Synthesis and Biological Activity of Piperine Derivatives as Potential PPARγ Agonists

Synthesis and Characterization of a New Carbon-11 Labeled Positron Emission Tomography Radiotracer for Orexin 2 Receptors Neuroimaging

Purpose

Orexin receptors (OXRs) play a crucial role in modulating various physiological and neuropsychiatric functions within the central nervous system (CNS). Despite their significance, the precise role of OXRs in the brain remains elusive. Positron emission tomography (PET) imaging is instrumental in unraveling CNS functions, and the development of specific PET tracers for OXRs is a current research focus.

Methods

The study investigated MDK-5220, an OX2R-selective agonist with promising binding properties (EC50 on OX2R: 0.023 μM, Ki on hOX2R: 0.14 μM). Synthesized and characterized as an OX2R PET probe, [11C]MDK-5220 was evaluated for its potential as a tracer. Biodistribution studies in mice were conducted to assess OX2R binding selectivity, with particular attention to its interaction with P-glycoprotein (P-gp) on the blood-brain barrier.

Results

[11C]MDK-5220 exhibited promising attributes as an OX2R PET probe, demonstrating robust OX2R binding selectivity in biodistribution studies. However, an observed interaction with P-gp impacted its brain uptake. Despite this limitation, [11C]MDK-5220 presents itself as a potential candidate for further development.

Discussion

The study provides insights into the functionality of the OX system and the potential of [11C]MDK-5220 as an OX2R PET probe. The observed interaction with P-gp highlights a consideration for future modifications to enhance brain uptake. The findings pave the way for innovative tracer development and propel ongoing research on OX systems, contributing to a deeper understanding of their role in the CNS.

Conclusion

[11C]MDK-5220 emerges as a promising OX2R PET probe, despite challenges related to P-gp interaction. This study lays the foundation for further exploration and development of PET probes targeting OXRs, opening avenues for advancing our understanding of OX system functionality within the brain.

Piperine: Chemistry and Biology

Piperine is a plant-derived promising piperamide candidate isolated from the black pepper (Piper nigrum L.). In the last few years, this natural botanical product and its derivatives have aroused much attention for their comprehensive biological activities, including not only medical but also agricultural bioactivities. In order to achieve sustainable development and improve survival conditions, looking for environmentally friendly pesticides with low toxicity and residue is an extremely urgent challenge. Fortunately, plant-derived pesticides are rising like a shining star, guiding us in the direction of development in pesticidal research. In the present review, the recent progress in the biological activities, mechanisms of action, and structural modifications of piperine and its derivatives from 2020 to 2023 are summarized. The structure-activity relationships were analyzed in order to pave the way for future development and utilization of piperine and its derivatives as potent drugs and pesticides for improving the local economic development.

Evaluation of Antimicrobial Activity and Cytotoxicity Effects of Extracts of Piper nigrum L. and Piperine

P. nigrum L. extracts and the piperine alkaloid have important antimicrobial, anti-inflammatory, and antioxidant properties. Therefore, in this study, we evaluated the antimicrobial activity and cytotoxicity of P. nigrum L. extracts and piperine, a compound isolated from the extracts of P. nigrum L. Extracts obtained via maceration, soxhlet, and purification steps, in addition to isolated piperine, were used in this study. Spectroscopic methods, such as nuclear magnetic resonance, scanning electron microscopy, X-ray diffraction, thermogravimetry, and differential scanning calorimetry, were used to characterize piperine. In the microbiological analyses, the extract obtained via maceration-derived sample showed high efficiency in inhibiting Salmonella spp. (MIC < 100 μg/mL). The extract obtained via a soxhlet-derived sample showed promising inhibitory activity against almost all microorganisms, with negligible inhibition of Pseudomonas aeruginosa. Favorable inhibition coefficients were also observed against Staphylococcus aureus and Salmonella spp. (MIC < 100 μg/mL) for the extract obtained via purification of the steps-derived sample. Piperine showed an excellent inhibition coefficient against most microorganisms, with inactivity only observed against P. aeruginosa. Cytotoxicity evaluation assays in cancer cell lines revealed that piperine exhibited inhibitory potential on all tested tumor cell lines, causing a decrease in cell viability and achieving an IC50 of less than 30 μg/mL. The analyzed extracts from P. nigrum L. seeds showed cytotoxic activity against tumor and non-tumor cell lines.

Modulation of interaction of BRCA1-RAD51 and BRCA1-AURKA protein complexes by natural metabolites using as possible therapeutic intervention toward cardiotoxic effects of cancer drugs: an in-silico approach

Breast cancer type 1 susceptibility protein (BRCA1) plays an important role in maintaining genome stability and is known to interact with several proteins involved in cellular pathways, gene transcription regulation and DNA damage response. More than 40% of inherited breast cancer cases are due to BRCA1 mutation. It is also a prognostic marker in non-small cell lung cancer patients as well as a gatekeeper of cardiac function. Interaction of mutant BRCA1 with other proteins is known to disrupt the tumor suppression mechanism. Two directly interacting proteins with BRCA1 namely, DNA repair protein RAD51 (RAD51) and Aurora kinase A (AURKA), known to regulate homologous recombination (HR) and G/M cell cycle transition, respectively, form protein complex with both wild and mutant BRCA1. To analyze the interactions, protein-protein complexes were generated for each pair of proteins. In order to combat the cardiotoxic effects of cancer drugs, pharmacokinetically screened natural metabolites derived from plant, marine and bacterial sources and along with FDA-approved cancer drugs as control, were subjected to molecular docking. Piperoleine B and dihydrocircumin were the best docked natural metabolites in both RAD51 and AURKA complexes, respectively. Molecular dynamics simulation (MDS) analysis and binding free energy calculations for the best docked natural metabolite and drug for both the mutant BRCA1 complexes suggested better stability for the natural metabolites piperolein B and dihydrocurcumin as compared to drug. Thus, both natural metabolites could be further analyzed for their role against the cardiotoxic effects of cancer drugs through wet lab experiments.Communicated by Ramaswamy H. Sarma.

Methylenedioxy Piperamide-Derived Compound D5 Regulates Inflammatory Cytokine Secretion in a Culture of Human Glial Cells

Neuroinflammation is the cornerstone of most neuronal disorders, particularly neurodegenerative diseases. During the inflammatory process, various pro-inflammatory cytokines, chemokines, and enzymes—such as interleukin 1-β (IL1-β), tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), inducible nitric oxide synthases (iNOS), inhibitory kappa kinase (IKK), and inducible nitric oxide (NO)—are over-expressed in response to every stimulus. Methods: In the present study, we focused on the anti-neuroinflammatory efficacy of (2E,4E)-N,5-bis(benzo[d][1,3]dioxol-5-yl)penta-2,4-dienamide, encoded D5. We investigated the efficacy of D5 on the upstream and downstream products of inflammatory pathways in CHME3 and SVG cell lines corresponding to human microglia and astrocytes, respectively, using various in silico, in vitro, and in situ techniques. Results: The results showed that D5 significantly reduced the level of pro-inflammatory cytokines by up-regulating PPAR-γ expression and suppressing IKK-β, iNOS, NO production, and NF-κB activation in inflamed astrocytes (SVG) and microglia (CHME3) after 24 h of incubation. The data demonstrated remarkably higher efficacy of D5 compared to ASA (Aspirin) in reducing NF-κB-dependent neuroinflammation. Conclusions: We observed that the functional-group alteration had an extreme influence on the levels of druggability and the immunomodulatory properties of two analogs of piperamide, D5, and D4 ((2E,4E)-5-(benzo[d][1,3]dioxol-5-yl)-N-(4-(hydroxymethyl)phenyl)penta-2,4-dienamide)). The present study suggested D5 as a potential anti-neuroinflammatory agent for further in vitro, in vivo, and clinical investigations.

Virtual screening and biological evaluation of PPARγ antagonists as potential anti-prostate cancer agents

The peroxisome proliferator-activated receptor gamma (PPARγ) was identified as an oncogene and it plays a key role in prostate cancer (PC) development and progression. PPARγ antagonists have been shown to inhibit PC cell growth. Herein, we describe a virtual screening-based approach that led to the discovery of novel PPARγ antagonist chemotypes that bind at the allosteric pocket. Arg288, Lys367, and His449 appear to be important for PPARγ antagonist binding.

Piperine: A review of its biological effects

Medicinal plants have been used for years as a source of food, spices, and, in traditional medicine, as a remedy to numerous diseases. Piper nigrum, belonging to the family Piperaceae is one of the most widely used spices all over the world. It has a distinct sharp flavor attributed to the presence of the phytochemical, piperine. Apart from its use as a spice, P. nigrum is frequently used for medicinal, preservation, and perfumery purposes. Black pepper contains 2-7.4% of piperine, varying in content is associated with the pepper plant. Piperine displays numerous pharmacological effects such as antiproliferative, antitumor, antiangiogenesis, antioxidant, antidiabetic, anti-obesity, cardioprotective, antimicrobial, antiaging, and immunomodulatory effects in various in vitro and in vivo experimental trials. Furthermore, piperine has also been documented for its hepatoprotective, anti-allergic, anti-inflammatory, and neuroprotective properties. This review highlights and discusses the medicinal and health-promoting effects of piperine, along with possible mechanisms of its action in health promotion and disease prevention. In addition, the present review summarizes the recent literature related to piperine as a therapeutic agent against several diseases.