Isolation, purification and cytotoxic evaluation of lutein from mixotrophically grown Chlorella sorokiniana TH01

Mixotrophic cultivation of several microalgae simultaneously utilizing two energy sources of light and organic carbon has been reported to significantly achieve higher biomass productivity than phototrophic and heterotrophic modes. In addition, microalgae have been reported as a promising alternative source of marigold for lutein production. In this work, C. sorokiniana TH01 strain was mixotrophically grown on glucose for production of biomass and lutein. Results revealed that algal biomass productivity, lutein content and productivity reached 0.86-2.08 g/L/d, 4.62-6.89 mg/g and 3.98-14.35 mg/L/d, respectively, from 10 g/L glucose, 3 g/L NaNO3 and 2% (v/v) CO2, under light intensity of 50-500 mu mol/m2/s and temperature of 27 degrees C for 10 days of the cultivation. The purification of lutein from the algal biomass was completed by a novel process of simultaneous cell disruption and extraction and silica-based column chromatography purification, reaching lutein purity of 98%. Moreover, the algal lutein can be preserved by solvation with 0.05 wt% ascorbic acid under temperature of <4 C in the darkness, achieving 90% stability for 120 days of the storage. Chemical structure of the purified algal lutein was fully characterized by NMR and UV-vis spectroscopy and MS spectrometry, showing similar characteristics as the standard lutein and other lutein reported in the literature. Furthermore, the analysis of antiproliferative activity of the algal lutein against human KB, HepG2, MCF-7 and SK-LU-1 cancer cell lines using SRB assay revealed that the algal lutein exhibited moderate activities with corresponding IC50 values determined of 58.07, 61.37, 71.52 and 81.69 mu g/mL, respectively. Despite unexpected cytotoxicity on these targeted human cancer cell lines, the algal lutein is a high value compound for commercial applications in food, feed, pharmaceutical and cosmetic industries. The C. sorokiniana TH01 strain was demonstrated to be a promising lutein source, alternatively replacing marigold-based lutein.

Automated summary

This study reports an efficient method for producing biomass and lutein from C. sorokiniana TH01 strain using mixotrophic cultivation on glucose. The purified algal lutein showed high value and stability, making it a promising alternative source for commercial applications.