title: Bioassay-guided isolation and evaluation of antimicrobial compounds from Ixora megalophylla against some oral pathogens.
abstract: Context Ixora megalophylla Chamch. (Rubiaceae) is a new plant species recently found in southern Thailand. Ethyl acetate extracts of its leaves and stems showed antimicrobial activities. Objectives To isolate and identify the antimicrobial compounds from I. megalophylla leaves and stems. Materials and methods The dried leaves (1.7 kg) and stems (3.5 kg) were consecutively extracted with petroleum ether (5 L × 4), ethyl acetate (5 L × 3) and ethanol (5 L × 4) under reflux conditions. The ethyl acetate extract was subjected to an antimicrobial assay guided isolation with Candida albicans and Streptococcus mutans. Compounds 1-10 were identified by (1)H NMR, (13)C NMR and EI-MS. Minimal lethal concentration (MLC) against C. albicans and Streptococcus spp. was determined using a broth microdilution method for 48 and 24 h, respectively. Results and discussion On the basis of the antimicrobial assay guided isolation, 10 known compounds, including vanillic acid (1), syringic acid (2), 4-hydroxy benzaldehyde (3), scopoletin (4), loliolide (5), syringaldehyde (6), sinapaldehyde (7), coniferaldehyde (8), syringaresinol (9) and 2,2'-dithiodipyridine (10), were identified. Compounds 1-5 were purified from the ethyl acetate extract of the leaves, while 6-9 and 10 were from the ethyl acetate and ethanol extracts of the stems, respectively. Among these isolates, 10 showed the strongest antibacterial activities against S. mutans and Streptococcus mitis, with minimum inhibitory concentrations (MICs) of 2-4 μg/mL, and MLC of 4 μg/mL, as well as having a weak antifungal activity against C. albicans (MIC of 125 μg/mL). This is the first report of the antimicrobial activities of 10.
authors.affiliation: a Department of Pharmacognosy and Pharmaceutical Botany , Prince of Songkla University , Hat-Yai , Songkhla , Thailand ;
authors.forename: J
authors.initials: J
authors.lastname: Panyo
authors.affiliation: b Department of Pharmacognosy, Graduate School of Biomedical Sciences , Hiroshima University , Minamiku , Hiroshima , Japan ;
authors.forename: K
authors.initials: K
authors.lastname: Matsunami
authors.affiliation: a Department of Pharmacognosy and Pharmaceutical Botany , Prince of Songkla University , Hat-Yai , Songkhla , Thailand ;|c Excellent Research Laboratory , Phytomedicine and Pharmaceutical Biotechnology Excellence Center, Faculty of Pharmaceutical Sciences, Prince of Songkla University , Hat-Yai , Songkhla , Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Panichayupakaranant
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D000935:Antifungal Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001681:Biological Assay; D002176:Candida albicans / Q000187:drug effects / Q000254:growth & development; D066241:Carbon-13 Magnetic Resonance Spectroscopy; D005591:Chemical Fractionation / Q000379:methods*; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D009055:Mouth / Q000382:microbiology*; D008517:Phytotherapy; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves; D018547:Plant Stems; D010946:Plants, Medicinal; D066244:Proton Magnetic Resonance Spectroscopy; D019666:Rubiaceae / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D034361:Streptococcus mitis / Q000187:drug effects* / Q000254:growth & development; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D010936:Plant Extracts; D012997:Solvents
keywords: 2,2′-dithiodipyridine; Antibacterial; Rubiaceae; antifungal