Spinach (<i>Spinacia oleracea</i>), a green leafy vegetable, is a rich source of flavonoids, phenolic acids, carotenoids, vitamin A, C and E. Previous research demonstrated significant anticarcinogenic, antimutagenic, antiinflammatory and free radical scavenging activities using certain natural compounds from spinach. To further understand the role of natural compounds in biological activities, optimization of environmental-friendly and cost effective extraction is critical. Accelerated solvent extraction (ASE) has become a popular green extraction technology due to reduction of harsh organic solvent. The concept of green solvents requires consideration of various aspects such as environmental impact, recycling or disposal procedure and environment, health and safety (EHS) characteristics. ASE was applied for the extraction of antioxidants from spinach leaves. The extraction conditions were optimized using different solvents such as hexane, ethyl acetate, acetone, methanol, methanol-water and water were carried out at 1500 psi pressure and various temperatures ranging from 40, 80, 120, 160 and 200°C. The results revealed that the methanol:water exhibited higher phenolics with maximum radical scavenging activities. The active fractions were identified by ultra-pressure liquid chromatography/high resolution mass spectrometry (UPLC-HR-QTOF-MS). For the first time, four spinacetin and one patuletin flavonoids derivatives were identified among a total of 17 flavonoids. The newly characterized compounds were identified by accurate mass spectral analysis, MS/MS fragmentation patterns and UV spectra. Three different collision energies (17ev, 35ev, and 100ev) were used to obtain the possible fragment ions for flavonoids identification. The present study demonstrated that accelerated solvent extraction is an innovative technique to achieve fast and efficient extraction of antioxidants and UPLC-HR-QTOF-MS was extremely useful for the identification of the bioactive compounds.

Combination of green solvents using accelerated extraction of spinach and LC-HR-ESI-QTOF-MS led five new flavonoids and yielded higher antioxidants

253rd National Meeting (2017)

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