Astaxanthin is one of the most attractive carotenoid in the cosmetic, food, pharmaceutical, and aquaculture industries due to its strong bioactive properties. Among the various sources, several algae species are considered as rich sources of astaxanthin. Downstream processing of algae involves the majority of the total processing costs. Thus, elimination of high energy involved steps is imperative to achieve cost-effective scale in industry. This study aimed to determine operation conditions for astaxanthin extraction from wet Haematococcus pluvialis using microwave-assisted extraction. The isolated astaxanthin extract was evaluated for cytotoxicity on human lung cancer cells. The microwave-assisted extraction process at 75 °C under the power of 700 Watt for 7 min gave the highest astaxanthin yield (12.24 ± 0.54 mg astaxanthin/g wet cell weight). Based on MTT cell viability and Hoechst 33342 nuclear staining assays on A549 lung cancer cells, astaxanthin inhibited cell growth in dose- and time-dependent manners, where IC₅₀ value was determined as 111.8 ± 14.8 µg/mL and apoptotic bodies were observed along with positive control group at 72 hr. These results showed that the treatment with astaxanthin extracted from wet H. pluvialis by microwave-assisted extraction exhibited anti-cancer activity on lung cancer cells indicating a newly potential to be utilized in industry.

Diatoms are the major group of microalgae which have been utilized by the potential applications as food industries, aquatic feeds, cosmetics, biofuels, and pharmaceuticals. In this study, current approaches were made in order to determine growth rate, biomass productivity, protein, carbohydrate, lipid and fatty acid composition for Nanofrustulum shiloi cultures using both aeration and mixing conditions in flat-plate photobioreactor (PBR). Physical (the intensity of aeration, mixing, light intensity etc.) and chemical (nutritional materials) factors are affecting the growth and bioproduct contents of a diatom. Biomass and lipid productivities of N. shiloi were measured as 31.29 and 36.9622±0.0598 mg L-1 day-1 in flat-plate PBR having the combination of aeration and stirring system, respectively. A slightly higher amount of saturated fatty acids was detected in PBR having only bubbling system while the increase of mono- and poly- unsaturated fatty acids were found in PBR having the combination of aeration and stirring system. Flat-plate PBR design was also investigated for improving not only biomass but also the lipid productivity of N. shiloi.