Metabolomic profile of cacao cell suspensions growing in blue light/dark conditions with potential in food biotechnology

Theobroma cacao is a rich source of flavonoid compounds, which are potent antioxidants. Flavonoids are well-known for their health benefits against cardiovascular diseases, cancer, and improvement of blood pressure. For this reason, cacao mass production has drawn the attention from the functional foods industry. Furthermore, cacao cell suspensions can be used to evaluate complex biosynthetic pathways, such as flavonoids due to the homogeneity of the cell population, the unlimited availability of raw material, the high cell growth and division rates, and the reproducibility of in vitro growth conditions. However, the metabolome of cacao could be affected by exposure to light; especially shorter wavelengths such as blue light trigger targeted flavonoid synthesis. Here, we provide the first report of the metabolomic profile of cacao cell suspensions grown under white-blue and dark conditions. For this, targeted metabolomics was conducted on flavonoids, including bioactive compounds such as catechin, epicatechin and proanthocyanidins (PAs). Moreover, untargeted metabolomics was performed to evaluate the response of the endogenous metabolites exposed to darkness and light. For this, unsupervised and supervised multivariate methods were used. Additionally, a chemical annotation and classification was conducted for the top 50 features obtained from the PLS-DA, in order to identify metabolic pathways that are associated to the light treatments. An increase of glycosylated flavonoids and PAs with higher degrees of polymerization from cells grown under light compared to dark, suggested that light conditions may trigger mechanisms associated with moderate stress. Additionally, lipids, flavonoids, and phytosterols increased after light treatment. The potential of cacao cell suspensions in food biotechnology is discussed, considering that the characterization and quantification of the cacao flavonoid composition are the first steps to evaluate the putative contribution of chocolate to human health. Metabolomic profiles of cacao cell suspensions under light and dark conditions suggest that flavonoid modification processes could be involved in defense response under light stress.