| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 100 === The aims of this study were to investigate the antioxidant and anti-inflammatory activities of Bacillus subtilis natto-fermented Porphyra dentata product. The whole fermented P. dentata product (F) was devided into 2 parts of the supernatant (S) and precipitate (P). The raw material (R) and the fermented P. dantata samples were extracted by hot water (W), ethanol (95%, E), or hot water extraction of the residue after ethanol extraction (EW), and in total 12 freeze-dried extracted samples of WR, WF, WS, WP, ER, EF, ES, EP, EWR, EWF, EWS, and EWP were prepared. The antioxidant activities investigated include reducing power, DPPH radical scavenging and ferrous chelating effects, total antioxidant capacity, inhibition effects on hemoglobin-induced peroxidation of linoleic acid (LA), peroxidation of low-density lipoprotein (LDL), and the production of reactive oxygen species (ROS) in murine macrophages of RAW 264.7. The inhibition effect on LPS-induced nitric oxide (NO) production in RAW 264.7 cells was used for investigating the anti-inflammatory activities of the tested samples. In general, the reducing power and DPPH scavenging activities were significantly increased after fermentation of P. dentata suspension by B. subtilis natto. Especially, these activities mainly reside in the supernatant of the fermented P. dentata. The reducing power (expressed as vitamin C equivalents) and DPPH scavenging (EC50) effect for WS were 6.15 mg/g sample and 4.95 mg/mL, respectively. Similarly, the inhibition effects on the hemoglobin-induced LA peroxidation, LDL peroxidation, and total antioxidant capacity were significantly increased for the fermented P. dentata product, compared to those of P. dentata raw material. The highest activities for inhibition on LA peroxidation and LDL peroxidation were observed for the WP sample with IC50 for the formal activity being 1.47 mg/mL. The lag time and maximal oxidation intensity in the LDL peroxidation test for WR vs. WP was 20 min vs. 300 min, and 0.325 vs. 0.116, respectively. The total phenolic and flavonoid contents were also significantly increased after fermentation, with the highest contents of 30.18 mg GAE/g and 8.19 mg QE/g, respectively, for ES sample. The ROS and NO production in LPS-induced RAW 264.7 cells were inhibited by 41.65% and 50.93%, respectively, by EP sample at 125 g/mL, which was significantly lower than those of ER sample (0% and 12.62 %).
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