Antioxidant and antimicrobial activities of Ixora coccinea root and quantification of phenolic compounds using HPLC

Abstract

Antioxidants scavenge free radicals thereby prevent or delay oxidative stress and associated degenerative diseases. Antioxidant capacity of plant-based natural compounds depends on their molecular structure and type of radicals. We report here the content and composition (by HPLC) of Ixora coccinea Linn. root methanol extract (ICME) and its fractions separated by petroleum ether (ICPEF), chloroform (ICCFF), and ethyl acetate (ICEAF). Antioxidant capacity of all root samples have been evaluated by conventional radical scavenging (DPPH) and reducing power (FRAP) tests, as well as by electrochemical method using cyclic voltammetry (CV). In addition, antimicrobial activities of root samples were also determined against pathogenic bacterial strains. All samples showed considerable antioxidant activity, however, ICEAF and ICME were the most active samples in DPPH and FRAP, which were comparable to ascorbic acid and better than BHT. Both samples also showed potent superoxide anion (O2●−) radical scavenging activity in CV. All extracts displayed significant antibacterial activity against all test stains except Escherichia coli, where ICCFF showed highest inhibition against Shigella dysentriae. Both ICEAF and ICME contained higher quantities of total phenols, flavonoids, proanthocyandins and tannins than other samples. HPLC analysis showed that both samples contained 7 identified phenolic compounds, of which pyrocatechol, catechin, and chlorogenic acid were most abundant. This study highlights the importance of I. coccinea root as a natural source of bioactive molecules with potent antioxidant and antimicrobial activities.