The ameliorating effects of 2,3-dihydroxy-4-methoxyacetophenone on scopolamine-induced memory impairment in mice and its neuroprotective activity

We isolated 2,3-dihydroxy-4-methoxyacetophenone, a neuroprotective compound from Cynenchum paniculatum in our previous study.The present study was conducted to investigate the possible neuroprotective effect of 2,3-dihydroxy-4-methoxyacetophenone that has been previously isolated from Cynenchum paniculatum on hippocampal neuronal cell line, HT22 cells and its possible cognitive-enhancing effect on scopolamine-induced amnesia in mice.Neuroprotective effect against glutamate-induced neurotoxicity in HT22 cells was evaluated by MTT assay. Also, cognitive enhancing effect against scopolamine (1 mg/kg, ip) induced learning and memory deficit was measured by Morris water maze test. Oral administered of 2,3-dihydroxy-4-methoxyacetophenone (1, 10, 20, 40 and 50 mg/kg) to amnesic mice induced by scopolamine. In Morris water maze test, 2,3-dihydroxy-4-methoxyacetophenone (50 mg/kg) improved the impairment of spatial memory induced by scopolamine. 2,3-Dihydroxy-4-methoxyacetophenone protect HT22 cells on glutamate induced cell-death in a dose-dependent manner (EC₅₀ value: 10.94 μM). Furthermore, 2,3-dihydroxy-4-methoxyacetophenone was found to inhibit [Ca²⁺] accumulation in HT22 cells and had antioxidantive activity. The results showed that 2,3-dihydroxy-4-methoxyacetophenone exert neuroprotective and cognitive-enhancing activities through its antioxidant activity. We suggest that 2,3-dihydroxy-4-methoxyacetophenone improves cognitive function and may be helpful for the treatment of Alzheimer’s disease.     

Synthesis and anticancer activity of focused compound libraries from the natural product lead,oroidin

Oroidin (1), (E)-N-(3-(2-amino-1H-imidazol-4-yl)allyl)-4,5-dibromo-1H-pyrrole-2-carboxamide, is a pyrrole alkaloid isolated from the marine sponge Agelas oroides. Routine screening in a panel of twelve cancer cell lines revealed 1 to be poorly cytotoxic with the 50% growth inhibition concentration (GI₅₀) of 42 μM in MCF-7 (breast) cells and 24 μM in A2780 (ovarian) cells and >50 μM in all other cell lines tested. The development of eight focused libraries comprising thirty compounds total identified N-(biphenyl-4-ylmethyl)-1H-pyrrole-2-carboxamide (4l), N-benzyl-4,5-dibromo-1H-pyrrole-2-carboxamide (5a) and N-(biphenyl-4-ylmethyl)-4,5-dibromo-1H-pyrrole-2-carboxamide (5l) as potent inhibitors of cell growth in our panel of cell lines. Of these compounds GI₅₀ values of <5 μM were observed with 4l against HT29 (colon) and SW480 (colon); 5a against HT29; and 5l against HT29, SW480, MCF-7, A431 (skin), Du145 (prostate), BE2-C (neuroblastoma) and MIA (pancreas) cell lines. As a cancer class, colon cancer appears to be more sensitive to the oroidin series of compounds, with analogue 5l being the most active.     

New cytotoxic dihydrochalcone and steroidal saponins from the aerial parts of Sansevieria cylindrica Bojer ex Hook

A new dihydrochalcone, 2‘,4‘-dihydroxy-3‘-methoxy-3,4-methylenedioxy-8-hydroxymethylene dihydrochalcone 1 and two new steroidal saponins, (25S)-ruscogenin-1-O-α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranoside 2, (25S)-ruscogenin-3-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranoside 3, together with three known steroidal saponins (25S)-ruscogenin-3-O-β-d-glucopyranoside 4, (25S)-ruscogenin-1-O-α-l-rhamnopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 3)]-α-l-arabinopyranoside 5 and (25R)-26-O-β-d-glucopyranosyl-furost-5-ene-1β,3β,22α,26-tetrol-1-O-α-L-rhamnopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 3)]-α-l-arabinopyranoside 6 were isolated from the aerial parts of Sansevieria cylindrica. The structures of the new compounds were established by UV, IR, EI-MS, HR-ESI–MS as well as 1D (¹H,¹³C and DEPT-135) and 2D (HSQC, HMBC and TOCSY) NMR spectral analysis. The isolated compounds 1-6 were assayed for in vitro cytotoxicities against the three human tumor cell lines HT116, MCF7 and HepG2. Compound 1 showed a moderate cytotoxicity against MCF7. Compounds 2, 3 and 6 exhibited moderate cytotoxicities against the three used cell lines and compound 5 showed marked cytotoxicities against all used cell lines.     

Comparing anti-HIV,antibacterial, antifungal,micellar, and cytotoxic properties of tricarboxylato dendritic amphiphiles

Three series of homologous dendritic amphiphiles—RCONHC(CH₂CH₂COOH)₃, 1(n); ROCONHC(CH₂CH₂COOH)₃, 2(n); RNHCONHC(CH₂CH₂COOH)₃, 3(n), where R = n-C_nH_2n+1 and n = 13–22 carbon atoms—were assayed for their potential to serve as antimicrobial components in a topical vaginal formulation. Comparing epithelial cytotoxicities to the ability of these homologues to inhibit HIV, Neisseria gonorrhoeae, and Candida albicans provided a measure of their prophylactic/therapeutic potential. Measurements of the ability to inhibit Lactobacillus plantarum, a beneficial bacterium in the vagina, and critical micelle concentrations (CMCs), an indicator of the potential detergency of these amphiphiles, provided additional assessments of safety. Several amphiphiles from each homologous series had modest anti-HIV activity (EC₅₀ = 110–130 μM). Amphiphile 2(18) had the best anti-Neisseria activity (MIC = 65 μM), while 1(19) and 1(21) had MICs against C. albicans of 16 and 7.7 μM, respectively. Two measures of safety showed promise as all compounds had relatively low cytotoxic activity (EC₅₀ = 210–940 μM) against epithelial cells and low activity against L. plantarum, 1(n), 2(n), and 3(n) had MICs ? 490, 1300, and 940 μM, respectively. CMCs measured in aqueous triethanolamine and in aqueous potassium hydroxide showed linear dependences on chain length. As expected, the longest chain in each series had the lowest CMC—in triethanolamine: 1(21), 1500 μM; 2(22), 320 μM; 3(22), 340 μM, and in potassium hydroxide: 1(21), 130 μM; 3(22), 40 μM. The CMC in triethanolamine adjusted to pH 7.4 was 400 μM for 1(21) and 3900 μM for 3(16). The promising antifungal activity, low activity against L. plantarum, relatively high CMCs, and modest epithelial cytotoxicity in addition to their anti-Neisseria properties warrant further design studies with dendritic amphiphiles to improve their safety indices to produce suitable candidates for antimicrobial vaginal products.     

An unusual lanostane-type triterpenoid,spiroinonotsuoxodiol, and other triterpenoids from Inonotus obliquus

An unusual lanostane-type triterpenoid, spiroinonotsuoxodiol (1), and two lanostane-type triterpenoids, inonotsudiol A (2) and inonotsuoxodiol A (3), were isolated from the sclerotia of Inonotus obliquus. Their structures were determined to be (3S,7S,9R)-3,7-dihydroxy-7(8 → 9)abeo-lanost-24-en-8-one (1), lanosta-8,24-dien-3β,11β-diol (2), and (22R)-3β,22-dihydroxylanosta-8,24-dien-11-one (3) on the basis of NMR spectroscopy, including 1D and 2D (¹H–¹H COSY, NOESY, HMQC, HMBC) NMR, and FABMS. Compounds 1–3 showed moderate activity against cultured P388, L1210, HL-60 and KB cells.     

Two new spirostanol saponins from the the roots and rhizomes of Tupistra chinensis

Two new spirostanol saponins (1) and (2), together with three known saponins (3–5), were isolated from the roots and rhizomes of Tupistra chinensis, and their structures were determined as (20S, 22R)-spirost-25(27)-en-1β, 3β, 4β, 5β-tetraol-5-O-β-d-glucopyranoside (1) and (20S, 22R)-spirost-25(27)-en-1β, 3β, 5β-triol-5-O-β-d-glucopyranoside (2), (20S, 22R)-spirost-25(27)-en-1β, 2β, 3β, 4β, 5β-pentaol-5-O-β-d-glucopyranoside (3), Δ²⁵⁽²⁷⁾-pentrogenin (4) and ranmogenin A (5) on the basis of physicochemical properties and spectral analysis. The isolated compounds were evaluated for their cytotoxic activities against A549 and H1299 tumor cell lines in vitro. Among them, compound 2 showed cytotoxicities against A549 cells (IC₅₀ 52.66 ± 3.12 μmol L⁻¹) and H1299 cells (IC₅₀ 57.29 ± 2.51 μmol L⁻¹), respectively.     

Aspernolides F and G,new butyrolactones from the endophytic fungus Aspergillus terreus

Two new butyrolactones: aspernolides F (6) and G (7), together with three stigmasterol derivatives: (22E,24R)-stigmasta-5,7,22-trien-3-β-ol (1), stigmast-4-ene-3-one (2), and stigmasta-4,6,8(14), 22-tetraen-3-one (3), two meroterpenoids: terretonin A (4) and terretonin (5), and a butyrolactone derivative: butyrolactone VI (8) have been isolated from the endophytic fungus Aspergillus terreus isolated from the roots of Carthamus lanatus (Asteraceae). Their structures were determined by spectroscopic means (1D, 2D NMR, and HRESIMS), as well as optical rotation measurement and comparison with literature data. The isolated compounds were evaluated for their anti-microbial, anti-malarial, anti-leishmanial, and cytotoxic activities. Compound 1 displayed a potent activity against MRSA and C. neoformans with IC₅₀ values of 0.96 μg/mL and 4.38 μg/mL, respectively compared to ciprofloxacin (IC₅₀ 0.07 μg/mL) and amphotericin B (IC₅₀ 0.34 μg/mL), respectively. While, 6 showed good activity against C. neoformans (IC₅₀ 5.19 μg/mL) and mild activity against MRSA (IC₅₀ 6.39 μg/mL). Moreover, 1 and 2 exhibited very good anti-leishmanial activity towards L. donovani with IC₅₀ values of 4.61 and 6.31 μg/mL, respectively and IC₉₀ values of 6.02 and 16.71 μg/mL, respectively.     

Design,synthesis and evaluation of novel indandione derivatives as multifunctional agents with cholinesterase inhibition,anti-β-amyloid aggregation,antioxidant and neuroprotection properties against Alzheimer’s disease

A series of novel 2-(4-(4-substituted piperazin-1-yl)benzylidene)-1H-indene-1,3(2H)-diones were designed, synthesized and appraised as multifunctional anti-Alzheimer agents. In vitro studies of compounds 27–38 showed that these compounds exhibit moderate to excellent AChE, BuChE and Aβ aggregation inhibitory activity. Notably, compounds 34 and 38 appeared as most active multifunctional agents in the entire series and exhibited excellent inhibition against AChE (IC₅₀ = 0.048 μM: 34; 0.036 μM: 38), Aβ aggregation (max% inhibition 82.2%, IC₅₀ = 9.2 μM: 34; max% inhibition 80.9%, IC₅₀ = 10.11 μM: 38) and displayed significant antioxidant potential in ORAC-FL assay. Both compounds also successfully diminished H₂O₂ induced oxidative stress in SH-SY5Y cells. Fascinatingly, compounds 34 and 38 showed admirable neuroprotective effects against H₂O₂ and Aβ induced toxicity in SH-SY5Y cells. Additionally, both derivatives showed no considerable toxicity in neuronal cell viability assay and represented drug likeness properties in the primarily pharmacokinetics study. All these results together, propelled out that compounds 34 and 38 might serve as promising multi-functional lead candidates for treatment of AD in the future.     

New 30-norlupane derivatives through chemical-microbial semi-synthesis of betulinic acid and their neuroprotective effect

In this study, seven 30-norlupane derivatives (2–8) was obtained from the chemical oxidation of betulinic acid followed by biotransformation via Bacillus megaterium CGMCC 1.1741. And metabolites 2–4 and 6–8 were newly identified products. In the first step, betulinic acid was chemically oxidized to platanic acid (1). Following the chemical oxidation, B. megaterium catalyzed the hydroxylation at C-7, C-11, C-15 and C-23 of platanic acid (1) as well as the oxidation of C-3 hydroxyl group. Compared to the labor-intensive isolation from natural plants, this chemical-microbial semi-synthesis is more capable to provide increased structural diversity of oxygenated 30-norlupane. Finally, the potential neuroprotective effect of the derivatives was assessed on neuron-like PC12 cells induced by cobalt chloride (CoCl₂). Metabolite 6 showed a potent neuroprotective activity.     

Isolation,structure, and bioactivities of abiesadines A–Y, 25 new diterpenes from Abies georgei Orr

Twenty-five new (abiesadines A–Y, 1–25) and 29 known (26–54) diterpenes were isolated from the aerial parts of Abies georgei. Abiesadine A (1) is a novel 8,14-seco-abietane, while abiesadine B (2) is a novel 9,10-seco-abietane. The structures of the new compounds were established on the basis of spectroscopic data analysis. Manool (52) showed the strongest effect against LPS-induced NO production in RAW264.7 macrophages with the IC₅₀ value of 11.0 μg/mL. In another anti-inflammatory assay against TNFα-triggered NF-κB activity, (12R,13R)-8,12-epoxy-14-labden-13-ol (54) exhibited the strongest effect (IC₅₀ = 8.7 μg/mL). For antitumor assays, pomiferin A (26) and 8,11,13-abietatriene-7α,18-diol (29) both showed the most significant activity against LOVO cells (IC₅₀ = 9.2 μg/mL). While 7-oxocallitrisic acid (46) exhibited significant cytotoxicity against QGY-7703 tumor cells (IC₅₀ = 10.2 μg/mL).     

Triterpenoid saponins and C-glycosyl flavones from stem bark of Erythrina abyssinica Lam and their cytotoxic effects.

Six new compounds including two oleanane-type triterpenoid saponins (1, 2) and four C-glycosyl flavones (3–6), along with a known saponin (7), three di-C-glycosyl flavones (8–10) and a glycosyl auronol (11), were isolated from the stem bark of Erythrina abyssinica Lam. The structures of the new compounds, identified as 3-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-galactopyranosyl-(1 → 2)-β-d-glucuronopyranosyl]-22-O-β-d-glucopyranosyl sophoradiol (1), 3-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 2)-β-d-glucuronopyranosyl]-22-O-β-d-glucopyranosyl sophoradiol (2), 6-C-β-glucopyranosyl-8-C-β-quinovopyranosyl apigenin (3), 6-C-β-quinovopyranosyl-8-C-β-glucopyranosyl apigenin (4), 8-C-[6″-O-α-l-rhamnopyranosyl-(1‴ → 6″)]-β-glucopyranosyl 7,4′-dihydroxyflavone (5) and 8-C-[6″-O-β-d-xylopyranosyl-(1‴ → 6″)]-β-glucopyranosyl 7,4′-dihydroxyflavone (6), were determined by comprehensive spectroscopic analysis, including 1D and 2D NMR techniques, mass spectrometry and acid hydrolysis. These new compounds together with the known saponins 7 were evaluated for their cytotoxic activity against MCF-7 (estrogen dependent) and MDA-MB-231 (estrogen independent) cell lines. The new saponin 2 exhibited the highest cytotoxic activity among tested compounds, exerting a selective inhibitory effect against the proliferation of MCF-7 cells, with lower IC₅₀ value (12.90 μM) than that of the positive control, resveratrol (13.91 μM). Structure–activity relationship of these compounds is also discussed.     

Natural potential neuroinflammatory inhibitors from Alhagi sparsifolia Shap.

Neuroinflammation is a key contributor to neuronal damage in neurodegenerative diseases. In our previous work on natural effective neuroinflammatory inhibitors, Alhagi sparsifolia Shap. (Leguminosae), a folk medicine widely distributed in Xinjiang, attracted our attention because of its significant anti-neuroinflammatory effect. Therefore, further investigation of the bioactive material basis was carried out. As a result, 33 major components were characterized and identified by chromatographic and spectral methods, respectively. Furthermore, the anti-neuroinflammatory effects of the extract and purified constituents were evaluated in LPS-induced N9 cells in vitro. The results displayed that compounds 1, 2, 3, 5, 6, 8, 11, 15, 16, 17, 22, 23, 25, 26, 28, 30, 33 could exhibit significant inhibitory activities without obvious cytotoxicities at their effective concentrations. Especially, isorhamnetin (1) (IC₅₀ 17.87 μM), quercetin (2) (10.22 μM), 3′,7-dihydroxyl-4′-methoxylisoflavone (5) (17.43 μM), 3′,7-dihydroxyl-4′,6-dimethoxylisoflavone (6) (11.21 μM), syringgaresinol (16) (2.68 μM), bombasinol A (17) (7.61 μM), aurantiamide (23) (14.91 μM) and 1,3,3,4-tetramethyl cyclopentene (33) (2.63 μM) showed much stronger inhibiting effect than that of the positive control minocycline (19.89 μM). Therefore, the effective compositions might be responsible for the significant neuroinflammation inhibitory activities exhibited by the herb. Moreover, compounds 16 and 33 could be good leading compounds for the development of potential therapeutic agents against neurodegenerative diseases.     

Triterpenoid saponins from Aesculus sylvatica W. Bartram

16 triterpenoid saponins including two new compounds were isolated from the seeds of A esculus sylvatica W. Bartram. The two new saponins were assigned as 3-O-[β-D-glucopyranosyl-(1 → 2)]-α-L-arabinofuranosyl-(1 → 3)-β-D-glucuronopyranosyl-21,22-O-ditigloyl-3β,16α,21β,22α,24,28 hexahydroxyolean-12-ene (aesculioside S1, 1) and 3-O-[β-D-glucopyranosyl-(1 → 2)]-α-L-arabinofuranosyl-(1 → 3)-β-D-glucuronopyranosyl-21-O-tigloyl-22-O-angeloyl 3β,16α,21β,22α,24,28-hexahydroxyolean-12-ene (aesculioside S2, 2). Aesculioside S1 and S2 displayed moderate cytotoxicity against human non-small cell lung cancer cells (A549) and prostate cancer cells (PC3) (GI₅₀ ranged from 8.7 to 18.2 μM). The structural analysis of the saponins isolated from Aesculus supports the taxonomic placement of A. sylvatica under the section Pavia of Aesculus genus.     

Synthesis of novel chromenones linked to 1,2,3-triazole ring system: Investigation of biological activities against Alzheimer’s disease

In this work, novel chromenones linked to 1,2,3-triazole ring system were synthesized and evaluated for their anti-ChE activity. Among them, N-((1-(2-chlorobenzyl)-1H-1,2,3-triazol-5-yl)methyl)-8-methoxy-2-oxo-2H-chromene-3-carboxamide (6m) showed good anti-acetylcholinesterase activity (IC₅₀ = 15.42 μM). Also, compound 6m demonstrated neuroprotective effect against H₂O₂-induced cell death in PC12 neurons, however, it showed no beta-secretase (BACE1) inhibitory activity. Docking and kinetic studies separately confirmed dual binding activity of compound 6m since it targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE.     

Inhibitory effect of novel tetrahydropyrimidine-2(1H)-thiones on melanogenesis

The series of imidazoldine-2-thiones 2 and tetrahydropyrimidine-2-thiones 3 were discovered as inhibitor of α-MSH-induced melanin production in melanoma B16 cells. The primary bioassay showed that 1-(4-ethylbenzyl)-tetrahydropyrimidine-2(1H)-thione 3e (>100% inhibition at 10 μM, IC₅₀ = 1.2 μM) and 1-(4-tert-butylbenzyl)-tetrahydropyrimidine-2(1H)-thione 3f (>100% inhibition at 10 μM, IC₅₀ = 0.76 μM) exhibited potent inhibitory effect against α-MSH-induced melanin production. Compounds 3 inhibit the biosynthesis of tyrosinase without affecting its catalytic activity in melanogenesis.     

5-((1-Aroyl-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-diones as potential anticancer agents with anti-inflammatory properties

A series of novel 5-((1-aroyl-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-diones (3a–z) have been evaluated for in vitro cytotoxicity against a panel of 60 human tumor cell lines. Compound 3k exhibited the most potent growth inhibition against melanoma MDA-MB-435 cells (GI₅₀ = 850 nM), against leukemia SR cancer cells (GI₅₀ = 1.45 μM), and OVCAR-3 (GI₅₀ = 1.26 μM) ovarian cancer cell lines. The structurally related compound 3s had a GI₅₀ value of 1.77 μM against MDA-MB-435 cells. The N-naphthoyl analogue 3t had GI₅₀ values of 1.30 and 1.91 μM against HOP-92 non-small cell lung cancer and MDA-MB-435 melanoma cell lines, respectively. The related analogue 3w had GI₅₀ values of 1.09 μM against HOP-92 non-small cell lung cancer cell lines. Interestingly, docking of the two active molecules 3k and 3w into the active site of COX-2 indicates that these compounds are COX-2 ligands with strong hydrophobic and hydrogen bonding interactions. Thus, compounds 3k, 3t, 3s, and 3w constitute a new class of anticancer/anti-inflammatory agents that may have unique potential for cancer therapy.     

Synthesis,X-ray crystal structure,DNA/protein binding and cytotoxicity studies of five α-aminophosphonate N-derivatives

Five new α-aminophosphonates are synthesized and characterized by EA, FT-IR, ¹H NMR, ¹³C NMR, ³¹P NMR, ESI-MS and X-ray crystallography. The X-ray analyses reveal that the crystal structures of 1–5 are monoclinic or triclinic system with the space group P 21/c, P − 1, P − 1, P2(1)/c and P − 1, respectively. All P atoms of 1–5 have tetrahedral geometries involving two O-ethyl groups, one C_α atom, and a double bond O atom. The binding interaction of five new α-aminophosphonate N-derivatives (1–5) with calf thymus(CT)-DNA have been investigated by UV–visible and fluorescence emission spectrometry. The apparent binding constant (Kapp) values follows the order: 1 (3.38 × 10⁵ M⁻¹) > 2 (3.04 × 10⁵ M⁻¹) > 4 (2.52 × 10⁵ M⁻¹) > 5 (2.32 × 10⁵ M⁻¹) > 3 (2.10 × 10⁵ M⁻¹), suggesting moderate intercalative binding mode between the compounds and DNA. In addition, fluorescence spectrometry of bovine serum albumin (BSA) with the compounds 1–5 showed that the quenching mechanism might be a static quenching procedure. For the compounds 1–5, the number of binding sites were about one for BSA and the binding constants follow the order: 1 (2.72 × 10⁴ M⁻¹) > 2 (2.27 × 10⁴ M⁻¹) > 4 (2.08 × 10⁴ M⁻¹) > 5 (1.79 × 10⁴ M⁻¹) > 3 (1.17 × 10⁴ M⁻¹). Moreover, the DNA cleavage abilities of 1 exhibit remarkable changes and the in vitro cytotoxicity of 1 on tumor cells lines (MCF-7, HepG2 and HT29) have been examined by MTT and shown antitumor effect on the tested cells.     

Kelsoenethiol and dikelsoenyl ether,two unique kelsoane-type sesquiterpenes,from the Formosan soft coral Nephthea erecta

Two new kelsoane-type sesquiterpenes, namely kelsoenethiol (1) and dikelsoenyl ether (2), were obtained from the Formosan soft coral Nephthea erecta. Their structures were elucidated through extensive spectroscopic analyses, ESI orbitrap mass and quantum chemical calculations (QCC). The cytotoxicity against A-459 (human lung carcinoma), P-388 (mouse lymphocytic leukemia), and HT-29 (human colon adenocarcinoma) cancer cell lines of 1 and 2 was evaluated in vitro. Compound 1 showed cytotoxicity against P-388 and HT-29 cells with ED_50s of 1.3 and 1.8 μg/mL, respectively.     

Indole derivatives as dual-effective agents for the treatment of neurodegenerative diseases: Synthesis,biological evaluation,and molecular modeling studies

Several indole derivatives, that were highly potent ligands of GluN2B-subunit-containing N-methyl-d-aspartate (NMDA) receptor, also demonstrated antioxidant properties in ABTS method. In particular, the 2-(4-benzylpiperidin-1-yl)-1-(5-hydroxy-1H-indol-3-yl)ethanone (1) proved to be a dual-effective neuroprotective agent. With the aim to increase the antioxidant properties we added a catechol moiety onto piperidine moiety. The designed hybrid derivative 3,4-dihydroxy-N-[1-[2-(5-hydroxy-1H-indol-3-yl)-2-oxoethyl]piperidin-4-yl]benzamide (10) was the most effective antioxidant agent (>94.1 ± 0.1% of inhibition at 17 μM) and showed GluN2B/NMDA receptor affinity at low micromolar concentration (IC₅₀ 0.66 μM). By means of computational studies we explored the effect of the presence of this antioxidant fragment during the recognition process to binding pocket.     

Synthesis and antioxidant evaluation of (S,S)- and (R,R)-secoisolariciresinol diglucosides (SDGs)

Secoisolariciresinol diglucosides (SDGs) (S,S)-SDG-1 (major isomer in flaxseed) and (R,R)-SDG-2 (minor isomer in flaxseed) were synthesized from vanillin via secoisolariciresinol (6) and glucosyl donor 7 through a concise route that involved chromatographic separation of diastereomeric diglucoside derivatives (S,S)-8 and (R,R)-9. Synthetic (S,S)-SDG-1 and (R,R)-SDG-2 exhibited potent antioxidant properties (EC₅₀ = 292.17 ± 27.71 μM and 331.94 ± 21.21 μM, respectively), which compared well with that of natural (S,S)-SDG-1 (EC₅₀ = 275.24 ± 13.15 μM). These values are significantly lower than those of ascorbic acid (EC₅₀ = 1129.32 ± 88.79 μM) and α-tocopherol (EC₅₀ = 944.62 ± 148.00 μM). Compounds (S,S)-SDG-1 and (R,R)-SDG-2 also demonstrated powerful scavenging activities against hydroxyl [natural (S,S)-SDG-1: 3.68 ± 0.27; synthetic (S,S)-SDG-1: 2.09 ± 0.16; synthetic (R,R)-SDG-2: 1.96 ± 0.27], peroxyl [natural (S,S)-SDG-1: 2.55 ± 0.11; synthetic (S,S)-SDG-1: 2.20 ± 0.10; synthetic (R,R)-SDG-2: 3.03 ± 0.04] and DPPH [natural (S,S)-SDG-1: EC₅₀ = 83.94 ± 2.80 μM; synthetic (S,S)-SDG-1: EC₅₀ = 157.54 ± 21.30 μM; synthetic (R,R)-SDG-2: EC₅₀ = 123.63 ± 8.67 μM] radicals. These results confirm previous studies with naturally occurring (S,S)-SDG-1 and establish both (S,S)-SDG-1 and (R,R)-SDG-2 as potent antioxidants and free radical scavengers for potential in vivo use.