A novel polyrotaxane-based delivery system for scutellarin: preparation, characterization, and in vitro evaluation

Isolation and identification of the new baicalin target protein to develop flavonoid structure-based therapeutic agents

Proteins are vital constituents of all living organisms. As many therapeutic agents alter the activity of functional proteins, identifying functional target proteins of small bioactive molecules isessential for the rational design of stronger medicines. Flavonoids with antioxidant, anti-allergy, and anti-inflammatory effects are expected to have preventive effects for several diseases closely related to oxidation and inflammation, including heart disease, cancer, neurodegenerative disorders, and eye diseases. Therefore, identifying the proteins involved in the pharmacological actions of flavonoids, and designing a flavonoid structure-based medicine that strongly and specifically inhibits flavonoid target proteins, could aid the development of more effective medicines for treating heart disease, cancer, neurodegenerative disorders, and ocular diseases with few side effects. To isolate the flavonoid target protein, we conducted a novel affinity chromatography in a column wherein baicalin, a representative flavonoid, was attached to Affi-Gel 102. Through affinity chromatography and nano LC-MS/MS, we identified GAPDH as a flavonoid target protein. Then, we performed fluorescence quenching and an enzyme inhibition assay to experimentally confirmbaicalin's binding affinity for, and inhibition of, GAPDH. We also conducted in silico docking simulations to visualize the binding modes of baicalin and the newly identified flavonoid target protein, GAPDH. From the results of this study, it was considered that one of the reasons why baicalin exhibits the effects on cancer and neurodegenerative diseases is that it inhibits the activity of GAPDH. In summary, we showed that Affi-Gel102 could quickly and accurately isolate the target protein for bioactive small molecules, without the need for isotopic labeling or a fluorescent probe. By using the method presented here, it was possible to easily isolate the target protein of a medicine containing a carboxylic acid.

Scutellarin, a promising flavonoid in cancer treatment

Natural substances are increasingly being used as cancer treatments. Scutellarin, as a flavonoid, recently has been identified in a Chinese herbal extract called Erigeron breviscapus (Vant.). Scutellarin is being researched for its potential benefits due to the discovery that it possesses a variety of biological effects, such as neuroprotective, anti-coagulant, and anti-viral. In addition to these biological functions, scutellarin has also been found to have anti-tumor properties. Scutellarin first inhibits the activity of tumor cells by altering cancer cell signaling pathways such as Jak/STAT, ERK/AMPK, and Wnt/β-catenin. Additionally, scutellarin activates intrinsic and extrinsic apoptotic pathways, which causes the death of tumor cells, interrupts the cell cycle, and promotes its arrest. By limiting metastasis, angiogenesis, drug resistance, and other tumorigenic processes, scutellarin also reduces the aggressiveness of tumors. Utilizing scutellarin in combination with other anti-tumor therapies like 5-fluorouracil is another method to overcome tumor cell resistance. Moreover, it has been suggested that certain modifications, such as conjugation with cyclodextrin, aliphatic chains, and hybridization with nitric oxide, can enhance the pharmacogenetic capabilities of scutellarin to decrease its limited water solubility. It is believed that scutellarin may provide innovative chemotherapeutic treatments for cancer in the future.

Preparation of stereocomplex and pseudo-polyrotaxane with various cyclodextrins as wheel components using triblock copolymer of poly(ethylene glycol) and polylactide

The ABA-type triblock-copolymers (BCPs) of polylactide (PLA) and poly(ethylene glycol) (PEG) were synthesized as axle components for rotaxane formation. It is known that α-cyclodextrin (CD) exists near the PEG moiety in pseudo-polyrotaxane (PPRX), and the PLA moiety can form a stereocomplex (SC), by mixing with L- and D-isomers. In this study, various CDs, including β-CD and γ-CD, were used as wheel components, and effects of CD structures on both PPRX and SC formations were studied. The solubility of CDs is influenced to form the PPRX, resulting in differing numbers of CDs in the axle. PPRX structures were investigated by ¹H NMR, NOESY, and DOSY, and SC structures were investigated by FT-IR and XRD. Their thermal properties were also evaluated by DSC and TGA, to consider the physical properties of the simultaneous formation of PPRX and SC. This study gave insight into the complicated host-guest and polymer-polymer interactions.

Combined Scutellarin and C18H17NO6 Imperils the Survival of Glioma: Partly Associated With the Repression of PSEN1/PI3K-AKT Signaling Axis

Glioma, the most common intracranial tumor, harbors great harm. Since the treatment for it has reached the bottleneck stage, the development of new drugs becomes a trend. Therefore, we focus on the effect of scutellarin (SCU) and its combination with C₁₈H₁₇NO₆ (abbreviated as combination) on glioma and its possible mechanism in this study. Firstly, SCU and C₁₈H₁₇NO₆ both suppressed the proliferation of U251 and LN229 cells in a dose-dependent manner, and C₁₈H₁₇NO₆ augmented the inhibition effect of SCU on U251 and LN229 cells in vitro. Moreover, there was an interactive effect between them. Secondly, SCU and C₁₈H₁₇NO₆ decreased U251 cells in G2 phase and LN229 cells in G2 and S phases but increased U251 cells in S phase, respectively. Meanwhile, the combination could further reduce U251 cells in G2 phase and LN229 cells in G2 and S phases. Thirdly, SCU and C₁₈H₁₇NO₆ both induced the apoptosis of U251 and LN229. The combination further increased the apoptosis rate of both cells compared with the two drugs alone. Furthermore, SCU and C₁₈H₁₇NO₆ both inhibited the lateral and vertical migration of both cells, which was further repressed by the combination. More importantly, the effect of SCU and the combination was better than positive control-temozolomide, and the toxicity was low. Additionally, SCU and C₁₈H₁₇NO₆ could suppress the growth of glioma in vivo, and the effect of the combination was better. Finally, SCU and the combination upregulated the presenilin 1 (PSEN1) level but inactivated the phosphatidylinositol 3−kinase (PI3K)-protein kinase B (AKT) signaling in vitro and in vivo. Accordingly, we concluded that scutellarin and its combination with C₁₈H₁₇NO₆ suppressed the proliferation/growth and migration and induced the apoptosis of glioma, in which the mechanism might be associated with the repression of PSEN1/PI3K-AKT signaling axis.

Post-synthesis modification of slide-ring gels for thermal and mechanical reconfiguration

Ring-sliding behavior in polyrotaxanes imbues gels, elastomers, and glasses with remarkable stress-dissipation and actuation properties. Since these properties can be modulated and tuned by structural parameters, many efforts have been devoted to developing synthetic protocols that define the structures and properties of slide-ring materials. We introduce post-synthetic modifications of slide-ring gels derived from unmodified α-cyclodextrin and poly(ethylene glycol) polyrotaxanes that enable (i) actuation and control of the thermo-responsive lower critical solution temperature (LCST) behavior of ring-modified slide-ring hydrogels, and (ii) chemically bonding separate gels into hybrid or shape-reconfigured macro-structures with a slide-ring adhesive solution. The mechanical properties of the post-modified gels have been characterized by shear rheology and uniaxial tensile tests, while the corresponding xerogels were characterized by wide-angle X-ray scattering. These demonstrations show that post-synthetic modification offers a practical solution for re-configuring the properties and shapes of slide-ring gels.

Effectiveness of Scutellaria barbata water extract on inhibiting colon tumor growth and metastasis in tumor-bearing mice

The plant Scutellaria barbata (SB) is commonly used as herbal medicines for treating cancer. The present pre-clinical study aimed to validate the Chinese Pharmacopoeia (CP) recommended dosages of SB water extract (SBW) in treating colon tumors. The content of chemical marker scutellarin in SBW was quantified using UPLC. Mice bearing human HCT116 xenografts or murine colon26 tumors received oral administration of SBW or scutellarin for 4 weeks. Results showed that SBW (615 and 1,230 mg/kg) and scutellarin (7 mg/kg) treatments significantly reduced human xenograft weights by 28.7, 36.9 and 28.8%, respectively. Lung metastasis area could be ameliorated after SBW (615 mg/kg) and scutellarin (7 mg/kg) treatments by 23.4 and 29.5%, respectively. Expressions of colon cancer metastasis-related proteins E-cadherin, Tspan 8 and CXCR4, as well as Src kinase in tumors were first shown to be regulated by SBW. Furthermore, in murine colon26 tumor-bearing mice, SBW (615 mg/kg) and scutellarin (7 mg/kg) treatments reduced the orthotopic tumor burden by 94.7% and lung metastatic tumor burden by 94.1%, respectively. Our findings provided evidences that SBW (at the mouse equivalent dosages to clinical dosages recommended by CP) could exert anti-tumor and anti-metastatic effects in colon cancer animal models.

Control of the threading ratio of cyclic molecules in polyrotaxanes consisting of poly(ethylene glycol) and α-cyclodextrins

We demonstrated a feasible method for providing polyrotaxanes (PRxs) with a controlled threading ratio of cyclic molecules and chain length of linear polymers by extending the linear polymers in the pseudo-PRx. This method gave PRxs with a lower threading ratio and a higher mobility of cyclic molecules compared to usual methods used previously with a high threading ratio. In addition, our PRx improved the thermal stability of the linear polymers in PRx despite the low threading ratio.

Synthesis and Bioactivity Characterization of Scutellarein Sulfonated Derivative

Scutellarin (1) has been widely used to treat acute cerebral infarction in clinic, but poor aqueous solubility decreases its bioavailability. Interestingly, scutellarin (1) could be metabolized into scutellarein (2) in vivo. In this study, a sulfonic group was introduced at position C-8 of scutellarein (2) to enhance the aqueous solubility of the obtained derivative (3). DPPH (1,1-diphenyl-2-picrylhydrazyl)-radical scavenging ability and antithrombic activity were also conducted to determine its bioactivity. The result showed that scutellarein derivate (3) could be a better agent for ischemic cerebrovascular disease treatment.

Solid inclusion complexes of oleanolic acid with amino-appended β-cyclodextrins (ACDs): Preparation, characterization, water solubility and anticancer activity

Oleanolic acid (OA) is a pentacyclic triterpenoid acid of natural abundance in plants which possesses important biological activities. However, its medicinal applications were severely impeded by the poor water solubility and resultant low bioavailability and potency. In this work, studies on solid inclusion complexes of OA with a series of amino-appended β-cyclodextrins (ACDs) were conducted in order to address this issue. These complexes were prepared by suspension method and were well characterized by NMR, SEM, XRD, TG, DSC and Zeta potential measurement. The 2:1 inclusion mode of ACDs/OA complexes was elucidated by elaborate 2D NMR (ROESY). Besides, water solubility of OA was dramatically promoted by inclusion complexation with ACDs. Moreover, in vitro anticancer activities of OA against human cancer cell lines HepG2, HT29 and HCT116 were significantly enhanced after formation of inclusion complexes, while the apoptotic response results indicated their induction of apoptosis of cancer cells. This could provide a novel approach to development of novel pharmaceutical formulations of OA.

Synthesis, characterization, and in vitro evaluation of artesunate-β-cyclodextrin conjugates as novel anti-cancer prodrugs

A novel series of artesunate-β-cyclodextrin (ATS-β-CD) conjugates, in which artesunate (ATS) was coupled covalently to one of the primary hydroxyl groups of β-cyclodextrin (β-CD) through amino bond formation, were synthesized and characterized by (1)H NMR, HRMS, 2D NMR (ROESY), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the aqueous solubility of ATS-β-CD conjugates was 26-45 times better than that of free ATS. The cytotoxicity of the ATS-β-CD conjugates was evaluated on human colon cancer cell lines HCT116, LOVO, SW480, and HT-29, and the results indicated that ATS-2NβCD exhibited a very high cytotoxicity against HCT116, LOVO, and HT-29 with IC50 values of 0.58, 1.62, and 5.18μmol/L, respectively. In addition, the supposition of better cytotoxicity was further supported by the control experiment of fluorescent cyclodextrin.