ABSTRACT
Objective To compare chemical composition in the different parts (leaf, branch, and fruit) of Rhodomyrtus tomentosa, and to study the chemical constituents from fruits of R. tomentosa. Methods High performance liquid chromatography/time-of-flight mass spectrometry (HPLC-TOF-MS) method was executed to analyze the samples. Principle component analysis (PCA) and partial minimum variance discriminant analysis (OPLS-DA) in MassLynx XS software were used to analyze the obtained data. The chemical constituents of fruits were isolated and purified by column chromatography, including silica gel, Sephedex LH-20 and re-HPLC, and the structures were elucidated based on their NMR and MS data. Results The PCA results indicated that the constituents existed in leaf were significantly different from those in branch and fruit, while constituents in branch and fruit were similar. Furthermore, based on OPLS-DA, combined with chromatographic retention regulation, accurate molecular mass, isotopic matching and literature searching, four marker compounds from leaves had been found and identified as myricitrin (1), myricitrin-3-O-L-furanoarabinoside (2), iridin (3), and 3,3’-didemethyl-9-oxo-pinoresinol (4). Besides, five compounds were isolated from fruits and identified as maslinic acid (5), ethyl gallate (6), gallic acid (7), resveratrol (8), and piceatannol (9). Conclusion This research provides an effective strategy for analyzing chemical difference from different parts of R. tomentosa, which can be applied to study the chemical difference from different parts of other species.
ABSTRACT
Objective: To study the chemical constituents from the leaves of Rhodomyrtus tomentosa and its antibacterial activities. Methods: The compounds were isolated and purified by various column chromatographies. Their structures were elucidated by means of spectral analyses (MS and NMR). The antibacterial activity of the compounds was tested by micro dilution method Results: A total of 21 compounds were isolated from the 95% ethanol extract in the leaves of R. tomentosa and identified as (2R,4'R,8'R)-α-tocopherol (1), (2R,4'R,8'R)-β-tocopherol (2), α-tocopherol-quinone (3), α-tocopherol A (4), (-)-a-tocospirone (5), rhodomyrtosone F (6), rhodomyrtosone C (7), watsonianone A (8), rhodomyrtone (9), verimol K (10), methyl cinnamate (11), naringenin (12), quercetin (13), myricetin (14), 3,7,3'-trimethoxy-5,4',5'-trihydroxy flavone (15), 5,7,3',5'- tetrahydroxyflavanone (16), blumeatin (17), dihydroquercetin-7,4'-dimethylether (18), dihydroquercetin-4'-dimethoxy (19), 2,4,7,8,9,10-hexahydroxy-3-methoxyanthracene-6-O-β-L-rhamnopyranoside (20), and 4,8,9,10-tetrahydroxy-2,3,7-trimethoxyanthracene-6-O-β-D-glucopyranoside (21). Conclusion: Compound 6 is a new natural product and compounds 2-5, 10-13, and 15-19 are isolated from the plants of Rhodomyrtus (DC.) Reich for the first time. Compounds 3 and 6-9 exhibit the antibacterial activities.
ABSTRACT
Objective: Five phenolic compounds in fruits of Rhodomyrtus tomentosa from six different regiones were measured by HPLC, and the ability of scavenging free radicals of five kinds of phenolics and myrtle fruits extracts in different regions was investigated. Methods: The determination was performed on Inertsil ODS-SP column (150 mm × 4.6 mm, 5 μm), the mobile phase consisted of acetonitrile and 0.1% phosphate aqueous solution with gradient elution program, flow rate was 1 mL/min with 10 μL of sample quantity at 280 nm, and the antiradical efficiency of five phenolic compounds and extrcts were evaluated by DPPH radical scavenging assay. Results: Five kinds of phenolic components showed a good linear relationship, and the precision, stability, repeatability, and sample recovery rate all met the requirements. Five phenolic compounds and extracts had good antiradical efficiency. The IC50 values of the myrtle fruits extracts from Xinfeng, Wengyuan counties in Guangdong province, Nanning, Guilin in Guangxi province, Yunnan province, and Guizhou province were 58.82, 61.57, 17.73, 7.91, 14.77, and 8.11 μg/mL, and the IC50 values of gallic acid, protocatechuic acid, catechin, ellagic acid, and resveratrol were 0.02, 0.04, 0.03, 0.05, and 5.70 μg/mL, respectively. The IC50 of positive control VC was 6.31 μg/mL. Conclusion: Material basis of antiradical efficiency of fruits is preliminary identified and it provides a scientific basis for the comprehensive utilization of the resources of R. tomentosa.