Model 1 where; Yijkl = Phenolic acid content, µ = Overall mean of phenolic acid content, Treati = fixed effect of Treatment (i = IN, LG, IS, MCoA and control),

Timej = fixed effect of harvesting time in hours (j = 2, 24, 48, 96, 144, 192, 240 and 280), FWk = fixed effect of fresh weight (k = sample), Treati*Timej = interaction between treatment and time of harvest (i = treatment, j = time) eijkl = residual error. 4. Conclusions Inhibitors,research,lifescience,medical This study showed and confirmed many phenolic metabolites in a grape suspension GSK-J4 culture such as stilbenes, phenolic acid and anthocyanins, to name just a few. Treatment with IN, LG, MCoA or IS did not provide any significant inhibitory effect on the cell growth. The stimulation with biological substances such as IN, saliva and MCoA improved the biosynthesis of phenolic compounds and promising higher yields

of bioactive metabolites. The rapid effect of these biological stimulants on the amounts of phenolic substances may be of high pharmaceutical importance as well as economic value because of the high exploitation rate of secondary metabolites Inhibitors,research,lifescience,medical within a very short time lapse. Although all treatments positively influenced the synthesis of phenolic acid and biomass, it is advisable to use them for phenolic acid extraction rather than biomass. The major reason is the inhibitory effect of the stimulants on cell propagation after some time, whereas indefinite growth is achieved with untreated grape cells. Inhibitors,research,lifescience,medical Nevertheless, MCoA was the preferred stimulant with the highest yield in phenolic acid within just 2 h of treatment. Furthermore, MCoA is an important natural regulator and metabolite Inhibitors,research,lifescience,medical in the biosynthesis of phenolic compounds. It remains of interest to evaluate in future studies whether the effect of MCoA is by its regulatory

role or as a direct substrate. Naturally, plants have to activate their defense mechanisms by producing signaling molecules within a short time for survival. This explains why different biological elicitors used in this study serve as excellent stimulants to plant Inhibitors,research,lifescience,medical in vitro cultures of V. vinifera. Although MCoA directly may be too expensive for use in a production process, our results may provide ideas for genetic modifications or metabolic treatments PDK4 to obtain a similar effect, also with cheaper compounds. Acknowledgments The authors are very grateful to Knorr for providing the grape cell culture and also to Irene Hemmerich for technical and scientific assistance. This special experiment was supported by Boland (MPI Jena) and his working group as well as Steppuhn from the Free University Berlin who provided us with the substances without complications. Conflict of Interest Conflict of Interest All authors have read and approve this version of the manuscript and due care has been taken to ensure the integrity of the work. No part of this paper has been published elsewhere and no conflict of interest exists in the submission of this manuscript.