Effects of clove oil‐phospholipid mixtures on rheology of gum tragacanth – possible application for surfactant action on mucus gel simulants

Abstract

The present study evaluates the effectiveness of specialised biomaterials consisting of clove oil‐ phospholipid mixtures as possible substitute surfactants in diseases of altered mucus viscosity by studying their effect on the viscosity of mucus gel simulants in vitro. Test surfactants consisting of phospholipid‐clove oil mixtures in the ratio of 1 part of oil to 9 parts of phospholipid were prepared. The phospholipids used were dipalmitoyl phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) and binary mixtures of PC : PE and PC : PG in the ratio of 2 parts of PC to 3 parts of PE or PG. The effects of the phospholipid‐clove oil mixtures on the viscosity of mucus gel simulant (MGS: a polymeric gel consisting predominantly of gum tragacanth and simulating respiratory mucus), was studied by application of steady shear rates ranging from 0.512 to 51.2/s in a concentric cylinder viscometer at 37^○C. The change in MGS viscosity, after incubation with surfactants, was found to have a non‐Newtonian character and to follow the power law model with R² values >0.8. The addition of clove oil‐phospholipid mixtures caused a decrease in the MGS viscosity when compared with the effect of the phospholipid alone at low shear rates in case of PC, PG and PCPG. The combination of PC : PG with clove oil caused ratios of change in MGS viscosity <1 i.e., caused a decrease in the MGS viscosity. PC : PG with clove oil was capable of lowering MGS viscosity and should be further researched as possible therapies for diseases of altered mucus rheology.