Isolation of Flavonoid Glycosides with Cholinesterase Inhibition Activity and Quantification from Stachys japonica

The three flavone glycosides, 4′-O-methylisoscutellarein 7-O-(6‴-O-acetyl)-β-D-allopyranosyl(1→2)-β-D-glucopyranoside (1), isoscutellarein 7-O-(6‴-O-acetyl)-β-D-allopyranosyl(1→2)-β-D-glucopyranoside (3), and isoscutellarein 7-O-β-D-allopyranosyl(1→2)-β-D-glucopyranoside (4) in addition to a flavonol glycoside, kaempferol 3-O-β-D-glucopyranoside (astragalin, 2), were isolated from Stachys japonica (Lamiaceae). In cholinesterase inhibition assay, compound 1 significantly inhibited aceylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities (IC₅₀s, 39.94 µg/ml for AChE and 86.98 µg/ml for BChE). The content of isolated compounds were evaluated in this plant extract by HPLC analysis. Our experimental results suggest that the flavonoid glycosides of S. japonica could prevent the memory impairment of Alzheimer's disease.

Analysis of Essential oil, Quantification of Six Glycosides, and Nitric Oxide Synthase Inhibition Activity in Caryopteris incana

Caryopteris incana (Verbenaceae) has been used to treat cough, arthritis, and eczema in Oriental medicine. The two fractions (CHCl₃- and BuOH fractions) and the essential oil of the plant material were subjected to the inducible nitric oxide synthase (iNOS) assay. The IC₅₀ of the CHCl₃ fraction and the essential oil on LPS-induced macrophage RAW 264.7 cells were 16.4 µg/mL and 23.08 µg/mL, respectively. On gas chromatography (GC)-mass spectroscopy (MS) analysis, twenty-five components representing 85.5% amount of total essential oil were identified. On the chromatogram, three main substances, trans-pinocarveol, cis-citral, and pinocarvone, occupied 18.8%, 13.5% and 18.37% of total peak area. Furthermore, by HPLC-UV analysis, six compounds including one iridoid (8-O-acetylharpagide)- and five phenylethanoid glycosides (caryopteroside, acteoside, phlinoside A, 6-O-caffeoylphlinoside, and leucosceptoside A) isolated from the BuOH fraction were quantified. The content of six compounds were shown as the following order: caryopteroside (162.35 mg/g) > 8-O-acetylharpagide (93.28 mg/g) > 6-O-caffeoylphlinoside (28.15mg/g) > phlinoside (22.60mg/g) > leucosceptoside A (16.87 mg) > acteoside (7.05 mg/g).

HPLC analysis of Phenolic Substances and Anti-Alzheimer's Activity of Korean Quercus Species

This study aimed to establish the quantitative method to analyze the content of peroxynitrite-scavengers belonging to polyphenols in six Korean Quercus species (Quercus mongolica, Q. dentata, Q. acutissima, Q. alienta, Q. serrata, and Q. variabilis) by HPLC. The twelve peroxynitrite-scavengers, flavanols (catechins: (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin), flavonols (kaempferol and quercetin), flavonol glycosides (astragalin, quercitrin, and isoquercitrin), flavonol acylated glycosides (astragalin 6″-gallate and isoquercitrin 6″-gallate), gallic acid and its dimer (ellagic acid) were analyzed by HPLC. Further, anti-Alzheimer's activity was assayed in a passive avoidance testusing mice by measuring the retention latency (sec), the concentration of acetylcholine (ACh), and acetylcholinesterase (AChE) activity. Simultaneous analysis of the extracts of the six Quercus leaves was achieved on a Capcell C18 column (5 µm, 250 mm × 4.6 mm i.d.) with a gradient elution of 0.05% HAc and 0.05% HAc in CH₃CN. In the extract of Q. mongolica leaves, the content of gallic acid (32.53 mg/g), (+)-catechin (28.78 mg/g), (−)-epicatehin (22.03 mg/g), astragalin 6″-gallate (20.94 mg/g), and isoquercitrin 6″-gallate (44.11 mg/g) and peroxynitrite-scavenging activity (IC₅₀, 0.831 µg/ml) were high. This extract delayed the retention latency and inhibited acetylcholinesterase activity in scopolamine-induced memory impairment of mice, suggesting that it has anti-Alzheimer's activity.

HPLC and GC-MS Analysis of Phenolic Substances in Acer tegmentosum

The stem barks, heartwoods, and leaves of Acer tegmentosum (Aceraceae) are widely used in Korea to treat hepatic or cerebral disorders mainly due to alcohol poisoning. This study was aimed to analyze phenolic substances in A. tegmentosum. Quantitative analysis of the three phenolic substances (salidroside, (+)-catechin and scopoletin) was performed by HPLC and the identification of volatile phenolic substances were done by GC-MS. The contents of the three compounds in the three MeOH extracts were higher in the stem bark (salidroside: 80.22 mg/g, (+)-catechin: 23.31 mg/g, and scopoletin: 9.45 mg/g) compared to the heartwoods and leaves. And GC-MS analysis of the stem bark extract demonstrated that p-tyrosol is a main substance of twenty-one compounds identified.