Selective reduction in the expression of UGTs and SULTs, a novel mechanism by which piperine enhances the bioavailability of curcumin in rat

Enhancing oral bioavailability of andrographolide using solubilizing agents and bioenhancer: comparative pharmacokinetics of Andrographis paniculata formulations in beagle dogs

CONTEXT

The therapeutic potential of andrographolide is hindered by its poor oral bioavailability and unpredictable pharmacokinetics, primarily due to its limited water solubility.

OBJECTIVE

This work aimed to enhance the solubility and pharmacokinetics of andrographolide, a bioactive compound in Andrographis paniculata (Burm. f.) Nees (Acanthaceae), using solubilizing agents and a bioenhancer.

MATERIALS AND METHODS

Four groups of beagles were compared: (1) A. paniculata powder alone (control), (2) A. paniculata powder with 50% weight/weight (w/w) β-cyclodextrin solubilizer, (3) A. paniculata powder with 1% w/w sodium dodecyl sulfate (SDS) solubilizer, and (4) A. paniculata powder co-administered with 1% w/w SDS solubilizer and 10% piperine bioenhancer. All groups received a consistent oral dose of 3 mg/kg of andrographolide, administered both as a single dose and multiple doses over seven consecutive days.

RESULTS

Thirteen chemical compounds were identified in A. paniculata powder, including 7 diterpenoids, 5 flavonoids, and 1 phenolic compound. A. paniculata co-administration with either 50% w/w β-cyclodextrin or 1% w/w SDS, alone or in combination with 10% w/w piperine, significantly increased systemic andrographolide exposure by enhancing bioavailability (131.01% to 196.05%) following single and multiple oral co-administration. Glucuronidation is one possible biotransformation pathway for andrographolide, as evidenced by the excretion of glucuronide conjugates in urine and feces.

CONCLUSION

The combination of solubilizing agents and a bioenhancer improved the oral bioavailability and pharmacokinetics of andrographolide, indicating potential implications for A. paniculata formulations and clinical therapeutic benefits. Further investigation in clinical studies is warranted.

Curcumin and omega-3 polyunsaturated fatty acids as bioactive food components with synergistic effects on Alzheimer's disease

Curcumin and omega-3 polyunsaturated fatty acids (ω-3 PUFA) are multifunctional compounds which play an important role in Alzheimer's disease (AD) and little has been addressed about the role of these two compounds together in the progression of the disease. There is evidence of the beneficial effect of combined administration of ω-3 PUFA and other dietary supplements such as vitamins and polyphenols in the prevention of AD, although much remains to be understood about their possible complementary or synergistic activity. Therefore, the objective of this work is to review the research focused on studying the effect and mechanisms of action of curcumin, ω-3 PUFA, and the combination of these nutraceutical compounds, particularly on AD, and to integrate the possible ways in which these compounds can potentiate their effect. The most important pathophysiologies that manifest in AD will be addressed, in order to have a better understanding of the mechanisms of action through which these bioactive compounds exert a neuroprotective effect.

Comprehensive review of the phytochemistry, pharmacology, pharmacokinetics, and toxicology of alkamides (2016-2022)

Alkamides refer to a class of natural active small-molecule products composed of fatty acids and amine groups. These compounds are widely distributed in plants, and their unique structures and various pharmacological activities have caught the attention of scholars. This review provides a collection of literatures related to the phytochemistry, pharmacological effects, pharmacokinetics, and toxicity of alkamides published in 2016-2022 and their summary to provide references for further development of this class of ingredients. A total of 234 components (including chiral isomers) were summarized, pharmacological activities, such as anti-inflammatory, antitumor, antidiabetic, analgesic, neuroprotective, insecticidal, antioxidant, and antibacterial, and miscellaneous properties of alkamides were discussed. In addition, the pharmacokinetic characteristics and toxicity of alkamides were reviewed. However, information on the pharmacological mechanisms of the action, drug safety, and pharmacokinetics of alkamides is limited and thus requires further investigation and evaluation.

Protein-polysaccharide-based delivery systems for enhancing the bioavailability of curcumin: A review

In recent years, a wide attention has been paid to curcumin in medicine due to its excellent physiological activities, including anti-inflammatory, antioxidant, antibacterial, and nerve damage repair. However, the low solubility, poor stability, and rapid metabolism of curcumin make its bioavailability low, which affects its development and application. As a unique biopolymer structure, protein-polysaccharide (PRO-POL)-based delivery system has the advantages of low toxicity, biocompatibility, biodegradability, and delayed release. Many scholars have investigated PRO-POL -based delivery systems to improve the bioavailability of curcumin. In this paper, we focus on the interactions between different proteins (e.g. casein, whey protein, soybean protein isolate, pea protein, zein, etc.) and polysaccharides (chitosan, sodium alginate, hyaluronic acid, pectin, etc.) and their effects on complexes diameter, surface charge, encapsulation drive, and release characteristics. The mechanism of the PRO-POL-based delivery system to enhance the bioavailability of curcumin is highlighted. In addition, the application of PRO-POL complexes loaded with curcumin is summarized, aiming to provide a reference for the construction and application of PRO-POL delivery systems.

Effect of Curcumin Consumption on Inflammation and Oxidative Stress in Patients on Hemodialysis: A Literature Review

Advanced chronic kidney disease (CKD) stages lead to exacerbated inflammation and oxidative stress. Patients with CKD in stage 5 need renal hemodialysis (HD) to remove toxins and waste products. However, this renal replacement therapy is inefficient in controlling inflammation. Regular curcumin consumption has been shown to reduce inflammation and oxidative stress in subjects with chronic pathologies, suggesting that the daily intake of curcumin may alleviate these conditions in HD patients. This review analyzes the available scientific evidence regarding the effect of curcumin intake on oxidative stress and inflammation in HD patients, focusing on the mechanisms and consequences of HD and curcumin consumption. The inclusion of curcumin as a dietary therapeutic supplement in HD patients has shown to control the inflammation status. However, the optimal dose and oral vehicle for curcumin administration are yet to be determined. It is important to consider studies on curcumin bioaccessibility to design effective oral administration vehicles. This information will contribute to the achievement of future nutritional interventions that validate the efficacy of curcumin supplementation as part of diet therapy in HD.

Therapeutic potential and limitations of curcumin as antimetastatic agent

Treatment of metastatic cancer is one of the biggest challenges in anticancer therapy. Curcumin is interesting nature polyphenolic compound with unique biological and medicinal effects, including repression of metastases. High impact studies imply that curcumin can modulate the immune system, independently target various metastatic signalling pathways, and repress migration and invasiveness of cancer cells. This review discusses the potential of curcumin as an antimetastatic agent and describes potential mechanisms of its antimetastatic activity. In addition, possible strategies (curcumin formulation, optimization of the method of administration and modification of its structure motif) to overcome its limitation such as low solubility and bioactivity are also presented. These strategies are discussed in the context of clinical trials and relevant biological studies.

A Unifying Perspective in Blunting the Limited Oral Bioavailability of Curcumin: A Succinct Look

BACKGROUND

Curcumin is a polyphenolic compound derived from rhizomes of Curcuma longa, the golden spice. Curcumin has drawn much attention in recent years of biomedical research owing to its wide variety of biologic and pharmacologic actions. It exerts antiproliferative, antifibrogenic, anti-inflammatory, and antioxidative effects, among various imperative pharmacologic actions. In spite of its well-documented efficacies against numerous disease conditions, the limited systemic bioavailability of curcumin is a continuing concern. Perhaps, the poor bioavailability of curcumin may have curtailed its significant development from kitchen to clinic as a potential therapeutic agent. Subsequently, there have been a considerable number of studies over decades researching the scientific basis of curcumin's reduced bioavailability and eventually improvement of its bioavailability employing a variety of therapeutic approaches, for instance, in combination with piperine, the bio-active constituent of black pepper. Piperine has remarkable potential to modulate the functional activity of metabolic enzymes and drug transporters, and thus there has been a great interest in the therapeutic application of this widely used spice as alternative medicine and bioavailability enhancer. Growing body of evidence supports the synergistic potential of curcumin against numerous pathologic conditions when administered with piperine.

CONCLUSION

In light of current challenges, the major concern pertaining to poor systemic bioavailability of curcumin, its improvement, especially in combination with piperine, and the necessity of additional research in this setting are together described in this review. Besides, the recent advances in the potential therapeutic rationale and efficacy of curcumin-piperine combination, a promising duo, against various pathologic conditions are delineated.

Alpinetin: A Review of Its Pharmacology and Pharmacokinetics

Flavonoids isolated from medicinal herbs have been utilized as valuable health-care agents due to their virous biological applications. Alpinetin is a natural flavonoid that emerges in many widely used medicinal plants, and has been frequently applied in Chinese patent drugs. Accumulated evidence has demonstrated that alpinetin possesses a broad range of pharmacological activities such as antitumor, antiinflammation, hepatoprotective, cardiovascular protective, lung protective, antibacterial, antiviral, neuroprotective, and other properties through regulating multiple signaling pathways with low systemic toxicity. However, pharmacokinetic studies have documented that alpinetin may have poor oral bioavailability correlated to its extensive glucuronidation. Currently, the reported pharmacological properties and pharmacokinetics profiles of alpinetin are rare to be scientifically reviewed. In this article, we aimed to highlight the mechanisms of action of alpinetin in various diseases to strongly support its curative potentials for prospective clinical applications. We also summarized the pharmacokinetics properties and proposed some viable strategies to convey an appreciable reference for future advances of alpinetin in drug development.

Molecular and pharmacological aspects of piperine as a potential molecule for disease prevention and management: evidence from clinical trials

BACKGROUND

Piperine is a type of amide alkaloid that exhibits pleiotropic properties like antioxidant, anticancer, anti-inflammatory, antihypertensive, hepatoprotective, neuroprotective and enhancing bioavailability and fertility-related activities. Piperine has the ability to alter gastrointestinal disorders, drug-metabolizing enzymes, and bioavailability of several drugs. The present review explores the available clinical and preclinical data, nanoformulations, extraction process, structure-activity relationships, molecular docking, bioavailability enhancement of phytochemicals and drugs, and brain penetration properties of piperine in the prevention, management, and treatment of various diseases and disorders.

MAIN BODY

Piperine provides therapeutic benefits in patients suffering from diabetes, obesity, arthritis, oral cancer, breast cancer, multiple myeloma, metabolic syndrome, hypertension, Parkinson's disease, Alzheimer's disease, cerebral stroke, cardiovascular diseases, kidney diseases, inflammatory diseases, and rhinopharyngitis. The molecular basis for the pleiotropic activities of piperine is based on its ability to regulate multiple signaling molecules such as cell cycle proteins, anti-apoptotic proteins, P-glycoprotein, cytochrome P450 3A4, multidrug resistance protein 1, breast cancer resistance protein, transient receptor potential vanilloid 1 proinflammatory cytokine, nuclear factor-κB, c-Fos, cAMP response element-binding protein, activation transcription factor-2, peroxisome proliferator-activated receptor-gamma, Human G-quadruplex DNA, Cyclooxygenase-2, Nitric oxide synthases-2, MicroRNA, and coronaviruses. Piperine also regulates multiple signaling pathways such as Akt/mTOR/MMP-9, 5'-AMP-activated protein kinase-activated NLR family pyrin domain containing-3 inflammasome, voltage-gated K+ current, PKCα/ERK1/2, NF-κB/AP-1/MMP-9, Wnt/β-catenin, JNK/P38 MAPK, and gut microbiota.

SHORT CONCLUSION

Based on the current evidence, piperine can be the potential molecule for treatment of disease, and its significance of this molecule in the clinic is discussed.

GRAPHICAL ABSTRACT

Therapeutic spectrum of piperine for clinical practice: a scoping review

Translation of traditional knowledge of herbs into a viable product for clinical use is still an uphill task. Piperine, a pungent alkaloid molecule derived from Piper nigrum and Piper longum possesses diverse pharmacological effects. Traditionally, pepper is used for arthritis, bronchitis, gastritis, diarrhea, snake bite, menstrual pain, fever, and bacterial infections, etc. The anti-inflammatory, antioxidant and immunomodulatory actions of piperine are the possible mechanisms behind its therapeutic potential. Various in-silico and experimental studies have shown piperine as a possible promising molecule in coronavirus disease (COVID-19), ebola, and dengue due to its immunomodulatory and antiviral activities. The other important clinical applications of piperine are due to its bio enhancing effect on drugs, by modulating, absorption in the gastrointestinal tract, altering activities of transporters like p-glycoprotein substrates, and modulating drug metabolism by altering the expression of cytochrome P450 or UDP-glucuronosyltransferase enzymes. Piperine attracted clinicians in treating patients with arthritis, metabolic syndrome, diabetes, skin infections, gastric and liver disorders. This review focused on systematic, evidence-based insight into the use of piperine in clinical settings and mechanistic details behind its therapeutic actions. Also, highlights a number of clinical trials of piperine at various stages exploring its clinical application in cancer, neurological, respiratory, and viral disease, etc.

The Multifaceted Role of Curcumin in Advanced Nanocurcumin Form in the Treatment and Management of Chronic Disorders

Curcumin is the primary polyphenol in turmeric's curcuminoid class. It has a wide range of therapeutic applications, such as anti-inflammatory, antioxidant, antidiabetic, hepatoprotective, antibacterial, and anticancer effects against various cancers, but has poor solubility and low bioavailability. Objective: To improve curcumin's bioavailability, plasma concentration, and cellular permeability processes. The nanocurcumin approach over curcumin has been proven appropriate for encapsulating or loading curcumin (nanocurcumin) to increase its therapeutic potential. Conclusion: Though incorporating curcumin into nanocurcumin form may be a viable method for overcoming its intrinsic limitations, and there are reasonable concerns regarding its toxicological safety once it enters biological pathways. This review article mainly highlights the therapeutic benefits of nanocurcumin over curcumin.

The Inhibitory Activity of Curcumin on P-Glycoprotein and Its Uptake by and Efflux from LS180 Cells Is Not Affected by Its Galenic Formulation

The biological activities of curcumin in humans, including its antioxidative and anti-inflammatory functions, are limited by its naturally low bioavailability. Different formulation strategies have been developed, but the uptake of curcumin from these galenic formulations into and efflux from intestinal cells, which may be critical processes limiting bioavailability, have not been directly compared. Furthermore, little is known about their effect on P-glycoprotein activity, an important determinant of the pharmacokinetics of potentially co-administered drugs. P-glycoprotein activity was determined in LS180 cells, incubated with 30 or 60 µmol/L of curcumin in the form of seven different formulations or native curcuma extract for 1 h. All formulations inhibited P-glycoprotein activity at both concentrations. Curcumin uptake, after 1 h incubation of LS180 cells with the formulations (60 µmol/L), showed significant variability but no consistent effects. After 1 h pre-treatment with the formulations and further 8 h with curcumin-free medium, curcumin in cell culture supernatants, reflecting the efflux, differed between individual formulations, again without a clear effect. In conclusion, curcumin inhibits P-glycoprotein activity independently of its formulation. Its uptake by and efflux from intestinal cells was not significantly different between formulations, indicating that these processes are not important regulatory points for its bioavailability.

A review on the bioavailability, bio-efficacies and novel delivery systems for piperine

As the major naturally occurring alkaloid in pepper with a pungent taste, piperine is known for its beneficial biological functions and therapeutic effects. In this work, the bioavailability and biological activities of piperine were presented and discussed. Novel delivery systems for enhancing the bioavailability of piperine were also reviewed. This study could provide a better understanding of the physiological and biochemical aspects of piperine to be further developed in the food and nutraceutical industries.

Pharmacokinetics of a Single Dose of Turmeric Curcuminoids Depends on Formulation: Results of a Human Crossover Study

BACKGROUND

Curcuminoids from turmeric rhizome have significant health benefits but low bioavailability.

OBJECTIVES

To assess the pharmacokinetics of a novel natural turmeric dried colloidal suspension compared with 4 other turmeric formulations (including a standardized extract) at their respective recommended dosages.

METHODS

Thirty healthy men and women (18 to 45 y old) were enrolled in a randomized, open-labeled, crossover trial, and sequentially consumed single oral doses of standard turmeric extract (1500 mg), liquid micellar preparation (1000 mg), piperine-curcuminoid combination (1515 mg), phytosome formulation (1000 mg), or the dried colloidal suspension (300 mg). Eleven blood samples were obtained over 24 h, plasma was extracted with or without deconjugation with β-glucuronidase or sulfatase, and ultra-high-pressure liquid chromatography/tandem MS was used to quantify the 3 parent curcuminoids and 12 metabolites. Classical pharmacokinetics parameters were derived.

RESULTS

The total AUC values of unconjugated curcuminoids were highly variable within participants, with no significant differences between formulations. However, the AUC values for total curcuminoids (including all metabolites) showed significant product effects. Indeed, the micellar preparation delivered higher levels of total curcuminoids than any other formulation (8540 ng·h/mL), reaching significance when compared with the dried colloidal suspension and standard extract (6520 and 5080 ng·h/mL, respectively). After dose normalization, both micellar and dried colloidal formulations showed significantly higher AUC levels than the standard extract (respectively 136 and 72.9, compared with 3.7 ng·h/mL/mg). Total curcuminoid absorption levels were also significantly higher for the dried colloidal suspension when compared with either piperine or phytosome formulations. Interestingly, no significant differences were observed between the piperine-curcuminoid combination and the standard extract. No serious adverse events were reported.

CONCLUSIONS

The administration of a low dose of the novel natural dried colloidal suspension provided high unconjugated and conjugated curcuminoid absorption, with significant beneficial differences when compared with the high dose of standard extract.This trial was registered at clinicaltrials.gov as NCT03621865.

In vitro evaluation of curcumin-loaded chitosan-coated hydroxyapatite nanocarriers as a potential system for effective treatment of cancer

Nanotechnology has many potential applications in cancer treatment. For example, nano-drug delivery systems (NDDS) with high bioavailability, biodegradability, and biocompatibility have been developed, in order to increase the therapeutic effects of anticancer drugs. Among these NDDS, high-performance hydroxyapatite (HA) nanoparticles are rapidly advancing in the targeted cancer treatment due to their numerous benefits. Curcumin is an herbal metabolite that acts as a chemical inhibitor through the inhibition of tumor cells and the progression of many cancers. However, the poor bioavailability of curcumin is the most important challenge in using this substance. In this study, HA nanoparticles coated by chitosan were used as a pH-sensitive biopolymer to improve the efficiency and bioavailability of curcumin. For this purpose, HA nanoparticles were first synthesized by the sol-gel method. Then, a layer of chitosan was coated on it, and the curcumin drug was encapsulated in the nanocarrier, under controlled conditions. Techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the nanocarriers. In the second part, nano-drugs prepared by various bioassays were examined. For this purpose, the rate of cytotoxicity by the methyl-thiazol-tetrazolium (MTT) assay and the rate of apoptosis induction by the acridine orange and ethidium bromide (AO/EB) staining method on the brain carcinoma U87MG cell line were investigated.

Physiologically-Based Pharmacokinetic Predictions of the Effect of Curcumin on Metabolism of Imatinib and Bosutinib: In Vitro and In Vivo Disconnect

PURPOSE

This study aimed to investigate the potential pharmacokinetic interactions between curcumin, imatinib and bosutinib, combining In Vitro and in silico methods.

METHODS

In Vitro metabolism of imatinib and bosutinib were investigated in pooled human liver microsomes and recombinant CYP3A4 enzyme in the presence and absence of curcumin and curcumin glucuronide using an LC-MS/MS assay for N-desmethyl metabolites. A physiologically-based pharmacokinetic (PBPK) model for curcumin formulated as solid lipid nanoparticles (SLN) was constructed using In Vitro glucuronidation kinetics and published clinical pharmacokinetic data. The potential effects of curcumin coadministration on systemic exposures of imatinib and bosutinib were predicted in silico using PBPK simulations.

RESULTS

Curcumin demonstrated potent reversible inhibition of cytochrome P450 (CYP)3A4-mediated N-demethylation of imatinib and bosutinib and CYP2C8-mediated metabolism of imatinib with inhibitory constants (k_i,u) of ≤1.5 μmol. L^-1. A confirmatory In Vitro study with paclitaxel, the 6α-hydroxylation of which is exclusively mediated by CYP2C8, was consistent with a potent inhibition of this enzyme by curcumin. Curcumin glucuronide also inhibited both CYP enzymes In Vitro, albeit to a lesser extent than that of curcumin. PBPK model simulations predicted that at recommended dosing regimens of SLN curcumin, coadministration would result in an increase in systemic exposures of imatinib and bosutinib of up to only 10%.

CONCLUSION

A PBPK model for curcumin in a SLN formulation was successfully developed. Although curcumin possesses a strong In Vitro inhibitory activity towards CYP3A4 and CYP2C8 enzymes, its interactions with imatinib and bosutinib were unlikely to be of clinical importance due to curcumin's poor bioavailability.

Pharmacokinetic Interactions of a Hop Dietary Supplement with Drug Metabolism in Perimenopausal and Postmenopausal Women

Botanical dietary supplements produced from hops (Humulus lupulus) containing the chemopreventive compound xanthohumol and phytoestrogen 8-prenylnaringenin are used by women to manage menopausal symptoms. Because of the long half-lives of prenylated hop phenols and reports that they inhibit certain cytochrome P450 enzymes, a botanically authenticated and chemically standardized hop extract was tested for Phase I pharmacokinetic drug interactions. Sixteen peri- and postmenopausal women consumed the hop extract twice daily for 2 weeks, and the pharmacokinetics of tolbutamide, caffeine, dextromethorphan, and alprazolam were evaluated before and after supplementation as probe substrates for the enzymes CYP2C9, CYP1A2, CYP2D6, and CYP3A4/5, respectively. The observed area under the time-concentration curves were unaffected, except for alprazolam which decreased 7.6% (564.6 ± 46.1 h·μg/L pre-hop and 521.9 ± 36.1 h·μg/L post-hop; p-value 0.047), suggesting minor induction of CYP3A4/5. No enzyme inhibition was detected. According to FDA guidelines, this hop dietary supplement caused no clinically relevant pharmacokinetic interactions with respect to CYP2C9, CYP1A2, CYP2D6, or CYP3A4/5. The serum obtained after consumption of the hop extract was analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry to confirm compliance. Abundant Phase II conjugates of the hop prenylated phenols were observed including monoglucuronides and monosulfates as well as previously unreported diglucuronides and sulfate-glucuronic acid diconjugates.

Spectroscopic studies on the molecular interactions of curcumin and piperine

Abstract

The diarylheptanoid curcumin is the yellow coloring agent accumulated in the rhizome of the common spice turmeric (Curcuma longa L.). It has gathered a lot of pharmaceutical interest over the last decades due to some positive effects on human health. However, the use of curcumin as a drug is prevented by its low bioavailability and solubility in water. Interestingly, piperine, the pungent constituent of household pepper (Piper nigrum L.) is able to increase the bioavailability of curcumin up to 20-fold without any known adverse effects. The mechanism responsible for this piperine-based increase of curcumin bioavailability is, however, not fully understood. In a recent publication, a quantum chemical study suggested the formation of a molecular complex between curcumin and piperine being responsible for this effect. The present work now revealed that indeed a 1:1 complex formation can be observed in NMR titration experiments and by mass spectrometry, but the complex strength is rather low (K ~ 1.5 dm3/mol). Furthermore, it is shown that the presence of piperine does not increase the water solubility of curcumin, which makes it rather improbable that such a complex is the main reason for an enhanced curcumin bioavailability.

Graphic abstract

A Phase 2 Study to Assess the Immunomodulatory Capacity of a Lecithin-based Delivery System of Curcumin in Endometrial Cancer

Curcumin is a botanical with anti-tumor and immunomodulatory properties. We hypothesized that curcumin supplementation might influence inflammatory biomarker levels in endometrial carcinoma (EC). In this open-label, non-randomized phase 2 study (NCT02017353), seven EC patients consumed 2 g/day Curcumin Phytosome (CP) orally for 2 weeks. Blood was taken at baseline, days 1, 7, 14, and 21. The following analytes were measured: curcuminoids and metabolites, 56 inflammatory biomarkers, COX-2, frequencies of myeloid-derived suppressor cells, dendritic cells and NK cells, expression of MHC molecules on leukocytes and monocytes and activation/memory status of T cells. Patients completed quality of life (QoL) questionnaires at baseline and end of treatment. Curcumin metabolites were detectable in plasma upon CP intake. CP downregulated MHC expression levels on leukocytes (P = 0.0313), the frequency of monocytes (P = 0.0114) and ICOS expression by CD8⁺ T cells (P = 0.0002). However, CP upregulated CD69 levels on CD16⁻ NK cells (P = 0.0313). No differences were observed regarding inflammatory biomarkers, frequencies of other immune cell types, T cell activation and COX-2 expression. A non-significant trend to improved QoL was observed. Overall, CP-induced immunomodulatory effects in EC were modest without significant QoL changes. Given the small population and the observed variability in inter-patient biomarker levels, more research is necessary to explore whether benefits of CP can be obtained in EC by different supplementation regimens.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT02017353; www.clinicaltrialsregister.eu, identifier 2013-001737-40.

Development and evaluation of a novel drug delivery: Soluplus®/TPGS mixed micelles loaded with piperine in vitro and in vivo

BACKGROUND

Although piperine can inhibit cells of tumors, the poor water solubility restricted its clinical application. This paper aimed to develop mixed micelles based on Soluplus^® and D-α-tocopherol polyethylene glycol succinate (TPGS) to improve the aqueous solubility and anti-cancer effect.

METHODS

Piperine-loaded mixed micelles were prepared using a thin-film hydration method, and their physicochemical properties were characterized. The cellular uptake of the micelles was confirmed by confocal laser scanning microscopy in A549 lung cancer cells and HepG₂ liver cancer cells. In addition, cytotoxicity of the piperine mixed micelles was studied in A549 lung cancer cells and HepG₂ liver cancer cells. Free piperine or piperine-loaded Soluplus^®/TPGS mixed micelles were administered at an equivalent dose of piperine at 3.2 mg/kg via a single intravenous injection in the tail vain for the pharmacokinetic study in vivo.

RESULTS

The diameter of piperine-loaded Soluplus^®/TPGS (4:1) mixed micelles was about 61.9 nm and the zeta potential -1.16 ± 1.06 mV with 90.9% of drug encapsulation efficiency and 4.67% of drug-loading efficiency. Differential scanning calorimetry (DSC) studies confirmed that piperine is encapsulated by the Soluplus^®/TPGS. The release results in vitro showed that the piperine-loaded Soluplus^®/TPGS mixed micelles presented sustained release behavior compared to the free piperine. The mixed micelles exhibited better antitumor efficacy compared to free piperine and physical mixture against in A549 and HepG₂ cells by MTT assay. The pharmacokinetic study revealed that the AUC of piperine-loaded mixed micelles was 2.56 times higher than that of piperine and the MRT for piperine-loaded mixed micelles was 1.2-fold higher than piperine (p < .05).

CONCLUSION

The results of the study suggested that the piperine-loaded mixed micelles developed might be a potential nano-drug delivery system for cancer chemotherapy. These results demonstrated that piperine-loaded Soluplus^®/TPGS mixed micelles are an effective strategy to deliver piperine for cancer therapy.

Piperine potentiates curcumin-mediated repression of mTORC1 signaling in human intestinal epithelial cells: implications for the inhibition of protein synthesis and TNFα signaling

Persistent activation of the mechanistic target of rapamycin complex 1 (mTORC1) is linked to sustained inflammation and progression of colorectal cancer. Widely available dietary phenolics, curcumin and piperine are purported to have antiinflammatory and anticarcinogenic activities through yet-to-be-delineated multitarget mechanisms. Piperine is also known to increase the bioavailability of dietary components, including curcumin. The objective of the study was to determine whether curcumin and piperine have individual and combined effects in the setting of gut inflammation by regulating mTORC1 in human intestinal epithelial cells. Results show that curcumin repressed (a) mTORC1 activity (measured as changes in the phosphorylation state of p70 ribosomal protein S6 kinase B1 and 40S ribosomal protein S6) in a dose-dependent manner (2.5-20 μM, P<.007) and (b) synthesis of nascent proteins. Piperine inhibited mTORC1 activity albeit at comparatively higher concentrations than curcumin. The combination of curcumin + piperine further repressed mTORC1 signaling (P<.02). Mechanistically, curcumin may repress mTORC1 by preventing TSC2 degradation, the conserved inhibitor of mTORC1. Results also show that a functional mTORC1 was required for the transcription of TNFα as Raptor knockdown abrogated TNFα gene expression. Curcumin, piperine and their combination inhibited TNFα gene expression at baseline but failed to do so under conditions of mTORC1 hyperactivation. TNF∝-induced cyclooxygenase-2 expression was repressed by curcumin or curcumin + piperine at baseline and high mTORC1 levels. We conclude that curcumin and piperine, either alone or in combination, have the potential to down-regulate mTORC1 signaling in the intestinal epithelium with implications for tumorigenesis and inflammation.

Piperine-mediated drug interactions and formulation strategy for piperine: recent advances and future perspectives

INTRODUCTION

Piperine has various pharmacological effects and can modulate the functional activity of metabolic enzymes and drug transporters. Consequently, there is a great interest in the application of piperine as an alternative medicine or bioavailability enhancer. Areas covered: This review deals with the effects of piperine on metabolizing enzymes and drug transporters. It provides the readers with an update on transporter-mediated and also metabolic enzyme-mediated piperine-drug interactions, with emphasis on its in vivo implications. This article also encompasses recent advances in the formulation approaches and technologies for optimizing the delivery of piperine. Expert opinion: Piperine can influence the pharmacokinetics of coadministered drugs, which may result in a therapeutically beneficial or adverse effect. Given that piperine inhibits or stimulates the activity of metabolic enzymes and transporters depending on the treatment conditions, the clinical significance of piperine-drug interactions should be assessed by varying the dose, dosing frequency, and the duration of treatment. In particular, better understanding the clinical relevance of piperine-drug interactions based on long-term assessments will provide a strong basis for the feasibility and applicability of piperine as a bioenhancer or a health-promoting agent. The development of effective formulations is also critical to facilitate the therapeutic applications of piperine.

Nanoparticle formulations to enhance tumor targeting of poorly soluble polyphenols with potential anticancer properties

Polyphenols have been extensively studied for their relevant anticancer activity. Quite often however their instability, extensive metabolization, low bioavailability and poor solubility limit their application in cancer prevention and therapy. Formulation in nanoparticles has been widely proposed as a means to overcome these limits, maximize localization and specific activity at tumor site. The present review is intended as an update of literature regarding nanoparticulate carriers aimed to deliver polyphenols to the cancer site. Three molecules were chosen, all of which were hydrophobic and poorly soluble, representative of different polyphenol classes: quercetin (QT) among the flavonoid group, curcumin (CUR) as representative of curcuminoids, and resveratrol (RSV) among the stilbenes. In particular, nanoparticulate systems suitable for poorly soluble drugs will be described and attention will be paid to characteristics designed to improve tumor targeting, specific delivery and interaction with tumor cells.

New insights into therapeutic activity and anticancer properties of curcumin

Natural compounds obtained from plants are capable of garnering considerable attention from the scientific community, primarily due to their ability to check and prevent the onset and progress of cancer. These natural compounds are primarily used due to their nontoxic nature and the fewer side effects they cause compared to chemotherapeutic drugs. Furthermore, such natural products perform even better when given as an adjuvant along with traditional chemotherapeutic drugs, thereby enhancing the potential of chemotherapeutics and simultaneously reducing their undesired side effects. Curcumin, a naturally occurring polyphenol compound found in the plant Curcuma longa, is used as an Indian spice. It regulates not only the various pathways of the immune system, cell cycle checkpoints, apoptosis, and antioxidant response but also numerous intracellular targets, including pathways and protein molecules controlling tumor progression. Many recent studies conducted by major research groups around the globe suggest the use of curcumin as a chemopreventive adjuvant molecule to maximize and minimize the desired effects and side effects of chemotherapeutic drugs. However, low bioavailability of a curcumin molecule is the primary challenge encountered in adjuvant therapy. This review explores different therapeutic interactions of curcumin along with its targeted pathways and molecules that are involved in the regulation of onset and progression of different types of cancers, cancer treatment, and the strategies to overcome bioavailability issues and new targets of curcumin in the ever-growing field of cancer.