Proliferative activity of Echinacea angustifolia root extracts on cancer cells: Interference with doxorubicin cytotoxicity

Doxorubicin is an anticancer drug that causes apoptosis in cells, but cardiotoxicity limits the cumulative dose that can remain in the blood. Echinacea extracts have been prescribed to supplement cancer chemotherapy. In a recent study, it was reported that Echinacea purpurea extracts protected noncancerous cells from apoptosis. Our study aimed to determine interference with doxorubicin chemotherapy, and if fractions and compounds from Echinacea angustifolia roots protected the cells. Cervical and breast cancer cells were treated with the Echinacea samples and doxorubicin. At 0.05 and 0.5 microM doxorubicin concentration, cynarine increased HeLa cell growth by 48-125% and 29-101%, respectively (p<0.01). At 0.05 microM doxorubicin concentration, chicoric acid increased cell growth by 23-100% (p<0.01). When MCF-7 cells were treated with Echinacea and doxorubicin, the ethyl acetate fraction increased cell growth by 20-25%, and chicoric acid increased cell growth by 10-15%. Cynarine showed proliferative activity on HeLa cells, but showed antiproliferative activity on MCF-7 cells. Results indicate that phenolic compounds are responsible for proliferative activity. Studies with individual compounds show that chicoric acid and cynarine interfered with cells treated with 0.5 microM doxorubicin. The results of this study show that Echinacea herbal medicines affect cell proliferation despite cancer treatment, and that herbal medicines require further study with respect to anticancer drugs.     

Antibacterial Activity and Drug Release of Chitosan Sponge Containing Doxycycline Hyclate

The purpose of the present study was to develop and characterize the chitosan sponges loading with doxycycline hyclate and their antibacterial activities. The pore density of chitosan sponge prepared with freeze drying technique was increased as the higher concentrated chitosan solution was used. The sponge prepared from 10% w/w of the chitosan solution and crosslinking with glutaraldehyde solution was utilized for loading with doxycycline hyclate. The drug release and sustainable antibacterial activity of fabricated sponge were assessed using dissolution test and agar diffusion test, respectively. Drug release from non-crosslinked sponge into phosphate buffer pH7.4 was slower than that from crosslinked sponge since the former could absorb the medium and form gel to retard the initial drug diffusion. Sustainable antibacterial activity of developed sponge was evident against S. aureus and E. coli. In conclusion, the in vitro release profile and antibacterial efficiency indicated that doxycycline hyclate could be sustained using chitosan sponge.     

A Comparative Study Between the Antibacterial Effect of Nisin and Nisin-Loaded Chitosan/Alginate Nanoparticles on the Growth of Staphylococcus aureus in Raw and Pasteurized Milk Samples

The aim of this study was to evaluate the antibacterial effect of nisin-loaded chitosan/alginate nanoparticles as a novel antibacterial delivery vehicle. The nisin-loaded nanoparticles were prepared using colloidal dispersion of the chitosan/alginate polymers in the presence of nisin. After the preparation of the nisin-loaded nanoparticles, their physicochemical properties such as size, shape, and zeta potential of the formulations were studied using scanning electron microscope and nanosizer instruments, consecutively. FTIR and differential scanning calorimetery studies were performed to investigate polymer–polymer or polymer–protein interactions. Next, the release kinetics and entrapment efficiency of the nisin-loaded nanoparticles were examined to assess the application potential of these formulations as a candidate vector. For measuring the antibacterial activity of the nisin-loaded nanoparticles, agar diffusion and MIC methods were employed. The samples under investigation for total microbial counts were pasteurized and raw milks each of which contained the nisin-loaded nanoparticles and inoculated Staphylococcus aureus (ATCC 19117 at 10⁶ CFU/mL), pasteurized and raw milks each included free nisin and S. aureus (10⁶ CFU/mL), and pasteurized and raw milks each had S. aureus (10⁶ CFU/mL) in as control. Total counts of S. aureus were measured after 24 and 48 h for the pasteurized milk samples and after the time intervals of 0, 6, 10, 14, 18, and 24 h for the raw milk samples, respectively. According to the results, entrapment efficiency of nisin inside of the nanoparticles was about 90–95%. The average size of the nanoparticles was 205 nm, and the average zeta potential of them was ?47 mV. In agar diffusion assay, an antibacterial activity (inhibition zone diameter, at 450 IU/mL) about 2 times higher than that of free nisin was observed for the nisin-loaded nanoparticles. MIC of the nisin-loaded nanoparticles (0.5 mg/mL) was about four times less than that of free nisin (2 mg/mL). Evaluation of the kinetic of the growth of S. aureus based on the total counts in the raw and pasteurized milks revealed that the nisin-loaded nanoparticles were able to inhibit more effectively the growth of S. aureus than free nisin during longer incubation periods. In other words, the decrease in the population of S. aureus for free nisin and the nisin-loaded nanoparticles in pasteurized milk was the same after 24 h of incubation while lessening in the growth of S. aureus was more marked for the nisin-loaded nanoparticles than the samples containing only free nisin after 48 h of incubation. Although the same growth reduction profile in S. aureus was noticed for free nisin and the nisin-loaded nanoparticles in the raw milk up to 14 h of incubation, after this time the nisin-loaded nanoparticles showed higher growth inhibition than free nisin. Since, generally, naked nisin has greater interactions with the ingredients present in milk samples in comparison with the protected nisin. Therefore, it is concluded that the antibacterial activity of nisin naturally decreases more during longer times of incubation than the protected nisin with the chitosan/alginate nanoparticles. Consequently, this protection increases and keeps antibacterial efficiency of nisin in comparison with free nisin during longer times of storage. These results can pave the way for further research and use of these nanoparticles as new antimicrobial agents in various realms of dairy products.     

Applying the Taguchi Design for Optimized Formulation of Sustained Release Gliclazide Chitosan Beads: An In Vitro/In Vivo Study

Gliclazide is a second generation of hypoglycemic sulfonylurea and acts selectively on pancreatic β cell to control diabetes mellitus. The objective of this study was to produce a controlled release system of gliclazide using chitosan beads. Chitosan beads were produced by dispersion technique using tripolyphosphate (TPP) as gelating agent. The effects of process variables including chitosan molecular weight, concentration of chitosan and TPP, pH of TPP, and cross-linking time after addition of chitosan were evaluated by Taguchi design on the rate of drug release, mean release time (MRT), release efficiency (RE₈%), and particle size of the beads. The blood glucose lowering effect of the beads was studied in normal and streptozotocin-diabetic rats. The optimized formulation CL₂T₅P₂t₁₀ with about 31% drug loading, 2.4 h MRT, and 69.16% RE₈% decreased blood glucose level in normal rats for 24 h compared to pure powder of gliclazide that lasted for just 10 h.     

LUVs Recovered with Chitosan: A New Preparation for Vaccine Delivery

Chitosan, α-(1–4)-amino-2-deoxy-β-D-glucan, is a deacetylated form of chitin, an abundant natural polysaccharide present in crustacean shells. Its unique characteristics such as positive charge, biodegradability, biocompatibility, nontoxicity, and rigid linear molecular structure make this macromolecule ideal as drug carrier. The association between chitosan and liposomes was carefully described, where REVs (reverse phase evaporation vesicles) were sandwiched by chitosan. The usage of these particles in vaccine formulation is here proposed for the first time in the literature. The Chitosan-REVs now stabilized by polyvinilic alcohol were the vehicle for Diphtheria toxoid (Dtxd). Round chitosan-sandwiched REVs (REVs-Chi) particles of 373 ± 17 nm containing 65% Dtxd were obtained. After 200 min of incubation in a simulated gastric fluid, 70% of the Dtxd was liberated from REVs-Chi in comparison to 100% of Dtxd liberated from pure REVs. In PBS, the Dtxd liberation from REVS-Chi was about 60%. Mice were immunized with Dtxd encapsulated within REVs-Chi and with other REVs/Dtxd formulations adsorbed onto Freund adjuvant or alumen [AIF and Al(OH)₃]. The response patterns and the immune maturity were measured by IgG₁ and IgG_2a titrations. REVs-Chi containing Dtxd elicited both antibodies production giving the animals higher immune response and selectivity. It was interesting that the memory of those mice immunized with REVs-Chi containing Dtxd enhanced, after booster, antibody production by 47% in contrast with 17 and 7% in mice immunized with the antigen vehiculated in REVs-AIF or REVs-Al(OH)₃, respectively.     

综述——纳米材料与药物输递：基于聚合物的环境敏感型纳米抗肿瘤药物传输系统的研究

环境敏感型聚合物纳米抗肿瘤药物传递系统能够响应外界环境的微小刺激,引起自身结构的变化,释放出药物,在肿瘤治疗方面具长效低毒、可控及高载药量等优势,已被广泛应用于生物医学领域．本文介绍了聚合物环境响应型纳米药物传输系统的发展近况,并从pH 值敏感型、温度敏感型、氧化还原敏感型、酶敏感型以及其他敏感型给药系统角度,阐述了环境敏感型药物传输系统在抗肿瘤领域的研究现状及未来展望．     

Designing Chimeric Peptides: A Powerful Tool for Enhancing Antibacterial Activity

Chimeric peptides containing short sequences derived from bovine Lactoferricin (LfcinB) and Buforin II (BFII) were synthetized using solid-phase peptide synthesis (SPPS) and characterized via reversed-phase liquid chromatography and mass spectrometry. The chimeras were obtained with high purity, demonstrating their synthetic viability. The chimeras’ antibacterial activity against Gram-positive and Gram-negative strains was evaluated. Our results showed that all the chimeras exhibited greater antibacterial activity against the evaluated strains than the individual sequences, suggesting that chemical binding of short sequences derived from AMPs significantly increased the antibacterial activity. For each strain, the chimera with the best antibacterial activity exerted a bacteriostatic and/or bactericidal effect, which was dependent on the concentration. It was found that: (i) the antibacterial activity of a chimera is mainly influenced by the linked sequences, the palindromic motif RLLRRLLR being the most relevant one; (ii) the inclusion of a spacer between the short sequences did not significantly affect the chimera's synthesis process; however, it enhanced its antibacterial activity against Gram-negative and Gram-positive strains; on the other hand, (iii) the replacement of Arg with Lys in the LfcinB or BFII sequences improved the chimeras’ synthesis process without significantly affecting their antibacterial activity. These results illustrate the great importance of the synthesis of chimeric peptides for the generation of promising antibacterial peptides.     

Chitosan-based delivery systems for curcumin: A review of pharmacodynamic and pharmacokinetic aspects

Effective drug delivery is one of the most important issues associated with the administration of therapeutic agents that have low oral bioavailability. Curcumin is an active ingredient in the turmeric plant, which has low oral bioavailability due to its poor aqueous solubility. One strategy that has been considered for enhancing the aqueous solubility, and, thus, its oral bioavailability, is the use of chitosan as a carrier for curcumin. Chitosan is a biodegradable and biocompatible polymer that is relatively water-soluble. Therefore, various studies have sought to improve the aqueous solubility of chitosan. The use of different pharmaceutical excipients and formulation strategies has the potential to improve aqueous solubility, formulation processing, and the overall delivery of hydrophobic drugs. This review focuses on various methods utilized for chitosan-based delivery of curcumin.     

大鼠在体海马CA1区场电位引导新技术——刺激/记录/给药一体化装置的开发和应用

大鼠海马场电位记录是研究学习记忆的一个重要手段,尤以在体记录更具生理学意义.为克服目前在体海马场电位记录的弊端和诸多不便,提高实验效率,设计并完善了一套简便易行,融刺激、记录、给药于一体的大鼠海马在体CA1区场电位实验技术.将雄性SD大鼠麻醉后固定于脑立体定位仪上,利用自制的刺激/记录/给药联合装置,引导海马CA1区场兴奋性突触后电位(fEPSP).结果表明,使用刺激/记录/给药联合装置能长时间稳定记录由测试刺激诱发的海马CA1区fEPSP.高频刺激条件下,能成功诱导早期时相长时程增强(E-LTP)和晚期时相型长时程增强(L-LTP).海马内注射AMPA受体阻断剂CNQX(100μmol/L,1μl)可迅速抑制fEPSP,注射NMDA受体拮抗剂AP-5(100μmol/L,1μl)可明显压抑LTP,药物发挥作用的时间较侧脑室给药明显缩短,剂量减少.采用此联合装置还成功实现了PPF的稳定记录.总之,采用刺激/记录/给药一体化技术进行在体海马CA1区场电位记录的特点是简单、可靠、高效,可以为开展脑认知功能活动的电生理学研究奠定良好的基础.     

Novel role for pectin methylesterase in Arabidopsis: A new function showing ribosome-inactivating protein (RIP) activity

Ribosome-inactivating proteins (RIPs, EC 3.2.2.22) are plant enzymes that can inhibit the translation process by removing single adenine residues of the large rRNA. These enzymes are known to function in defense against pathogens, but their biological role is unknown, partly due to the absence of work on RIPs in a model plant. In this study, we purified a protein showing RIP activity from Arabidopsis thaliana by employing chromatography separations coupled with an enzymatic activity. Based on N-terminal and internal amino acid sequencing, the RIP purified was identified as a mature form of pectin methylesterase (PME, At1g11580). The purified native protein showed both PME and RIP activity. PME catalyzes pectin deesterification, releasing acid pectin and methanol, which cause cell wall changes. We expressed the full-length and mature form of cDNA clones into an expression vector and transformed it in Escherichia coli for protein expression. The recombinant PME proteins (full-length and mature) expressed in E. coli did not show either PME or RIP activity, suggesting that post-translational modifications are important for these enzymatic activities. This study demonstrates a new function for an old enzyme identified in a model plant and discusses the possible role of a protein's conformational changes corresponding to its dual enzymatic activity.     

Temperature-sensitive paramagnetic liposomes for image-guided drug delivery: Mn versus [Gd(HPDO3A)(H2O)]

Temperature-sensitive liposomes (TSLs) loaded with doxorubicin (Dox), and Magnetic Resonance Imaging contrast agents (CAs), either manganese (Mn^2 +) or [Gd(HPDO3A)(H₂O)], provide the advantage of drug delivery under MR image guidance. Encapsulated MRI CAs have low longitudinal relaxivity (r₁) due to limited transmembrane water exchange. Upon triggered release at hyperthermic temperature, the r₁ will increase and hence, provides a means to monitor drug distribution in situ. Here, the effects of encapsulated CAs on the phospholipid bilayer and the resulting change in r₁ were investigated using MR titration studies and ¹H Nuclear Magnetic Relaxation Dispersion (NMRD) profiles. Our results show that Mn^2 + interacted with the phospholipid bilayer of TSLs and consequently, reduced doxorubicin retention capability at 37 °C within the interior of the liposomes over time. Despite that, Mn^2 +-phospholipid interaction resulted in higher r₁ increase, from 5.1 ± 1.3 mM^− 1 s^− 1 before heating to 32.2 ± 3 mM^− 1 s^− 1 after heating at 60 MHz and 37 °C as compared to TSL(Gd,Dox) where the longitudinal relaxivities before and after heating were 1.2 ± 0.3 mM^− 1 s^− 1 and 4.4 ± 0.3 mM^− 1 s^− 1, respectively. Upon heating, Dox was released from TSL(Mn,Dox) and complexation of Mn^2 + to Dox resulted in a similar Mn^2 + release profile. From 25 to 38 °C, r₁ of [Gd(HPDO3A)(H₂O)] gradually increased due to increase transmembrane water exchange, while no Dox release was observed. From 38 °C, the release of [Gd(HPDO3A)(H₂O)] and Dox was irreversible and the release profiles coincided. By understanding the non-covalent interactions between the MRI CAs and phospholipid bilayer, the properties of the paramagnetic TSLs can be tailored for MR guided drug delivery.