Synthesis, Characterization, and Evaluation of Triptolide Cell-Penetrating Peptide Derivative for Transdermal Delivery of Triptolide

Aptamer-functionalized triptolide with release controllability as a promising targeted therapy against triple-negative breast cancer

Targeted delivery and precise release of toxins is a prospective strategy for the treatment of triple-negative breast cancer (TNBC), yet the flexibility to incorporate both properties simultaneously remains tremendously challenging in the X-drug conjugate fields. As critical components in conjugates, linkers could flourish in achieving optimal functionalities. Here, we pioneered a pH-hypersensitive tumor-targeting aptamer AS1411-triptolide conjugate (AS-TP) to achieve smart release of the toxin and targeted therapy against TNBC. The multifunctional acetal ester linker in the AS-TP site-specifically blocked triptolide toxicity, quantitatively sustained aptamer targeting, and ensured the circulating stability. Furthermore, the aptamer modification endowed triptolide with favorable water solubility and bioavailability and facilitated endocytosis of conjugated triptolide by TNBC cells in a nucleolin-dependent manner. The integrated superiorities of AS-TP promoted the preferential intra-tumor triptolide accumulation in xenografted TNBC mice and triggered the in-situ triptolide release in the weakly acidic tumor microenvironment, manifesting striking anti-TNBC efficacy and virtually eliminated toxic effects beyond clinical drugs. This study illustrated the therapeutic potential of AS-TP against TNBC and proposed a promising concept for the development of nucleic acid-based targeted anticancer drugs.

Mechanisms of cancer cell death induction by triptolide: A comprehensive overview

The need for naturally occurring constituents is driven by the rise in the cancer prevalence and the unpleasant side effects associated with chemotherapeutics. Triptolide, the primary active component of "Tripterygium Wilfordii", has exploited for biological mechanisms and therapeutic potential against various tumors. Based on the recent pre-clinical investigations, triptolide is linked to the induction of death of cancerous cells by triggering cellular apoptosis via inhibiting heat shock protein expression (HSP70), and cyclin dependent kinase (CDKs) by up regulating expression of P21. MKP1, histone methyl transferases and RNA polymerases have all recently identified as potential targets of triptolide in cells. Autophagy, AKT signaling pathway and various pathways involving targeted proteins such as A-disintegrin & metalloprotease-10 (ADAM10), Polycystin-2 (PC-2), dCTP pyro-phosphatase 1 (DCTP1), peroxiredoxin-I (Prx-I), TAK1 binding protein (TAB1), kinase subunit (DNA-PKcs) and the xeroderma-pigmentosum B (XPB or ERCC3) have been exploited. Besides that, triptolide is responsible for enhancing the effectiveness of various chemotherapeutics. In addition, several triptolide moieties, including minnelide and LLDT8, have progressed in investigations on humans for the treatment of cancer. Targeted strategies, such as triptolide conjugation with ligands or triptolide loaded nano-carriers, are efficient techniques to confront toxicities associated with triptolide. We expect and anticipate that advances in near future, regarding combination therapies of triptolide, might be beneficial against cancerous cells.

CD-MOFs: From preparation to drug delivery and therapeutic application

Cyclodextrin metal-organic frameworks (CD-MOFs) show considerable advantages of edibility, degradability, low toxicity, and high drug loading, which have attracted enormous interest, especially in drug delivery. This review summarizes the typical synthesis approaches of CD-MOFs, the drug loading methods, and the mechanism of encapsulation and release. The influence of the structure of CD-MOFs on their drug encapsulation and release is highlighted. Finally, the challenges CD-MOFs face are discussed regarding biosafety assessment systems, stability in aqueous solution, and metal ion effect.

Therapeutic Potential of Triptolide in Treating Bone-Related Disorders

Triptolide, a diterpene triepoxide, is a pharmacologically active compound isolated from a Chinese medicinal herb Tripterygium wilfordii Hook F (TwHF). Triptolide has attracted considerable attention in recent times due to its multiple biological and pharmaceutical activities, with an emphasis on therapeutic importance in the treatment of diverse disorders. With essential medicinal implications, TwHF’s extracts have been used as anti-inflammatory, antiproliferative, antioxidative, and immunosuppressive agents for centuries, with continuous and relevant modifications to date to enhance its utility in several diseases and pathophysiology. Here, in this review, we accentuate the studies, highlighting the effects of triptolide on treating bone-related disorders, both inflammatory and cancerous, particularly osteosarcoma, and their manifestations. Based on this review, future avenues could be estimated for potential research strategies, molecular mechanisms, and outcomes that might contribute toward reinforcing new dimensions in the clinical application of triptolide in treating bone-related disorders.

Detoxification strategies of triptolide based on drug combinations and targeted delivery methods

Tripterygium wilfordii Hook f. has a long history of use in Chinese medicine. Triptolide (TP), as its main pharmacological component, has been widely explored in various diseases, including systemic lupus erythematosus, rheumatoid arthritis and cancer. However, due to its poor water solubility, limited therapeutic range and multi-organ toxicity, TP's clinical application has been greatly hampered. To improve its clinical potential, many attenuated drug combinations have been developed based on its toxicity mechanism and targeted delivery systems aimed at its water-solubility and structure. This review, conducted a systematic review of TP detoxification strategies including drug combination detoxification strategies from metabolic and toxic mechanisms, as well as drug delivery detoxification strategies from the prodrug strategy and nanotechnology. Many detoxification strategies have demonstrated promising potential in vitro and in vivo due to previous extensive studies on TP. Therefore, summarizing and discussing TP detoxification strategies for clinical problems can serve as a reference for developing novel TP detoxification strategies, and provide opportunities for future clinical applications.

Esterase-activatable and GSH-responsive Triptolide Nano-prodrug for the Eradication of Pancreatic Cancer

Triptolide (TPL) is a small molecule isolated from a traditional Chinese herb Tripterygium wilfordii Hook F and shows excellent anticancer effect for pancreatic cancer cells. However, the poor water solubility and severe liver toxicity of TPL hindered its clinical application. In this study, TPL was covalently conjugated to a polymer and entrapped inside the core of the TPL nanogel (nTPL) to protect it from premature leakage during blood circulation. With the help of lactobionic acid (LBA), nTPL-LBA could selectively target the tumors in an orthotopic pancreatic cancer mouse model. TPL could be subsequently released intracellularly in its original form due to the presence of elevated intracellular esterase and GSH, and eventually kills cancer cells. nTPL-LBA treatment reduced tumor burden by 99% while not introducing TPL associated liver and kidney toxicities. Most importantly, more than half of the nTPL-LBA treated animals were tumor-free, suggesting that nTPL-LBA is an effective approach in eradicating pancreatic cancer.

Source and exploration of the peptides used to construct peptide-drug conjugates

Peptide-drug conjugates (PDCs) are a class of novel molecules widely designed and synthesized for delivering payload drugs. The peptide part plays a vital role in the whole molecule, because they determine the ability of the molecules to penetrate the membrane and target to the specific targets. Here, we introduce the source of different kinds of cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs) that have been used or could be used in constructing PDCs as well as their latest application in delivering drugs. What's more, the approaches of developing CPPs and CTPs and the techniques to discover novel peptides are focused on and summarized in the review. This review aims to help relevant researchers fast understand the research status of peptides in PDCs and carry forward the process of novel peptides discovery.

Triptolide laden reduced graphene oxide transdermal hydrogel to manage knee arthritis: in vitro and in vivo studies

Triptolide (extract of herb Tripterygium wilfordii) is widely used in rheumatoid arthritis due to its potent immunosuppressant effect. The marketed oral (tablet dosage forms) and parenteral injections have short duration of action (half-life = 38 min) and not limited to multiorgan toxicity, which restrict the use of triptolide in clinical practice. In this study, a triptolide-loaded Pluronic® F68-reduced graphene oxide transdermal (non-invasive) hydrogel was developed to achieve sustained release of triptolide. Fourier transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy confirmed the synthesis of Pluronic^® F68-reduced graphene oxide. Transmission electron microscopy showed flat wrinkled-nanosheets. The developed hydrogel showed desirable viscosity (11,261-11,365 cps), adhesiveness (0.25 mJ), hardness (6.5 g), and cohesiveness (1.85) for transdermal application. The ex vivo release study demonstrated the ability of the Pluronic^® F68-reduced graphene oxide hydrogel to prolong release up to 14 h (63.64-96.78%), owing to the strong π-π interactions between the graphene oxide and the triptolide. The in vivo pharmacokinetic parameters in the rat model confirmed the improvement in the relative bioavailability (3.3-fold) with Pluronic^® F68-reduced graphene oxide hydrogel in comparison to the control hydrogel without reduced graphene oxide. The anti-rheumatoid efficacy model suggest the potential application of Pluronic^® F68-reduced graphene oxide hydrogel to treat knee rheumatoid arthritis (70-75% resolution) to substitute tablets and parenteral injections.

Exploring a novel triptolide derivative possess anti-colitis effect via regulating T cell differentiation

Inflammatory bowel disease (IBD) is generally characterized by chronic inflammatory disorders of the gastrointestinal tract that are known as ulcerative colitis (UC) or Crohn's disease (CD). Although the underlying mechanism of action of IBD is unclear and because of the lack of satisfactory treatment, increasing evidence has indicated that pro-inflammatory cytokines that activate JAK-STAT signaling pathway regulate the differentiation of naïve T cells towards T helper (Th)1 and Th17 cell subsets and contribute to the development of IBD. ZT01 is a newly obtained triptolide derivative with strong anti-inflammatory effects and low toxicity. In this study, we evaluated the effects of ZT01 on DSS-induced colitis and investigated the underlying mechanism of action involved. Mice with DSS-induced acute or chronic colitis were used to assess the efficacy of ZT01 treatment, and T cells were cultured to analyze the differentiation of Th1 and Th17 cell by flow cytometry. In addition, intestinal epithelial barrier function, macrophage polarization, activation of the JAK-STAT signaling pathway, and the expression of cytokines and transcription factors were measured to assess the possible mechanisms of ZT01. We found that ZT01 had an obviously beneficial effect on DSS-induced colitis by improving the symptoms of bloody diarrhea, weight loss, and a shortened colon, thereby preserving the epithelial barrier function in the mouse colon. Furthermore, ZT01 significantly inhibited T cell differentiation into Th1 and/or Th17 cell subsets and macrophage polarization towards into an inflammatory phenotype via regulating the JAK-STAT signaling pathway. Thus, our findings suggested that ZT01 might be a potential pharmaceutical candidate that deserves to be further investigated as a treatment for IBD patients.

Triptolide: reflections on two decades of research and prospects for the future

Covering: 2000 to 2020 Triptolide is a bioactive diterpene triepoxide isolated from Tripterygium wilfordii Hook F, a traditional Chinese medicinal plant whose extracts have been used as anti-inflammatory and immunosuppressive remedies for centuries. Although triptolide and its analogs exhibit potent bioactivities against various cancers, and inflammatory and autoimmune diseases, none of them has been approved to be used in the clinic. This review highlights advances in material sourcing, molecular mechanisms, clinical progress and new drug design strategies for triptolide over the past two decades, along with some prospects for the future course of development of triptolide.

Co-hybridized composite nanovesicles for enhanced transdermal eugenol and cinnamaldehyde delivery and their potential efficacy in ulcerative colitis

Percutaneous absorption of drugs can be enhanced by ethosomes, which are nanocarriers with excellent deformability and drug-loading properties. However, the ethanol within ethosomes increases phospholipid membrane fluidity and permeability, leading to drug leakage during storage. Here, we developed and characterized a new phospholipid nanovesicles that is co-hybridized with hyaluronic acid (HA), ethanol and the encapsulated volatile oil medicines (eugenol and cinnamaldehyde [EUG/CAH]) for transdermal administration. In comparison with EUG/CAH-loaded ethosomes (ES), the formulation stability and percutaneous drug absorption of EUG/CAH-loaded HA-immobilized ethosomes (HA-ES) were significantly improved. After transdermal administration of HA-ES, the interstitial cells of Cajal in the colon of rats with trinitrobenzene sulfonate-induced ulcerative colitis (UC) were significantly increased, and the stem cell factor/c-kit signaling pathway was partly repaired. Overall, HA-ES possesses excellent deformability and showed improved efficacy against UC compared with ES, which is demonstrated as a promising transdermal delivery vehicle for volatile oil medicines.

pH-Responsive Polypeptide-Based Smart Nano-Carriers for Theranostic Applications

Smart nano-carriers have attained great significance in the biomedical field due to their versatile and interesting designs with different functionalities. The initial stages of the development of nanocarriers mainly focused on the guest loading efficiency, biocompatibility of the host and the circulation time. Later the requirements of less side effects with more efficacy arose by attributing targetability and stimuli-responsive characteristics to nano-carriers along with their bio- compatibility. Researchers are utilizing many stimuli-responsive polymers for the better release of the guest molecules at the targeted sites. Among these, pH-triggered release achieves increasing importance because of the pH variation in different organ and cancer cells of acidic pH. This specific feature is utilized to release the guest molecules more precisely in the targeted site by designing polymers having specific functionality with the pH dependent morphology change characteristics. In this review, we mainly concert on the pH-responsive polypeptides and some interesting nano-carrier designs for the effective theranostic applications. Also, emphasis is made on pharmaceutical application of the different nano-carriers with respect to the organ, tissue and cellular level pH environment.