Betulinic Acid-Nitrogen Heterocyclic Derivatives: Design, Synthesis, and Antitumor Evaluation in Vitro.

Betulinic acid (BA) is a star member of the pentacyclic triterpenoid family, which exhibits great prospects for antitumor drug development. In an attempt to develop novel antitumor candidates, 21 BA-nitrogen heterocyclic derivatives were synthetized, in addition to four intermediates, 23 of which were first reported. Moreover, they were screened for in-vitro cytotoxicity against four tumor cell lines (Hela, HepG-2, BGC-823 and SK-SY5Y) by a standard methylthiazol tetrazolium (MTT) assay. The majority of these derivatives showed much stronger cytotoxic activity than BA. Remarkably, the most potent compound 7e (the half maximal inhibitory concentration (IC50) of which was 2.05 ± 0.66 µM) was 12-fold more toxic in vitro than BA-treated Hela. Furthermore, multiple fluorescent staining techniques and flow cytometry collectively revealed that compound 7e could induce the early apoptosis of Hela cells. Structure-activity relationships were also briefly discussed. The present study highlighted the importance of introducing nitrogen heterocyclic rings into betulinic acid in the discovery and development of novel antitumor agents.

A New Oleanolic Acid Derivative against CCl4-Induced Hepatic Fibrosis in Rats.

A novel hepatoprotective oleanolic acid derivative, 3-oxours-oleana-9(11), 12-dien-28-oic acid (Oxy-Di-OA), has been reported. In previous studies, we found that Oxy-Di-OA presented the anti-HBV (Hepatitis B Virus) activity (IC50 = 3.13 µg/mL). Remarkably, it is superior to lamivudine in the inhibition of the rebound of the viral replication rate. Furthermore, Oxy-Di-OA showed good performance of anti-HBV activity in vivo. Some studies showed that liver fibrosis may affiliate with HBV gene mutations. In addition, the anti-hepatic fibrosis activity of Oxy-Di-OA has not been studied. Therefore, we evaluated the protective effect of Oxy-Di-OA against carbon tetrachloride (CCl4)-induced liver injury in rats. Daily intraperitoneally administration of Oxy-Di-OA prevented the development of CCl4-induced liver fibrosis, which was evidenced by histological study and immunohistochemical analysis. The entire experimental protocol lasted nine weeks. Oxy-Di-OA significantly suppressed the increases of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels (p < 0.05). Furthermore, Oxy-Di-OA could prevent expression of transforming growth factor ß1 (TGF-ß1). It is worth noting that the high-dose group Oxy-Di-OA is superior to bifendate in elevating hepatic function. Compared to the model group, Oxy-Di-OA in the high-dose group and low-dose group can significantly reduce the liver and spleen indices (p < 0.05). The acute toxicity test showed that LD50 and a 95% confidence interval (CIs) value of Oxy-Di-OA were 714.83 mg/kg and 639.73-798.73 mg/kg via intraperitoneal injection in mice, respectively. The LD50 value of Oxy-Di-OA exceeded 2000 mg/kg via gavage in mice. In addition, a simple and rapid high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed and validated to study the pharmacokinetic characteristics of the compound. After single-dose oral administration, time to reach peak concentration of Oxy-Di-OA (Cmax = 8.18 ± 0.66 µg/mL) was 10 ± 2.19 h; the elimination half-life and area under the concentration-time curve from t = 0 to the last time of Oxy-Di-OA was 2.19 h and 90.21 µg·h/mL, respectively.

Origin and Formation Mechanism Investigation of Compound Precipitation from the Traditional Chinese Prescription Huang-Lian-Jie-Du-Tang by Isothermal Titration Calorimetry.

Previous studies have shown that compounds in the form of precipitate (CFP) from Huang-Lian-Jie-Du-Tang (HLJDT) were stable, and the CFP content reached 2.63% of the whole decoction and had good neuroprotective effects. However, there has been no research on their specific source. In this study, it was found that HLJDT CFP mainly came from the reaction of Scutellaria baicalensis and Coptis chinensis by studying the separated prescription components (accounting for 81.33% of HLJDT CFP). Unlike previous studies on HLJDT CFP, in this research the chemical composition of Scutellaria baicalensis-Coptis chinensis (SB-CC) CFP was identified by high performance liquid chromatography coupled with mass spectrometry (HPLC-MSn), which further proved that the main source of HLJDT CFP was Scutellaria baicalensis-Coptis chinensis CFP compared with previous HLJDT CFP studies. To explain the reaction mechanism between the decoctions of Scutellaria baicalensis and Coptis chinensis, isothermal titration calorimetry (ITC) was used to analyze their binding heat and the thermodynamic parameters (ΔH, ΔS, ΔG, n, Ka) of the reaction between baicalin and berberine, which are the main components of Scutellaria baicalensis and Coptis chinensis, respectively. The results showed that the reaction between decoctions of Scutellaria baicalensis and Coptis chinensis was exothermic and the reaction between baicalin and berberine was a spontaneous and enthalpy-driven chemical reaction, the binding ratio being 1:1. In addition, HLJDT CFP (EC50 = 14.71 ± 0.91 µg/mL) and SB-CC CFP (EC50 = 6.11 ± 0.12 µg/mL) showed similar protective activities on PC12 cells injured by cobalt chloride (CoCl2). This study provided a new angle to research on the main chemical components and therapeutic values of CFP in Traditional Chinese Medicine compounds.

Hydroxyethyl-Modified Cycloheptatriene-BODIPY Derivatives as Specific Tau Imaging Probes.

Near-infrared fluorescence (NIRF) imaging as an exquisite sensitive, high spatial-resolution, and real-time tool plays an important role in visualizing pathologies in the brain. In this study, we designed and synthesized a series of NIR probes of hydroxyethyl cycloheptatriene-BODIPY derivatives that have demonstrated strong binding specificity to native neurofibrillary tangles (NFTs) in Alzheimer's disease (AD) brain sections. The improved hydrophilicity of TNIR7-9 and TNIR7-11 resulted in faster clearance rates from healthy brains (4.2 and 10.9, respectively) compared to previously reported compounds. Furthermore, TNIR7-13, which features a fluorinated modification, exhibited a high binding affinity to Tau aggregates (Kd = 11.8 nM) and held promise for future PET studies.

Fused Cycloheptatriene-BODIPY Is a High-Performance Near-Infrared Probe to Image Tau Tangles.

Neurofibrillary tangles (NFTs), which are composed of abnormally hyperphosphorylated Tau, are one of the main pathologic hallmarks of Alzheimer's disease and other tauopathies. The fluorescent imaging probes currently used to target NFTs cannot distinguish them well from ß-amyloid plaques, thus limiting their utility to diagnose diseases. Here, we developed a fused cycloheptatriene-BODIPY derivative (TNIR7-1A) that displays properties favorable for near-infrared (NIR) imaging with high affinity and specificity to NFTs in vitro. In addition, TNIR7-1A effectively penetrated the blood-brain barrier and clearly distinguished tauopathy in transgenic mice (rTg4510) from control mice using NIR fluorescence imaging in vivo. The sensitivity and specificity of TNIR7-1A for NFTs were confirmed ex vivo by fluorescence staining of the tauopathy mouse model, while molecular docking studies indicated that TNIR7-1A bound to NFTs through hydrophobic interactions. These results suggest that TNIR7-1A can act as a high-performance probe to detect NFTs in vitro and in vivo selectively.

Synthesis, Preclinical Evaluation, and First-in-Human PET Study of Quinoline-Containing PSMA Tracers with Decreased Renal Excretion.

The prostate-specific membrane antigen (PSMA) is considered to be an excellent theranostic target of prostate cancer (PCa). In this study, three 18F-labeled PSMA tracers with a more lipophilic quinoline functional spacer were designed, synthesized, and evaluated based on the Glu-Ureido-Lys binding motif. The effect of structure-related lipophilic difference on distribution and excretion of these tracers in vitro and in vivo (cells, rodent, primate, and human) was investigated by comparing with [18F]DCFPyL. There is no significant correlation between the renal elimination and the lipophilicity of the tracers in all species. However, the higher the lipophilicity of tracer, the higher the radioactivity accumulation in the liver of primate and human, and the less radioactivity is to excrete to the bladder with urine. The screened tracer [18F]8c, with a Ki value of 4.58 nM, displayed notable low bladder retention and demonstrated good imaging properties in patients with PCa.

N,O-Benzamide difluoroboron complexes as near-infrared probes for the detection of ß-amyloid and tau fibrils.

In this study, a series of organo difluoroboron probes with a BF2 benzamide moiety was designed, prepared and evaluated. Among them, 2c displayed the best optical and biological properties, and may be used as a useful near-infrared fluorescent probe for the detection of Aß plaques and neurofibrillary tangles in AD.

A comparative study of plasmonic-enhanced single-molecule fluorescence induced by gold nanoantennas and its application for illuminating telomerase.

A comparative study of plasmonic-enhanced single-molecule fluorescence (PESMF) induced by four gold nanoantennas is reported. The gold triangular nanoplate (Au TNP) is the optimal PESMF substrate for Cy5.5 owing to its sharpest point and strongest electric fields. The Au TNP is chosen for the preparation of a telomerase sensor.

Synthesis and protective effect of new ligustrazine-vanillic acid derivatives against CoCl2-induced neurotoxicity in differentiated PC12 cells.

Ligustrazine-vanillic acid derivatives had been reported to exhibit promising neuroprotective activities. In our continuous effort to develop new ligustrazine derivatives with neuroprotective effects, we attempted the synthesis of several ligustrazine-vanillic acid amide derivatives and screened their protective effect on the injured PC12 cells damaged by CoCl2. The results showed that most of the newly synthesized derivatives exhibited higher activity than ligustrazine, of which, compound VA-06 displayed the highest potency with EC50 values of 17.39 ± 1.34 µM. Structure-activity relationships were briefly discussed.Graphical abstractNew series of ligustrazine-vanillic acid amide derivatives were synthesized and evaluated for their protective effect on the injured PC12 cells damaged by CoCl2. VA-06 was found to be the most active one.

Synthesis and biological activity evaluation of novel peroxo-bridged derivatives as potential anti-hepatitis B virus agents.

Previous studies have demonstrated that natural steroid compounds containing a peroxide bridge exhibited potential anti-hepatitis B virus activity. To continue our research, a simple and regioselective methodology, using Eosin Y as a clean photosensitized oxidation catalyst, was developed for the synthesis of a peroxide bridge in steroids. The method that using Eosin Y as the catalyst was exposed to visible light and furbished in high yields, did not involve tedious work-up or purification, and avoided using environmentally hazardous solvents. It can be regarded as a green protocol. Moreover, a series of cholesterol and ß-sitosterol derivatives containing a peroxide bridge were synthesized using this method and screened for their anti-HBV activity. Among the compounds synthesized in this research, 5α,8α-cyclicobioxygen-6-vinyl-3-oxo-cholesterone (1f, 3.13 µg ml-1) had the most potent activity with inhibition rates of 77.45% ± 6.01% and 58.73% ± 8.64% on the secretion of HBsAg and HBeAg antigens, respectively, after 8 days. Further acute toxicity test showed that the LD50 value of compound 1f was 362.46 mg kg-1 after an intraperitoneal injection in mice. Moreover, structure-activity relationships of cholesterol and ß-sitosterol derivatives were briefly discussed.