Hwa-Won Lee

Quinoline-2-carboxylic Acid Isolated from Ephedra pachyclada and Its Structural Derivatives Show Inhibitory Effects against α-Glucosidase and α-Amylase

The aim of present study was to isolate a bioactive compound from the chloroform fraction of Ephedra pachyclada stems and to evaluate antidiabetic activities against α-glucosidase and α-amylase. According to various chromatographic and spectroscopic analyses, the bioactive compound of E. pachyclada was identified as quinoline-2-carboxylic acid. Based on the IC50 values of quinoline-2-carboxylic acid derivatives against α-glucosidase and α-amylase, quinoline-2-carboxylic acid (9.1 and 15.5 μg/mL) exhibited potent inhibitory activities, followed by quinoline-3-carboxylic acid (10.6 and 31.4 μg/mL), quinoline-4-carboxylic acid (60.2 and 152.4 μg/mL), and acarbose (66.5 and 180.6 μg/mL) against α-glucosidase and α-amylase, respectively. However, quinoline-2-carboxaldehyde, quinoline-3-carboxaldehyde, and quinoline-4-carboxaldehyde showed no inhibitory activities. Antidiabetic activity depended on the existence of a carboxyl group on quinoline for activities against α-glucosidase and α-amylase. Therefore, E. pachyclada and quinoline-2-carboxylic acid derivatives could be suitable as alternative synthetic antidiabetic agents.

Growth inhibitory activities of myrtanol and structural analogues from Thymus tosevii against intestinal bacteria

The growth-inhibitory activity of Thymus tosevii oil was evaluated using the agar diffusion method against 7 intestinal bacteria. The essential oil of T. tosevii exhibited potent growth-inhibitory activities against harmful intestinal bacteria. The growth-inhibitory activities of 5 oil components were evaluated against 7 intestinal bacteria to identify the active compound in T. tosevii oil. The growth-inhibitory activities of T. tosevii oil against harmful intestinal bacteria were attributed to myrtanol. Study of the structure-activity relationships between myrtanol structural analogues and antimicrobial activities revealed that (−)-cis-myrtanol, (+)-trans-myrtanol, and (−)-trans-myrtanol exhibited potent antimicrobial activities against harmful intestinal bacteria. Tetracycline was more active than the myrtanol analogues against intestinal bacteria as tetracycline inhibited growth of both beneficial and harmful intestinal bacteria. Some myrtanol analogues exerted selective growth inhibitory activities against harmful intestinal bacteria without adverse effects against beneficial intestinal bacteria.