Optimization of Culture Conditions for High Cell Productivity and Astaxanthin Accumulation in Vietnam's Green Microalgae Haematococcus pluvialis HB and a Neuroprotective Activity of Its Astaxanthin.

BACKGROUND: Haematococcus pluvialis, a green microalga, is a rich source of natural astaxanthin and a potent antioxidant with high commercial value. This study investigates the biological characteristics and potential of H. pluvialis HB isolated from Hoa Binh, Vietnam, for growth and astaxanthin accumulation using a two-phase culture method. METHODS: H. pluvialis HB was cultured in a C/RM medium at 25 °C, and morphological characteristics were examined. NMR spectroscopy was used to determine the structure of the astaxanthin, which was extracted using the Soxhlet method. RESULTS: After 22 days, the highest cell density (4.96 × 10(6) cells mL(-1)) was achieved under optimized light and ultraviolet conditions. Nutrient deprivation followed by bicarbonate supplementation resulted in a maximal astaxanthin accumulation of 48.8 mg g(-1) dry cell weight within two days. The extracted astaxanthin demonstrated potent antioxidant activity (IC(50): 3.74 mg mL(-1)) compared to ascorbic acid (IC(50): 18.53 µg mL(-1)) and exhibited strong acetylcholinesterase inhibition (IC(50): 297.99 µg mL(-1)). It also showed neuroprotective effects against H(2)O(2) and amyloid beta-induced neurotoxicity in C6 cells. CONCLUSIONS: This study highlights H. pluvialis HB as a promising source for large-scale astaxanthin production with potential applications in neuroprotective health products.