Dae-Young Lee

Potential neuroprotective flavonoid-based inhibitors of CDK5/p25 from Rhus parviflora

Rhus parviflora (Anacardiaceae) is an indigenous medicinal shrub found in South Asia with flavonoid rich edible fruit. This study examined flavonoid derivatives of R. parviflora fruit with CDK5/p25 inhibition activity. Evaluation by in vitro assay and docking simulations for CDK5/p25 revealed that the aurones, sulfuretin (1) and aureusidin (2), the aurone glycoside, aureusidin-6-O-β-D-glucopyranoside (3) and hovetrichoside C (4), the flavonoid glycoside, quercetin-3-O-β-D-galactopyranoside (5), and the biflavonoid, cupressuflavone (6), had the potential to inhibit CDK5/p25, which could be useful in the treatment of neurodegenerative disorders such as Alzheimers disease. Compound2 showed the significant in vitro inhibition capacity (IC50 value of 4.81 μM) as well as binding affinity with docking energy of -8.73 (kcal/mol) for active sites CYS83 and GLN130 of CDK5/p25 enzyme in comparison to reference compound R-roscovitine.

Flavonoids from the fruits of Nepalese sumac (Rhus parviflora) attenuate glutamate-induced neurotoxicity in HT22 cells

Nepalese sumac (Rhus parviflora) is a wild edible fruit used for the treatment of various ailments including neurological complications and stomach disorders in the traditional medicinal system of south Asia (Ayurveda). Four flavonoids were isolated from ethyl acetate (EtOAc) fraction of Nepalese sumac fruits and their chemical structures were determined on the basis of NMR, fast atom bombardment mass spectrometry (FAB/MS), and IR. The efficiency of isolated compounds in attenuating glutamateinduced cell death in an immortalized mouse hippocampal cell line (HT-22) and inhibition of cycline dependent kinase 5 (Cdk5) were investigated. Among the compounds, flavanols, fustin (1) and taxifolin (2), an aurone, aureusidin (3), and a biflavonoid, agathisflavone (4) were found to have protective effect against glutamate induced oxidative injury in HT22 cells. Aureusidin (3), a Cdk5/p25 inhibitor (IC50 3.5 μM), was the most potent neuroprotector with an EC50 value of 11.90 μM.

Phenolic components from Rhus parviflora fruits and their inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages

Nine phenolic compounds, phloracetophenone-4-O-β-d-glucopyranoside (1), p-hydroxybenzoic acid-4-O-β-d-glucopyranoside (2), leonuriside A (3), 3-methoxy-4-hydroxyphenol-1-O-β-d-glucopyranoside (4), cis-p-coumaric acid-4-O-β-d-glucopyranoside (5), trans-p-coumaric acid-4-O-β-d-glucopyranoside (6), trans-p-coumaric acid-9-O-β-d-glucopyranoside (7), (–)-shikimic acid (8) and (–)-methyl shikimate (9), were isolated for the first time from the fruits of Rhus parviflora. Compounds 1, 3–6 and 8 inhibited lipopolysaccharide-stimulated nitric oxide (NO) production and inducible NO synthase expression in RAW 264.7 macrophages with IC50 values of 9.24 ± 1.20, 21.37 ± 2.02, 23.07 ± 1.58, 9.86 ± 0.98, 19.05 ± 1.66 and 11.3 ± 1.54 μM, respectively. The results indicated possible use of compounds for the treatment of inflammatory diseases.

Glycosyl glycerides from hydroponic Panax ginseng inhibited NO production in lipopolysaccharide-stimulated RAW264.7 cells

Background Although the aerial parts of hydroponic Panax ginseng are reported to contain higher contents of total ginsenosides than those of roots, the isolation and identification of active metabolites from the aerial parts of hydroponic P. ginseng have not been carried out so far. Methods The aerial parts of hydroponic P. ginseng were applied on repeated silica gel and octadecylsilane columns to yield four glycosyl glycerides (Compounds 1–4), which were identified based on nuclear magnetic resonance, infrared, fast atom bombardment mass spectrometry, and gas chromatography/mass spectrometry data. Compounds 1–4 were evaluated for inhibition activity on NO production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Results and conclusion The glycosyl glycerides were identified to be (2S)-1-O-7(Z),10(Z),13(Z)-hexadecatrienoyl-3-O-β-d-galactopyranosyl-sn-glycerol (1), (2S)-1-O-linolenoyl-3-O-β-d-galactopyranosyl-sn-glycerol (2), (2S)-1-O-linolenoyl-2-O-linolenoyl-3-O-β-d-galactopyranosyl-sn-glycerol (3), and 2(S)-1-O-linoleoyl-2-O-linoleoyl-3-O-β-d-galactopyranosyl-sn-glycerol (4). Compounds 1 and 2 showed moderate inhibition activity on NO production in LPS-stimulated RAW264.7 cells [half maximal inhibitory concentration (IC50): 63.8 ± 6.4μM and 59.4 ± 6.8μM, respectively] without cytotoxicity at concentrations < 100μM, whereas Compounds 3 and 4 showed good inhibition effect (IC50: 7.7 ± 0.6μM and 8.0 ± 0.9μM, respectively) without cytotoxicity at concentrations < 20μM. All isolated compounds showed reduced messenger RNA (mRNA) expression of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α in LPS-induced macrophage cells with strong inhibition of mRNA activity observed for Compounds 3 and 4.

Re-evaluation of physicochemical and NMR data of triol ginsenosides Re, Rf, Rg2, and 20-gluco-Rf from Panax ginseng roots.

Ginseng roots were extracted with aqueous methanol, and extracts were suspended in water and extracted successively with ethyl acetate and n-butanol. Column chromatography using the n-butanol fraction yielded four purified triol ginseng saponins: the ginsenosides Re, Rf, Rg2, and 20-gluco-Rf. The physicochemical, spectroscopic, and chromatographic characteristics of the ginsenosides were measured and compared with reports from the literature. For spectroscopic analysis, two-dimensional nuclear magnetic resonance (NMR) methods such as 1H-1H correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity were employed to identify exact peak assignments. Some peak assignments for previously published 1H- and 13C-NMR spectra were found to be inaccurate. This study reports the complete NMR assignment of 20-gluco-Rf for the first time.

Phytochemical constituents from the florets of tiger grass Thysanolaena latifolia from Nepal

Phytochemical investigation on the florets of Thysanolaena latifolia leads to the isolation of a new compound 6″-O-acetylorientin-2″-O-α-L-rhamnopyranoside (1), named amrisoside and other 34 known compounds. The chemical structures of the compounds were determined from the interpretation of spectroscopic data including NMR, MS, and IR. This is the first report of phytochemical constituents from the monotypic genus Thysanolaena.

Phytochemical Constituents of the Urena lobata Fruit

Urena lobata L. (Malvaceae), commonly known as Caesar s weed, is a shrub with rhomboid leaves, pink flowers, and 8–10 mm bristly, globose fruits. Its range extends into tropical and subtropical areas across the world [1]. Traditionally the plant is used as a diuretic, febrifuge, and for treatment of rheumatism, malaria, gonorrhea, wound, and toothache [2]. A paste of the fruit is used to treat diarrhea in Nepal [1]. Previous chemical work on the seeds of this plant revealed the presence of cyclopropenoic fatty acids [3]. Some constituents reported from aerial parts include flavonoids, flavonoid glycosides [4–7], triglycerides [8], and phenolic and phenolic glycosides [9–10]. A furocoumarin, imperatorin [11], was isolated from the plant roots. We conducted this study to isolate major secondary metabolites from the fruit. Our phytochemical investigation led to the isolation of 14 compounds (1–14) from the fruit of U. lobata, among which compound 14 was isolated from a natural source for the first time. Comparison of the collected spectroscopic data with those of authentic samples and literature values led to the identification of the known compounds ergosterol peroxide (1) [12], daucosterol (2) [12], 7 -methoxysitosterol (3) [13], 7 -hydroxysitosterol (4) [14], 7 -hydroxysitosterol (5) [14], kaempferol3-O-D-glucopyranoside (6) [5], tiliroside (7) [5], benzoic acid (8) [15], protocatechuic acid (9) [16], monordicophenoide A (10) [17], glycerol (11) [18], -adenosine (12) [19], and L-tryptophan (13) [20]. Compound 14 (2-hydroxy-4(1H)-quinolinone), a light yellow powder (MeOH), showed EI-MS m/z 143 [M – H2O] and HR-EI-MS m/z 143.0372 [M – H2O] (calcd for C9H5NO, 143.0375), indicating the molecular formula to be C9H7NO2. The IR spectrum (KBr, ) showed absorption bands from hydroxyl (3354 cm–1), carbonyl (1738 cm–1), and aromatic ring (1650 cm–1).The PMR spectrum (400 MHz, CD3OD, , ppm, J/Hz) showed four olefin methine proton signals at 8.21 (1H, dd, J = 8.2, 1.6, H-5), 7.80 (1H, dd, J = 8.4, 1.6, H-8), 7.69 (1H, ddd, J = 8.4, 6.8, 1.6, H-7), and 7.38 (ddd, J = 8.2, 6.8, 1.6, H-6) due to an ortho-substituted benzene ring. A singlet olefin methine proton signal was present at 6.93 (1H, s, H-3). In the 13C NMR spectrum (100 MHz, CD3OD, , ppm), nine carbon signals, including a conjugated ketone carbon at 182.05 (C-4), one oxygenated olefin quaternary carbon at 147.84 (C-2), five olefin methine carbons at 133.67 (C-7), 125.95 (C-5), 125.24 (C-6), 120.22 (C-8), and 109.47 (C-3), and two olefin quaternary carbons at 140.88 (C-9) and 126.49 (C-10) were observed. In a gHMBC experiment, the singlet olefin methine signal at 6.93 (1H, s, H-3) showed correlated cross peaks with an olefin quaternary carbon signal at C-10 ( 126.49) and an oxygenated olefin quaternary carbon signal at C-2 ( 147.84).

Phytochemical Investigation of Rhus parviflora Fruit from Nepal

Rhus parviflora Roxb. (Anacardiaceae) is an edible drupe-bearing subdeciduous shrub distributed in Nepal, northern India, Bhutan, and Sri Lanka at an altitudinal range of 700–1100 m. R. parviflora fruits are used in Ayurvedic medicine for curing neurological and stomach disorders [1]. From the fruits of R. parviflora there exist reports of echinulin, trimethyl citrate, and citric acid 2-methyl ester [2, 3]. We previously reported the isolation of flavonoid glycosides [4], a flavanone and biflavonoids [5, 6], aurones and aurone glycosides [7], flavanonols [8], and phenolics [9] from the fruits. In continuation of our studies on the phytochemical constituents of Rhus parviflora, 18 compounds (1–18) were isolated from the fruits. The compounds were elucidated from interpretation of their spectroscopic data, including NMR, MS, and IR, and by comparison of their spectroscopic data with literature values as vaginatin (1) [10], -sitosterol (2) [11], daucosterol (3) [11], 7 -methoxy-sitosterol (4) [12], 7 -methoxy-sitosterol (5) [12], ergosterol peroxide (6) [13], -amyrin (7) [14], lupeol (8) [14], linolenic acid methyl ester (9) [11], glycerol (10) [15], 1,2-dioleoyl-3-linolein (11) [16], isoliquirtigenin (12) [17], quercetin (13) [17], (–)-syringaresinol (14) [18], (–)-pinoresinol-4 -O-D-glucopyranoside (15) [18], (+)-5,5 dimethoxylariciresinol (16) [19], (+)-isolariciresinol-9 -O-L-rhamnopyranoside (17) [20], and methyl-D-fructofuranose (18) [21]. All compounds are reported here for the first time from the fruits of R. parviflora. Although the 13C NMR are similar in CDCl3 and pyridine-d5, some signals in the 1H NMR that have been previously reported as overlapped for H-6, H-7, 13-CH3, and 15-CH3 in CDCl3 [10] showed better resolution in pyridine-d5, so we have dealt here the structure determination of compound 1. The IR spectrum indicated hydroxyl (3454 cm–1), cyclopentanone (1748 cm–1), conjugated aromatic ester (1685 cm–1), and double bond (1610 cm–1). The PMR spectrum showed two olefin proton signals [ 5.92 (1H, qq, J = 1.6, 7.2 Hz, H-3 ) and 5.89 (1H, d, J = 7.6 Hz, H-9)], an oxygenated methine signal [ 5.76 (1H, d, J = 7.6 Hz, H-10)], three cyclic methylene signals [ 2.75 (1H, m, H-7a), 2.68 (1H, dd, J = 14.8, 7.6 Hz, H-3a), 2.54 (1H, m, H-6a), 2.41 (1H, m, H-3b), 2.39 (1H, m, H-6b), 2.11 (1H, dd, J = 18.0, 6.4 Hz, H-7b)], two methine signals [ 2.30 (1H, m, H-11), 2.49 (1H, m, H-4)], and six methyl signals [ 2.00 (3H, dq, J = 7.2, 1.2 Hz, 4 -CH3), 1.84 (3H, dq, J = 1.6, 1.2 Hz, 5 -CH3), 1.65 (3H, s, 14-CH3), 1.37 (3H, s, 15-CH3), 1.12 (3H, d, J = 6.8 Hz, 13-CH3), 1.08 (3H, d, J = 6.8 Hz, 12-CH3)]. In the 13C NMR spectrum a ketone carbon at 220.79 (C-2), one conjugated ester at 166.41 (C-1 ), two olefin quaternary carbons at 146.95 (C-8) and 127.53 (C-2 ), two olefin methine carbons at 139.19 (C-3 ) and 119.94 (C-9), an oxygenated quaternary carbon at 81.95 (C-5), an oxygenated methine carbon at 75.48 (C-10), a quaternary carbon at 60.82 (C-1), two methine carbons at 51.74 (C-4) and 26.56 (C-11), three methylene carbons at 39.00 (C-3), 37.17 (C-6), and 29.60 (C-7), and six methyl carbons at 26.18 (C-14), 24.88 (C-13), 21.28 (C-12), 20.88 (C-5 ), 18.27 (C-15), and 15.80 (C-4 ) were observed. In the gHMBC spectrum, correlated cross-peaks are observed for methylene protons at H-3a ( 2.68) and H-3b ( 2.41), with a ketone carbon at 220.79 (C-2). The H-3 also showed a gCOSY relation to the H-4 ( 2.49).