Akşit, Hüseyin; Ozan, Erdem; Erenler, Ramazan

Background: Natural products have been used commonly in the pharmaceutical industry as well as traditional medicine due to their bioactive contents. Objective: The objective of this study is to isolate the polymethoxy flavones (PMFs) and evaluate the antiproliferative activity. Methods: The PMFs were extracted from Mentha dumetorum with boiling hot water and then partitioned with hexane and the extract was subjected to chromatographic techniques such as Sephadex LH-20, silica gel, and preparative TLC, and HPLC to isolate the compounds. The structures of isolated compounds were elucidated by spectroscopic techniques such as1H-NMR,13C-NMR, LC-TOF-MS, and UV-Vis. The antiproliferative effects of isolated compounds were evaluated using a real-time cell analyzer–single plate (RTCA-SP) instrument against HeLa and HT29 cell lines. Results: The isolated PMFs were identified as xanthomicrol (1), 5-hydroxy-6,7,8,4'-tetrametoxy flavanone (2), 5-desmetil sinensetin (3), 5-demetil nobiletin (4), gardenin B (5), 5-hydroxy-6,7,8,3',4'-penta methoxy flavanone (6) and 5-hydroxy-6,7,4'-trimethoxy flavone (7). Compounds 2 and 5 were found to be the most active against both cell lines. Conclusion: The isolated compounds as well as the plant extract of Mentha dumetorum could be promising agents for the drug development process, especially drugs for cancer treatment. Moreover, isolation methods were developed for the corresponding compounds.

Dede, Emine; Genc, Nusret; Elmastas, Mahfuz; Aksit, Huseyin; Erenler, Ramazan

Background: Plant in Rhododendron genus that contains phenolic compounds has been used in traditional medicine and revealed considerable biological activities. Objective: Isolation and identification of antioxidant natural products from Rhododendron ungernii. Methods: Rhododendron ungernii Trautv. flowers were collected and dried in shade. The dried flowers were extracted with methanol for 3 days. The solvent was removed by reduced pressure to yield the extract which was subjected to column chromatography (Sephadex LH-20, C18 reversed phase column) to isolate catechin-7-O-glucoside (1), quercetin-3-O-β-galactoside (2), quercetin-3-O-β-xyloside (3), farrerol (4), myricetin (5), and quercetin (6). The structures of isolated compounds were elucidated by spectroscopic methods such as 1D-NMR, 2D-NMR, and LC-TOF/MS. DPPH• scavenging effect, ABTS•+ scavenging activity, and reducing power (FRAP) were performed for antioxidant assays of isolated natural compounds. Results: Isolated flavonoids displayed the outstanding antioxidant activities. Catechin-7-O-glucoside (1) and quercetin-3-O-β-galactoside (2) (IC50, 3.66 µg/mL) had the most DPPH• scavenging effect among the compounds. The highest ABTS•+ scavenging activity (IC50, 1.41 µg/mL) and reducing power effect (6.05 mmol TE/g comp) were observed for myricetin (5). Conclusion: R. ungernii extract and isolated compounds could be a promising antioxidant for food and pharmaceutical industries.