Total synthesis of 6'-hydroxyjusticidin A

Total synthesis of justicidin B, justicidin E, and taiwanin C: A general and flexible approach toward the synthesis of natural arylnaphthalene lactone lignans

Lignans are widely present in traditional medicinal plants. Many natural arylnaphthalene lactone lignans (NALLs) isolated from the genera Justicia, Haplophyllum, and Phyllanthus possess interesting biological activities. Herein, we report a general strategy for the total synthesis of this kind of lignans. Features of this new approach are an aryl-alkyl Suzuki cross-coupling to introduce the dioxinone unit, a cation-induced cyclization to construct the aryl dihydronaphthalene, and base-mediated oxidative aromatization to furnish the arylnaphthalene core. By incorporating these key transformations, the total syntheses of justicidins B and E and taiwanin C covered type I and type II NALLs were accomplished.

Synthesis and Aldose Reductase Inhibition Effects of Novel N-Benzyl-4-Methoxyaniline Derivatives

In the current study, starting from 4-methoxyaniline, four Schiff bases were synthesized from benzaldehydes with Br and OMe. Corresponding N-benzylanilines and their derivatives were obtained from reductions (by NaBH₄ ) and substitutions (by acyl and tosyl chlorides) of these bases, respectively. The inhibitory effects of the sixteen compounds, twelve of which were novel compounds are examined. Then, we conducted molecular docking and binary QSAR studies to determine inhibitory-enzyme interactions of compounds that show an inhibitory effect. Our results reveal that methoxyanilline-derived compounds show good biological activities. The most active compound (22) has IC₅₀ values of 2.83 μM. These novel AR enzyme inhibitors may open new avenues for better AR inhibitors in the future.

Stable Axially Chiral Isomers of Arylnaphthalene Lignan Glycosides with Antiviral Potential Discovered from Justicia procumbens

Arylnaphthalene lignans (ANLs) were known to have axial chirality due to the biphenyl skeleton with hindered rotation at the single bond. However, the stable ANL atropisomers have not been isolated from nature until the present study. Phytochemical separation of the methanol extract of the stems and barks of Justicia procumbens led to the isolation of 11 ANL glycosides including four pairs of new atropisomers with stable confirmations at room temperature. Their structures were deduced from elucidation of the extensive spectral data, and their absolute configurations were determined by the circular dichroism, electronic circular dichroism, and X-ray methods as well as the total synthesis of one pair of the atropisomers. The ANL compounds were evaluated for their antiviral potential, and it was found that they displayed great antiviral activity discrepancy between a pair of atropisomers due to the geometric orientation. The 1'P-oriented atropisomers showed much more significant antiviral potency than their corresponding 1'M-oriented counterparts. The biological activity discrepancy caused by the axial chirality will not only inspire synthetic design of novel ANL atropisomers to enrich the structural diversity, but also provide important hints to direct the synthetic approaches toward the antiviral drug development of ANL compounds.

Synthesis, Bioevaluation, Structure-Activity Relationship and Docking Studies of Natural Product Inspired (Z)-3-benzylideneisobenzofuran-1(3H)-ones as Highly Potent antioxidants and Antiplatelet agents

For the first time, a series of highly potent natural product inspired substituted (Z)-3-benzylideneisobenzofuran-1(3H)-ones 28a-t, embraced with electron-withdrawing groups (EWG) and electron-donating groups (EDG) at site I and site II, were prepared and assessed for their in vitro antioxidant activities (DPPH free radical scavenging assay) and arachidonic acid (AA)-induced antiplatelet activities using ascorbic acid (IC₅₀ = 4.57 µg/mL) and aspirin (IC₅₀ = 21.34 µg/mL), as standard references, respectively. In this study, compounds 28f-g, 28k-l and 28q have shown high order of in vitro antioxidant activity. Infact, 28f and 28k were found to show 10-folds and 8-folds more antioxidant activity than ascorbic acid, respectively and was found to be the most active analogues of the series. Similarly, Compounds 28c-g, 28k-l, 28o and 28q-t were recognized as highly potent antiplatelet agents (upto 6-folds) than aspirin. Furthermore, in silico studies of the most active antioxidants 28f, 28k and 28l and very active antiplatelet molecules 28f, 28k, 28l and 28s were carrying out for the validation of the biological results. This is the first detailed study of the discovery of several (Z)-3-benzylideneisobenzofuran-1(3H)-ones as highly potent antioxidants and antiplatelet agents.

A regioselective facile synthesis of furo[3,4-b]carbazolones: application to the total synthesis of mafaicheenamine E and claulansine D

1-Hydroxycarbazole-2,3-dicarboxylates have been shown to undergo chemoselective reductive cyclization to furo[3,4-b]carbazolones with LiAlH₄.

The synthesis of justicidinoside B and its atropisomer

The first synthesis of justicidinoside B and its atropisomer was reported and their absolute configurations were determined by the CD exciton chirality method. The structures were confirmed by (1)H NMR, (13)C NMR, and HRMS.