Characteristic volatile fingerprints of three edible marine green algae (Ulva spp.) in China by HS-GC-IMS and evaluation of the antioxidant bioactivities

In this study, the volatile compounds fingerprinting as well as the relationship between phytochemical composition and antioxidant bioactivity of U. prolifera, U. linza and U. clathrata were investigated. The significant differences of volatile compounds in three dehydrated seaweeds were observed by headspace gas chromatography–ion mobility spectrometry (HS–GC–IMS), and the type of volatile compounds in U. clathrata (83 compounds) was highest, followed by U. linza (75 compounds) and U. prolifera (57 compounds). Furthermore, a variety of polarity solvents were used to extract Ulva spp. in order to determine the influence of total phenolics (TPC), flavonoids (TFC) and carbohydrates content (TCC) on antioxidant activities. The results showed that ethyl acetate extracts of U. prolifera had the highest antioxidant activity (IC50 = 143.18 μg/mL) in ABTS assay, and methanol extracts of U. clathrata revealed the highest scavenging activity (IC50 = 95.32 μg/mL) against OH radicals as well as the aqueous extracts of U. prolifera exhibited the strongest radical scavenging capacity (IC50 = 527.75 μg/mL) against DPPH radicals. Pearson correlation analysis revealed that the antioxidant capacity of Ulva spp. was significantly impacted by TFC and TPC. The findings presented in this thesis add to our understanding of volatilization characteristics and biological properties in edible marine green seaweeds.