Fisetin-In Search of Better Bioavailability-From Macro to Nano Modifications: A Review

As secondary plant metabolites, polyphenols are abundant in fruits and vegetables. They are in high demand because of their many health benefits. However, their low bioavailability makes them complex compounds to use for therapeutic purposes. Due to the limited solubility of phytocompounds, dietary supplements made from them may only be partially effective. Such molecules include fisetin, found in strawberries, and have shown great promise in treating Alzheimer's disease and cancer. Unfortunately, because of their limited water solubility, low absorption, and poor bioavailability, the assistance of nanotechnology is required to allow them to fulfil their potential fully. Here, we provide evidence that nanodelivery methods and structure modifications can improve fisetin bioavailability, which is linked to improvements in therapeutic efficacy. An open question remains as to which nanocarrier should be chosen to meet the abovementioned requirements and be able to enhance fisetin's therapeutic potential to treat a particular disease.

Nanoencapsulation of Polyphenols as Drugs and Supplements for Enhancing Therapeutic Profile - A Review

Polyphenolic phytoconstituents have been widely in use worldwide since ages and are categorised as secondary metabolites of plants. The application of polyphenols such as quercetin, resveratrol. curcumin as nutritional supplement has been researched widely. The use of polyphenols, and specifically quercetin for improving the memory and mental endurance have shown significant effects among rats. Even though similar results has not been resonated among human but encouraging preclinical results have encouraged researchers to explore other polyphenols to study the effects as supplements among athletes. The phytopharmacological research has elucidated the use of natural polyphenols to prevent and treat various physiological and metabolic disorders owing to its free radical scavenging properties, anti-inflammatory, anti-cancer and immunomodulatory effects. In spite of the tremendous pharmacological profile, one of the most dominant problem regarding the use of polyphenolic compounds is their low bioavailability. Nanonization is considered as one of the most prominent approaches among many. This article aims to review and discuss the molecular mechanisms of recently developed nanocarrier-based drug delivery systems for polyphenols and its application as drugs and supplements. Nanoformulations of natural polyphenols are bioactive agents, such as quercetin, kaempferol, fisetin, rutin, hesperetin, and naringenin epigalloccatechin-3-gallate, genistein, ellagic acid, gallic acid, chlorogenic acid, ferulic acid, curcuminoids and stilbenes is expected to have better efficacy. These delivery systems are expected to provide higher penetrability of polyphenols at cellular levels and exhibit a controlled release of the drugs. It is widely accepted that natural polyphenols do demonstrate significant therapeutic effect. However, the hindrances in their absorption, specificity and bioavailability can be overcome using nanotechnology.

Cancer chemopreventive role of fisetin: Regulation of cell signaling pathways in different cancers

It is becoming progressively more understandable that pharmaceutical targeting of drug-resistant cancers is challenging because of intra- and inter-tumor heterogeneity. Interestingly, naturally derived bioactive compounds have unique ability to modulate wide-ranging deregulated oncogenic cell signaling pathways. In this review, we have focused on the available evidence related to regulation of PI3K/AKT/mTOR, Wnt/β-catenin, NF-κB and TRAIL/TRAIL-R by fisetin in different cancers. Fisetin has also been shown to inhibit the metastatic spread of cancer cells in tumor-bearing mice. We have also summarized how fisetin regulated autophagy in different cancers. In addition, this review also covers fisetin-mediated regulation of VEGF/VEGFR, EGFR, necroptosis and Hippo pathway. Fisetin has entered into clinical trials particularly in context of COVID19-associated inflammations. Furthermore, fisetin mediated effects are also being tested in clinical trials with reference to osteoarthritis and senescence. These developments will surely pave the way for full-fledge and well-designed clinical trials of fisetin in different cancers. However, we still have to comprehensively analyze and fully unlock pharmacological potential of fisetin against different oncogenic signaling cascades and non-coding RNAs. Fisetin has remarkable potential as chemopreventive agent and future studies must converge on the identification of additional regulatory roles of fisetin for inhibition and prevention of cancers.

Olaparib nanoparticles potentiated radiosensitization effects on lung cancer

BACKGROUND

Poly (ADP-ribose) polymerase (PARP) is a key enzyme in the repair process of DNA strand breaks (DSBs). Olaparib (Ola) is a PARP inhibitor that is involved in arresting PARP release from radiotherapy (RT)-induced damaged DNA to potentiate the effect of RT. Although the underlying mechanisms for the radiosensitization effects of Ola are well understood in vitro, the radiosensitization effects in vivo are still unclear. Moreover, poor water solubility and severe toxicity are two major impediments for the clinical success of Ola.

MATERIALS AND METHODS

Here, we developed olaparib nanoparticles (Ola-NPs) and investigated their radiosensitization mechanisms and toxicity using human non-small-cell lung cancer xenograft models in mice.

RESULTS

The prepared Ola-NPs showed a mean size of 31.96±1.54 nm and a lower polydispersity index of about 0.126±0.014. In addition, the sensitization enhancement ratio of Ola-NPs (3.81) was much higher than that of free Ola (1.66). The combination of Ola-NPs and RT (Ola-NPs + RT) significantly inhibited tumor growth and prolonged survival in mice. The mechanism of enhanced antitumor efficacy might be related to the inhibition of DSB repair and the promotion of cell apoptosis in vivo. No additional toxicity caused by Ola-NPs was observed.

CONCLUSION

This study demonstrated the principle of using Ola-NPs as a potent radiosensitizer to improve the therapeutic effect of RT relative to free Ola (P<0.05 in all cases).

Subcellular Fate of a Fluorescent Cholesterol-Poly(ethylene glycol) Conjugate: An Excellent Plasma Membrane Imaging Reagent

Cholesterol-containing molecules or nanoparticles play a significant role in achieving favorable plasma membrane imaging and efficient cellular uptake of drugs by the excellent membrane anchoring capability of the cholesterol moiety. By linking cholesterol to a water-soluble component (such as poly(ethylene glycol), PEG), the resulting cholesterol-PEG conjugate can form micelles in aqueous solution through self-assembly, and such a micellar structure represents an important drug delivery vehicle in which hydrophobic drugs can be encapsulated. However, the understanding of the subcellular fate and cytotoxicity of cholesterol-PEG conjugates themselves remains elusive. Herein, by using cholesterol-PEG2000-fluorescein isothiocyanate (Chol-PEG-FITC) as a model system, we found that the Chol-PEG-FITC molecules could attach to the plasma membranes of mammalian cells within 10 min and such a firm membrane attachment could last at least 1 h, displaying excellent plasma membrane staining performance that surpassed that of commonly used commercial membrane dyes such as DiD and CellMask. Besides, we systematically studied the endocytosis pathway and intracellular distribution of Chol-PEG-FITC and found that the cell surface adsorption and endocytosis processes of Chol-PEG-FITC molecules were lipid-raft-dependent. After internalization, the Chol-PEG-FITC molecules gradually reached many organelles with membrane structures. At 5 h, they were mainly distributed in lysosomes and the Golgi apparatus, with some in the endoplasmic reticulum (ER) and very few in the mitochondrion. At 12 h, the Chol-PEG-FITC molecules mostly aggregated in the Golgi apparatus and ER close to the nucleus. Finally, we demonstrated that Chol-PEG-FITC was toxic to mammalian cells only at concentrations above 50 μM. In summary, Chol-PEG-FITC can be a promising plasma membrane imaging reagent to avoid the fast cellular internalization and quick membrane detachment problems faced by commercial membrane dyes. We believe that the investigation of the dynamic subcellular fate of Chol-PEG-FITC can provide important knowledge to facilitate the use of cholesterol-PEG conjugates in fields such as cell surface engineering and drug delivery.

Biodegradable polymeric micelles encapsulated JK184 suppress tumor growth through inhibiting Hedgehog signaling pathway

JK184 can specially inhibit Gli in the Hedgehog (Hh) pathway, which showed great promise for cancer therapeutics. For developing aqueous formulation and improving anti-tumor activity of JK184, we prepared JK184 encapsulated MPEG-PCL micelles by the solid dispersion method without using surfactants or toxic organic solvents. The cytotoxicity and cellular uptake of JK184 micelles were both increased compared with the free drug. JK184 micelles induced more apoptosis and blocked proliferation of Panc-1 and BxPC-3 tumor cells. In addition, JK184 micelles exerted a sustained in vitro release behavior and had a stronger inhibitory effect on proliferation, migration and invasion of HUVECs than free JK184. Furthermore, JK184 micelles had stronger tumor growth inhibiting effects in subcutaneous Panc-1 and BxPC-3 tumor models. Histological analysis showed that JK184 micelles improved anti-tumor activity by inducing more apoptosis, decreasing microvessel density and reducing expression of CD31, Ki67, and VEGF in tumor tissues. JK184 micelles showed a stronger inhibition of Gli expression in Hh signaling, which played an important role in pancreatic carcinoma. Furthermore, circulation time of JK184 in blood was prolonged after entrapment in polymeric micelles. Our results suggested that JK184 micelles are a promising drug candidate for treating pancreatic tumors with a highly inhibitory effect on Hh activity.

Synthesis and evaluation of MePEG-PCL diblock copolymers: surface properties and controlled release behavior

The amphiphilic block copolymers are composed of various combinations of hydrophilic and hydrophobic block unimers. The variation in unimer ratio alters the surface as well as micelle-forming properties of the block copolymers. These nanoscopic micelles have the ability to encapsulate hydrophobic compounds and act as potential drug carrier. MePEG-PCL copolymers with various block lengths were synthesized by ring-opening polymerization and characterized by ¹HNMR, GPC, WXRD and DSC. The number average molecular weight of the block copolymer was found to vary from 7511 to 21,270 as determined by GPC and ¹HNMR studies. The surface topology of the polymer films was determined by AFM analysis, which shows a smoother surface with increased MePEG contents in the block copolymers. The protein-binding assay indicates a better biocompatibility of the block copolymers in comparison to MePEG or PCL alone. The CMC of the block copolymer provides the information about micelle formations for encapsulation of hydrophobic materials and affects the in vitro release.

Synchronous microencapsulation of multiple components in silymarin into PLGA nanoparticles by an emulsification/solvent evaporation method

The development of polymeric carriers loaded with extracts suffers from the drawback not to be able to incorporate simultaneously various pharmacological compounds into the formulation. The aim of this study was therefore to achieve synchronous microencapsulation of multiple components of silymarin into poly (lactic-co-glycolic acid) nanoparticle, the most commonly used polymeric carrier with biodegradability and safety. The main strategy taken was to improve the overall entrapment efficiency and to reduce the escaping ratio of the components of different physicochemical properties. The optimized nanoparticles were spherical in morphology with a mean particle size of 150 ± 5 nm. Under common preparative conditions, silybin and isosilybin were entrapped in high efficiency, whereas taxifolin, silychristin and silydianin, especially taxifolin, showed less entrapment because they were more hydrophilic. By changing the pH of the outer aqueous phase and saturating it with silymarin, the entrapment efficiency of taxifolin, silychristin and silydianin could be significantly improved to over 90%, the level similar to silybin and isosilybin, thereby achieving synchronous encapsulation. It could be concluded that synchronous encapsulation of multiple components of silymarin was achieved by optimizing the preparative variables.

Composition controlled synthesis of PCL-PEG Janus nanoparticles: magnetite nanoparticles prepared from one-pot photo-click reaction

The aim of this study is to investigate the effect of polymer nature on the morphology of synthesized nanoparticles. Super paramagnetic iron oxide nanoparticles (SPIONs) were prepared by co-precipitation method and then reacted with (3-mercaptopropyl) trimethoxysilane to obtain thiol-decorated SPIONs. Acrylated poly(caprolactone) and methoxy poly(ethylene glycol) were prepared, and then "thiol-ene click" reaction was performed under UV irradiation to attach two types of polymers on the surface of magnetite nanoparticles via the "photo-click" reaction method. Computational modelling was used for the prediction of the self-assembly of polymers on the surface of SPIONs, which determines the morphology of polymer coated nanoparticles.

Combined cancer photothermal-chemotherapy based on doxorubicin/gold nanorod-loaded polymersomes

Gold nanorods (GNRs) are well known in photothermal therapy based on near-infrared (NIR) laser absorption of the longitudinal plasmon band. Herein, we developed an effective stimulus system -- GNRs and doxorubicin co-loaded polymersomes (P-GNRs-DOX) -- to facilitate co-therapy of photothermal and chemotherapy. DOX can be triggered to release once the polymersomes are corrupted under local hyperthermic condition of GNRs induced by NIR laser irradiation. Also, the cytotoxicity of GNRs caused by the residual cetyltrimethylacmmonium bromide (CTAB) was reduced by shielding the polymersomes. The GNRs-loaded polymersomes (P-GNRs) can be efficiently taken up by the tumor cells. The distribution of the nanomaterial was imaged by IR-820 and quantitatively analyzed by ICP-AES. We studied the ablation of tumor cells in vitro and in vivo, and found that co-therapy offers significantly improved therapeutic efficacy (tumors were eliminated without regrowth.) compared with chemotherapy or photothermal therapy alone. By TUNEL immunofluorescent staining of tumors after NIR laser irradiation, we found that the co-therapy showed more apoptotic tumor cells than the other groups. Furthermore, the toxicity study by pathologic examination of the heart tissues demonstrated a lower systematic toxicity of P-GNRs-DOX than free DOX. Thus, the chemo-photothermal treatment based on polymersomes loaded with DOX and GNRs is a useful strategy for maximizing the therapeutic efficacy and minimizing the dosage-related side effects in the treatment of solid tumors.