Bakuchiol targets mitochondrial proteins, prohibitins and voltage-dependent anion channels: New insights into developing antiviral agents

We previously reported that bakuchiol, a phenolic isoprenoid anticancer compound, and its analogs exert anti-influenza activity. However, the proteins targeted by bakuchiol remain unclear. Here, we investigated the chemical structures responsible for the anti-influenza activity of bakuchiol and found that all functional groups and C6 chirality of bakuchiol were required for its anti-influenza activity. Based on these results, we synthesized a molecular probe containing a biotin tag bound to the C1 position of bakuchiol. With this probe, we performed a pulldown assay for Madin-Darby canine kidney cell lysates and purified the specific bakuchiol-binding proteins with SDS-PAGE. Using nanoLC-MS/MS analysis, we identified prohibitin (PHB) 2, voltage-dependent anion channel (VDAC) 1, and VDAC2 as binding proteins of bakuchiol. We confirmed the binding of bakuchiol to PHB1, PHB2, and VDAC2 in vitro using Western blot analysis. Immunofluorescence analysis showed that bakuchiol was bound to PHBs and VDAC2 in cells and colocalized in the mitochondria. The knockdown of PHBs or VDAC2 by transfection with specific siRNAs, along with bakuchiol cotreatment, led to significantly reduced influenza nucleoprotein expression levels and viral titers in the conditioned medium of virus-infected Madin-Darby canine kidney cells, compared to the levels observed with transfection or treatment alone. These findings indicate that reducing PHBs or VDAC2 protein, combined with bakuchiol treatment, additively suppressed the growth of influenza virus. Our findings indicate that bakuchiol exerts anti-influenza activity via a novel mechanism involving these mitochondrial proteins, providing new insight for developing anti-influenza agents.

Synthesis of new coumarin[1,3]oxazine derivatives of 7-hydroxy-6-isobornyl-4-methylcoumarin and their antioxidant activity

In this work, we synthesized a series of new 9,10-dihydro-2H,8H-chromeno[8,7e][1,3]oxazine-2-on derivatives which incorporate isobornylcoumarin and 1,3-oxazine moieties. A structure-antioxidant activity relationship was analyzed. A comparative evaluation of their radical scavenging activity, antioxidant and membrane-protective properties was carried out in test with DPPH, as well as on the models of Fe²⁺ /ascorbate-initiated lipid peroxidation and oxidative hemolysis of mammalian red blood cells. The results suggest that all the obtained coumarin[1,3]oxazine derivatives of 7-hydroxy-6-isobornyl-4-methylcoumarin are capable of exhibiting antioxidant activity in various model systems. Compound 7 with a phenyl fragment, combining high radical scavenging activity and the ability to inhibit Fe²⁺ /ascorbate-initiated peroxidation of animal lipids in a heterogeneous environment, also proved to be the most effective membrane protector and antioxidant in the model of H₂ O₂ -induced erythrocyte hemolysis.

Antiproliferative Activity of (-)-Isopulegol-based 1,3-Oxazine, 1,3-Thiazine and 2,4-Diaminopyrimidine Derivatives

A series of novel heterocyclic structures, namely 1,3-oxazines, 1,3-thiazines and 2,4-diaminopyrimidines, were designed and synthesised. The bioassay tests demonstrated that, among these analogues, 2,4-diaminopyridine derivatives showed significant antiproliferative activity against different human cancer cell lines (A2780, SiHa, HeLa, MCF-7 and MDA-MB-231). Pyrimidines substituted with N2 -(p-trifluoromethyl)aniline, in particular, displayed a potent inhibitory effect on the growth of cancer cells. Structure-activity relationships were also studied from the aspects of stereochemistry on the aminodiol moiety as well as exploring the effects of substituents on the pyrimidine scaffold.

Anticancer activity of Mannich bases: a review of recent literature

This report summarizes the latest published data on the antiproliferative action and cytotoxic activity of Mannich bases, a structurally heterogeneous category of chemical entities that includes compounds which are synthesized via the grafting of an aminomethyl function onto diverse substrates by means of the Mannich reaction. The present overview of the topic is an update to the information assembled in a previously published review that covered the literature up to 2014.

Bakuchiol - a natural meroterpenoid: structure, isolation, synthesis and functionalization approaches

Bakuchiol is an emblematic meroterpene class of natural product extracted from Psoralea corylifolia. It has been reported to possess a broad range of biological and pharmacological properties and is considered as a leading biomolecule. It is highly desirable to devise an efficient approach to access bakuchiol and its chemical biology applications. In this review we provided structural features, isolation methods, various chemical routes and late-stage functionalization (LSF) approaches for bakuchiol and its derivatives. Moreover, this review encompasses the structure-activity relationships (SAR), value-added contributions and future perspectives of bakuchiol.

Evaluation of the immunomodulatory and anti-inflammatory activity of Bakuchiol using RAW 264.7 macrophage cell lines and in animal models stimulated by lipopolysaccharide (LPS)

Bakuchiol (BAK) has been reported to have a diverse pharmacological property as an antibiotic, anti-cancer, anti-hypolipidemic, anti-inflammatory and anti-convulsant agent. This study aimed to elucidate the immunomodulation and anti-inflammatory mechanism of bakuchiol using lipopolysaccharide stimulated RAW 264.7 macrophages and various animal models. The present study has shown that BAK significantly suppressed the pro-inflammatory cytokine expression in a dose-dependent manner and its oral administration significantly decreased delayed hypersensitivity responses as compared to control group. The assessment of immunomodulatory activity was carried out by the testing Hemagglutinating antibody (HA) titer, delayed type hypersensitivity (DTH) responses and phagocytic index by carbon clearance test. On the other hand, it showed significant decrease in circulating antibody titer and carbon clearance assay in a concentration-dependent manner. BAK has significantly potentiated the cellular immunity as well as humoral immunity by facilitating the footpad thickness responses in sheep RBCs in sensitized mice by significantly decreasing circulating antibody titer. Molecular studies revealed that BAK inhibited the activation of upstream mediator nuclear factor-κB by suppressing the phosphorylation of IκBα and p65. The responses were statistically significant as compared with the control (*p < 0.05, **p < 0.01).

Au-catalyzed skeletal rearrangement of O-propargylic oximes via N-O bond cleavage with the aid of a Brønsted base cocatalyst

Au-catalyzed skeletal rearrangement reaction of O-propargylic oxime proceeded via N–O bond cleavage with the aid of a Brønsted base cocatalyst.

O-Propargylic oximes that possess an electron-withdrawing aryl group on the oxime moiety undergo Au-catalyzed skeletal rearrangements via N–O bond cleavage to afford the corresponding 2H-1,3-oxazine derivatives. Our studies show that the inclusion of a Brønsted base cocatalyst not only accelerates the reaction but also switches pathways of the skeletal rearrangement reaction, realizing divergent synthesis of heterocyclic compounds. Computational studies indicate that the elimination of propargylic proton in the cyclized vinylgold intermediate is rate-determining and both electron-withdrawing substituents at the oxime moiety and base cocatalyst facilitate the proton elimination. Moreover, the protodeauration process proceeds stepwise involving N–O bond cleavage followed by recyclization to construct the oxazine core.

Synthesis and biological evaluation of novel bavachinin analogs as anticancer agents

A library of 28 analogs of bavachinin including aliphatic and aromatic ethers, epoxide, chalcone, oxime, semicarbazide, oxime ether and triazole derivatives have been synthesized and evaluated for cytotoxicity against four different human cancer cell lines. Bio-evaluation studies exhibited better cytotoxic profile for many analogs compare to bavachinin. Best results were observed for a 1,2,3-triazole analog (17i) with IC₅₀ values 7.72, 16.08, 7.13 and 11.67 μM against lung (A549), prostate (PC-3), colon (HCT-116) and breast (MCF-7) cancer cell lines respectively. This analog showed three and four fold improvement in cytotoxicity against HCT-116 and A549 cell lines than parent molecule (1). Structure activity relationship (SAR) study for all synthesized analogs was carried out. Further, mechanistic study of the lead molecule (17i) revealed that it inhibits colony formation and in vitro migration of human colon cancer cells (HCT-116). Also, it induced the morphological changes and mediated the apoptotic cell death of HCT-116 cells with perturbance in mitochondrial membrane potential (MMP) and PARP cleavage.

A convergent synthesis of novel alkyne-azide cycloaddition congeners of betulinic acid as potent cytotoxic agent

In an endeavour to develop potent anti-tumor agents from betulinic acid (BA), a series of C-28 derived 1,2,3-triazolyl derivatives were designed and synthesized by employing Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition reaction. All the derivatives were evaluated for cytotoxic activity by MTT assay against five different human cancer cell lines: lung (A549), colon (HCT116), prostate (PC3), pancreatic (MIA PaCa-2) and breast (T47D). The data revealed that compounds 11c, 11d, 11g, 11h and 13a possess most promising cytotoxic potential. The compound 11h was one of the most active compounds, with IC₅₀ values in the range of 4-6µM against all the five cancer cell lines. The results of this study suggested that derivatives with free -OH (11c, 11d and 11g) and free -COOH (11h and 13a) substitutions in the triazole moiety introduced at the C-28 position significantly improved the anti-tumor activity and may be the favourable position to synthesize potent anticancer leads from BA. Introduction of a non polar alkyl groups at C-28 position (10, 12 and 14) resulted in the significant loss of the activity. Further, DAPI staining, ROS generation and wound healing experiments revealed that compound 11h induces apoptosis in HCT-116 cells.