Royal jelly is an important bioactive compound that possesses several health promoting properties. It has been widely used in commercial medical products, healthy foods and cosmetics in many countries. Trans-10-hydroxy-2-decenoic acid (10-HDA) is the main fatty acid present in royal jelly and the 10-HDA content has been proposed as a freshness parameter for royal jelly quality analysis [1]. This work has been aimed to assess the 10-HDA stability (storage temperature 2 – 8 °C) in 5 different home-made royal jelly skin care products, presented in Table 1.
Tab. 1: Composition of royal jelly skin care products
|
Component
|
Sample 1
|
Sample 2
|
Sample 3
|
Sample 4
|
Sample 5
|
|
Frash royal jelly
|
5%w/w
|
|
|
5%w/w
|
10%w/w
|
|
Lyophilized royal jelly
|
|
5%w/w
|
5%w/w
|
|
|
|
Cream base
|
|
|
X
|
|
|
|
Sweet almond oil
|
X
|
X
|
|
X
|
X
|
|
Cocoa butter
|
X
|
X
|
|
X
|
X
|
|
Beeswax
|
X
|
X
|
|
X
|
X
|
|
Distilled water
|
X
|
X
|
X
|
X
|
X
|
|
Grape seed oil
|
X
|
X
|
X
|
X
|
X
|
|
Lavender oil
|
X
|
X
|
X
|
X
|
X
|
|
Bee pollen
|
|
|
|
2%w/w
|
|
|
Propolis
|
|
|
|
2%w/w
|
|
|
Honey
|
|
|
|
2%w/w
|
|
The HPLC method proposed by Kim et al. (2010) has been optimized and validated for the determination of 10-HDA in royal jelly skin care products [2]. All analyses were performed on a Waters Acquity UPLC system, equipped with a variable wavelength UV absorbance detector, operated with Waters EmpowerTM 2 software. UPLC analysis was performed using Agilent Poroshell 120 2,7um (100 mm x 4,6 mm) column, adjusted to 25 °C as a column temperature. The maximum absorbance of 10-HDA was confirmed to be 215nm. The mobile phase was a mixture of methanol, water, and phosphoric acid (55:45:2.7, v/v/v) and the flow rate was 1.0 mL/min. The total run time of each injected sample was 5 min, as indicated in the figure below. 10-HDA content in home-made royal jelly skin care products after 80 days varies from 0.52 ± 0.44 to 91.61 ± 1.73 percent of the initial content of 10-HDA (2 mg/g).
According to the results obtained in this study, we confirm the impact of change in composition on stability of the finished products.
