A homogenate-assisted vacuum-powered bubble extraction (HVBE) method using ethanol was applied for extraction of flavonoids from Phyllostachys pubescens (P. pubescens) leaves. The mechanisms of homogenate-assisted extraction and vacuum-powered bubble generation were discussed in detail. Furthermore, a method for the rapid determination of flavonoids by HPLC was established. HVBE followed by HPLC was successfully applied for the extraction and quantification of four flavonoids in P. pubescens, including orientin, isoorientin, vitexin, and isovitexin. This method provides a fast and effective means for the preparation and determination of plant active components. Moreover, the on-line antioxidant capacity, including scavenging positive ion and negative ion free radical capacity of different fractions from the bamboo flavonoid extract was evaluated. Results showed that the scavenging DPPH˙ free radical capacity of vitexin and isovitexin was larger than that of isoorientin and orientin. On the contrary, the scavenging ABTS⁺˙free radical capacity of isoorientin and orientin was larger than that of vitexin and isovitexin.
Keywords: HPLC; Phyllostachys pubescens (P. pubescens); flavonoids; homogenate-assisted vacuum-powered bubble extraction (HVBE); on-line antioxidant capacity.