Lithuanian Royal jelly: quality assessment, biological activity and quantitative determination of trans-10-hydroxy-2-decenoic acid in various solvents

Abstract

Royal jelly is a bee product with a high commercial interest due to its exceptional biological properties and unique composition. In this study, we evaluated the quality of Lithuanian Royal jelly, including the water content, antioxidant activity, amount of polyphenolic compounds and pH. The results indicated that Lithuanian Royal jelly had the values of pH, water content as well as polyphenols that were comparable to the data already published. In the study, we also evaluated the impact of various solvents on the amount of 10-hydroxy-2-decenoic acid (10-HDA), the main fatty acid, naturally occurring only in Royal jelly and which is the quality marker, in solutions obtaining the amount using the HPLC method. According to solubility tests performed, 10-HDA from Royal jelly is best soluble in ethanol of various concentrations, yet in order to be used for exceptional Royal jelly antibacterial and many other biological properties it was important to increase the solubility in aqueous solutions. Addition of β-cyclodextrin has increased the amount of 10-HDA in solution up to the level of ethanol solutions. The antioxidant and antibacterial tests have demonstrated that Lithuanian Royal jelly exhibits positive effects against free radicals, as well as mostly occurring bacterial strains, such as Esherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus. As the conclusion of this study, we can assume that the quality assessment methods chosen for this study, are significant for standardizing the procedures for further studies.

Comprehensive Study of the Physicochemical Properties of Royal Jelly from Various Regions of Türkiye**

“…In agreement with those reports, the pH values of the analysed RJ samples were found to be 3.45‐3.80 [31,40] . But the pH values obtained in this study were a little lower than the results of Flanjak et al.…”

“…In agreement with those reports, the pH values of the analysed RJ samples were found to be 3.45-3.80. [31,40] But the pH values obtained in this study were a little lower than the results of Flanjak et al ( 2019) and Kolayli et al (2016), who found pH values between 3.98 and 4.21 and between 3.60 and 5.10, respectively. [33,41] According to the literature, having small differences or close values was completely normal when comparing the current data because the pH value of RJ depends on the acidic substances in its composition, such as fatty acids, phenolic acids, organic acids, and proteins.…”

Preparation of Ophthalmic Microemulsions Containing Lithuanian Royal Jelly and Their Biopharmaceutical Evaluation

“…Based on the solubility results of RJ and in order to create the biological conditions in the release studies, phosphate buffer saline was used as the acceptor medium [16]. Each experiment was carried out in triplicate.…”

“…where ABS s is the absorbance of cells treated with test formulations and ABS control is the absorbance of control cells. Cytotoxicity was expressed as the percentage of cells alive [16].…”