| Summary: | <i>Oroxylum indicum</i> is a medicinal plant in Thailand, which has been used as a tonic and for the treatment of various diseases. Extracts from various parts of <i>O. indicum</i> were reported as promoting in vitro antioxidant and antibacterial effects. Phytochemical analysis suggested that this plant contained some flavones. <i>O</i>. <i>indicum</i> fruit and seed water and ethanol extracts and their major flavonoids including baicalein, baicalin, and chrysin were tested for in vitro antibacterial activities on four clinical isolated bacteria, namely, <i>Staphylococcus intermedius</i>, <i>Streptococcus suis</i>, <i>Pseudomonas aeruginosa</i>, and <i>β-Escherichia coli</i>, using a broth micro-dilution assay. The amounts of these three major flavonoids were also quantitatively analyzed using the high-performance liquid chromatographic (HPLC) method. <i>O. indicum</i> fruit ethanol extract from Nakhon Pathom province (OFNE) promoted the strongest antimicrobial activity against four clinical pathogenic bacteria, including <i>S. intermedius</i> (IC<sub>50</sub> = 1.30 mg/mL), <i>S. suis</i> (13.59% inhibition at 7.81 mg/mL), <i>P. aeruginosa</i> (IC<sub>50</sub> = 39.20 mg/mL), and <i>β-E. coli</i> (IC<sub>50</sub> = 66.85 mg/mL). Baicalin showed high in vitro antibacterial effect to all tested bacteria. From the optimized and validated HPLC method, baicalin, baicalein, and chrysin contents in <i>O. indicum</i> extracts were 0.19 ± 0.00 − 9.45 ± 0.13, 0.14 ± 0.00 − 1.27 ± 0.02, and 0.02 ± 0.00 − 0.96 ± 0.02 g/100 g extract, respectively. Baicalin was found to be the major compound in <i>O. indicum</i> seed extract followed by baicalein, whereas chrysin was found in lower amounts than the amounts of the other two flavonoids in all <i>O. indicum</i> extracts.
|
|---|