Inhibitory Effects of Quinoline Isolated from Ruta chalepensis and Its Structurally Related Derivatives against α-Amylase or α-Glucosidase

Abstract

Abstract This study was to isolate an active component of thechloroform fraction from the methanol extract of Ruta chalepensisleaves and to measure inhibitory effects against α-glucosidase orα-amylase. The inhibitory compound of R. chalepensis leaves wasisolated using chromatographic methods and identified as quinoline.Quinoline and its structurally related derivatives were tested fortheir inhibitory activities by evaluating the IC 50 values against α-amylase or α-glucosidase and were compared with that of acarbose.Based on the IC 50 values, quinazoline exhibited the greatestinhibitory activity (20.5µg/mL), followed by acarbose (66.5µg/mL), and quinoline (80.3µg/mL) against α-glucosidase. In caseof α-amylase, quinazoline had potent inhibitory activity, followedby quinoline (179.5µg/mL) and acarbose (180.6µg/mL). Theseresults indicate that R. chalepensis extract, quinoline, and quinazolinecould be useful for inhibiting α-glucosidase or α-amylase.Keywords α-amylase · α-glucosidase · inhibitory activity · quin-oline · Ruta chalepensis IntroductionDiabetes mellitus is the most serious global health problem andresults in considerable morbidity and mortality (Nilubon et al.,2006). Complications of diabetes such as terminal nephritis andcardiovascular disorders are the principal cause of irreversibleblindness (Perez et al., 1998; Jeong et al., 2012). Diabetes fallsinto two etiopathogenetic categories, types 1 and 2 (AmericanDiabetes Association., 2005; Nilubon et al., 2006). Diabetes type1 is resulted in absolute deficiency of insulin secretion (Nilubon etal., 2006; Frode and Medeiros, 2008). Diabetes type 2 is causedby insufficient compensatory insulin secretion and a combinationof resistance to insulin action (Nilubon et al., 2006; Frode andMedeiros, 2008). Attention to herbal remedies has increasedbecause of the side effects associated with treatment of oralhypoglycemic agents and insulin (Holman and Turner, 1991; Lee,2005; Kim et al., 2006; Jeong et al., 2012; Lee et al., 2014).Ruta chalepensis L. (Rutaceae) is a perennial herb that isextensively used in folk medicine. R. chalepensis is well-knownas an alternative medical therapy (antispasmodic, antirheumatic,aphrodisiac) and a treatment for snakebites, headache, andwounds (Ghazanfar, 1994). Furthermore, this plant is a rich sourceof several acridones and coumarins, as well as quinoline alkaloids(Ulubelen and Guner, 1988; Ulubelen and Terem, 1988; Lee andAhn, 1998; Lee, 2002). R. chalepensis exhibits insecticidalactivity against pests, with no noxious effects on parasitoids (Al-mazraawi and Ateyyat, 2009) and shows antibacterial, antifungal,anthelmintic, and anthelmintic effects (Di Stasi et al., 2002;Alzoreky and Nakahara, 2003; Iauk et al., 2004; Yarnell andAbascal, 2004; Cho et al., 2005; Rigat et al., 2007; Barrera-Nechaet al., 2009). However, no report on the inhibitory activity ofactive compound isolated from R. chalepensis leaves andstructurally related derivatives against α-amylase or α-glucosidaseis available. Therefore, we isolated an active constituent from R.chalepensis leaves and assessed the inhibitory effects of quinolinederivatives against α-glucosidase or α-amylase.Materials and MethodsIsolation and identification. R. chalepensis leaves were collectedfrom a market in Korea. R. chalepensis leaves (3.0 kg) were