Exopolysaccharides from the Energy Microalga Strain Botryococcus braunii: Purification, Characterization, and Antioxidant Activity.

Botryococcus braunii, a prestigious energy microalga, has recently received widespread attention because it can secrete large amounts of exopolysaccharides (EPS) with potential applications in food, cosmetics, and nutraceuticals. Unfortunately, the insufficiency of research on the bioactivity and structure-activity relationship of B. braunii EPS has impeded the downstream applications. In the present study, alcohol precipitation, deproteinization, and DEAE-cellulose column chromatography were used to extract and purify B. braunii SCS-1905 EPS. It was found that B. braunii SCS-1905 EPS were high-molecular-weight heteropolysaccharides containing uronic acid (7.43-8.83%), protein (2.30-4.04%), and sulfate groups (1.52-1.95%). Additionally, the EPS primarily comprised galactose (52.34-54.12%), glucose (34.60-35.53%), arabinose (9.41-10.32%), and minor amounts of fucose (1.80-1.99%), with the presence of a pyranose ring linked by a ß-configurational glycosidic bond. Notably, the antioxidant activity of crude exopolysaccharides (CEPS) was stronger, and the half maximal inhibitory concentration (IC50) for ABTS and hydroxyl radicals was significantly lower than that of deproteinized exopolysaccharides (DEPS). Overall, this study indicated a potential application of B. braunii SCS-1905 EPS as a natural antioxidant. In summary, B. braunii EPS could be used as a potential feedstock for the production of antioxidant health foods.

Induction of Apoptosis in Human Glioma Cells by Fucoxanthin via Triggering of ROS-Mediated Oxidative Damage and Regulation of MAPKs and PI3K-AKT Pathways.

Fucoxanthin, a natural carotenoid derived from algae, exhibits novel anticancer potential. However, fucoxanthin with high purity is hard to prepare, and the anticancer mechanism remains elusive. In the present study, fucoxanthin with high purity was prepared and purified from the marine microalgae Nitzschia sp. by silica-gel column chromatography (SGCC), and the underlying mechanism against human glioma cells was evaluated. The results showed that fucoxanthin time- and dose-dependently inhibited U251-human-glioma-cell growth by induction of apoptosis (64.4 ± 4.8, P < 0.01) accompanied by PARP cleavage and caspase activation (244 ± 14.2, P < 0.01). Mechanically, fucoxanthin time-dependently triggered reactive-oxygen-species (ROS)-mediated DNA damage (100 ± 7.38, P < 0.01), as evidenced by the phosphorylation activation of Ser1981-ATM, Ser428-ATR, Ser15-p53, and Ser139-histone. Moreover, fucoxanthin treatment also time-dependently caused dysfunction of MAPKs and PI3K-AKT pathways, as demonstrated by the phosphorylation activation of Thr183-JNK, Thr180-p38, and Thr202-ERK and the phosphorylation inactivation of Ser473-AKT. The addition of kinase inhibitors further confirmed the importance of MAPKs and PI3K-AKT pathways in fucoxanthin-induced cell-growth inhibition (32.5 ± 3.6, P < 0.01). However, ROS inhibition by the antioxidant glutathione (GSH) effectively inhibited fucoxanthin-induced DNA damage, attenuated the dysfunction of MAPKs and PI3K-AKT pathways, and eventually blocked fucoxanthin-induced cytotoxicity (54.3 ± 5.6, P < 0.05) and cell apoptosis (32.7 ± 2.5, P < 0.05), indicating that ROS production, an early apoptotic event, is involved in the fucoxanthin-mediated anticancer mechanism. Taken together, these results suggested that fucoxanthin induced U251-human-glioma-cell apoptosis by triggering ROS-mediated oxidative damage and dysfunction of MAPKs and PI3K-AKT pathways, which validated that fucoxanthin may be a candidate for potential applications in cancer chemotherapy and chemoprevention.

Spirulina (Arthrospira) industry in Inner Mongolia of China: current status and prospects.

This paper outlines an investigation on current situation of Spirulina (Arthrospira) industry in Inner Mongolia, an internal region of China with temperate continental climate. More than 20 Spirulina plants have been established in Inner Mongolia since 2001, most of which are located at Wulan Town in the Ordos Plateau. By the end of 2009, the total annual production of Spirulina in the Ordos Plateau surpassed 700 t (dw), which account for ca. 80% of the total productivity of Inner Mongolia, and ca. 20% of China. Besides abundant solar radiation and enough freshwater favorable for Spirulina production, the three technical strategies contribute to the prosperity and success of Spirulina industry in the region: (1) reducing the cost or investment by overall advantages of rich local natural resources with low cost for Spirulina production, such as alkaline lakes, coal, electricity, and sandy land; (2) controlling the culture temperature and to avoid contamination by building plastic greenhouses on raceway ponds, (3) reducing investment by simplifying the construction of the ponds and the greenhouses. As the result, the growth period of Spirulina has been prolonged from about 120 to about 165 days, the cost of Spirulina has decreased by 25-30%, and the quality of products has been enhanced substantially. Inner Mongolia is expected to become the largest base for Spirulina production not only in China, but also in the world in the near future.