Structures, physicochemical and bioactive properties of polysaccharides extracted from Panax notoginseng using ultrasonic/microwave-assisted extraction

The extracting technology including ultrasonic and microwave assisted extraction (UMAE) and ultrasonic assisted extraction (UAE) of lycopene from tomato paste were optimized and compared. The results showed that the optimal conditions for UMAE were 98 W microwave power together with 40 KHz ultrasonic processing, the ratio of solvents to tomato paste was 10.6:1 (V/W) and the extracting time should be 367 s; as for UAE, the extracting temperature was 86.4 degrees C, the ratio of the solvents to tomato paste was 8.0:1 (V/W) and the extracting time should be 29.1 min, while the percentage of lycopene yield was 97.4% and 89.4% for UMAE and UAE, respectively. These results implied that UMAE was far more efficient extracting method than UAE.

Sulfated polysaccharides (fucoidan) from brown seaweed Ascophyllum nodosum were extracted by microwave assisted extraction (MAE) technology. Different conditions of temperature (90-150°C), extraction time (5-30 min) were evaluated and optimal fucoidan yield was 16.08%, obtained from 120°C for 15 min's extraction. Compositional analysis, GPC, HPAEC and IR analysis were employed for characterization of extracted sulfated polysaccharides. Fucose was the main monosaccharide of fucoidan extracted at 90°C while glucuronic acid was the main monosaccharide of fucoidan extracted at 150°C. Both the molecular weight and sulfate content of extracted fucoidan increased with decreasing extraction temperature. All fucoidans exhibited antioxidant activities as measured by DPPH scavenging and reducing power, among which fucoidan extracted at 90°C was highest. This study shows that MAE is an efficient technology to extract sulfated polysaccharides from seaweed and Ascophyllum nodosum could potentially be a resource for natural antioxidants.