Novel flavonoid hybrids as potent antiviral agents against hepatitis A: Design, synthesis and biological evaluation.

Two series of flavonoid hybrids, totaling 42 compounds, were designed, synthesized and evaluated to develop antiviral compounds effective against hepatitis A virus (HAV). A recombinant viral screening system revealed that most of the synthesized derivatives exhibited significant anti-HAV activity, and compounds B2, B3, B5 and B27 were identified as potential inhibitors of HAV. Post-treatment of cells with B2, B3, B5 and B27 after HAV infection strongly suppressed HAV infection, whereas pretreatment or simultaneous treatment were ineffective. Furthermore, these four compounds significantly inhibited HAV (HM175/18f strain) production in a dose-dependent manner. Analyses using HAV subgenomic replicon systems indicated that these compounds specifically inhibit HAV RNA replication. More importantly, the most potent compounds B2 and B27 also showed clear inhibitory effects on two other HAV strains, KRM031 and TKM005, which also isolated from clinical patients. Our study is the first to report these newly designed flavonoid hybrids as lead compounds for the development of novel anti-HAV drugs.

A comprehensive review: Biological activity, modification and synthetic methodologies of prenylated flavonoids.

Prenylated flavonoids, a unique class of flavonoids which combine a flavonoid skeleton and a lipophilic prenyl side-chain, possess great potential biological activities including cytotoxicity, anti-inflammation, anti-Alzheimer, anti-microbial, anti-oxidant, anti-diabetes, estrogenic, vasorelaxant and enzyme inhibition. Recently, prenylated flavonoids have become an indispensable anchor for the development of new therapeutic agents, and have received increasing from medicinal chemists. The prenylated flavonoids have been outstanding developed through isolation, semi or fully synthesis in a very short period of time, which proves the great value in medicinal chemistry researches. In this review, research progress of prenylated flavonoids including natural prenylated flavonoids, structural modification, synthetic methodologies and pharmacological activities was summarized comprehensively. Furthermore, the structure-activity relationships (SARs) of prenylated flavonoids were summarized which provided a basis for the selective design and optimization of multifunctional prenylated flavonoid derivatives for the treatment of multi-factorial diseases in clinic.

Benzoic acid derivatives from the root barks of Ailanthus altissima.

Two new benzoic acid derivatives (1-2), together with four known compounds (3-6) have been isolated from the n-BuOH soluble fraction of ethanolic extract from Ailanthus altissima. The gross structures of the new compounds were deduced by detailed spectroscopic analysis including HRESIMS and 1D/2D NMR spectroscopy. The stereochemistry of 1 was determined by modified Mosher's method. All compounds were evaluated for their neuroprotective effects against H2O2-induced oxidative stress in human neuroblastoma SH-SY5Y cells and none of them displayed obvious neuroprotective activities. [Formula: see text].

Semi-synthesis and biological evaluation of flavone hybrids as multifunctional agents for the potential treatment of Alzheimer's disease.

7-O-galloyltricetiflavan (GTF), a natural flavonoid, is known to exert anti-oxidation and neuroprotective activity, which are related to the prevention of Alzheimer's disease (AD). In this study, three series of GTF hybrids have been designed, synthesized and evaluated as multifunctional agents for treatment AD. The biological assays indicated that most of them showed strong inhibitory effect on self-induced ß-amyloid (Aß) aggregation, and a significant ability to inhibit ChEs. Among them, compound A15 exhibited best inhibition of Aß aggregation (78.81% at 20 µM), potent AChE inhibitory potencies (IC50, 0.56 µM), and compound C4 presented the highest ability to inhibit BuChE (IC50, 5.77 µM). Furthermore, kinetic, molecular modeling and molecular dynamics studies revealed that A15 and C4 could interact with the catalytic active site of AChE and BuChE, respectively. In addition, compounds A15 and C4 could cross the blood-brain barrier in vitro. More importantly, A15 and C4 also showed excellent neuroprotective activities against H2O2-induced human neuroblastoma SH-SY5Y cells damage and nearly no toxicity on SH-SY5Y cells. All of these outstanding in vitro results indicated A15 and C4 as the leading structure worthy of further investigation.

Terpenylated coumarins from the root bark of Ailanthus altissima (Mill.) Swingle.

Seven undescribed terpenylated coumarins, named altissimacoumarin I-O, together with seven known compounds, altissimacoumarin C, altissimacoumarin E, altissimacoumarin G, altissimacoumarin H, puberulin, 7-(3-Methyl-2-butenyloxy)-6-methoxycoumarin and artelin were isolated from the root bark of Ailanthus altissima (Mill.) Swingle. Their structures were elucidated by comprehensive spectra data analysis, NMR calculation, DP4+ analysis and ACD/Structure Elucidator software simulation. The absolute configurations of altissimacoumarins K, L, M and N were determined by modified Mosher's method. All isolates were tested for their cytotoxic effect against two hepatoma carcinoma cell lines (HepG2, Hep3B). Altissimacoumarin C exhibited moderate cytotoxic effect against Hep3B cells, with IC50 of 45.21 µM.

Oxylipin vanillyl acetals from Solanum lyratum.

Four undescribed oxylipin vanillyl acetals with four stereogenic carbons were isolated from the herbs of Solanum lyratum. A comprehensive set of spectroscopic methods were used to elucidate the structures and relative configurations of 1-4. The absolute configurations of the naturally occurring compounds are assigned as 7S, 9'S, 10'S, 11'R at the site of six-membered cyclic acetal attachment by electronic circular dichroism (ECD) calculations and the modified Mosher's method. Compounds 1 and 3 displayed moderate selective inhibition against Hep3B and HepG2 cells, respectively. Further Annexin V-FITC/PI staining assay revealed that 1 and 3 might have inhibitory effects on hepatoma cells through induction of apoptosis.

Discovery of guaiane-type sesquiterpenoids from the roots of Daphne genkwa with neuroprotective effects.

A phytochemical study on the roots of Daphne genkwa yielded seven new guaiane-type sesquiterpenoids (1-7), daphne A-G. Their structures were elucidated through comprehensive spectroscopic analyses. The absolute configurations were determined by comparison between experimental electronic circular dichroism (ECD) and calculated ECD spectra via time-dependent density functional theory (TDDFT) and the modified Mosher's method. Furthermore, all isolates were evaluated for their neuroprotective activities against H2O2-induced injury in human neuroblastoma SH-SY5Y cells. Among them, compounds 1 (78.42%) and 4 (79.34%) exhibited potent neuroprotective effects against H2O2-induced neurotoxicity at 25 µM. Further Annexin V-FITC/propidium iodide (PI) doubling staining exhibited that the neuroprotective effects of compounds 1 and 4 appeared to be mediated via suppressing cell apoptosis. Flow cytometry assays also proved that compounds 1 and 4 could attenuate mitochondrial dysfunction in SH-SY5Y cells.

Isolation of macrocarpene-type sesquiterpenes from stigma maydis with neuroprotective activities.

Five undescribed macrocarpene-type sesquiterpenes (1-5), along with a known analogue (6) were isolated from the crude extract of stigma maydis. The structures of these compounds were elucidated based on comprehensive spectroscopic analyses together with quantum chemical calculations of 13C NMR data and electronic circular dichroism (ECD) curves. All isolated compounds were tested for their neuroprotective effects against the injury of human neuroblastoma SH-SY5Y cells induced by H2O2. Among them, compounds 3 (65.89%) and 5 (64.38%) showed moderate neuroprotective activity at 50 µM.

Guaiane-Type Sesquiterpenoids from the Roots of Daphne genkwa and Evaluation of Their Neuroprotective Effects.

Chromatographic purification of the roots of Daphne genkwa led to 11 new guaiane-type sesquiterpenoids (1-11), named genkwanoids A-K, and six known analogues (12-17). A comprehensive set of spectroscopic methods including IR, UV, HRESIMS, and 1D/2D NMR were used to elucidate the structures and relative configurations of 1-11. The absolute configurations were determined by the optical rotation calculations and the modified Mosher's method. The possible biosynthetic pathways for 1-11 are proposed. Furthermore, the neuroprotective effects of 1-17 on H2O2-induced damage in human neuroblastoma SH-SY5Y cells were screened using an MTT assay. Compounds 9, 10, and 16 exhibited moderate neuroprotective effects, with survival rates of 79.34%, 79.94%, and 75.64% after treatment with 12.5 µM, values that were comparable to the positive control, Trolox (78.65%). Furthermore, annexin V-FITC/PI staining of cells treated with 9, 10, and 16 showed that the neuroprotective effects of these compounds may arise from inhibiting cell apoptosis.

Phenylpropanoids and lignans from Prunus tomentosa seeds as efficient ß-amyloid (Aß) aggregation inhibitors.

Alzheimer's disease (AD) is characterized by the progressive accumulation of extracellular ß-amyloid (Aß) aggregates. Recently, lignans and phenylpropanoids are attracting increasing attention to discovery useful agents of inhibition on Aß aggregation. In the present study, to develop potential agents for slowing the progression of AD, Prunus tomentosa seeds were selected as a raw material for bioactive compounds, which led to the separation of two pairs of new enantiomeric lignans and phenylpropanoids using chiral HPLC. The planar structures of these compounds were elucidated by spectroscopic data analyses. And their absolute configurations were determined by comparing of experimental and calculated electronic circular dichroism (ECD). The biosynthesis pathway was also discussed. Additionally, the inhibitory activity on Aß aggregation of all optical pure compounds was tested by thioflavin T (ThT) assay. The isolates (1a, 1b, 2a and 2b) showed more potent inhibitory activity than positive control curcumin with inhibitory rate of 73.89 ±â€¯3.41% 78.69 ±â€¯1.50%, 63.25 ±â€¯2.68%, and 67.13 ±â€¯0.90% at 20 µM, respectively. More importantly, the inhibition profiles were explained by molecular dynamics and docking simulation studies.