Induction of a photomixotrophic plant cell culture of Helianthus annuus and optimization of culture conditions for improved α-tocopherol production

Abstract

Tocopherols, collectively known as vitamin E, are lipophilic antioxidants, which are synthesized only by photosynthetic organisms. Due to their enormous potential to protect cells from oxidative damage, tocopherols are used, e.g., as nutraceuticals and additives in pharmaceuticals. The most biologically active form of vitamin E is α-tocopherol. Most tocopherols are currently produced via chemical synthesis. Nevertheless, this always results in a racemic mixture of different and less effective stereoisomers because the natural isomer has the highest biological activity. Therefore, tocopherols synthesized in natural sources are preferred for medical purposes. The annual sunflower (Helianthus annuus L.) is a well-known source for α-tocopherol. Within the presented work, sunflower callus and suspension cultures were established growing under photomixotrophic conditions to enhance α-tocopherol yield. The most efficient callus induction was achieved with sunflower stems cultivated on solid Murashige and Skoog medium supplemented with 30 g l(-1) sucrose, 0.5 mg l(-1) of the auxin 1-naphthalene acetic acid, and 0.5 mg l(-1) of the cytokinin 6-benzylaminopurine. Photomixotrophic sunflower suspension cultures were induced by transferring previously established callus into liquid medium. The effects of light intensity, sugar concentration, and culture age on growth rate and α-tocopherol synthesis rate were characterized. A considerable increase (max. 230%) of α-tocopherol production in the cells was obtained within the photomixotrophic cell culture compared to a heterotrophic cell culture. These results will be useful for improving α-tocopherol yields of plant in vitro cultures.

New strategies for the use of Linum usitatissimum cell factories for the production of bioactive compounds

“…In fact, Martinchik et al (2011) analyzed the nutritional facts of flaxseed and detected that the production of tocopherols was of 92 mg g seed À1 . When comparing these data with our tocopherol values, they are higher those found in flaxseeds and other SCC like sunflower (Geipel et al, 2014), safflower (Furuya et al, 1987) and tobacco (Harish et al, 2013). In fact, Geipel et al (2014) showed that the highest tocopherol levels (77 mg g DW À1 )…”

Enhanced accumulation of phytosterols and phenolic compounds in cyclodextrin-elicited cell suspension culture of Daucus carota

“…However, these levels of α-tocopherol found were higher than those found in other SCC, e.g., sunflower [52], safflower [53] and tobacco [54]. When Geipel et al [52] characterized the production of α-tocopherol using photomixotrophic and heterorotrophic sunflower SCC, they found that the highest intracellular α-tocopherol levels (77 µg gDW -1 ) were obtained with a photomixotrophic cell culture grown in liquid MS supplemented with 0,5 mg L -1 naphthalene acetic acid, 0,5 mg L -1 benzylaminopurine, 15 g L -1 sucrose and maintained at 26 ºC and a light intensity of 125 µmol m -2 s -1 . Likewise, sunflower and tobacco SCC produced 24 µg gFW -1 and 41 µg gFW -1 of α-tocopherol when 150 µM homogentisic acid alone or in combination with 200 µM phytol was added, respectively [55,54].…”

Cyclodextrins increase phytosterol and tocopherol levels in suspension cultured cells obtained from mung beans and safflower

“…Moreover, the levels of tocopherols are similar to those found in in other SCC. In fact, photomixotrophic SCC of sunflower were able to produce 77 µg g DW −1 . Likewise, the addition of precursors like homogentisic acid to sunflower SCC enhanced the levels of tocopherol (24 µg g FW −1 ) .…”