Xianming Hu

Biological and pharmacological activities of amaryllidaceae alkaloids

The amaryllidaceae family consists of about 75 genera and 1100 species that are wide-spread in the tropics and warm temperate regions of the world. Since the first isolation of lycorine, more than 500 amaryllidaceae alkaloids have been isolated over the past three decades. The enormous numbers of diverse amaryllidaceae alkaloids are classified into different groups mainly according to their structural features. The representative alkaloids are norbelladine, lycorine, hippeastrine, narwedine, haemanthamine, pancratistatin, pretazettine, montanine, galanthindole, cherylline and ismine. Recently, more extensive studies have revealed that amaryllidaceae alkaloids exhibit a wide range of bioactivities, such as antitumor, antiviral, antibacterial, antifungal, antimalarial and analgesic. Acetylcholinesterase (AChE) inhibitory and cytotoxic activities have also been reported. The aim of the present review is to discuss the recent developments on the biological and pharmacological activities of amaryllidaceae alkaloids with IC50 or EC50 values since 2005, supporting the potential therapeutic possibilities for the use of these compounds.

Microbial transformation of androst-4-ene-3,17-dione by Beauveria bassiana.

The microbial transformation of androst-4-ene-3,17-dione (I) by the fungus Beauveria bassiana CCTCC AF206001 has been investigated using pH 6.0 and 7.0 media. Two hydroxylated metabolites were obtained with the pH 6.0 medium. The major product was 11alpha-hydroxyandrost-4-ene-3,17-dione (II) whereas the minor product was 6beta,11alpha-dihydroxyandrost-4-ene-3,17-dione (III). On the other hand, four hydroxylated and/or reduced metabolites were obtained with the pH 7.0 medium. The major product was 11alpha,17beta-dihydroxyandrost-ene-3-one (V) and the minor products were 17beta-hydroxyandrost-ene-3-one (IV), 6beta,11alpha,17beta-trihydroxyandrost-ene-3-one (VI) and 3alpha,11alpha,17beta-trihydroxy-5alpha-androstane (VII). The products were purified by chromatographic methods, and were identified on the basis of spectroscopic methods. This fungus strain is clearly an efficient biocatalyst for 11alpha-hydroxylation and reduction of the 17-carbonyl group.

Aesculetin-induced apoptosis through a ROS-mediated mitochondrial dysfunction pathway in human cervical cancer cells

Aesculetin (1) is an important coumarin found in various plant materials. It has been shown to have antiproliferative effects on several types of human cancer cells, but its effect on cervical cancer cells in vitro is unknown. In this study, we investigated that the cytotoxic effect of 1 on a non-cancer cell line (293) was smaller than on a tumor cell line (HeLa). This is the first report showing the possible mechanism of antiproliferative effect of 1 for the prevention of cervical cancer in cell culture models. It was found that 1 inhibited cell viability by inducing apoptosis, as evidenced by the formation of apoptotic bodies, generation of reactive oxygen species (ROS), and the accumulation of cells in the sub-G1 phase. Treatment with compound 1 decreased the cell growth in a dose-dependent manner with an IC50 value of 37.8 μM. Aesculetin-induced apoptosis was correlated with mitochondrial dysfunction (ΔΨm), leading to the release of cytochrome c from the mitochondria to the cytosol, as well as the proteolytic activation of caspases in HeLa cells. These results indicate that 1 induces apoptosis in HeLa cells through a ROS-mediated mitochondrial dysfunction pathway.

Doxorubicin-Loaded Glycyrrhetinic Acid Modified Recombinant Human Serum Albumin Nanoparticles for Targeting Liver Tumor Chemotherapy

Due to overexpression of glycyrrhetinic acid (GA) receptor in liver cancer cells, glycyrrhetinic acid modified recombinant human serum albumin (rHSA) nanoparticles for targeting liver tumor cells may result in increased therapeutic efficacy and decreased adverse effects of cancer therapy. In this study, doxorubicin (DOX) loaded and glycyrrhetinic acid modified recombinant human serum albumin nanoparticles (DOX/GA-rHSA NPs) were prepared for targeting therapy for liver cancer. GA was covalently coupled to recombinant human serum albumin nanoparticles, which could efficiently deliver DOX into liver cancer cells. The resultant GA-rHSA NPs exhibited uniform spherical shape and high stability in plasma with fixed negative charge (∼-25 mV) and a size about 170 nm. DOX was loaded into GA-rHSA NPs with a maximal encapsulation efficiency of 75.8%. Moreover, the targeted NPs (DOX/GA-rHSA NPs) showed increased cytotoxic activity in liver tumor cells compared to the nontargeted NPs (DOX/rHSA NPs, DOX loaded recombinant human serum albumin nanoparticles without GA conjugating). The targeted NPs exhibited higher cellular uptake in a GA receptor-positive liver cancer cell line than nontargeted NPs as measured by both flow cytometry and confocal laser scanning microscopy. Biodistribution experiments showed that DOX/GA-rHSA NPs exhibited a much higher level of tumor accumulation than nontargeted NPs at 1 h after injection in hepatoma-bearing Balb/c mice. Therefore, the DOX/GA-rHSA NPs could be considered as an efficient nanoplatform for targeting drug delivery system for liver cancer.

Synthesis and potential anticonvulsant activity of new N-3-substituted 5,5-cyclopropanespirohydantoins

Thirteen new 5-cyclopropanespirohydantoins with various N-3 substituents were synthesized and their pharmacological activity was determined with the objective to better understand their structure-activity relationship (SAR) for anticonvulsant activity. The anticonvulsant effects of these compounds were evaluated by maximal electroshock seizure (MES) test and subcutaneous pentylenetetrazole (scPTZ) test models in mice. All compounds substituted with cyclopropyl group at fifth position of hydantoin ring showed better protection against MES test. Compounds 5b, 5d, 5e, 5g and 5j were found to be the most potent compounds of this series and compared with the reference drug phenytoin sodium in MES test. Compound 5j also showed equipotent activity with the standard drug sodium valproate at the doses of 20 and 40 mg kg(-1) in scPTZ test.

Preparation and body distribution of freeze-dried powder of ursolic acid phospholipid nanoparticles.

Ursolic acid (UA) is a poor soluble natural triterpenoid. It has a wide variety of antitumor activities. We extracted it from Crataegus pinnatifida for the first time. To achieve a high bioavailability, targeting effect, stability, and an intravenous (i.v.) administration, the UA phospholipid nanopowders (UA-PL-NP) were prepared, characterized, and evaluated. With soybean phospholipid as the carrier and poloxamer 188 as emulsifier, the UA nanoparticle suspension was prepared by solvent emulsification–evaporation and ultrasonic dispersion. The UA-PL-NP was obtained by freeze drying. The body distribution in mice was studied after i.v. administration of UA-PL-NP and an UA control solution (UA-Sol). The entrapment efficiency (EE) and UA concentration in vitro and in vivo were analyzed by high-performance liquid chromatography (HPLC). The results showed that the UA-PL-NP had an average diameter of 273.8 nm with a zeta potential of −23.2 mV. The EE was up to 86.0%, and the drug loading (DL) was 12.8%. After i.v. administration of UA-PL-NP with low, middle and high doses, UA concentration in the livers of mice obviously increased during tested period and was highest in tested organs at 4 h. The AUC0–12 ratio of UA-PL-NP in liver to that in plasma was much higher than that of UA-Sol, and the liver AUC0–12 ratio of UA-PL-NP to UA-Sol was 8.6. These results indicate the UA-PL-NP have a good targeting to the liver after i.v. administration. Therefore, the UA-PL-NP is demonstrated to be available as an i.v. and liver targeting system for lipophilic antitumor triterpenoids.

Time lasting S-nitrosoglutathione polymeric nanoparticles delay cellular protein S-nitrosation.

Physiological S-nitrosothiols (RSNO), such as S-nitrosoglutathione (GSNO), can be used as nitric oxide (NO) donor for the treatment of vascular diseases. However, despite a half-life measured in hours, the stability of RSNO, limited by enzymatic and non-enzymatic degradations, is too low for clinical application. So, to provide a long-lasting effect and to deliver appropriate NO concentrations to target tissues, RSNO have to be protected. RSNO encapsulation is an interesting response to overcome degradation and provide protection. However, RSNO such as GSNO raise difficulties for encapsulation due to its hydrophilic nature and the instability of the S-NO bound during the formulation process. To our knowledge, the present study is the first description of the direct encapsulation of GSNO within polymeric nanoparticles (NP). The GSNO-loaded NP (GSNO-NP) formulated by a double emulsion process, presented a mean diameter of 289 ± 7 nm. They were positively charged (+40 mV) due to the methacrylic acid and ethylacrylate polymer (Eudragit® RL) used and encapsulated GSNO with a satisfactory efficiency (i.e. 54% or 40 mM GSNO loaded in the NP). In phosphate buffer (37 °C; pH 7.4), GSNO-NP released 100% of encapsulated GSNO within 3h and remained stable still 6h. However, in contact with smooth muscle cells, maximum protein nitrosation (a marker of NO bioavailability) was delayed from 1h for free GSNO to 18h for GSNO-NP. Therefore, protection and sustained release of NO were achieved by the association of a NO donor with a drug delivery system (such as polymeric NP), providing opportunities for vascular diseases treatment.

Synthesis and anticonvulsant activity of new 6-methyl-1-substituted-4,6-diazaspiro[2.4]heptane-5,7-diones.

In the present study on the development of new anticonvulsants, twenty new 6-methyl-1-substituted-4,6-diazaspiro[2.4]heptane-5,7-diones were synthesized and tested for anticonvulsant activity using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) screens. Their neurotoxicity was determined by the rotorod test. In this series, all of the alkyl- and aryl-substituted 5,5-cyclopropanespirohydantoins showed more or less protection against MES and/or scPTZ models. The most active of the series was 6-methyl-1-(4-(methylsulfonyl)phenyl)-4,6-diazaspiro[2.4]heptane-5,7-dione (6 t), which showed a MES ED(50) value of 12.5 mg/kg in mice. The median toxic dose (TD(50)) was 310 mg/kg, providing compound 6 t with a protection index (PI = TD(50)/ED(50)) of 24.8 in the MES test which is better than phenytoin.

A novel pH-responsive hydrogel based on natural polysaccharides for controlled release of protein drugs

A biocompatible and biodegradable hydrogel based on a natural polysaccharide was prepared and characterized to evaluate its applicability as an effective carrier for controlled protein delivery. The hydrogel exhibited significant pH-sensitivity, which was favorable for protein release in a simulated intestinal medium. It is capable of incorporating considerable amounts of protein drugs (encapsulation efficiency up to 97.6 wt%) following a protein-friendly preparation procedure. It was shown that the hydrogel is able to release two entrapped model protein drugs (bovine serum albumin and lysozyme) in a controlled manner with full preservation of protein stability and enzymatic activity for lysozyme. Moreover, the insulin-loaded hydrogel was effective in reducing blood glucose level in diabetic animal models. Importantly, the hydrogel showed no evidence of cytotoxicity in vitro and in vivo, rather, it is biodegradable. The synthesized hydrogel shows favorable features as a promising delivery carrier candidate for targeted delivery of protein drugs to specific sites.

Synthesis, characterization and biological evaluation of some 16E-arylidene androstane derivatives as potential anticancer agents.

A series of new 16E-arylidene androstane derivatives were synthesized and characterized. The new compounds were screened for their anticancer activities against the human cancer cell lines SW480, A549, HepG2 and HeLa in vitro using the MTT assay. The results of the in vitro study showed that a number of compounds have shown IC(50) values lower than 20 μM against the four cancer cell lines.