Phytochemical Screening of Callus and Cell Suspensions Cultures of Thevetia peruviana

Abstract Thevetia peruviana is an ornamental shrub grown-up in many tropical region of the world. This plant produces secondary metabolites with biological properties of interest for the pharmaceutical industry. The objective was to determine the secondary metabolites profile of callus and cell suspension cultures of T. peruviana and compare them with those from explant (fruit pulp). Extracts in 50% aqueous ethanol and ethyl acetate were prepared. The phytochemical analysis was performed using standard chemical tests and thin layer chromatography. In addition, total phenolic and flavonoids compounds (TPC and TFC), total cardiac glycosides (TCG) and total antioxidant activity (TAA) was determined during the cell suspension growth. Phenolic chemical profile was also analyzed by high performance liquid chromatography (HPLC). Common metabolites (alkaloids, amino acids, antioxidants, cardiac glycosides, leucoanthocyanidins, flavonoids, phenols, sugars and triterpenes) were detected in all samples. The maximum production of extracellular TCG, TPC, TFC and TAA in cells suspensions were at 6-12 days; in contrast, intracellular content was relatively constant during the exponential grown phase (0 to 12-days). HPLC analysis detected one compound with retention time at 11.6 min; this compound was tentatively identified as dihydroquercetin, a flavonoid with anti-cancer properties. These results provide evidence on the utility of the in vitro cell cultures of T. peruviana for valuable pharmaceutical compounds production.

Structured model and parameter estimation in plant cell cultures of Thevetia peruviana.

In this work, a mechanistic model for predicting the dynamic behavior of extracellular and intracellular nutrients, biomass production, and the main metabolites involved in the central carbon metabolism in plant cell cultures of Thevetia peruviana is presented. The proposed model is the first mechanistic model implemented for plant cell cultures of this species, and includes 28 metabolites, 33 metabolic reactions, and 61 parameters. Given the over-parametrization of the model, its nonlinear nature and the strong correlation among the effects of the parameters, a parameter estimation routine based on identifiability analysis was implemented. This routine reduces the parameter's search space by selecting the most sensitive and linearly independent parameters. Results have shown that only 19 parameters are identifiable. Finally, the model was used for analyzing the fluxes distribution in plant cell cultures of T. peruviana. This analysis shows high uptake of phosphates and parallel uptake of glucose and fructose. Furthermore, it has pointed out the main central carbon metabolism routes for promoting biomass production in this cell culture.

Effect of light wavelength on cell growth, content of phenolic compounds and antioxidant activity in cell suspension cultures of Thevetia peruviana.

Thevetia peruviana (T. peruviana) has been considered as a potentially important plant for industrial and pharmacological application. Among the number of compounds which are produced by T. peruviana, antioxidants and polyphenols are of particular interest due to their benefits on human health. Cell suspension cultures of T. peruviana were established under different conditions: 1) constant illumination (24h/day) at different light wavelengths (red, green, blue, yellow and white), 2) darkness and 3) control (12h/12h: day light/dark) to investigate their biomass, substrate uptake, polyphenols production and oxidizing activity. The results showed biomass concentrations between 17.1g dry weight (DW)/l (green light) and 18.2g DW/l (control) after 13days. The cultures that grew under green light conditions consumed completely all substrates after 10days, while other cultures required at least 13days or more. The total phenolic content was between 7.21 and 9.46mg gallic acid (GA)/g DW for all light conditions. In addition the ferric reducing antioxidant power and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid antioxidant activity ranged from 5.41-6.58mg ascorbic acid (AA)/g DW and 82.93-110.39µmol Trolox/g DW, respectively. Interestingly, the samples which grew under the darkness presented a higher phenolic content and antioxidant capacity when compared to the light conditions. All together, these results demonstrate the extraordinary effect of different lighting conditions on polyphenols production and antioxidant compounds by T. peruviana.