Flavone-Rich Fractions and Extracts from and Their Antibacterial Activities against Clinically Isolated Zoonotic Bacteria and Free Radical Scavenging Effects.

extracts from the seeds collected from Lampang and Pattani provinces in Thailand, and young fruits and flowers exhibited in vitro display antioxidant and antibacterial activities against clinically isolated zoonotic bacteria including , , , -hemolytic and . The orange crystals and yellow precipitates were obtained from the preparation processes of the seed extracts. The orange-red crystals from the seeds collected from Lampang province exhibited strong in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging effects (EC value = 25.99 ± 3.30 μg/mL) and antibacterial effects on and -hemolytic while the yellow precipitate from the same source exhibited only antioxidant activity. Quantitative analysis of phytochemicals in samples by spectrophotometric and HPLC techniques showed that they contained different amounts of total phenolic, total flavonoid and three major flavones; baicalin, baicalein and chrysin contents. Young fruit extract, which contained low amounts of flavone contents, still promoted antibacterial effects against the tested bacteria with IC values lower than 1 mg/mL and MIC values between 4 to 10 mg/mL in and while higher IC and MIC values against and -hemolytic were found. From scanning electron microscopy, the extract of the young fruit of promoted morphological changes in the bacterial cells by disrupting the bacterial cell walls, inducing leakage of the cellular content, and generating the abnormal accumulation of cells. The mechanism of action of the extract for this antibacterial effect may be the disruption of the cell membrane and abnormal cell aggregations. Regression analysis of the results suggests the correlation between total phenolic and total flavonoid contents and antioxidant and antibacterial effects. Baicalin was found to have a high correlation with an inhibitory effect against -hemolytic while three unidentified peaks, which could be flavones, showed high correlations with an inhibitory effect against , , and .