Effect of Lactic Acid Bacteria Fermentation on Rosmarinic Acid and Antioxidant Properties of in vitro Shoot Culture of Orthosiphon aristatus as a Model Study

Abstract

In vitro shoot culture of Orthosiphon aristatus was selected as a model system for lactic acid bacteria (LAB) fermentation study. This in vitro plant was subjected to different types of LAB fermentations (Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM) for a different time periods of 24, 48, and 72 h at 37oC. The LAB fermentations consisted of solid state fermentations in a climatic incubator and liquid state of fermentations in a DCU fermenter system. The aim was to determine the effect of fermentation on antioxidant properties of the in vitro plant extract. Results indicate that all types of LAB fermentation decreased the level of rosmarinic acid and total phenolic compounds; however, a slight increase in total flavonoids and flavonols was observed in solid state fermentations samples. The highest reduction was obtained in the sample of liquid state fermentation inoculated with L. plantarum for a period of 72 h. The loss in rosmarinic acid and phenolics was concomitant with a loss of total antioxidant activity (DPPH, TEAC, and SOD-like activity). HPLC result confirmed that the longer fermentation was the greater reduction phenolic acids content was found. These results indicate LAB fermentation caused a decrease on antioxidant properties of in vitro shoot culture of Orthosiphon aristatus.