Combined Control of the Bioprocess for Production of C-glycosylflavones from Linum thracicum in Bioreactor

Abstract

The high intake of foods and beverages rich in polyphenols, especially in flavonoids, has been associated with decreased risk of neoplasm. Luteolin shows therapeutic potential as a lead anticancer compound because it induces topoisomerase II-mediated apoptosis. The objective of this study is to develop cost-effective laboratory bio-technology for production of anticancer Cglycosylflavones. For the first time, callus and suspension cultures of Linum thracicum ssp. thracicum were initiated. The C-glycosylflavones were identified in plant and cell extracts on grounds of their characteristic LC-PDA-ESI-MS spectra and retention data in comparison with authentic reference samples. The main flavonoids were identified as an isoorientin (luteolin 6-C-glucoside) and isovitexin (apigenin 6-C-glucoside).Combining two fundamentally different control laws -the sliding nonlinear control and the linear controller, we are able to control a bioreactor in production of flavonoids in cell suspension of sensitive L. thracicum ssp. thracicum with a high concentration. After 24 days of sterile run cultivation of suspension in bioreactor, 22.8 g.l −1 dry wt of cell biomass was harvested from the bioreactor culture vessel, recording an increase of about 8 times over initial inoculum, with 2.47% ± 0.11 total flavonoids, which is with 1.18% ± 0.09 greater than yields from 300 ml flasks. Our findings are the first work on large cultivation of suspension of L. thracicum and bioreactor production of plant anticancer C-glycosylflavones. 139Key words: L. thracicum ssp. thracicum, in vitro cell cultures, Cglycosylflavones, stirred-tank bioreactor, combined bioreactor control Introduction. Flavonoids are phenolic substances isolated from a wide range of vascular plants. The role of dietary flavonoids in cancer prevention is widely discussed. They inhibit the proliferation of various cancer cells and tumour growth at nontoxic concentrations in organisms [ 1 ]. The high intake of foods and beverages rich in polyphenols, especially in flavonoids, has been associated with decreased risk of neoplasm. Chemoprevention has the potential to be a major component of colon, lung, prostate and bladder cancer control. These aspects made flavonoids an interesting object for industrial production. Luteolin shows therapeutic potential as a lead anti-cancer compound because it induces topoisomerase II-mediated apoptosis [ 5 ]. These aspects made luteolin and its glycosides an interesting object for pharmaceutical production.Different Linum species are shown to produce considerable amounts of lignans [ 2 ]. Only a few species from genus Linum are investigated for flavonoids [ 3,4 ]. In this genus, C-glycosylflavones were found only in the leaves of L. usitatissimum [ 4 ]. South-eastern Europe and the Balkan Peninsula in particular is a region rich in representatives of genus Linum, which could be a source of valuable molecules. Linum thracicum (Linaceae) -endemic species, native to the Balkan region, was not investigated in vitro up to now.For the first t...