Caged Polyprenylated Xanthones in Garcinia hanburyi and the Biological Activities of Them

The previous phytochemical analyses of Garcinia hanburyi revealed that the main structural characteristic associated with its biological activity is the caged polyprenylated xanthones with a unique 4-oxatricyclo [4.3.1.03,7] dec-2-one scaffold, which contains a highly substituted tetrahydrofuran ring with three quaternary carbons. Based on the progress in research of the chemical constituents, pharmacological effects and modification methods of the caged polyprenylated xanthones, this paper presents a preliminary predictive analysis of their drug-like properties based on the absorption, distribution, metabolism, excretion and toxicity (ADME/T) properties. It was found out that these compounds have very similar pharmacokinetic properties because they possess the same caged xanthone structure, the 9,10-double bond in a,b-unsaturated ketones are critical for the antitumor activity. The author believes that there is an urgent need to seek new breakthroughs in the study of these caged polyprenylated xanthones. Thus, the research on the route of administration, therapeutic effect, structural modification and development of such active ingredients is of great interest. It is hoped that this paper will provide ideas for researchers to develop and utilize the active ingredients derived from natural products.

Carrier-Free Gambogic Acid Dimer Self-Assembly Nanomedicines for Rheumatoid Arthritis Treatment

Introduction

The insufficient targeting delivery of therapeutic agents greatly impeded the treatment outcomes of rheumatoid arthritis (RA). Despite the recognized therapeutic advantages of gambogic acid (GBA) in inflammatory diseases, its high delivery efficiency to inflammatory site still limits its clinical application. Self-assembly of drug dimers into carrier-free nanoparticles (NPs) has become a straightforward and attractive approach to develop nanomedicines for RA treatment. Herein, homodimers of GBA were designed to form the carrier-free NPs by self-assembly for RA treatment.

Methods

The synthetic gambogic acid dimers (GBA2) were self-assembled into NPs using a one-step solvent evaporation method. The size distribution, morphology, drug-loading efficiency (DLE) and storage stability were evaluated. A molecular dynamic simulation was conducted to gain further insight into the self-assembly mechanisms of GBA2/NPs. Besides, we investigated the cytotoxicity, apoptosis and cellular uptake profiles of GBA2/NPs in macrophages and osteoclasts. Finally, the specific biodistribution on the ankles of adjuvant-induced arthritis (AIA) mice, and the anti-RA efficacy of the AIA rat model were assessed.

Results

GBA2/NPs exhibited the uniform spherical structure, possessing excellent colloidal stability, high self-assembly stability, high drug loading and low hemolytic activity. Comparing with GBA, GBA2/NPs showed higher cytotoxicity, cellular uptake and apoptosis rate against osteoclasts. In addition, GBA2/NPs exhibited much higher accumulation in ankle joints in vivo. As expected, the systematic administration of GBA2/NPs resulted in the greater alleviation of arthritic symptoms, cartilage protection, and inflammation, notably the reduced systemic toxicity compared to free GBA.

Conclusion

GBA2/NPs formed GBA dimers exhibited the superior accumulation in the inflamed joint and anti-RA activity, potentially attributing to the similar extravasation through leaky vasculature and subsequent inflammatory cell-mediated sequestration ("ELVIS") effects in inflamed joint and the enhanced cellular uptake in macrophages and osteoclasts. Our findings provide substantial evidence that self-assembly of GBA2/NPs would be a promising therapeutic alternative for RA treatment.

Improving Anticancer Activity of Chrysin using Tumor Microenvironment pH-Responsive and Self-Assembled Nanoparticles

Chrysin is a natural bioactive compound with potential biological activities. However, unfavorable physicochemical properties of native chrysin make it difficult to achieve good therapeutic efficacies. In this study, poly(ethylene) glycol (PEG₄₀₀₀)-conjugated chrysin nanoparticles were prepared. The PEG₄₀₀₀ was conjugated to chrysin through cis-aconityl and succinoyl linkers to achieve tumor microenvironment-specific drug release from PEGylated nanoparticles. The conjugation of PEG and chrysin via succinoyl (PCNP-1) and cis-aconityl (PCNP-2) linkers was confirmed by the ¹H NMR and FTIR analysis. The nanoparticles were characterized by DLS, TEM, XRD, and DSC analysis. Comparatively, PCNP-2 showed a better drug release profile and higher anticancer activity against human breast cancer cells than chrysin or PCNP-1. The apoptosis studies and colony formation inhibition assay revealed that the PCNP-2 induced more apoptosis and more greatly controlled the growth of human breast cancer cells than pure chrysin. Thus, the use of PCNPs may help to overcome the issues of chrysin and could be a better therapeutic approach.

Interplay Between the Linker and Polymer Molecular Weight of a Self-Assembling Prodrug on the Pharmacokinetics and Therapeutic Efficacy

Poorly water-soluble small hydrophobic compounds can be conjugated to a hydrophilic polymer such as methoxypolyethylene glycol (mPEG) to form amphiphilic prodrugs that can self-assemble into nanoparticles (NPs) with increased aqueous...

Recent trends in bioresponsive linker technologies of Prodrug-Based Self-Assembling nanomaterials

Prodrugs are designed to improve pharmaceutical properties of potent compounds and represent a central approach in drug development. The success of the prodrug strategy relies on incorporation of a reversible linkage facilitating controlled release of the parent drug. While prodrug approaches enhance pharmacokinetic properties over their parent drug, they still face challenges in absorption, distribution, metabolism, elimination, and toxicity (ADMET). Conjugating a drug to a carrier molecule such as a polymer can create an amphiphile that self-assembles into nanoparticles. These nanoparticles display prolonged blood circulation and passive targeting ability. Furthermore, the drug release can be tailored using a variety of linkers between the parent drug and the carrier molecule. In this review, we introduce the concept of self-assembling prodrugs and summarize different approaches for controlling the drug release with a focus on the linker technology. We also summarize recent clinical trials, discuss the emerging challenges, and provide our perspective on the utility and future potential of this technology.