Optimised extraction of β‐carotene from Spirulina platensis and hypoglycaemic effect in streptozotocin‐induced diabetic mice

BACKGROUND: Spirulina platensis is rich in β‐carotene, which possesses many important biological activities. This study investigated the ultrasound‐assisted extraction and purification of β‐carotene from Spirulina platensis by using response surface methodology (RSM), determined its antioxidant capacity in vitro and explored its hypoglycaemic effect in diabetic mice. RESULTS: The raw β‐carotene extract with a concentration of 1942.14 ± 10.03 µg mL⁻¹ was obtained at the optimised condition by RSM (0.40 of the solid–liquid ratio, 51% of the extraction power, and 17 min of the extraction time), and the purity of evaporated β‐carotene extract reached 816.32 ± 10.57 mg g⁻¹ after purified by a NKA‐9 resin with a sampling and elution rate of 1 mL min⁻¹. The β‐carotene extract scavenged 1,1‐diphenyl‐2‐picrylhydrazyl and hydroxyl free radicals with the highest ratios of 44 ± 0.26% and 35 ± 0.45% respectively, and exhibited strong inhibiting capacity on anti‐lipid peroxidation. The blood glucose level of streptozotocin‐induced diabetic mice was significantly reduced from 15.81 ± 1.71 mmol L⁻¹ to 8.10 ± 0.88 mmol L⁻¹ after 10 d administration of the β‐carotene extract [100 mg kg⁻¹ body weight (BW)], and the increased food and water intakes in the diabetic mice were also significantly relieved after β‐carotene treatment. CONCLUSION: Our results suggested that extraction of β‐carotene from Spirulina platensis had potential prospects in scaled‐up industrialisation and healthcare applications. © 2015 Society of Chemical Industry