Bavachinin analogues as agonists of pan-peroxisome proliferator-activated receptors

Bioisosteric heterocyclic analogues of natural bioactive flavonoids by scaffold-hopping approaches: State-of-the-art and perspectives in medicinal chemistry

The flavonoid family is a set of well-known bioactive natural molecules, with a wide range of potential therapeutic applications. Despite the promising results obtained in preliminary in vitro/vivo studies, their pharmacokinetic and pharmacodynamic profiles are severely compromised by chemical instability. To address this issue, the scaffold-hopping approach is a promising strategy for the structural optimization of natural leads to discover more potent analogues. In this scenario, this Perspective provides a critical analysis on how the replacement of the chromon-4-one flavonoid core with other bioisosteric nitrogen/sulphur heterocycles might affect the chemical, pharmaceutical and biological properties of the resulting new chemical entities. The investigated derivatives were classified on the basis of their biological activity and potential therapeutic indications. For each session, the target(s), the specific mechanism of action, if available, and the key pharmacophoric moieties were highlighted, as revealed by X-ray crystal structures and in silico structure-based studies. Biological activity data, in vitro/vivo studies, were examined: a particular focus was given on the improvements observed with the new heterocyclic analogues compared to the natural flavonoids. This overview of the scaffold-hopping advantages in flavonoid compounds is of great interest to the medicinal chemistry community to better exploit the vast potential of these natural molecules and to identify new bioactive molecules.

Total Synthesis and Anti-Inflammatory Evaluation of Osajin, Scandenone and Analogues

In this study, the total synthesis of osajin, scandenone and their analogues have been accomplished. The key synthetic steps include aldol/intramolecular iodoetherification/elimination sequence reactions and a Suzuki coupling reaction to assemble the tricyclic core, chemoselective propargylation and Claisen rearrangement reactions to obtain natural compounds. In addition, we also designed and synthesized twenty-five natural product analogues. All synthetic compounds were screened for anti-inflammatory activity against tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Collectively, Compound 39e and 39d were considered as promising lead compounds for further development.

The Suzuki-Miyaura Cross-Coupling-Claisen Rearrangement-Cross-Metathesis Approach to Prenylated Isoflavones

Isoflavones were synthesized via Suzuki-Miyaura coupling of 3-iodochromones and para-methoxybenzene- and para-phenolboronic acid. In our hands, conditions commonly used for similar cross couplings turned out to be unsuccessful or difficult to reproduce, for example, due to the unplanned partial cleavage of MOM-protecting groups. Using Pd(dba)₂ as a precatalyst and tricyclohexylphosphine as an activating ligand, reliable cross-coupling conditions were identified. In all cases, notably higher yields of isoflavones were obtained with para-phenolboronic acid than with para-methoxybenzene boronic acid. This observation and the commercial availability of para-phenolboronic acid suggest that for the synthesis of the important 3'-prenyl- or 3',5'-diprenylisoflavone substitution pattern a synthetic route that introduces the prenyl substituents after the Pd-catalyzed cross-coupling step, thereby avoiding laborious and protecting-group-intensive multistep syntheses of C-prenylated arene boronic acids, is advantageous.

Development of Heterocyclic PPAR Ligands for Potential Therapeutic Applications

The family of nuclear peroxisome proliferator-activated receptors (PPARα, PPARβ/δ, and PPARγ) is a set of ligand-activated transcription factors that regulate different functions in the body. Whereas activation of PPARα is known to reduce the levels of circulating triglycerides and regulate energy homeostasis, the activation of PPARγ brings about insulin sensitization and increases the metabolism of glucose. On the other hand, PPARβ when activated increases the metabolism of fatty acids. Further, these PPARs have been claimed to be utilized in various metabolic, neurological, and inflammatory diseases, neurodegenerative disorders, fertility or reproduction, pain, and obesity. A series of different heterocyclic scaffolds have been synthesized and evaluated for their ability to act as PPAR agonists. This review is a compilation of efforts on the part of medicinal chemists around the world to find novel compounds that may act as PPAR ligands along with patents in regards to PPAR ligands. The structure-activity relationship, as well as docking studies, have been documented to better understand the mechanistic investigations of various compounds, which will eventually aid in the design and development of new PPAR ligands. From the results of the structural activity relationship through the pharmacological and in silico evaluation the potency of heterocycles as PPAR ligands can be described in terms of their hydrogen bonding, hydrophobic interactions, and other interactions with PPAR.

A bavachinin analog, D36, induces cell death by targeting both autophagy and apoptosis pathway in acute myeloid leukemia cells

PURPOSE

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy with high mortality, and it is urgent to find new and optimized treatment strategies for AML. In this study, bavachinin, isolated from Psoralea corylifolia L. exhibiting extensive anti-tumor activity in many solid tumors and a series of its synthesized analogs, were screened for their anti-cancer activity on AML cell lines.

METHODS

The cell viability of AML cells was measured using CCK-8 assays. Cell apoptosis and cell cycle were detected by flow cytometry. The expression of apoptosis-related protein and autophagy-related protein/gene was detected by western blot, immunofluorescence or RT-PCR. Subcutaneous mice tumor model was used to evaluate the anti-cancer activity of D36 in vivo.

RESULTS

D36 robustly induced AML cells death in a dose-dependent manner with the IC₅₀ value of 1.0 μM for HL-60 cells and 0.81 μM for MV4-11 cells at 24 h. D36 activated autophagy by inducing the accumulation of LC3B and promoting the autophagy flux. In addition, D36 triggered the extrinsic apoptosis by upregulating the protein level of FAS, cleaved-caspase 8, cleaved-caspase 3 and cleaved-PARP. D36 also blocked the cell cycle at S phase or G₂/M phase in AML cells. In addition, we find that activation of caspase cascade induced apoptosis and meanwhile activated autophagy, autophagy activation in turns contributes to apoptosis. Furthermore, D36 suppressed the tumor growth in HL-60 AML-bearing mice without obvious side effects.

CONCLUSION

This study suggests that D36 is a promising small-molecule for the treatment of acute myeloid leukemia.