Oleogels with Birch Bark Dry Extract: Extract Saving Formulations through Gelation Enhancing Additives

Abstract

Triterpenes from the outer bark of birch have many beneficial biological and pharmacological activities. In particular, its wound healing efficacy is of paramount importance. Apart from that, particles of a birch bark dry extract aggregate into a three dimensional network when they are dispersed in lipids yielding a semi-solid oleogel. However, gel formation requires high amounts of the extract, which then acts at once as the active ingredient and the gelling agent. Infrared spectra of the respective mixtures proved that hydrogen bonds play a crucial role in the formation of the gel network. Dicarboxylic acids had almost no effect on gel strength. Monoalcohols increased the firmness of the oleogel with a decreasing effect from methanol > ethanol > butanol > octanol. All tested terminal diols increased the gel strength whereas vicinal diols affected the gel strength negatively. The effect was highly dependent on their concentration. The different effects of the diols are linked to their structure and polarity. The most pronounced enhancement of gelation was found for 1,6-hexanediol, which reduced the amount of triterpene extract (TE), which is necessary for the formation of an oleogel by a factor of 10.

Semisolid Dosage

“…Three papers in this Special Issue deal with formulations intended to treat wounds. In particular, the paper by Ghaffar et al describes a concept to enhance the gelling ability of an oleogel consisting of sunflower oil and a birch bark extract where the triterpene extract functions as the active substance as well as the gelling agent [1]. In order to save the extract, the authors studied several additives, which can act as linkers between the extract particles and thereby enhance the formation of a particulate network.…”

Application of Analytical Methods for the Comprehensive Analysis of Oleogels—A Review

“…In the study of [36], the light intensity as a function of temperature is monitored and the results highlighted that beeswax crystallization behavior is influenced by its concentration in a specific temperature range, or by the oil type. Laser diffraction was also involved in tracking the particle size changes of an oleogel during storage, in order to evaluate the aggregation of the particles [59].…”

Innovative Approach to Enhance Bioavailability of Birch Bark Extracts: Novel Method of Oleogel Development Contrasted with Other Dispersed Systems

“…BBE extracts contain several active components, among which betulin, lupeol, and betulinic acid are the most abundant and well-studied triterpenes [ 6 , 7 ]. Betulin has been reported to be effective against inflammation and oxidative stress [ 8 , 9 , 10 ].…”