Thermosensitive Polymeric Nanoparticles for Drug Co-Encapsulation and Breast Cancer Treatment

Despite advances in breast cancer treatment, there remains a need for local management of noninvasive, low-grade ductal carcinoma in situ (DCIS). These focal lesions are well suited for local intraductal treatment. Intraductal administration supported target site drug retention, improved efficacy, and reduced systemic exposure. Here, we used a poly(N-isopropyl acrylamide, pNIPAM) nanoparticle delivery system loaded with cytotoxic piplartine and an MAPKAP Kinase 2 inhibitor (YARA) for this purpose. For tumor environment targeting, a collagen-binding peptide SILY (RRANAALKAGELYKSILYGSG-hydrazide) was attached to pNIPAM nanoparticles, and the nanoparticle diameter, zeta potential, drug loading, and release were assessed. The system was evaluated for cytotoxicity in a 2D cell culture and 3D spheroids. In vivo efficacy was evaluated using a chemical carcinogenesis model in female Sprague-Dawley rats. Nanoparticle delivery significantly reduced the IC50 of piplartine (4.9 times) compared to the drug in solution. The combination of piplartine and YARA in nanoparticles further reduced the piplartine IC50 (~15 times). Treatment with these nanoparticles decreased the in vivo tumor incidence (5.2 times). Notably, the concentration of piplartine in mammary glands treated with nanoparticles (35.3 ± 22.4 μg/mL) was substantially higher than in plasma (0.7 ± 0.05 μg/mL), demonstrating targeted drug retention. These results indicate that our nanocarrier system effectively reduced tumor development with low systemic exposure.

Piplartine-Inspired 3,4,5-Trimethoxycinnamates: Trypanocidal, Mechanism of Action, and In Silico Evaluation

Chagas disease (CD) is one of the main neglected tropical diseases that promote relevant socioeconomic impacts in several countries. The therapeutic options for the treatment of CD are limited, and parasite resistance has been reported. Piplartine is a phenylpropanoid imide that has diverse biological activities, including trypanocidal action. Thus, the objective of the present work was to prepare a collection of thirteen esters analogous to piplartine (1-13) and evaluate their trypanocidal activity against Trypanosoma cruzi. Of the tested analogues, compound 11 ((E)-furan-2-ylmethyl 3-(3,4,5-trimethoxyphenyl)acrylate) showed good activity with IC₅₀ values = 28.21 ± 5.34 μM and 47.02 ± 8.70 μM, against the epimastigote and trypomastigote forms, respectively. In addition, it showed a high rate of selectivity to the parasite. The trypanocidal mechanism of action occurs through the induction of oxidative stress and mitochondrial damage. In addition, scanning electron microscopy showed the formation of pores and leakage of cytoplasmic content. Molecular docking indicated that 11 probably produces a trypanocidal effect through a multi-target mechanism, including affinity with proteins CRK1, MPK13, GSK3B, AKR, UCE-1, and UCE-2, which are important for the survival of the parasite. Therefore, the results suggest chemical characteristics that can serve for the development of new trypanocidal prototypes for researching drugs against Chagas disease.

Molecular Modeling and In Vitro Evaluation of Piplartine Analogs against Oral Squamous Cell Carcinoma

Cancer is a principal cause of death in the world, and providing a better quality of life and reducing mortality through effective pharmacological treatment remains a challenge. Among malignant tumor types, squamous cell carcinoma-esophageal cancer (EC) is usually located in the mouth, with approximately 90% located mainly on the tongue and floor of the mouth. Piplartine is an alkamide found in certain species of the genus Piper and presents many pharmacological properties including antitumor activity. In the present study, the cytotoxic potential of a collection of piplartine analogs against human oral SCC9 carcinoma cells was evaluated. The analogs were prepared via Fischer esterification reactions, alkyl and aryl halide esterification, and a coupling reaction with PyBOP using the natural compound 3,4,5-trimethoxybenzoic acid as a starting material. The products were structurally characterized using ¹H and ¹³C nuclear magnetic resonance, infrared spectroscopy, and high-resolution mass spectrometry for the unpublished compounds. The compound 4-methoxy-benzyl 3,4,5-trimethoxybenzoate (9) presented an IC₅₀ of 46.21 µM, high selectively (SI > 16), and caused apoptosis in SCC9 cancer cells. The molecular modeling study suggested a multi-target mechanism of action for the antitumor activity of compound 9 with CRM1 as the main target receptor.

Protective Effect of Piplartine against LPS-Induced Sepsis through Attenuating the MAPKs/NF-κB Signaling Pathway and NLRP3 Inflammasome Activation

Piplartine (or Piperlongumine) is a natural alkaloid isolated from Piper longum L., which has been proposed to exhibit various biological properties such as anti-inflammatory effects; however, the effect of piplartine on sepsis has not been examined. This study was performed to examine the anti-inflammatory activities of piplartine in vitro, ex vivo and in vivo using murine J774A.1 macrophage cell line, peritoneal macrophages, bone marrow-derived macrophages and an animal sepsis model. The results demonstrated that piplartine suppresses iNOS and COX-2 expression, reduces PGE₂, TNF-α and IL-6 production, decreases the phosphorylation of MAPKs and NF-κB and attenuates NF-κB activity by LPS-activated macrophages. Piplartine also inhibits IL-1β production and suppresses NLRP3 inflammasome activation by LPS/ATP- and LPS/nigericin-activated macrophages. Moreover, piplartine reduces the production of nitric oxide (NO) and TNF-α, IL-6 and IL-1β, decreases LPS-induced tissue damage, attenuates infiltration of inflammatory cells and enhances the survival rate. Collectively, these results demonstrate piplartine exhibits anti-inflammatory activities in LPS-induced inflammation and sepsis and suggest that piplartine might have benefits for sepsis treatment.

Piplartine attenuates the proliferation of hepatocellular carcinoma cells via regulating hsa_circ_100338 expression

Researches have pointed that piplartine inhibits the proliferation of hepatocellular carcinoma (HCC) cells, however, the underlying mechanisms has not been well defined. Currently, more and more studies have pointed out that circRNAs can regulate tumor cell proliferation, involve in the tumorigenesis mechanism of various tumors. In this study, we explored whether piplartine may participate in the development of HCC through the regulation of ability of HCC cell proliferation by circRNA. Based on the chip analysis, we selected candidate circRNAs that are highly correlated with HCC. CircRNA expression in OSCC cells treated with piplartine was detected by qRT-PCR. We found that only the expression of hsa_circ_100338 (circ-100338) was observably reduced. The expression characteristics of circ-100338 in HCC cell lines were also verified by qRT-PCR. Subsequently, whether or notcirc-100338 can regulate ZEB1 via competitively binding to miR-141-3p was determined by the RIP assay and dual luciferase reporter gene assay. The effect of the circ-100338/miR-141-3p/ZEB1 axis on the proliferation of HCC cell was tested by EdU and CCK-8 assay. Results showed that circ-100338 expression was observably increased in HCC cell lines. Simultaneously, circ-100338 can regulate the expression of ZEB1by competitively binding to miR-141-3p. Moreover high expression of circ-100338 can stimulate the proliferation of HCC cells. Our current study revealed that circ-100338 played as a ceRNA in promoting the progression of HCC by sponging miR-141-3p, while piplartine can participate in the development of HCC by inhibiting the expression of circ-100338.

Ruthenium Complexes With Piplartine Cause Apoptosis Through MAPK Signaling by a p53-Dependent Pathway in Human Colon Carcinoma Cells and Inhibit Tumor Development in a Xenograft Model

Ruthenium complexes with piplartine, [Ru(piplartine)(dppf)(bipy)](PF₆)₂ (1) and [Ru(piplartine)(dppb)(bipy)](PF₆)₂ (2) (dppf = 1,1-bis(diphenylphosphino) ferrocene; dppb = 1,4-bis(diphenylphosphino)butane and bipy = 2,2′-bipyridine), were recently synthesized and displayed more potent cytotoxicity than piplartine in different cancer cells, regulated RNA transcripts of several apoptosis-related genes, and induced reactive oxygen species (ROS)-mediated apoptosis in human colon carcinoma HCT116 cells. The present work aimed to explore the underlying mechanisms through which these ruthenium complexes induce cell death in HCT116 cells in vitro, as well as their in vivo action in a xenograft model. Both complexes significantly increased the percentage of apoptotic HCT116 cells, and co-treatment with inhibitors of JNK/SAPK, p38 MAPK, and MEK, which inhibits the activation of ERK1/2, significantly reduced the apoptosis rate induced by these complexes. Moreover, significant increase in phospho-JNK2 (T183/Y185), phospho-p38α (T180/Y182), and phospho-ERK1 (T202/Y204) expressions were observed in cells treated with these complexes, indicating MAPK-mediated apoptosis. In addition, co-treatment with a p53 inhibitor (cyclic pifithrin-α) and the ruthenium complexes significantly reduced the apoptosis rate in HCT116 cells, and increased phospho-p53 (S15) and phospho-histone H2AX (S139) expressions, indicating induction of DNA damage and p53-dependent apoptosis. Both complexes also reduced HCT116 cell growth in a xenograft model. Tumor mass inhibition rates were 35.06, 29.71, and 32.03% for the complex 1 (15 μmol/kg/day), complex 2 (15 μmol/kg/day), and piplartine (60 μmol/kg/day), respectively. These data indicate these ruthenium complexes as new anti-colon cancer drugs candidates.

NFBTA: A Potent Cytotoxic Agent against Glioblastoma

Piplartine (PPL), also known as piperlongumine, is a biologically active alkaloid extracted from the Piper genus which has been found to have highly effective anticancer activity against several tumor cell lines. This study investigates in detail the antitumoral potential of a PPL analogue; (E)-N-(4-fluorobenzyl)-3-(3,4,5-trimethoxyphenyl) acrylamide (NFBTA). The anticancer potential of NFBTA on the glioblastoma multiforme (GBM) cell line (U87MG) was determined by 3-(4,5-dimethyl-2-thia-zolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT), and lactate dehydrogenase (LDH) release analysis, and the selectivity index (SI) was calculated. To detect cell apoptosis, fluorescent staining via flow cytometry and Hoechst 33258 staining were performed. Oxidative alterations were assessed via colorimetric measurement methods. Alterations in expressions of key genes related to carcinogenesis were determined. Additionally, in terms of NFBTA cytotoxic, oxidative, and genotoxic damage potential, the biosafety of this novel agent was evaluated in cultured human whole blood cells. Cell viability analyses revealed that NFBTA exhibited strong cytotoxic activity in cultured U87MG cells, with high selectivity and inhibitory activity in apoptotic processes, as well as potential for altering the principal molecular genetic responses in U87MG cell growth. Molecular docking studies strongly suggested a plausible anti-proliferative mechanism for NBFTA. The results of the experimental in vitro human glioblastoma model and computational approach revealed promising cytotoxic activity for NFBTA, helping to orient further studies evaluating its antitumor profile for safe and effective therapeutic applications.

Development of a method for quantitative determination of the cytotoxic agent piplartine (piperlongumine) in multiple skin layers

This study reports the development of a simple and reproducible method, with high rates of recovery, to extract the cytotoxic agent piplartine from skin layers, and a sensitive and rapid UV-HPLC method for its quantification. Considering the potential of piplartine for topical treatment of skin cancer, this method may find application for formulation development and pharmacokinetics studies to assess cutaneous bioavailability. Porcine skin was employed as a model for human tissue. Piplartine was extracted from the stratum corneum (SC) and remaining viable skin layers (VS) using methanol, vortex homogenization and bath sonication, and subsequently assayed by HPLC using a C18 column, and 1:1 (v/v) acetonitrile-water (adjusted to pH 4.0 with acetic acid 0.1%) as mobile phase. The quantification limit of piplartine was 0.2 μg/mL (0.6 μm), and the assay was linear up to 5 μg/mL (15.8 μm), with within-day and between-days assay coefficients of variation and relative errors <15%. Piplartine recovery from SC and VS varied from 86 to 96%. The method was suitable to assay samples from skin penetration studies, enabling detection of differences in cutaneous delivery in different skin compartments resulting from treatment with various formulations and time periods.

Structure⁻Activity Relationship of Piplartine and Synthetic Analogues against Schistosoma mansoni and Cytotoxicity to Mammalian Cells

Schistosomiasis, caused by helminth flatworms of the genus Schistosoma, is an infectious disease mainly associated with poverty that affects millions of people worldwide. Since treatment for this disease relies only on the use of praziquantel, there is an urgent need to identify new antischistosomal drugs. Piplartine is an amide alkaloid found in several Piper species (Piperaceae) that exhibits antischistosomal properties. The aim of this study was to evaluate the structure–function relationship between piplartine and its five synthetic analogues (19A, 1G, 1M, 14B and 6B) against Schistosoma mansoni adult worms, as well as its cytotoxicity to mammalian cells using murine fibroblast (NIH-3T3) and BALB/cN macrophage (J774A.1) cell lines. In addition, density functional theory calculations and in silico analysis were used to predict physicochemical and toxicity parameters. Bioassays revealed that piplartine is active against S. mansoni at low concentrations (5⁻10 µM), but its analogues did not. In contrast, based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, piplartine exhibited toxicity in mammalian cells at 785 µM, while its analogues 19A and 6B did not reduce cell viability at the same concentrations. This study demonstrated that piplartine analogues showed less activity against S. mansoni but presented lower toxicity than piplartine.

Novel piplartine-containing ruthenium complexes: synthesis, cell growth inhibition, apoptosis induction and ROS production on HCT116 cells

Piplartine (piperlongumine) is a plant-derived molecule that has been receiving intense interest due to its anticancer characteristics that target the oxidative stress. In the present paper, two novel piplartine-containing ruthenium complexes [Ru(piplartine)(dppf)(bipy)](PF₆)₂ (1) and [Ru(piplartine)(dppb)(bipy)](PF₆)₂ (2) were synthesized and investigated for their cellular and molecular responses on cancer cell lines. We found that both complexes are more potent than metal-free piplartine in a panel of cancer cell lines on monolayer cultures, as well in 3D model of cancer multicellular spheroids formed from human colon carcinoma HCT116 cells. Mechanistic studies uncovered that the complexes reduced the cell growth and caused phosphatidylserine externalization, internucleosomal DNA fragmentation, caspase-3 activation and loss of the mitochondrial transmembrane potential on HCT116 cells. Moreover, the pre-treatment with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, reduced the complexes-induced apoptosis, indicating cell death by apoptosis through caspase-dependent and mitochondrial intrinsic pathways. Treatment with the complexes also caused a marked increase in the production of reactive oxygen species (ROS), including hydrogen peroxide, superoxide anion and nitric oxide, and decreased reduced glutathione levels. Application of N-acetyl-cysteine, an antioxidant, reduced the ROS levels and apoptosis induced by the complexes, indicating activation of ROS-mediated apoptosis pathway. RNA transcripts of several genes, including gene related to the cell cycle, apoptosis and oxidative stress, were regulated under treatment. However, the complexes failed to induce DNA intercalation. In conclusion, the complexes are more potent than piplartine against different cancer cell lines and are able to induce caspase-dependent and mitochondrial intrinsic apoptosis on HCT116 cells by ROS-mediated pathway.

Gas-phase fragmentation of protonated piplartine and its fungal metabolites using tandem mass spectrometry and computational chemistry

Piplartine, an alkaloid produced by plants in the genus Piper, displays promising anticancer activity. Understanding the gas-phase fragmentation of piplartine by electrospray ionization tandem mass spectrometry can be a useful tool to characterize biotransformed compounds produced by in vitro and in vivo metabolism studies. As part of our efforts to understand natural product fragmentation in electrospray ionization tandem mass spectrometry, the gas-phase fragmentation of piplartine and its two metabolites 3,4-dihydropiplartine and 8,9-dihydropiplartine, produced by the endophytic fungus Penicillium crustosum VR4 biotransformation, were systematically investigated. Proposed fragmentation reactions were supported by ESI-MS/MS data and computational thermochemistry. Cleavage of the C-7 and N-amide bond, followed by the formation of an acylium ion, were characteristic fragmentation reactions of piplartine and its analogs. The production of the acylium ion was followed by three consecutive and competitive reactions that involved methyl and methoxyl radical eliminations and neutral CO elimination, followed by the formation of a four-member ring with a stabilized tertiary carbocation. The absence of a double bond between carbons C-8 and C-9 in 8,9-dihydropiplartine destabilized the acylium ion and resulted in a fragmentation pathway not observed for piplartine and 3,4-dihydropiplartine. These results contribute to the further understanding of alkaloid gas-phase fragmentation and the future identification of piplartine metabolites and analogs using tandem mass spectrometry techniques. Copyright © 2017 John Wiley & Sons, Ltd.

Synthesis and biological evaluation of new piplartine analogues as potent aldose reductase inhibitors (ARIs)

As a continuation of our efforts directed towards the development of anti-diabetic agents from natural sources, piplartine was isolated from Piper chaba, and was found to inhibit recombinant human ALR2 with an IC(50) of 160 μM. To improve the efficacy, a series of analogues have been synthesized by modification of the styryl/aromatic and heterocyclic ring functionalities of this natural product lead. All the derivatives were tested for their ALR2 inhibitory activity, and results indicated that adducts 3c, 3e and 2j prepared by the Michael addition of piplartine with indole derivatives displayed potent ARI activity, while the other compounds displayed varying degrees of inhibition. The active compounds were also capable of preventing sorbitol accumulation in human red blood cells.