show 5 more

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https://doi.org/10.3390/molecules26164959

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Abstract

Phosphatidylglycerols represent a large share of the lipids in the plasmamembrane of procaryotes. Therefore, this study investigates the role of charged lipids in the plasma membrane with respect to the interaction of the antiviral saponin glycyrrhizin with such membranes. Glycyrrhizin is a natural triterpenic-based surfactant found in licorice. Vesicles made of 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1’-glycerol) (DOPG)/glycyrrhizin are characterized by small-angle scattering with neutrons and X-rays (SANS and SAXS). Small-angle scattering data are first evaluated by the model-independent modified Kratky–Porod method and afterwards fitted by a model describing the shape of small unilamellar vesicles (SUV) with an internal head-tail contrast. Complete miscibility of DOPG and glycyrrhizin was revealed even at a ratio of lipid:saponin of 1:1. Additional information about the chain-chain correlation distance of the lipid/saponin mixtures in the SUV structures is obtained from wide-angle X-ray scattering (WAXS).

Highlights

Saponins are amphiphilic molecules which are found in a large variety in plants, granting them the name bio-surfactants [1,2,3,4]
To verify the small unilamellar vesicles (SUV) structure, cryoTEM imaging was performed on a sample composed of pure DOPG and a sample with xglycyrrhizin = 50 mol%, both prepared in D2O buffer
Whereas from Small-Angle Neutron Scattering (SANS) data alone the influence of glycyrrhizin addition was only hardly resolvable on the membrane scale, Small-Angle X-ray Scattering (SAXS) data clearly indicated an incorporation of glycyrrhizin into the hydrophobic membrane part

Summary

Introduction

Saponins are amphiphilic molecules which are found in a large variety in plants, granting them the name bio-surfactants [1,2,3,4]. Like many other saponins [1,2,11,12], glycyrrhizin exhibits several pharmacological actions, such as an anti-inflammatory, an antimicrobial and -viral, an antioxidative and an antitumor activities [9,13]. In Japan, glycyrrhizin is already used for the treatment of different types of hepatitis [17,18]. In this context, vesicles carrying glycyrrhizin are promising for the delivery of saponin [19]. Vesicles carrying glycyrrhizin are promising for the delivery of saponin [19] Such systems might allow the treatment of inflammations of the skin [20]

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