1C), although the level of intracellular resveratrol at day 10 was higher than that at day
7 (Fig. 1A). The degradation of extracellular resveratrol could be due to the activities of extracellular acidic peroxidases that were reported to degrade extracellular phytoalexins [30]. The appearance of extracellular ɛ-viniferin, which was tentatively identified based on its UV spectrum and HPLC retention time (Supplemental Fig. 1), supported the occurrence of peroxidative processes in the medium. The pattern for the production of this stilbene selleck kinase inhibitor is identical to that of resveratrol, but its concentration is always lower than the level of resveratrol in the same experimental condition. The ratio of resveratrol to ɛ-viniferin levels in response to the combined treatment with 1 mg/L GLU and 10 μM JA is about 2–3-fold. In the presence of XAD-7, www.selleckchem.com/products/z-vad-fmk.html this ratio increased by several hundred-fold. This difference suggested that the adsorption by XAD-7 prevented resveratrol from its extracellular conversion. Of stilbenes that were produced intracellularly, piceid was the most abundant (Supplemental Fig. 1). The average level of piceid at day 10 in controls was approximately 500 mg/L while that of intracellular resveratrol was less than 5 mg/L. However, when XAD-7 was added and adsorbed extracellular resveratrol, it probably created a concentration gradient of resveratrol from cells to the medium. As
a result, there would be less intracellular resveratrol to be converted into piceid. Therefore, the total piceid yield was significantly reduced in response to the combined
treatment of XAD-7 and elicitors (Fig. 5A). The total concentration of piceid at day 10 in the control was approximately 729 mg/L; however, Thalidomide in cultures treated with 200 g/L XAD-7 that level was just around 313 mg/L, and it was reduced further in the presence of elicitors (Fig. 5A). It is worth noting that resveratrol is the main phenolic that was released. The total phenolics concentrations in elicited cultures, which were co-cultured with 200 g/L XAD-7 at day 7 and day 10 were approximately 2300 mg/L and 3000 mg/L (Fig. 5B), while the levels of extracellular resveratrol extracted from the beads were 2100 mg/L and 2400 mg/L, respectively. A decrease in the level of other phenolics, accompanied with an increase in that of extracellular resveratrol suggests that the common precursors are redirected toward resveratrol production at the expense of other competing pathways. The combined elicitation with JA and GLU, integrated with the addition of XAD-7 for the in situ removal and artificial storage of resveratrol resulted in a synergistic effect on resveratrol production. The level of resveratrol in response to the combined treatment with 200 g/L XAD-7, 1 mg/L GLU and 10 μM JA was approximately 2400 mg/L, which meets the requirement for a commercial culture process.