Evaluation of the Antiviral Activity of Tabamide A and Its Structural Derivatives against Influenza Virus.

Influenza viruses cause severe endemic respiratory infections in both humans and animals worldwide. The emergence of drug-resistant viral strains requires the development of new influenza therapeutics. Tabamide A (TA0), a phenolic compound isolated from tobacco leaves, is known to have antiviral activity. We investigated whether synthetic TA0 and its derivatives exhibit anti-influenza virus activity. Analysis of structure-activity relationship revealed that two hydroxyl groups and a double bond between C7 and C8 in TA0 are crucial for maintaining its antiviral action. Among its derivatives, TA25 showed seven-fold higher activity than TA0. Administration of TA0 or TA25 effectively increased survival rate and reduced weight loss of virus-infected mice. TA25 appears to act early in the viral infection cycle by inhibiting viral mRNA synthesis on the template-negative strand. Thus, the anti-influenza virus activity of TA0 can be expanded by application of its synthetic derivatives, which may aid in the development of novel antiviral therapeutics.

Design and Synthesis of π-Extended Resveratrol Analogues and In Vitro Antioxidant and Anti-Inflammatory Activity Evaluation.

The research on resveratrol (1) has been conducted intensively over a long time due to its proven antioxidant activity and disease-fighting capabilities. Many efforts have also been made to increase these biological effects. In the present study, six new extended aromatic resveratrol analogues containing naphthalene (2) and its bioisosteres quinoline (3 and 4), isoquinoline (5) quinoxaline (6) and quinazoline (7) scaffolds were designed and synthesized using an annulation strategy. The antioxidant and anti-inflammatory activities of these compounds were investigated. All compounds showed better antioxidant activity than resveratrol in ABTS assay. As for the anti-inflammatory test, 5 and 7 exhibited better activity than resveratrol. It is worth noting that nitrogen substitution on the extended aromatic resveratrol analogues has a significant impact on cell viability. Taking the antioxidant activities and NO inhibition activities into consideration, we conclude that isoquinoline analogue 5 may qualify for the further investigation of antioxidant and anti-inflammatory therapy. Furthermore, our study results suggest that in order to improve the biological activity of polyphenolic compounds, extended aromaticity and nitrogen substitution strategy could be a viable method for the design of future drug candidates.

Synthesis and in vitro evaluation of homoisoflavonoids as potent inhibitors of nitric oxide production in RAW-264.7 cells.

Syntheses of natural homoisoflavonoids, (±)-portulacanones A-C (4, 8 and 9), portulacanone D (6), isolated from Portulaca oleracea L. (POL) and their derivatives (3, 5 and 7) have been achieved for the first time along with the synthesis of known derivatives (1 and 2) and their in vitro inhibitory effect against NO production in LPS-induced RAW-264.7 macrophages was evaluated as an indicator of anti-inflammatory activity. All the compounds tested had a concentration-dependent inhibitory effect on NO production by RAW-264.7 macrophages without obvious cytotoxicity. Compounds 3 (97.2% at 10 µM; IC50 = 1.26 µM) followed by 6 (portulacanone D) (92.5% at 10 µM; IC50 = 2.09 µM), 1 (91.4% at 10 µM; IC50 = 1.75 µM) and 7 (83.0% at 10 µM; IC50 = 2.91 µM) were the most potent from the series. This finding was further correlated with the suppressed expression of iNOS induced by LPS. Our promising preliminary results may provide the basis for the assessment of compound 3 as a lead structure for a NO production-targeted anti-inflammatory drug development and also could support the usefulness of POL as a folklore medicinal plant in the treatment of inflammatory diseases.

Dihydrostilbenes and diarylpropanes: Synthesis and in vitro pharmacological evaluation as potent nitric oxide production inhibition agents.

An efficient synthesis of dihydrostilbenes (1-5) and diarylpropanes (6-10) is achieved from the commercially available starting materials and Wittig-Horner reaction, Claisen-Schmidt condensation and hydrogenation as key steps. Later, their nitric oxide (NO) production inhibition effects were evaluated in lipopolysaccharide (LPS)-induced RAW-264.7 macrophages as an indicator of anti-inflammatory activity. All the tested compounds significantly decreased NO production in a concentration-dependent manner except compounds 2, 6 and 8 and did not show notable cytotoxicity except compound 1. Two compounds i.e., compound 9 (hindsiipropane B) (100%; IC50=1.84µM) possessed the most potent NO inhibitory activity which was even stronger than the positive control, L-NMMA (90.1%; IC50=2.73µM) followed by compound 4 (75.5%; IC50=2.98µM) at 10µM concentration and this finding was also further correlated by suppressed expression of LPS stimulated inducible NO synthase. Our study revealed that compound 9, a 1,3-diarylpropane scaffold with 3″,4″-dimethoxyphenyl and 3',4'-dihydroxy-2'-methoxyphenyl motifs could be considered as potential compound or lead compound for further development of NO production-targeted anti-inflammatory agents.

Synthesis and biological evaluation of 2-aroylbenzofurans, rugchalcones A, B and their derivatives as potent anti-inflammatory agents.

An efficient synthesis of 2-aroylbenzofurans, rugchalcones A, B and their derivatives was accomplished in excellent yields by the Rap-Stoermer reaction between substituted salicylaldehydes and phenacyl bromides. Later their anti-inflammatory effects were evaluated in lipopolysaccharide (LPS)-induced RAW-264.7 macrophages. The compounds were exhibited exceptional potency against inflammatory mediated NO production with no cytotoxicity at 10 µM concentration and IC50 values are found in the range from 0.75 to 13.27 µM. Among the 2-aroylbenzofurans prepared in this study, compounds 4 (99.6%; IC50=0.57), rugchalcone B (2) (99.3%; IC50=4.13), 7 (96.8%; IC50=1.90) and 8 (74.3%; IC50=0.99) were showed the maximum inhibitory activity. This study suggests that compounds 2, 4, 7 and 8 which are having 4-hydroxyphenyl group and/or hydroxy (-OH) group at 5- and/or 6-position of benzofuran motif could be considered as a promising scaffolds for the further development of iNOS inhibitors for potential anti-inflammatory applications.

Organic reactions in water: a distinct novel approach for an efficient synthesis of alpha-amino phosphonates starting directly from nitro compounds.

A distinct approach for high-yielding synthesis of alpha-amino phosphonates has been discovered through three-component reaction of nitro compounds, aldehydes, or ketones and dialkyl or trialkyl phosphites using indium in dilute aqueous HCl at room temperature. This one-pot conversion consists of the following steps: (i) reduction of nitro compounds to amines, (ii) formation of imines from amines and carbonyl compounds, and (iii) hydrophosphonylation of imines.

A simple and efficient access to alpha-amino phosphonates from N-benzyloxycarbonylamino sulfones using indium(III) chloride.

Treatment of N-benzyloxycarbonylamino sulfones with triethyl phosphite catalyzed by InCl3 produces the corresponding protected alpha-amino phosphonates in high yields (71-92%).

A mild and efficient stereoselective synthesis of (Z)- and (E)-allyl sulfides and potent antifungal agent, (Z)-3-(4-methoxybenzylidene)thiochroman-4-one from Morita-Baylis-Hillman acetates.

A facile stereoselective synthesis of (Z)- and (E)-allyl sulfides has been accomplished from Morita-Baylis-Hillman acetates in one-pot by treatment with benzene thiol in the presence of catalytic amounts of 15% aqueous NaOH and TBAI in DMSO at room temperature. The method has been applied for the synthesis of (Z)-3-(4-methoxybenzylidene)thiochroman-4-one, a potent antifungal compound.