Oxidative activation of indole-3-acetic acids to cytotoxic species- a potential new role for plant auxins in cancer therapy

Enzyme-Mediated Bioorthogonal Cascade Catalytic Reaction for Metabolism Intervention and Enhanced Ferroptosis on Neuroblastoma

It remains a tremendous challenge to explore effective therapeutic modalities against neuroblastoma, a lethal cancer of the sympathetic nervous system with poor prognosis and disappointing treatment outcomes. Considering the limitations of conventional treatment modalities and the intrinsic vulnerability of neuroblastoma, we herein develop a pioneering sequential catalytic therapeutic system that utilizes lactate oxidase (LOx)/horseradish peroxidase (HRP)-loaded amorphous zinc metal-organic framework, named LOx/HRP-aZIF, in combination with a 3-indole-acetic acid (IAA) prodrug. On the basis of abnormal lactate accumulation that occurs in the tumor microenvironment, the cascade reaction of LOx and HRP consumes endogenous glutathione and a reduced form of nicotinamide adenine dinucleotide to achieve the first stage of killing cancer cells via antioxidative incapacitation and electron transport chain interference. Furthermore, the generation of reactive oxygen species induced by HRP and IAA through bioorthogonal catalysis promotes ferritin degradation and lipid peroxidation, ultimately provoking self-enhanced ferroptosis with positive feedback by initiating an endogenous Fenton reaction. This work highlights the superiority of the natural enzyme-dependent cascade and bioorthogonal catalytic reaction, offering a paradigm for synergistically enzyme-based metabolism-ferroptosis anticancer therapy.

Small-molecule redox modulators with anticancer activity: A comprehensive mechanistic update

The pursuit of effective anticancer therapies has led to a burgeoning interest in the realm of redox modulation. This review provides a comprehensive exploration of the intricate mechanisms by which diverse anticancer molecules leverage redox pathways for therapeutic intervention. Redox modulation, encompassing the fine balance of oxidation-reduction processes within cells, has emerged as a pivotal player in cancer treatment. This review delves into the multifaceted mechanisms of action employed by various anticancer compounds, including small molecules and natural products, to disrupt cancer cell proliferation and survival. Beginning with an examination of the role of redox signaling in cancer development and resistance, the review highlights how aberrant redox dynamics can fuel tumorigenesis. It then meticulously dissects the strategies employed by anticancer agents to induce oxidative stress, perturb redox equilibrium, and trigger apoptosis within cancer cells. Furthermore, the review explores the challenges and potential side effects associated with redox-based treatments, along with the development of novel redox-targeted agents. In summary, this review offers a profound understanding of the dynamic interplay between redox modulation and anticancer molecules, presenting promising avenues to revolutionize cancer therapy and enhance patient outcomes.

Nanozymes and nanoflower: Physiochemical properties, mechanism and biomedical applications

Natural enzymes possess several drawbacks which limits their application in industries, wastewater remediation and biomedical field. Therefore, in recent years researchers have developed enzyme mimicking nanomaterials and enzymatic hybrid nanoflower which are alternatives of enzyme. Nanozymes and organic inorganic hybrid nanoflower have been developed which mimics natural enzymes functionalities such as diverse enzyme mimicking activities, enhanced catalytic activities, low cost, ease of preparation, stability and biocompatibility. Nanozymes include metal and metal oxide nanoparticles mimicking oxidases, peroxidases, superoxide dismutase and catalases while enzymatic and non-enzymatic biomolecules were used for preparing hybrid nanoflower. In this review nanozymes and hybrid nanoflower have been compared in terms of physiochemical properties, common synthetic routes, mechanism of action, modification, green synthesis and application in the field of disease diagnosis, imaging, environmental remediation and disease treatment. We also address the current challenges facing nanozyme and hybrid nanoflower research and the possible way to fulfil their potential in future.

Assessment toxic effects of exposure to 3-indoleacetic acid via hemato-biochemical, hormonal, and histopathological screening in rats

The current study purposed to investigate the 3-indoleacetic acid (IAA) possible adverse impacts on hematological parameters, hepatorenal function, cardiac, and skeletal muscles as well as testes of rats and histopathological alterations of respective organs and to determine the extent of reversing any adverse impacts occurred in animals after IAA withdrawal. Rats were exposed orally to 500 mg/kg BW by gastric intubation once daily for 14 days, after which one-half was sacrificed and the remaining half left for a further 14 days without IAA exposure. The exposure of rats to IAA produced anemia, leukopenia, neutrophilia, lymphopenia, and a significant increase in activities of serum transaminase, gamma-glutamyl transferase, creatine kinase-myocardial band, creatine kinase-muscle type, and levels of serum creatinine, sodium, chloride, and potassium. Furthermore, serum levels of testosterone, gonadotropins, and leptin significantly declined. The changes in most of measured parameters continued after IAA withdrawal. Histopathological alterations in different tissues supported these changes. In conclusion, subacute exposure to IAA at a high concentration could exert hematotoxicity and toxic effects on many soft organs and its withdrawal led to incomplete recovery of animals. Thus, IAA should be used cautiously as extensive use of it at high concentrations can cause harmful effects on the environment, animals and human beings.

Thermosensitive Polymer Conjugated Prodrug-Activating Enzyme with Enhanced Tumor Retention and Antitumor Efficacy

Enzyme-activated prodrug therapy has emerged as an effective strategy for cancer therapy. However, the inefficient delivery of prodrug-activating enzymes into tumor tissues leads to unsatisfactory antitumor efficacy and undesirable toxicity to normal tissues. Herein, we report in situ growth of a thermosensitive polymer of poly(diethylene glycol) methyl ether methacrylate (PDEGMA) from horseradish peroxidase (HRP) to yield a HRP-PDEGMA conjugate with well-retained activity as compared to HRP. The conjugate shows a sharp phase transition behavior with a lower critical solution temperature of 23 °C. The conjugate catalyzes the conversion of non-cytotoxic indole-3-acetic acid (IAA) into cytotoxic species for killing tumor cells. Notably, the PDEGMA conjugation not only increases the stability and cellular uptake of HRP but also prolongs the tumor retention time of HRP upon intratumoral injection. As a result, in mice bearing melanoma, the conjugate inhibits the growth of melanoma much more efficiently than HRP. These results demonstrate that the thermosensitive polymer conjugation of an enzyme is an effective strategy that can enhance the antitumor efficacy of an enzyme-activated prodrug.

Microbiota modulation and anti-obesity effects of fermented Pyrus ussuriensis Maxim extract against high-fat diet-induced obesity in rats

Pyrus ussuriensis Maxim (Korean pear) has been used for hundreds of years as a traditional herbal medicine due to its strong phytochemical profile and pharmacological efficacy. In this study, we evaluated the anti-obesity potential of Pyrus ussuriensis Maxim extracts (PUE) and investigated the underlying mechanisms using a combination of in vitro, in vivo, and microbiota regulation approaches. In an adipogenesis assay, the fermented (F)PUE and non-fermented (NF)PUE significantly reduced the differentiation of 3T3-L1 preadipocyte in a dose-dependent manner with an IC₅₀ of 85.33 and 96.67 µg/mL, respectively. In a high-fat diet (HFD)-induced obese rat model (n = 8 animals/group), oral administration of FPUE additionally reduced the total body weight gain significantly. No difference in food intake was observed, however, between the control-chow diet, FPUE, and NFPUE-treated HFD rats. Adipose tissue mass and systemic insulin resistance were markedly reduced in FPUE-treated HFD rats, in a dose-dependent manner. Treatment with FPUE also greatly improved obesity-related biomarkers, including total cholesterol, leptin, active ghrelin, Total GIP, adiponectin, and proinflammatory cytokines. Moreover, FPUE significantly suppressed HFD-induced adipogenic genes expression, while increasing fatty acid oxidation-related genes expression. Additionally, FPUE treatment attenuated the HFD-induced Firmicutes proportion within the intestinal microbiota by regulating key metabolic pathways, thus enhancing microbial population diversity (e.g., increasing Bacteroides, Bifidobacterium, Prevotella, Eubacterium, and Clostridium). Together, these results reveal a strong anti-obesity potential of FPUE through adipogenesis, lipid metabolism, weight reduction, and microbiota regulation, raising the possibility of developing FPUE as a novel therapeutic agent to control obesity and obesity-associated metabolic disorders.

State-of-the-Art Advances of Nanomedicine for Diagnosis and Treatment of Bladder Cancer

Bladder cancer is a common malignant tumor of the urinary system. Cystoscopy, urine cytology, and CT are the routine diagnostic methods. However, there are some problems such as low sensitivity and difficulty in staging, which must be urgently supplemented by novel diagnostic methods. Surgery, intravesical instillation, systemic chemotherapy, and radiotherapy are the main clinical treatments for bladder cancer. It is difficult for conventional treatment to deal with tumor recurrence, progression and drug resistance. In addition, the treatment agents usually have the defects of poor specific distribution ability to target tumor tissues and side effects. The rapid development of nanomedicine has brought hope for the treatment of bladder cancer in reducing side effects, enhancing tumor inhibition effects, and anti-drug resistance. Overall, we review the new progression of nano-platforms in the diagnosis and treatment of bladder cancer.

Bioorthogonal Catalysis for Treatment of Solid Tumors Using Thermostable, Self-Assembling, Single Enzyme Nanoparticles and Natural Product Conversion with Indole-3-acetic Acid

Bioorthogonal catalysis (BC) generates chemical reactions not present in normal physiology for the purpose of disease treatment. Because BC catalytically produces the desired therapy only at the site of disease, it holds the promise of site-specific treatment with little or no systemic exposure or side effects. Transition metals are typically used as catalytic centers in BC; however, solubility and substrate specificity typically necessitate a coordinating enzyme and/or stabilizing superstructure for in vivo application. We report the use of self-assembling, porous exoshells (tESs) to encapsulate and deliver an iron-containing reaction center for the treatment of breast cancer. The catalytic center is paired with indole-3-acetic acid (IAA), a natural product found in edible plants, which undergoes oxidative decarboxylation, via reduction of iron(III) to iron(II), to produce free radicals and bioactive metabolites. The tES encapsulation is critical for endocytic uptake of BC reaction centers and, when followed by administration of IAA, results in apoptosis of MDA-MB-231 triple negative cancer cells and complete regression of in vivo orthotopic xenograft tumors (p < 0.001, n = 8 per group). When Renilla luciferase (rLuc) is substituted for horseradish peroxidase (HRP), whole animal luminometry can be used to monitor in vivo activity.

Advances on Delivery of Cytotoxic Enzymes as Anticancer Agents

Cancer is one of the most serious human diseases, causing millions of deaths worldwide annually, and, therefore, it is one of the most investigated research disciplines. Developing efficient anticancer tools includes studying the effects of different natural enzymes of plant and microbial origin on tumor cells. The development of various smart delivery systems based on enzyme drugs has been conducted for more than two decades. Some of these delivery systems have been developed to the point that they have reached clinical stages, and a few have even found application in selected cancer treatments. Various biological, chemical, and physical approaches have been utilized to enhance their efficiencies by improving their delivery and targeting. In this paper, we review advanced delivery systems for enzyme drugs for use in cancer therapy. Their structure-based functions, mechanisms of action, fused forms with other peptides in terms of targeting and penetration, and other main results from in vivo and clinical studies of these advanced delivery systems are highlighted.

Role of Indole Derivatives in Agrochemistry: Synthesis and Future Insights

Abstract:

Heterocycles constitute a wider class of organic compounds which contribute significantly in every facet of pure and applied chemistry. Indole, one of the bicyclic heterocyclic compounds containing nitrogen atom, witnessed unparalleled biological activity such as antiviral, antibacterial, anticancer, anti-depressant and antifungal activities. Different biological activities exhibited by indole derivatives provide the impulsion to explore its activity against anti-phytopathogenic microbes to save the plants from pests and disease, as food security will once again become a rigid demand. This review mainly focuses on various methods related to the synthesis of indole derivatives and its role in agriculture.

Nanozymes: Versatile Platforms for Cancer Diagnosis and Therapy

Natural enzymes usually suffer from high production cost, ease of denaturation and inactivation, and low yield, making them difficult to be broadly applicable. As an emerging type of artificial enzyme, nanozymes that combine the characteristics of nanomaterials and enzymes are promising alternatives. On the one hand, nanozymes have high enzyme-like catalytic activities to regulate biochemical reactions. On the other hand, nanozymes also inherit the properties of nanomaterials, which can ameliorate the shortcomings of natural enzymes and serve as versatile platforms for diverse applications. In this review, various nanozymes that mimic the catalytic activity of different enzymes are introduced. The achievements of nanozymes in different cancer diagnosis and treatment technologies are summarized by highlighting the advantages of nanozymes in these applications. Finally, future research directions in this rapidly developing field are outlooked.

Iboga Inspired N-Indolylethyl-Substituted Isoquinuclidines as a Bioactive Scaffold: Chemoenzymatic Synthesis and Characterization as GDNF Releasers and Antitrypanosoma Agents

The first stage of the drug discovery process involves the identification of small compounds with biological activity. Iboga alkaloids are monoterpene indole alkaloids (MIAs) containing a fused isoquinuclidine-tetrahydroazepine ring. Both the natural products and the iboga-inspired synthetic analogs have shown a wide variety of biological activities. Herein, we describe the chemoenzymatic preparation of a small library of novel N-indolylethyl-substituted isoquinuclidines as iboga-inspired compounds, using toluene as a starting material and an imine Diels-Alder reaction as the key step in the synthesis. The new iboga series was investigated for its potential to promote the release of glial cell line-derived neurotrophic factor (GDNF) by C6 glioma cells, and to inhibit the growth of infective trypanosomes. GDNF is a neurotrophic factor widely recognized by its crucial role in development, survival, maintenance, and protection of dopaminergic neuronal circuitries affected in several neurological and psychiatric pathologies. Four compounds of the series showed promising activity as GDNF releasers, and a leading structure (compound 11) was identified for further studies. The same four compounds impaired the growth of bloodstream Trypanosoma brucei brucei (EC₅₀ 1-8 μM) and two of them (compounds 6 and 14) showed a good selectivity index.

Amelioration of indole acetic acid-induced cytotoxicity in mice using zinc nanoparticles biosynthesized with Ochradenus arabicus leaf extract

The diversity of natural phytochemicals represents an unlimited source for discovery and development of new drugs. Ochradenus arabicus, (family: Resedaceae) a notable medicinal plant displays a high content of flavonoid glycosides. This study investigates a possible preventative role of zinc nanoparticles biosynthesized by O. arabicus leaf extracts (OAZnO NPs) in limiting genotoxicity and cytotoxicity caused by indole acetic acid (IAA) in laboratory mice. ZnO NPs were synthesized using O. arabicus leaf extracts and characterized with UV–visible spectroscopy, scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The mice were randomly distributed into the following six groups: control, OAZnO NPs treated (10 mg/kg BW), IAA treated (50 mg/kg BW); simultaneous treatment, pre-treatment, and post-treatment. Reactive oxygen species (ROS), DNA damage, chromosome aberration, and apoptosis were analyzed as toxicity endpoints. IAA exposure significantly induced production of ROS, DNA damage, apoptosis, chromosome aberrations, and micronuclei. Pre-, post-, and simultaneous treatment with OAZnO NPs ameliorated the damage caused by IAA exposure. Exposure to OAZnO NPs alone caused no toxicity for any endpoint based on comparison to controls. This study demonstrated that IAA-induced cytotoxic damage in mice could be ameliorated by treatment with OAZnO NPs. These findings require additional verification in mechanistic and in vitro studies.

Enzyme prodrug therapy: cytotoxic potential of paracetamol turnover with recombinant horseradish peroxidase

Targeted cancer treatment is a promising, less invasive alternative to chemotherapy as it is precisely directed against tumor cells whilst leaving healthy tissue unaffected. The plant-derived enzyme horseradish peroxidase (HRP) can be used for enzyme prodrug cancer therapy with indole-3-acetic acid or the analgesic paracetamol (acetaminophen). Oxidation of paracetamol by HRP in the presence of hydrogen peroxide leads to N-acetyl-p-benzoquinone imine and polymer formation via a radical reaction mechanism. N-acetyl-p-benzoquinone imine binds to DNA and proteins, resulting in severe cytotoxicity. However, plant HRP is not suitable for this application since the foreign glycosylation pattern is recognized by the human immune system, causing rapid clearance from the body. Furthermore, plant-derived HRP is a mixture of isoenzymes with a heterogeneous composition. Here, we investigated the reaction of paracetamol with defined recombinant HRP variants produced in E. coli, as well as plant HRP, and found that they are equally effective in paracetamol oxidation at a concentration ≥ 400 µM. At low paracetamol concentrations, however, recombinant HRP seems to be more efficient in paracetamol oxidation. Yet upon treatment of HCT-116 colon carcinoma and FaDu squamous carcinoma cells with HRP-paracetamol no cytotoxic effect was observed, neither in the presence nor absence of hydrogen peroxide.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00706-021-02848-x.

Biogenic and characterizations of new silver nanoparticles stabilized with indole acetic acid derived from Azospirillum brasilense MMGH-SADAT1, their bioactivity, and histopathological assessment in rats

An Egyptian rhizobacterium Azospirillum sp. isolated from Sadat city was able to produce indole acetic acid (IAA) up to (30.59 µg/ml). The isolate was identified biochemically and by 16S rRNA sequencing which showed 99.9% similarity to Azospirillum brasilense. The new isolate has been registered in Genbank with accession number MH179119.1. Extracted IAA was used as reducing or stabilizing agent of sliver nanoparticles (AgNPs). Successful fabrication of biogenic IAA-AgNPs was confirmed by Fourier Transform Infrared Spectrophotometer (FTIR) analysis of IAA which showed absorbance peak at 3434.78 cm^-1 due to the N-H stretch of primary amines. Highly resolution Transmission Electron Microscopy (HR-TEM) showed AgNPs coating or capping with IAA in spherical shaped with size ranged from 6.01 to 44.02 nm. Energy dispersive X-ray (EDX) analysis revealed that Ag⁺ ions were attached to the surface of IAA-AgNPs particles. HR-TEM examination showed cell wall damage of Citrobacter freundii cells after exposure to IAA-AgNPs leading to cell death. In vivo results showed that C. freundii infection of rats induced significant increase in liver and kidney functions and deleterious histopathological alteration in rat's tissues. However, treatment by extracted IAA and IAA-AgNPs could normalize the biochemical and histopathological alterations occurred in infected rats. This is the first study to prove that IAA extracted from Azospirillum brasilense is a hopeful capping agent for NPs which has potential to protect against pathogenic infections, nontoxic and/or safe on rat's metabolisms.

Hyaluronic acid-coated chitosan nanoparticles as carrier for the enzyme/prodrug complex based on horseradish peroxidase/indole-3-acetic acid: Characterization and potential therapeutic for bladder cancer cells

Hybrid nanoparticles composed of different biopolymers for delivery of enzyme/prodrug systems are of interest for cancer therapy. Hyaluronic acid-coated chitosan nanoparticles (CS/HA NP) were prepared to encapsulate individually an enzyme/pro-drug complex based on horseradish peroxidase (HRP) and indole-3-acetic acid (IAA). CS/HA NP showed size around 158 nm and increase to 170 and 200 nm after IAA and HRP encapsulation, respectively. Nanoparticles showed positive zeta potential values (between +20.36 mV and +24.40 mV) and higher encapsulation efficiencies for both nanoparticles (up to 90 %) were obtained. Electron microscopy indicated the formation of spherical particles with smooth surface characteristic. Physicochemical and thermal characterizations suggest the encapsulation of HRP and IAA. Kinetic parameters for encapsulated HRP were similar to those of the free enzyme. IAA-CS/HA NP showed a bimodal release profile of IAA with a high initial release (72 %) followed by a slow-release pattern. The combination of HRP-CS/HA NP and IAA- CS/HA NP reduced by 88 % the cell viability of human bladder carcinoma cell line (T24) in the concentrations 0.5 mM of pro-drug and 1.2 μg/mL of the enzyme after 24 h.

Potential of unglycosylated horseradish peroxidase variants for enzyme prodrug cancer therapy

Fighting cancer still relies on chemo- and radiation therapy, which is a trade-off between effective clearance of malignant cells and severe side effects on healthy tissue. Targeted cancer treatment on the other hand is a promising and refined strategy with less systemic interference. The enzyme horseradish peroxidase (HRP) exhibits cytotoxic effects on cancer cells in combination with indole-3-acetic acid (IAA). However, the plant-derived enzyme is out of bounds for medical purposes due to its foreign glycosylation pattern and resulting rapid clearance and immunogenicity. In this study, we generated recombinant, unglycosylated HRP variants in Escherichia coli using random mutagenesis and investigated their biochemical properties and suitability for cancer treatment. The cytotoxicity of the HRP-IAA enzyme prodrug system was assessed in vitro with HCT-116 human colon, FaDu human nasopharyngeal squamous cell carcinoma and murine colon adenocarcinoma cells (MC38). Extensive cytotoxicity was shown in all three cancer cell lines: the cell viability of HCT-116 and MC38 cells treated with HRP-IAA was below 1% after 24 h incubation and the surviving fraction of FaDu cells was ≤ 10% after 72 h. However, no cytotoxic effect was observed upon in vivo intratumoral application of HRP-IAA on a MC38 tumor model in C57BL/6J mice. However, we expect that targeting of HRP to the tumor by conjugation to specific antibodies or antibody fragments will reduce HRP clearance and thereby enhance therapy efficacy.

Virus-Derived Peptides for Hepatic Enzyme Delivery

Recently, a lipopeptide derived from the hepatitis B virus (HBV) large surface protein has been developed as an HBV entry inhibitor. This lipopeptide, called MyrcludexB (MyrB), selectively binds to the sodium taurocholate cotransporting polypeptide (NTCP) on the basolateral membrane of hepatocytes. Here, the feasibility of coupling therapeutic enzymes to MyrB was investigated for the development of enzyme delivery strategies. Hepatotropic targeting shall enable enzyme prodrug therapies and detoxification procedures. Here, horseradish peroxidase (HRP) was conjugated to MyrB via maleimide chemistry, and coupling was validated by SDS-PAGE and reversed-phase HPLC. The specificity of the target recognition of HRP-MyrB could be shown in an NTCP-overexpressing liver parenchymal cell line, as demonstrated by competitive inhibition with an excess of free MyrB and displayed a strong linear dependency on the applied HRP-MyrB concentration. In vivo studies in zebrafish embryos revealed a dominating interaction of HRP-MyrB with scavenger endothelial cells vs xenografted NTCP expressing mammalian cells. In mice, radiolabeled ¹²⁵I-HRP-MyrBy, as well as the non-NTCP targeted control HRP-peptide-construct (¹²⁵I-HRP-alaMyrBy) demonstrated a strong liver accumulation confirming the nonspecific interaction with scavenger cells. Still, MyrB conjugation to HRP resulted in an increased and NTCP-mediated hepatotropism, as revealed by competitive inhibition. In conclusion, the model enzyme HRP was successfully conjugated to MyrB to achieve NTCP-specific targeting in vitro with the potential for ex vivo diagnostic applications. In vivo, target specificity was reduced by non-NTCP-mediated interactions. Nonetheless, tissue distribution experiments in zebrafish embryos provide mechanistic insight into underlying scavenging processes indicating partial involvement of stabilin receptors.

Chitosan and chitosan/PEG nanoparticles loaded with indole-3-carbinol: Characterization, computational study and potential effect on human bladder cancer cells

Indole-3-carbinol (I3C) is a plant molecule known to be active against several types of cancer, but some chemical characteristics limit its clinical applications. In order to overcome these limitations, polymeric nanoparticles can be used as carrier systems for targeted delivery of I3C. In this study, chitosan and chitosan/polyethylene glycol nanoparticles (CS NP and CS/PEG NP, respectively) were prepared to encapsulate I3C by ionic gelation method. The polymeric nanoparticles were characterized by Dynamic Scattering Light (DLS), Zeta Potential (ZP), Fourier Transform Infrared (FTIR) spetroscopy, X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Field Emission Gun Scanning Electron Microscopy (FEG-SEM). I3C release testing was performed at an acidic media and the interactions between I3C and chitosan or PEG were evaluated by Density Functional Theory (DFT). Cytotoxicity of nanoparticles in bladder cancer T24 cell line was evaluated by the Methyl-thiazolyl-tetrazolium (MTT) colorimetric assay. The average size of the nanoparticles was observed to be in the range from 133.3 ± 3.7 nm to 180.4 ± 2.7 nm with a relatively homogeneous distribution. Samples had relatively high positive zeta potential values (between +20.3 ± 0.5 mV and + 24.3 ± 0.5 mV). Similar encapsulation efficiencies (about 80%) for both nanoparticles were obtained. Physicochemical and thermal characterizations pointed to the encapsulation of I3c. electron microscopy showed spherical particles with smooth or ragged surface characteristics, depending on the presence of PEG. The mathematical fitting of the release profile demonstrated that I3C-CS NP followed the Higuchi model whereas I3C-CS/PEG NP the Korsmeyer-Peppas model. Chemical differences between the nanoparticles as based on the I3C/CS or I3C/PEG interactions were demonstrate by computational characterization. The assessment of cell viability by the MTT test showed that the presence of both free I3C and I3C-loaded nanoparticles lead to statistically significant reduction in T24 cells viability in the concentrations from 500 to 2000 μM, when comparison to the control group after 24 h of exposure. Thus, CS and CS/PEG nanoparticles present as feasible I3C carrier systems for cancer therapy.

Effects of Dietary Indole-3-Acetate Sodium on Laying Performance, Egg Quality, Serum Hormone Levels and Biochemical Parameters of Danzhou Chickens

This study was conducted to investigate the effects of indole-3-acetate sodium (IAA-Na) inclusion in diets on the egg production performance, egg quality, intestinal tissue morphology, serum hormone levels and biochemical parameters of Danzhou chickens to preliminarily explore the efficacy of IAA-Na as a feed additive. A total of 192 Danzhou chickens (50 weeks old) were randomly assigned to 2 groups of 96. The diets for the treatment group consisted of the basal diets, supplemented with IAA-Na (200 mg/kg). The formal feeding trial lasted for four weeks. The results showed that the feed supplemented with IAA-Na not only increased the laying rate (p < 0.05) and egg yolk ratio (0.05 < p < 0.1), but also significantly reduced the feed:egg ratio (p < 0.05). In addition, the dietary supplementation of IAA-Na significantly increased the serum estradiol levels (p < 0.05) and decreased serum alkaline phosphatase activity (p < 0.05). Compared with the control group, the addition of IAA-Na to the diet had no significant effect on the intestinal tissue morphology or serum antioxidant capacity of Danzhou chickens. This study preliminarily provides evidence that dietary IAA-Na can improve laying performance, indicating that IAA-Na is a potentially effective feed additive for laying hens, but further studies are required before arriving at definite conclusions.

Bis-indole substituted phthalocyanines: Photophysical and photochemical properties

Tetra substituted peripheral and non-peripheral Zn(II) phthalocyanines were successfully synthesized employing 4-(bis(3-methyl-1H-indol-2-yl)methyl)phenol as a starting material. The structure of these synthesized compounds was confirmed using 1H NMR, [Formula: see text]C NMR, infrared (IR), UV-vis, and MALDI-TOF spectral data. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation) properties of all synthesized peripheral and non-peripheral compounds were investigated in order to determine the potential of these compounds for application in photodynamic therapy.

Efficient enzyme-activated therapy based on the different locations of protein and prodrug in nanoMOFs

Enzyme-activated prodrug therapy (EAPT) is an effective cancer treatment strategy able to transport non-toxic prodrugs and subsequently convert them into drugs at specific times and locations. However, due to the limitation of easy biodegradability and the membrane-impermeable characteristic of exogenous enzymes, there is a need to exploit suitable carriers for the effective protection and simultaneous delivery of activating enzymes into cancer cells. Herein, hierarchically porous MOFs were employed for the loading of enzyme and prodrug in a single nanocarrier thanks to their different cavity sizes. The simple loading process allows entrapping of horseradish peroxidase (HRP) and a monocarboxyl-containing indole-3-acetic acid (IAA) prodrug with high loading capacities in different spaces, which keeps the catalytic activity of the enzyme perfectly intact and avoids the premature activation of the prodrug. The encapsulated HRP and IAA exhibit sustained and synchronized release behaviors. Compared to the native HRP enzyme, the current MOF nanocarriers not only facilitate enzyme delivery into cellular lysosomes and subsequent endosomal escape, but also effectively release enzyme and prodrug in the intracellular environment within 48 h. Eventually, HRP and IAA loaded MOF nanocarriers cause significant cell death with a low IC₅₀ of 4.2 mg L^-1, while the IAA prodrug alone is non-toxic even at high concentrations. Thus, hierarchically porous MOFs might offer a promising platform for EAPT with a highly consistent spatiotemporal distribution of enzymes and prodrugs in target tissues.

Rapid Degradation of Caenorhabditis elegans Proteins at Single-Cell Resolution with a Synthetic Auxin

As developmental biologists in the age of genome editing, we now have access to an ever-increasing array of tools to manipulate endogenous gene expression. The auxin-inducible degradation system allows for spatial and temporal control of protein degradation via a hormone-inducible Arabidopsis F-box protein, transport inhibitor response 1 (TIR1). In the presence of auxin, TIR1 serves as a substrate-recognition component of the E3 ubiquitin ligase complex SKP1-CUL1-F-box (SCF), ubiquitinating auxin-inducible degron (AID)-tagged proteins for proteasomal degradation. Here, we optimize the Caenorhabditis elegans AID system by utilizing 1-naphthaleneacetic acid (NAA), an indole-free synthetic analog of the natural auxin indole-3-acetic acid (IAA). We take advantage of the photostability of NAA to demonstrate via quantitative high-resolution microscopy that rapid degradation of target proteins can be detected in single cells within 30 min of exposure. Additionally, we show that NAA works robustly in both standard growth media and physiological buffer. We also demonstrate that K-NAA, the water-soluble, potassium salt of NAA, can be combined with microfluidics for targeted protein degradation in C. elegans larvae. We provide insight into how the AID system functions in C. elegans by determining that TIR1 depends on C. elegans SKR-1/2, CUL-1, and RBX-1 to degrade target proteins. Finally, we present highly penetrant defects from NAA-mediated degradation of the FTZ-F1 nuclear hormone receptor, NHR-25, during C. elegans uterine-vulval development. Together, this work improves our use and understanding of the AID system for dissecting gene function at the single-cell level during C. elegans development.

Auxin-mediated Protein Degradation in Caenorhabditis elegans

The auxin-inducible degron (AID) technology was recently adapted for use in the nematode Caenorhabditis elegans. Rapid degradation of C. elegans proteins tagged with an AID is mediated by a plant-specific F-box protein, transport inhibitor response 1 (TIR1), and occurs only in the presence of the phytohormone auxin. The first iteration of this technology elicited protein degradation in C. elegans through a naturally occurring form of auxin, indole-3-acetic acid (IAA). Here, we present a protocol that uses 1-naphthaleneacetic acid, potassium salt (K-NAA), an indole-free synthetic auxin analog. At equal concentration, K-NAA is as effective as IAA in standard nematode growth media (NGM). K-NAA is also effective in physiological buffer (M9), allowing for high-throughput experimentation. The main advantages of K-NAA are twofold: first, its photostability prevents light-induced compound degradation during storage and the production of toxic indole-derivatives during fluorescence microscopy of live cells; and second, its water solubility eliminates the need of using ethanol to dissolve the auxin compound, a solvent that may confound C. elegans lifespan and behavioral assays. In this protocol, we describe our method of degrading C. elegans proteins using K-NAA on solid and in liquid media, as well as our method of analyzing protein degradation.

Photodynamic therapy for cancer: Role of natural products

Photodynamic therapy (PDT) is a promising modality for the treatment of cancer. PDT involves administering a photosensitizing dye, i.e. photosensitizer, that selectively accumulates in tumors, and shining a light source on the lesion with a wavelength matching the absorption spectrum of the photosensitizer, that exerts a cytotoxic effect after excitation. The reactive oxygen species produced during PDT are responsible for the oxidation of biomolecules, which in turn cause cell death and the necrosis of malignant tissue. PDT is a multi-factorial process that generally involves apoptotic death of the tumor cells, degeneration of the tumor vasculature, stimulation of anti-tumor immune response, and induction of inflammatory reactions in the illuminated lesion. Numerous compounds with photosensitizing activity have been introduced commercially. Although many papers have been published with regard to PDT in the last decade, there has been relatively little focus on natural medicinal plant extracts and compounds derived therefrom. Herbal plants and their extracts are natural substances, and in comparison with synthetic chemicals are considered "green". This review focuses on the different mechanisms of PDT and discusses the role of various plant extracts and natural compounds either alone or in combination for carrying out PDT on different types of cancers.

Prodrugs for targeted cancer therapy

Introduction: Prodrugs have been used to improve the selectivity and efficacy of cancer therapy by targeting unique abnormal markers that are overexpressed by cancer cells and are absent in normal tissues. In this context, different strategies have been exploited and new ones are being developed each year. Areas covered: In this review, an integrated view of the potential use of prodrugs in targeted cancer therapy is provided. Passive and active strategies are discussed in light of the advantages of each one and some successful examples are provided, as well as the clinical status of several prodrugs. Among them, antibody-drug conjugates (ADCs) are the most commonly used. However, several drawbacks, including limited prodrug uptake, poor pharmacokinetics, immunogenicity problems, difficulties in selective targeting and gene expression, and optimized bystander effects limit their clinical applications. Expert opinion: Despite the efforts of different companies and research groups, several drawbacks, such as the lack of relevant in vivo models, complexity of the human metabolism, and economic limitations, have hampered the development of new prodrugs for targeted cancer therapy. As a result, we believe that the combination of prodrugs with cancer nanotechnology and other newly developed approaches, such as aptamer-conjugated nanomaterials, are efficient strategies.

Improving the Performance of Horseradish Peroxidase by Site-Directed Mutagenesis

Horseradish peroxidase (HRP) is an intensely studied enzyme with a wide range of commercial applications. Traditionally, HRP is extracted from plant; however, recombinant HRP (rHRP) production is a promising alternative. Here, non-glycosylated rHRP was produced in Escherichia coli as a DsbA fusion protein including a Dsb signal sequence for translocation to the periplasm and a His tag for purification. The missing N-glycosylation results in reduced catalytic activity and thermal stability, therefore enzyme engineering was used to improve these characteristics. The amino acids at four N-glycosylation sites, namely N13, N57, N255 and N268, were mutated by site-directed mutagenesis and combined to double, triple and quadruple enzyme variants. Subsequently, the rHRP fusion proteins were purified by immobilized metal affinity chromatography (IMAC) and biochemically characterized. We found that the quadruple mutant rHRP N13D/N57S/N255D/N268D showed 2-fold higher thermostability and 8-fold increased catalytic activity with 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as reducing substrate when compared to the non-mutated rHRP benchmark enzyme.

Origins of Suicide Gene Therapy

"Tumor chemosensitivity" can be achieved by the expression of the herpes simplex virus thymidine kinase gene in cells, followed by the conversion of the "prodrug" ganciclovir into the therapeutic drug inside the cells. This system presaged other combinations of suicide genes and prodrugs, including cytosine deaminase/5-fluorocytosine, purine nucleoside phosphorylase/6-methylpurine deoxyriboside, and horseradish peroxidase/indole-3-acetic acid.

Stimuli-Responsive Therapeutic Metallodrugs

The success of platinum-based anticancer agents has motivated the exploration of novel metal-based drugs for several decades, whereas problems such as drug-resistance and systemic toxicity hampered their clinical applications and efficacy. Stimuli-responsiveness of some metal complexes offers a good opportunity for designing site-specific prodrugs to maximize the therapeutic efficacy and minimize the side effect of metallodrugs. This review presents a comprehensive and up-to-date overview on the therapeutic stimuli-responsive metallodrugs that have appeared in the past two decades, where stimuli such as redox, pH, enzyme, light, temperature, and so forth were involved. The compounds are classified into three major categories based on the nature of stimuli, that is, endo-stimuli-responsive metallodrugs, exo-stimuli-responsive metallodrugs, and dual-stimuli-responsive metallodrugs. Representative examples of each type are discussed in terms of structure, response mechanism, and potential medical applications. In the end, future opportunities and challenges in this field are tentatively proposed. With diverse metal complexes being introduced, the foci of this review are pointed to platinum and ruthenium complexes.

The Development of Toad Toxins as Potential Therapeutic Agents

Toxins from toads have long been known to contain rich chemicals with great pharmaceutical potential. Recent studies have shown more than 100 such chemical components, including peptides, steroids, indole alkaloids, bufogargarizanines, organic acids, and others, in the parotoid and skins gland secretions from different species of toads. In traditional Chinese medicine (TCM), processed toad toxins have been used for treating various diseases for hundreds of years. Modern studies, including both experimental and clinical trials, have also revealed the molecular mechanisms that support the development of these components into medicines for the treatment of inflammatory diseases and cancers. More recently, there have been studies that demonstrated the therapeutic potential of toxins from other species of toads, such as Australian cane toads. Previous reviews mostly focused on the pharmaceutical effects of the whole extracts from parotoid glands or skins of toads. However, to fully understand the molecular basis of toad toxins in their use for therapy, a comprehensive understanding of the individual compound contained in toad toxins is necessary; thus, this paper seeks to review the recent studies of some typical compounds frequently identified in toad secretions.

Improvement of kinetic properties and thermostability of recombinant Lepidium draba peroxidase (LDP) upon exposed to osmolytes

In this study, effects of different concentrations of glycine and D-sorbitol were analyzed on the activity and thermostability of recombinant Lepidium draba peroxidase (LDP). Based on the results, activity of the enzyme increased in the presence of various concentrations of these osmolytes. Maximum activity was detected for the enzyme in the presence of 300 mM glycine and 600 mM sorbitol. In presence of the aforementioned doses of osmolytes, enzyme affinity for substrate (3,3',5,5'-tetramethylbenzidine and H₂O₂) and V_max increased. According to the results, enzyme stability improved against temperature and H₂O₂. Furthermore, structural changes of the enzyme upon exposure to the osmolytes were revealed by the use of far-UV circular dichroism and fluorescence methods. The results showed, whereas the secondary structure of the enzyme was not significantly changed upon exposed to the osmolytes, the fluorescence studies revealed microenvironment of the aromatic residues dramatically affected by them. Overall, it may be speculated, structural changes of the enzyme upon exposed to the osmolytes, lead to the improvement of its kinetic properties and stability that can be benefit for using of it in in vitro applications.

Rice Bran Metabolome Contains Amino Acids, Vitamins & Cofactors, and Phytochemicals with Medicinal and Nutritional Properties

BACKGROUND

Rice bran is a functional food that has shown protection against major chronic diseases (e.g. obesity, diabetes, cardiovascular disease and cancer) in animals and humans, and these health effects have been associated with the presence of bioactive phytochemicals. Food metabolomics uses multiple chromatography and mass spectrometry platforms to detect and identify a diverse range of small molecules with high sensitivity and precision, and has not been completed for rice bran.

RESULTS

This study utilized global, non-targeted metabolomics to identify small molecules in rice bran, and conducted a comprehensive search of peer-reviewed literature to determine bioactive compounds. Three U.S. rice varieties (Calrose, Dixiebelle, and Neptune), that have been used for human dietary intervention trials, were assessed herein for bioactive compounds that have disease control and prevention properties. The profiling of rice bran by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) identified 453 distinct phytochemicals, 209 of which were classified as amino acids, cofactors & vitamins, and secondary metabolites, and were further assessed for bioactivity. A scientific literature search revealed 65 compounds with health properties, 16 of which had not been previously identified in rice bran. This suite of amino acids, cofactors & vitamins, and secondary metabolites comprised 46% of the identified rice bran metabolome, which substantially enhanced our knowledge of health-promoting rice bran compounds provided during dietary supplementation.

CONCLUSION

Rice bran metabolite profiling revealed a suite of biochemical molecules that can be further investigated and exploited for multiple nutritional therapies and medical food applications. These bioactive compounds may also be biomarkers of dietary rice bran intake. The medicinal compounds associated with rice bran can function as a network across metabolic pathways and this metabolite network may occur via additive and synergistic effects between compounds in the food matrix.

Synergistic photodynamic therapeutic effect of indole-3-acetic acid using a pH sensitive nano-carrier based on poly(aspartic acid-graft-imidazole)-poly(ethylene glycol)

Poly(aspartic acid-graft-imidazole)-poly(ethylene glycol) (P(Asp-g-Im)-PEG) was utilized as a pH-sensitive nanocarrier of the photosensitizer indole-3-acetic acid (IAA) for the treatment of skin cancer. IAA loaded micelles (ILMs) exhibited the formation of ca. 140 nm spherical particles at pH 7.4. The micelles disintegrated at acidic pHs, resulting in pH-dependent IAA release and cytotoxicity. Treatment of ILMs with visible light at a wavelength of 480 nm caused pH dependent synergistic cell damage in both in vitro and in vivo models using the B16F10 melanoma cell line. Interestingly, ILMs synergistically produced reactive oxygen species (ROS) at an acidic pH of 6.5 with visible light irradiation by proton coupled electron transfer (PCET). The pH sensitive ILMs could be considered a potent nanomedicine used to exert synergistic photodynamic therapeutic effects to treat cancers.

Ethyl 2-[2-(4-Nitrobenzoyl)-1H-indol-3-yl]acetate

Ethyl 2-[2-(4-nitrobenzoyl)-1H-indol-3-yl]acetate was prepared in good yield and characterized by the aza-alkylation/intramolecular Michael cascade reaction of (E)-ethyl 3-[2-(tosylamino)phenyl]acrylate with 2-bromo-4′′-nitroacetophenone, followed by desulfonative dehydrogenation with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) The structure of the newly synthesized compound was determined using 1H-,13C-NMR, IR and mass spectral data.

Quantitative characterization of the auxin-inducible degron: a guide for dynamic protein depletion in single yeast cells

Perturbations are essential for the interrogation of biological systems. The auxin-inducible degron harbors great potential for dynamic protein depletion in yeast. Here, we thoroughly and quantitatively characterize the auxin-inducible degron in single yeast cells. We show that an auxin concentration of 0.25 mM is necessary for fast and uniform protein depletion between single cells, and that in mother cells proteins are depleted faster than their daughters. Although, protein recovery starts immediately after removal of auxin, it takes multiple generations before equilibrium is reached between protein synthesis and dilution, which is when the original protein levels are restored. Further, we found that blue light, used for GFP excitation, together with auxin results in growth defects, caused by the photo-destruction of auxin to its toxic derivatives, which can be avoided if indole-free auxin substitutes are used. Our work provides guidelines for the successful combination of microscopy, microfluidics and the auxin-inducible degron, offering the yeast community an unprecedented tool for dynamic perturbations on the single cell level.

Phytohormone Behavior in the Model Environment of Plant and Human Lipid Membranes

Interactions between three auxins (indole-3-acetic acid (IAA), 2-naphthoxyacetic acid (BNOA), and 2,4-dichlorophenoxyacetic acid (2,4-D)) and model two-dimensional lipid systems mimicking plant and human cell membranes were investigated in monolayers formed at the air/water solution interface. The analysis was based on the recorded π-A isotherm characteristics complemented with Brewster angle microscopy. The influence of auxins on model membranes was discussed on the basis of condensation changes, modification of mutual lipid-lipid interactions in the mixed films, and morphological alteration of the surface domains on the microscopic scale. It was demonstrated that the lipid composition and mutual proportion of the artificial membranes together with sterol to main the phospholipid ratio play a crucial role in the context of auxin behavior in the membrane-mimicking environment. Apart from specific molecular interactions between studied phytohormones represented by auxins and lipids, the condensation of the investigated monolayers was found to be a regulative factor of model systems' susceptibility toward auxin action. Two effects were recognized: fluidizing of monolayers being in the liquid state (model membranes) and initialization of the three-dimensional structure formation in ordered sterol films at high surface pressure. The influence of auxin molecules on lipid interactions in the monolayer and diminishing of the film condensation was the largest for BNOA, due to the presence of the most bulky nonpolar, aromatic fragment in the molecule. It was also demonstrated that auxins interact with model plant membranes more selectively, stronger, and at markedly lower concentration than with the human membrane models.

Oxidative Stress Induced by Pt(IV) Pro-drugs Based on the Cisplatin Scaffold and Indole Carboxylic Acids in Axial Position

The use of Pt(IV) complexes as pro-drugs that are activated by intracellular reduction is a widely investigated approach to overcome the limitations of Pt(II) anticancer agents. A series of ten mono- and bis-carboxylated Pt(IV) complexes with axial indole-3-acetic acid (IAA) and indole-3-propionic acid (IPA) ligands were synthesized and characterized by elemental analysis, ESI-MS, FT-IR, (1)H and (195)Pt NMR spectroscopy. Cellular uptake, DNA platination and cytotoxicity against a panel of human tumor cell lines were evaluated. All the complexes are able to overcome cisplatin-resistance and the most potent complex, cis,cis,trans-[Pt(NH3)2Cl2(IPA)(OH)] was on average three times more active than cisplatin. Mechanistic studies revealed that the trend in cytotoxicity of the Pt(IV) complexes is primarily consistent with their ability to accumulate into cancer cells and to increase intracellular basal reactive oxygen species levels, which in turn results in the loss of mitochondrial membrane potential and apoptosis induction. The role of the indole acid ligand as a redox modulator is discussed.

Indole-3-Acetic Acid Induces Microencephaly in Rat Fetuses

Indole-3-acetic acid (IAA), known as natural auxin, induces cleft palate in rodents. However, there has been no report about the neurodevelopmental toxicity of IAA in rats. In the present study, we found microencephaly in the fetuses from the rats exposed to IAA. The purpose of this work was to examine the effects of IAA administration in pregnant rats on neuroepithelial cells in the embryos/fetuses. IAA was administered at 500 and 1,000 mg/kg on gestation days (days) 12, 13, and 14, and then embryos/fetuses were harvested on days 14.5, 15, 16, and 21. Cleft palate was induced at 1,000 mg/kg. The brain in treated groups exhibited reduction in the size and weight on day 21 in a dose-dependent manner. Histopathologically, apoptotic cells were observed mainly in the medial and dorsal layer of the neuroepithelium at 500 and 1,000 mg/kg on day 14.5. On day 15, they were observed in the medial and dorsal layer of the neuroepithelium, and preplate at 1,000 mg/kg. On day 16, they existed in the dorsal layer of the neuroepithelium and intermediate zone in the embryos from 1 dam at 1,000 mg/kg. On day 21, an increase in cell proliferative activity was observed in the neuroepithelium at 500 and 1,000 mg/kg. The reduction of the cortical plate, the enlargement of the neuroepithelium and a slight increase in neuron density in the intermediate zone were observed at 1,000 mg/kg. These findings indicated IAA might induce the neuronal apoptosis in the S phase and lead to microencephaly.

Rapid Bioorthogonal Chemistry Turn-on through Enzymatic or Long Wavelength Photocatalytic Activation of Tetrazine Ligation

Rapid bioorthogonal reactivity can be induced by controllable, catalytic stimuli using air as the oxidant. Methylene blue (4 μM) irradiated with red light (660 nm) catalyzes the rapid oxidation of a dihydrotetrazine to a tetrazine thereby turning on reactivity toward trans-cyclooctene dienophiles. Alternately, the aerial oxidation of dihydrotetrazines can be efficiently catalyzed by nanomolar levels of horseradish peroxidase under peroxide-free conditions. Selection of dihydrotetrazine/tetrazine pairs of sufficient kinetic stability in aerobic aqueous solutions is key to the success of these approaches. In this work, polymer fibers carrying latent dihydrotetrazines were catalytically activated and covalently modified by trans-cyclooctene conjugates of small molecules, peptides, and proteins. In addition to visualization with fluorophores, fibers conjugated to a cell adhesive peptide exhibited a dramatically increased ability to mediate contact guidance of cells.

Interactions of Indole Derivatives with β-Cyclodextrin: A Quantitative Structure-Property Relationship Study

Retention factors for 31 indole derivatives, most of them with auxin activity, were determined by high-performance liquid chromatography, using bonded β-cyclodextrin as a stationary phase. A three-parameter QSPR (quantitative structure-property relationship) model, based on physico-chemical and structural descriptors was derived, which accounted for about 98% variations in the retention factors. The model suggests that the indole nucleus occupies the relatively apolar cavity of β-cyclodextrin while the carboxyl group of the indole -3-carboxylic acids makes hydrogen bonds with the hydroxyl groups of β-cyclodextrin. The length and flexibility of the side chain containing carboxyl group strongly affect the binding of these compounds to β-cyclodextrin. Non-acidic derivatives, unlike the indole-3-carboxylic acids, are poorly retained on the column. A reasonably well correlation was found between the retention factors of the indole-3-acetic acids and their relative binding affinities for human serum albumin, a carrier protein in the blood plasma. A less satisfactory correlation was obtained when the retention factors of the indole derivatives were compared with their affinities for auxin-binding protein 1, a plant auxin receptor.

Recombinant horseradish peroxidase variants for targeted cancer treatment

Cancer is a major cause of death. Common chemo‐ and radiation‐therapies damage healthy tissue and cause painful side effects. The enzyme horseradish peroxidase (HRP) has been shown to activate the plant hormone indole‐3‐acetic acid (IAA) to a powerful anticancer agent in in vitro studies, but gene directed enzyme prodrug therapy (GDEPT) studies showed ambivalent results. Thus, HRP/IAA in antibody directed enzyme prodrug therapy (ADEPT) was investigated as an alternative. However, this approach has not been intensively studied, since the enzyme preparation from plant describes an undefined mixture of isoenzymes with a heterogenic glycosylation pattern incompatible with the human system. Here, we describe the recombinant production of the two HRP isoenzymes C1A and A2A in a Pichia pastoris benchmark strain and a glyco‐engineered strain with a knockout of the α‐1,6‐mannosyltransferase (OCH1) responsible for hypermannosylation. We biochemically characterized the enzyme variants, tested them with IAA and applied them on cancer cells. In the absence of H₂O₂, HRP C1A turned out to be highly active with IAA, independent of its surface glycosylation. Subsequent in vitro cytotoxicity studies with human T24 bladder carcinoma and MDA‐MB‐231 breast carcinoma cells underlined the applicability of recombinant HRP C1A with reduced surface glycoslyation for targeted cancer treatment. Summarizing, this is the first study describing the successful use of recombinantly produced HRP for targeted cancer treatment. Our findings might pave the way for an increased use of the powerful isoenzyme HRP C1A in cancer research in the future.

Production and removal of superoxide anion radical by artificial metalloenzymes and redox-active metals

Generation of reactive oxygen species is useful for various medical, engineering and agricultural purposes. These include clinical modulation of immunological mechanism, enhanced degradation of organic compounds released to the environments, removal of microorganisms for the hygienic purpose, and agricultural pest control; both directly acting against pathogenic microorganisms and indirectly via stimulation of plant defense mechanism represented by systemic acquired resistance and hypersensitive response. By aiming to develop a novel classes of artificial redox-active biocatalysts involved in production and/or removal of superoxide anion radicals, recent attempts for understanding and modification of natural catalytic proteins and functional DNA sequences of mammalian and plant origins are covered in this review article.

Combination of cytokinin and auxin induces apoptosis, cell cycle progression arrest and blockage of the Akt pathway in HeLa cells

Plant cytokinins and auxins have recently been proposed as novel cancer therapies, which proceed via different mechanisms; however, their combined use has not been investigated. To the best of our knowledge, the present study was the first to show that the cytokinin ortho-methoxytopolin-riboside (MeoTR) strongly inhibited the proliferation of HeLa cells, the effect of which was synergistically enhanced by auxin indole-3-acetic acid (IAA), while IAA demonstrated to have no cytotoxic effects on cells. MeoTR was found to activate intrinsic and extrinsic caspase-dependent pathways, and IAA potentiated this activation. In addition, these effects were blocked by Z-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), a pan-specific-caspase-inhibitor. IAA increased the MeoTR- induced inhibition of B cell lymphoma 2 (Bcl-2) and survivin, whereas IAA-only decreased Bcl-2 expression. MeoTR downregulated phosphorylated (p)-pyruvate dehydrogenase kinase 1, p-Akt and p-glycogen synthase kinase 3β, the effect of which was more potent in combination with IAA, despite the weak effect of IAA alone. LY294002, an Akt-inhibitor, was able to increase the inhibition of p-Akt through MeoTR and combination treatment. IAA and MeoTR increased the proportion of cells in S phase independently. However, the combination treatment induced a further increase. In addition, IAA and MeoTR treatment downregulated protein levels of cyclin A, cyclin-dependent kinase 2 (CDK2) and p-CDK2, and upregulated protein levels of p21 and p27. Furthermore, the combination treatment enhanced these effects, indicating that IAA potentiated the inhibitory effect of MeoTR on HeLa cells via cell cycle progression arrest and accumulation in S phase, coupled with the negative regulation of Bcl-2. In conclusion, the results of the present study suggested that treatment with these two phytohormones in combination, may offer a novel therapeutic strategy for the treatment of malignant cervical cancer.