Ultrasonic Nanoliposomes for Stabilised Allicin Formulations

Allicin is a bioactive compound, which can be extracted from fresh garlic cloves. Allicin is prone to degradation and must be therefore formulated into a stabilised supplement form in order to obtain a long-term potent formula. Ultrasonic encapsulation of allicin into nanoliposomes protects allicin against degradation and results in a sustainable drug release.

Allicin Stability

The formulation of allicin products such as supplements is a challenging task due to the instability of allicin. Allicin is sensitive to oxidation and temperature, meaning allicin content decreased with time and temperature. Especially processing and storage temperatures are critical factors. Allicin activity is relatively stable at 4ºC when compared to allicin stored at room temperature (at approx. 22ºC). Its chemical half life at 4ºC was determined to be approx. 150 days, while at room temperature it was approx. 20 days.
Pre-processing of allicin sis another important factor that should be considered. Allicin seems to be more stable in sliced garlic than in ground garlic.
When it comes to ultrasonic extraction, generally sonication is more effective when larger surface area is available, i.e. when garlic is finely ground. Therefore, the optimum pre-treatment (grinding vs slicing) of garlic must be established as additional parameter besides the typical sonication process parameters. Read more about ultrasonic allicin extraction from garlic!

Structure of a liposome: Aqueous core and phospholipid bilayer with hydrophilic heads and hydrophobic/lipophilic tails.

Allicin Liposomes for Long-Term Stabilization

Allicin is prone to thermal degradation and is destroyed under acidic (pH 3.5 and lower) conditions. Allicin extracts and supplements should therefore stored in a called place, i.e. refrigerator, at approx. 4ºC to ensure a prolonged half life stability of approx. 1 year.
The formulation of allicin into lipid nano carriers such as liposomes and nanoemulsion gels prolongs the shelf life and stability of allicin products.

Ultasonic Formulation of Allicin-Loaded Liposomes

Lu et al. (2014) report the successful preparation of allicin nanoliposomes using ultrasonically assisted reverse-phase evaporation. The following parameters were used: lecithin-allicin ratio of 3.70 : 1, lecithin-cholesterol ratio of 3.77 : 1, ultrasonic time 3 min. 40 sec., organic phase-aqueous phase ratio of 3.02 : 1.The entrapment efficiency of ultrasonically encapsulated allicin was 75.20 ± 0.62% with a mean size of the allicin nanoliposome of 145.27 ± 15.19 nm. The ultrasonically prepared allicin nanoliposomes featured a sustained drug release, which enables a steady release of the active ingredient over an extended period of time. This facilitates the administration of drugs and supplements and reduces cytotoxic effects.
Read more about Ultrasonic Liposome Preparation!
 

Liposome Formation via Reverse Evaporation Method using Sonication

Ultrasonically Nanomemulsion Gels with Allicin

Nanomemulsion gels using polyethylene glycol was tested successfully as allicin drug carrier in order to improve the water solubility and bioavailability of allicin. (cf. Ranjbar et al.)
Read more about Ultrasonic Nano-Emulsification!

High-Performance Ultrasonicators for Liposomal Encapsulation

Hielscher ultrasonicators are reliable devices used in the pharmaceutical and supplement production to formulate high-quality liposomes loaded with antioxidants, polyphenols, fatty acids, vitamins, peptides, and other bioactive compounds. To meet its customer demands, Hielscher supplies ultrasonicators from the compact hand-held lab homogenizer and bench-top ultrasonicators to fully industrial ultrasonic systems for the production of high-volumes of liposomal formulations. Ultrasonic liposome formulation can be run as batch or as continuous inline process under precisely controlled conditions. A broad range of ultrasonic sonotrodes (also known as probes or horns) and reactor vessels are available to ensure an optimal setup for your liposome production. The robustness of Hielscher sonicators allows for 24/7 operation at heavy duty and in demanding environments.

The table below gives you an indication of the approximate processing capacity of our ultrasonicators:

After the formation of a lipidic film subsequent rehydration, sonication is used to promote the entrapment of active ingredients in the liposome. Additionally, ultrasonic downsizing achieves the desired liposome size.