ABSTRACT
<p><b>OBJECTIVE</b>To investigate the antioxidant activities as well as phytochemical constituents of Antidesma thwaitesianum Müll. Arg. leaf extracts.</p><p><b>METHODS</b>The leaves of A. thwaitesianum were extracted using three different methods: blending with distilled water, maceration with ethanol and decoction. The chemical antioxidant activity of the plant leaf extracts was evaluated using 2,2-diphenyl-1-picryhydrazyl (DPPH) radical and 2,2'-azinobis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS⁺) radical scavenging assays, as well as the ferric reducing antioxidant power assay. Cellular antioxidant activity was determined by superoxide and nitric oxide scavenging assays. The cytotoxicity of the leaf extracts in RAW 264.7 and differentiated HL-60 cells was tested in parallel using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assays, respectively. The total phenolic and flavonoid contents were also assessed by spectrophotometric analysis. Phytochemical constituents of the most potent extract were investigated by liquid chromatography with an electrospray ionization quadrupole time-of-flight mass spectrometer (LC-ESI-QTOF-MS/MS).</p><p><b>RESULTS</b>The ethanolic (ME) and decoction (LW) extracts of dried leaves had the highest chemical scavenging activity against DPPH and ABTS⁺ free radicals with half maximal effective concentration (EC) values ranging from 3.54 to 6.44 μg/mL. ME and LW exerted moderate ferric reducing activity, with ferric reducing antioxidant power values of 847.41 and 941.26 mg Fe/g extract, respectively. Similarly, ME showed potent cellular scavenging activity against superoxide and nitric oxide radicals with ECvalues of 58.12 and 71.90 μg/mL, respectively. However, LW exhibited only strong nitric oxide scavenging activity with an ECvalue of 91.20 μg/mL. The cell viability of RAW 264.7 and HL-60 cells was greater than 70% in all tested concentrations of both extracts, thus confirming the absence of their cytotoxicity. ME and LW contained high total phenolic contents of 231.14 and 274.42 mg gallic acid equivalents per gram, respectively, as well as high total flavonoid contents of 18.82 and 22.17 mg quercetin equivalents per gram, respectively. LC-ESI-QTOF-MS/MS analysis revealed the presence of 52 structurally characterized compounds in ME, 43 of which were tentatively identified. Hydroxycinnamic acids such as caffeic acid and its derivatives were the predominant phenolic compounds.</p><p><b>CONCLUSION</b>This is the first report describing potent chemical and cellular antioxidant effects of the ethanolic leaf extract of A. thwaitesianum. The extract contained high total phenolic and flavonoid contents. LC-ESI-QTOF-MS/MS analysis further revealed an abundance of caffeic acid derivatives and flavonoids. These data support its potential use as dietary supplements in oxidative stress prevention.</p>
ABSTRACT
Cleistocalyx nervosum var. paniala (known as Ma kiang) is found growing in scatter locations in some villages of the northern provinces of Thailand. The rich purplish red color of Ma kiang is characterized by an anthocyanin profile. It is now popular for functional health food, cosmetic ingredients and health drinks. The aim of this study was to identify the anthocyanins from its ripe berries. The ethanolic extract was pre-purified by vacuum liquid chromatography and subjected to high performance liquid chromatography (HPLC) system to give a purified compound. The structure elucidation of the compound was performed by spectroscopic (UV-Vis, ¹H NMR and MS) method. This purified compound was confirmed the identity to the authentic standard cyanidin 3-glucoside. The result found that major anthocyanin from ripe berries of C. nervosum var. paniala was cyaniding 3-glucoside. This is the first report of discovery of this ingredient, the most active antioxidant anthocyanin. This data demonstrated its usefulness for identification, content and assessment for quality evaluation of ripe berries of C. nervosum var. paniala products.
ABSTRACT
Hua-Khao-Yen-Tai (Dioscorea membranacea Pierre) has mostly been used as ingredient in Thai traditional anticancer preparations. The rhizome of D. membranacea was found potently cytotoxic and possibly contributed to such a therapeutic effect. Bioassay-guided isolation was used for the discovery of a selective novel cytotoxic compound, dioscorealide B. The objective of this research is to develop the method for quantitative analysis of dioscorealide B from extracts of Hua-Khao-Yen-Tai by High Performance Liquid Chromatography-UV detection (HPLC-UV). The separation was performed on a C18 column by stepwise gradient elution with water and acetonitrile system. Chromatographic separations were achieved at room temperature. The UV detector was used to detect the peak of dioscorealide B with the fixed wavelength at 270 nm. In the selected optimal experimental conditions, the dioscorealide B exhibited a well-defined chromatographic peak with a retention time at 21.93 min. Regression equation showed good linear relationship between the peak area of marker and its concentration. The recovery was 101.35%. The repeatability (1.06%RSD) and intermediate precision (1.23%RSD) indicated that the method is suitable for quantitative analysis.