Biological and Chemical Stability of Various Preparations of Garlic Extracts

Abstract

The beneficial effects of garlic (Allium Sativum) on cancer and on the cardiovascular system, as well as direct anti-bacterial and anti-viral properties, has been confirmed by multiple research papers, where organosulfur compounds (OSCs) are regarded as the main bioactive components of garlic. In this thesis the anti-growth effects of a simple water-based garlic extract (GE) on the human cancer cell line JJN-3 are demonstrated using a viability assay (MTT). In an attempt to identify the nature of the most active compounds, the GE was fractionated using evaporation and solid phase extraction (SPE) to enrich and concentrate volatile OSCs. The GE was entrapped in an ethanol-in-oil (E/O) emulsion to study the biological and chemical stability at three different temperatures over 12 weeks. The effect of freeze drying on the GE and garlic cloves was studied, and anti-growth activity of different garlic supplements: Kyolic, Kwai and Weissin was studied and compared with the GE. The chemical composition of the various preparations of garlic was analyzed qualitatively using liquid chromatography - mass spectrometry (LC-MS) and gas chromatography - mass spectrometry (GC-MS).

The growth-inhibiting effects of the GE were proved to be highly active, also compared to other garlic supplements, and dose-dependent. High amounts of OSCs, especially diallyl disulfides (DADs) and diallyl trisulfides (DATs) were detected in the GE, suggesting the effect of these compounds in growth-inhibition. Fractionation of the GE led to a more enriched and concentrated fraction of volatile OSCs, with higher anti-growth activity. This was lost during freeze drying, which further suggests the involvement of these compounds. The biological activity of the GE-containing E/O-emulsion decreased with time and increasing temperature, but remained relatively stable at 4 degrees C for 10 weeks. The amount of OSCs, however, only decreased slightly, which suggests the influence of other compounds not detected by GC-MS on cancer growth. Furthermore, a high amount of OSCs detected in a freeze dried garlic clove, which showed low anti-growth activity, also suggests the involvement of other non-volatile compounds. The results from the LC-MS analysis would need more attention in future work and the GE-containing E/O-emulsion would need to be optimized to provide a more stable product for future commercialization.