Green Synthesis, Characterization, Encapsulation, and Measurement of the Release Potential of Novel Alkali Lignin Micro-/Submicron Particles

The applicability of biopolymer micro-/nano- technology in human, veterinary medicine, pharmaceutical, and food technology is rapidly growing due to the great potential of biopolymer-based particles as effective carrier systems. The use of lignin as a basic heteropolymer biomatrix for the design of innovative micro-/submicron formulations allows the achievement of increased biocompatibility and offers various active functional groups presenting opportunities for customization of the physicochemical properties and bioactivities of the formulations for diverse applications. The aim of the present study was to develop a simple and ecofriendly methodology for the synthesis of lignin particles with micro- and submicron size; to evaluate their physicochemical, spectral, and structural characteristics; and to examine their capacity for encapsulation of biologically active molecules and potential for in vitro release of bioflavonoids in simulated gastrointestinal media. The presented methodologies apply cheap and green solvents; easy, straightforward, quick, and sensitive processes requiring little equipment, non-toxic substances, and simple methods for their characterization, the determination of encapsulation capacity towards the poorly water-soluble bioactive compounds morin and quercetin, and the in vitro release potential of the lignin matrices.

Green Solvents for Extraction of Natural Food Colorants from Plants: Selectivity and Stability Issues

Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

Menadione Contribution to the In Vitro Radical Scavenging Potential of Phytochemicals Naringenin and Lignin

Vitamin K3 (menadione), classified as a pro-vitamin, is a synthetic form of the fat-soluble family of vitamin K compounds. The combination of the vitamin with other molecules sharing structural and/or functional similarities, such as naturally occurring polyphenols, vitamins, or biopolymers, could potentiate mutual improvement of their antioxidant activity. The aim of the present study was to evaluate the role and contribution of vitamin K3 to the in vitro radical scavenging capacity of double and triple combinations with the phytochemicals naringenin and lignin, as well as assess possible intermolecular interactions between the bioactive compounds. Comparative analyses of the DPPH and ABTS radical scavenging activity of the pure substances vitamin K3, naringenin, and lignin; the two-component systems lignin/vitamin K3 and vitamin K3/naringenin; and the triple combination vitamin K3/flavonoid/lignin were carried out. The experimental results demonstrated increased DPPH and ABTS activities of the vitamin in combination with lignin compared to those of the two pure substances, i.e., a synergistic effect was observed. The registered significant increases in the radical scavenging activity of the triple combination determined via both methods are indicative of a remarkable potentiation effect, i.e., higher antioxidant potential exceeding the additive activity of the three pure substances.

Water-Soluble Alkali Lignin as a Natural Radical Scavenger and Anticancer Alternative

Several phytochemicals, which display antioxidant activity and inhibit cancer cell phenotypes, could be used for cancer treatment and prevention. Lignin, as a part of plant biomass, is the second most abundant natural biopolymer worldwide, and represents approximately 30% of the total organic carbon content of the biosphere. Historically, lignin-based products have been viewed as waste materials of limited industrial usefulness, but modern technologies highlight the applicability of lignin in a variety of industrial branches, including biomedicine. The aims of our preliminary study were to compare the antioxidant properties of water-soluble alkali lignin solutions, before and after UV-B irradiation, as well as to clarify their effect on colon cancer cell viability (Colon 26), applied at low (tolerable) concentrations. The results showed a high antioxidant capacity of lignin solutions, compared to a water-soluble control antioxidant standard (Trolox) and remarkable radical scavenging activity was observed after their UV-B irradiation. Diminishment of cell viability as well as inhibition of the proliferative activity of the colon cancer cell line with an increase in alkali lignin concentrations were observed. Our results confirmed that, due to its biodegradable and biocompatible nature, lignin could be a potential agent for cancer therapy, especially in nanomedicine as a drug delivery system.

Newly Synthesized Lignin Microparticles as Bioinspired Oral Drug-Delivery Vehicles: Flavonoid-Carrier Potential and In Vitro Radical-Scavenging Activity

The aim of the present study was to synthesize lignin microparticles, to evaluate their physicochemical, spectral, morphological and structural characteristics, to examine their encapsulation and in vitro release potential and behaviour towards the flavonoid morin in simulated physiological medium and to assess the in vitro radical-scavenging potential of the morin-loaded lignin microcarrier systems. The physicochemical, structural and morphological characteristics of alkali lignin, lignin particles (LP) and morin-encapsulated lignin microparticles (LMP) were determined based on particle size distribution, SEM, UV/Vis spectrophotometric, FTIR and potentiometric titration analyses. The encapsulation efficiency of LMP was 98.1%. The FTIR analyses proved that morin was successfully encapsulated in the LP without unexpected chemical reactions between the flavonoid and the heteropolymer. The in vitro release performance of the microcarrier system was successfully mathematically described by Korsmeyer–Peppas and the sigmoidal models outlining the general role of diffusion during the initial stages of the in vitro release process in simulated gastric fluid (SGF), and the predominant contribution of biopolymer relaxation and erosion was determined in simulated intestinal medium (SIF). The higher radical-scavenging potential of LMP, as compared to that of LP, was proven via DPPH and ABTS assays. The synthesis of lignin microcarriers not only provides a facile approach for the utilization of the heteropolymer but also determines its potential for the design of drug-delivery matrices.

Docosahexaenoic Acid Potentiates the Anticancer Effect of the Menadione/Ascorbate Redox Couple by Increasing Mitochondrial Superoxide and Accelerating ATP Depletion

BACKGROUND/AIM

Mitochondria-targeted anticancer drugs ("mitocans") of natural origin are attractive candidates as adjuvants in cancer therapy. The redox couple menadione/ascorbate (M/A), which belongs to the "mitocans" family, induces selective oxidative stress in cancerous mitochondria and cells, respectively. DHA has also been found to regulate the mevalonate pathway, which is closely related to the prenylation of the cytotoxic menadione to the non-cytotoxic menaquinone. The aim of this study was to elucidate the ability of docosahexaenoic acid (DHA) to potentiate the anticancer effect of M/A by increasing ROS production, as well as affecting steady-state ATP levels in cancer cells.

MATERIALS AND METHODS

The experiments were performed on leukemic lymphocyte Jurkat. Cells were treated with DHA, M/A, and their combination (M/A/DHA) and four parameters were examined using the following assays: cell viability and proliferation, steady-state ATP, mitochondrial superoxide, intracellular hydroperoxides. Three independent experiments with two or six parallel measurements were performed for each parameter.

RESULTS

The triple combination M/A/DHA was characterized by much higher antiproliferative activity and cytotoxicity than M/A and DHA administered alone. DHA significantly accelerated M/A-induced ATP depletion in cells, which was accompanied by an additional increase in mitochondrial superoxide compared to cells treated with M/A or DHA alone.

CONCLUSION

DHA significantly enhanced M/A-induced cytotoxicity in leukemic lymphocytes by inducing severe mitochondrial oxidative stress and accelerated ATP depletion. Selective DHA-mediated suppression of cholesterol synthesis in cancer cells (involved in the prenylation of cytotoxic menadione to the less cytotoxic phylloquinone), as well as DHA-mediated inhibition of superoxide dismutase are suggested to underlie the potentiation of the anticancer effect of M/A.

Investigation of the Effect of pH on the Adsorption-Desorption of Doxycycline in Feed for Small Ruminants

Orally administered tetracycline antibiotics interact with feed, which may impact their bioavailability and efficacy. Therefore, the pH-dependent adsorption of doxycycline and its interaction with feed for ruminants was studied in vitro. Adsorption experiments on animal feed (135 and 270 mg) with initial doxycycline concentrations of 35, 75, and 150 µg/mL were performed. Desorption experiments were conducted by agitation of a predetermined mass of doxycycline-loaded animal feed in PBS, at pH = 3.0, 6.0, and 7.4, to simulate changes in the gastrointestinal tract. Antibiotic concentrations were determined by LC-MS/MS analysis. The adsorption/desorption of doxycycline was described by mathematical models. Chemisorption with strong intermolecular interactions between the active functional groups of doxycycline and the organic biomass was found. The experimental release curve comprised three sections: initial prolonged 27-30% release (pH = 6.0), followed by moderate 56-59% release (pH = 3.0), and final 63-74% release (pH = 7.4). The sigmoidal model showed a considerable role of diffusion with an initial prevalence of desorption and a decreased desorption rate thereafter. The Weibull equation revealed an initial release stage followed by a lag time section and sustained release. The study of doxycycline adsorption by the animal feed proved a maximum 80% encapsulation efficiency and revealed initial diffusion followed by chemisorption. The highest release efficiency of 74% suggests high bioavailability of doxycycline after oral administration in ruminants.

Effect of Alpha-tocopheryl Succinate on the Cytotoxicity of Anticancer Drugs Towards Leukemia Lymphocytes

BACKGROUND/AIM

This study analysed the effect of α-tocopheryl succinate (α-TS) on the redox-state of leukemia and normal lymphocytes, as well as their sensitization to fifteen anticancer drugs.

MATERIALS AND METHODS

Cell viability was analyzed by trypan blue staining and automated counting of live and dead cells. Apoptosis was analyzed by FITC-Annexin V test. Oxidative stress was evaluated by the intracellular levels of reactive oxygen species (ROS) and protein-carbonyl products.

RESULTS

Most combinations (α-TS plus anticancer drug) exerted additive or antagonistic effects on the proliferation and viability of leukemia lymphocytes. α-TS combined with barasertib, bortezomib or lonafarnib showed a strong synergistic cytotoxic effect, which was best expressed in the case of barasestib. It was accompanied by impressive induction of apoptosis and increased production of ROS, but insignificant changes in protein-carbonyl levels. α-TS plus barasertib did not alter the viability and did not induce oxidative stress and apoptosis in normal lymphocytes.

CONCLUSION

α-TS could be a promising adjuvant in second-line anticancer therapy, particularly in acute lymphoblastic leukemia, to reduce the therapeutic doses of barasertib, bortezomib, and lonafarnib, increasing their effectiveness and minimizing their side effects.

Clinoptilolite Microparticles as Carriers of Catechin-Rich Acacia catechu Extracts: Microencapsulation and In Vitro Release Study

The main goal of the present study was to investigate the microencapsulation, in vitro release capacity and efficiency of catechin-rich Acacia catechu extract by Clinosorbent-5 (CLS-5) microparticles by in-depth detailed analyses and mathematical modelling of the encapsulation and in vitro release kinetics behaviour of the polyphenol-mineral composite system. The bioflavanol encapsulation and release efficiency on/from the mineral matrix were assessed by sorption experiments and interpretative modelling of the experimental data. The surface and spectral characteristics of the natural bioactive substance and the inorganic microcarrier were determined by Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet/Visible (UV/Vis) spectrophotometric analyses. The maximum extent of catechin microencapsulation in acidic medium was 32%. The in vitro release kinetics study in simulated enzyme-free gastric medium (pH = 1.2) approved 88% maximum release efficiency achieved after 24 h. The in vitro release profile displayed that the developed bioflavanol/clinoptilolite microcarrier system provided sustained catechin in vitro release behaviour without an initial burst effect. Thus, the results from the present study are essential for the design and development of innovative catechin-CLS-5 microcarrier systems for application in human and veterinary medicine.

Extraction of Protodioscin from Tribulus terrestris-Optimisation of Kinetics and Modeling

The aim of the present study was to establish the optimal conditions for protodioscin extraction from Tribulus terrestris plant and to investigate the possibilities of mathematical modeling of the process and calculation of the diffusion coefficients essential for the industrial scale-up and management of the extraction process. The kinetics of protodioscin extraction from Tribulus terrestris was experimentally studied at varying the solvent type (70% and 96% ethanol) and temperature (20�C, 30�C, 40�C). The optimal process conditions for these parameters were determined. The experimental results were mathematically modelled. Numerical solutions of the propsed in the study empirical model with constant and variable effective diffusivity in the solid phase, Deff, were obtained. The empirical model was based on comparative analyses with the Regular regime model solutions. It was established that the experimental data complied satisfactorily with the the resulting numerical solutions.

The antimalaria drug artemisinin displays strong cytotoxic effect on leukaemia lymphocytes in combination with vitamin C and pro-vitamin K3

This study investigated the anticancer effect of the anti-parasitic drug artemisinin in combination with two redox modulators: vitamin C and pro-vitamin K3 (C/K3) The experiments were conducted on leukaemia cells Jurkat. Cells were treated with either artemisinin or C/K3 alone and with all three compounds. Cell proliferation and viability were analysed using trypan blue stating and automated cell counting. The results showed that artemisinin (>10 mM) suppressed cell proliferation activity, but did not induce cell death up to 500 mM. The drug demonstrated a clear cytostatic effect at concentrations 250- 500 mM – Jurkat cells did not proliferate, but were alive. The combination C/K3 (200:2, 300:3 mM/mM) applied alone did not affect cell proliferation and viability. Vitamins C/K3 in concentration ratio 500:5 (μM/mM) decreased cell proliferation activity by ~10%. The triple combination artemisinin/C/K3 manifested synergistic anti-proliferative effects at all concentration ratios analysed. This synergistic effect increased with increasing C/K3 concentration. Based on literature data, it was assumed that the anti-proliferative effect of the triple combination was mediated by changes in the redox-homeostasis of cancer cells. The C/K3 redox system likely acted on cancer mitochondria and increased superoxide production and activation of pro-apoptotic signals, specific for cancer cells. On the other hand, artemisinin could generate hydroxyl radicals as a result of activation of Fenton reactions, depleting intracellular reducing equivalents. Both redox mechanisms lead to activation of signal pathways for induction of cancer cell death.

Investigation of Anti-Proliferative Effects of Natural Products Quercetin Hydrate and Catechin Hydrate on Leukemia Lymphocytes

The major problem of conventional cancer therapy is lack of selectivity and induction of harmful side-effects on normal (healthy) cells and tissues. In the recent years, scientific efforts are focused to find a proper approach for highly selective influence on cell viability, as well as induction of cell death in cancer cells only. In this regard, natural herbal products are of great interest due to their low cytotoxicity to normal cells and tissues and their potential as supplements to conventional chemotherapeutics. It is well known that flavonoids exhibit various biological activities, such as anti oxidative, anti bacterial, anti inflammatory, anti viral and anti cancer, and may play a role in cancer prevention. In the present study, the effects of low concentrations of quercetin hydrate and catechin hydrate on cell viability of leukemia lymphocytes were investigated, in order to provide an experimental basis for their future incorporation into newly-synthesized biocompatible nano-formulations.

Catechins within the Biopolymer Matrix-Design Concepts and Bioactivity Prospects

Epidemiological studies and clinical investigations proposed that catechins extracts alone may not provide a sufficient level of bioactivities and promising therapeutic effects to achieve health benefits due to a number of constraints related to poor oral absorption, limited bioavailability, sensitivity to oxidation, etc. Modern scientific studies have reported numerous techniques for the design of micro- and nano-bio-delivery systems as novel and promising strategies to overcome these obstacles and to enhance catechins' therapeutic activity. The objective assessment of their benefits, however, requires a critical comparative estimation of the advantages and disadvantages of the designed catechins-biocarrier systems, their biological activities and safety administration aspects. In this respect, the present review objectively outlines, compares and assesses the recent advances related to newly developed design concepts of catechins' encapsulation into various biopolymer carriers and their release behaviour, with a special emphasis on the specific physiological biofunctionalities of the innovative bioflavonoid/biopolymer delivery systems.

Sorption equilibrium, thermodynamics and pH-indicator properties of cresyl violet dye/bentonite composite system

The aim of the present study was to develop cresyl violet (CV)/bentonite composite system, to investigate the equilibrium sorption of the fluorescent dye on bentonite, to determine the characteristic equilibrium and thermodynamic parameters of the system by appropriate empirical isotherm models and to assess its pH-indicator properties. The absorption characteristics of CV solutions were investigated by UV/VIS spectrophotometer. Equilibrium experiments were conducted and the experimental data were modelled by six mathematical isotherm models. The analyses of the experimental data showed that bentonite exhibited significantly high capacity - 169.92 mg/g, towards CV. The encapsulation efficiency was 85%. The Langmuir, Flory-Huggins and El-Awady models best represented the experimental results. The free Gibbs energy of adsorption (ΔG_o) was calculated on the basis of the values of the equilibrium coefficients determined by the proposed models. The values of ΔG determined by the Langmuir, Temkin and Flory-Huggins models are within the range -20 to -40 kJ/mol, which indicates that the adsorption process is spontaneous and chemisorption takes place due to charge sharing or transfer from the dye molecules to the sorbent surface as a coordinate type of bond. The investigations of the obtained CV/bentonite hybrid systems for application as pH-markers showed satisfactory results.

Low-temperature plasma-modified zeolite (LTPMZ) vs. natural Bulgarian zeolite (NBZ) – Comparative physicochemical, UV/VIS and FTIR studies

The aim of the present study was to investigate and compare the physicochemical, morphological properties and sorption potential of natural Bulgarian zeolite (NBZ) and low-temperature plasma modified zeolite (LTPMZ). NBZ was treated by low-temperature arc plasma. The evolution of the modifications was followed using FTIR, UV-VIS, physicochemical and sorption studies. The digital microscope analyses proved that crystallinity, sheet structure and textural properties of the natural material were not significantly affected by the plasma treatment. The comparative analyses of the FTIR spectra obtained showed that the plasma treatment caused the breakdown of structural bounds at the clay surface and induced the formation of new hydroxyl groups (Si–OH and Al–OH) on the clay edges. According to the UV/VIS and FTIR studies of Rhodamine 6G (Rh6G) sorption, LTPMZ displayed higher affinity to the cationic dye. This study demonstrates that low-temperature plasma treatments could be used to activate zeolite for environmental application.

Zinc Supplementation against Eimeria acervulina-Induced Oxidative Damage in Broiler Chickens

This study was undertaken to determine the dietary supplements of Zn containing diet on the antioxidant status in chickens experimentally infected with Eimeria acervulina. The antioxidant status was monitored via determination of MDA concentrations and erythrocyte SOD and CAT activities, as well as vitamin E, vitamin C, Cu, and Zn in liver, muscle, and serum. The results showed increased MDA (P < .05), CAT (P < .001), and decreased SOD (P < .001) in the infected birds. Significant changes in Cu and Zn concentrations and dramatically reduction of vitamin C and E concentrations in the infected chickens were found. The observed deviations in the studied enzymes and nonenzymatic parameters evidence the occurrence of oxidative stress following the infection and impaired antioxidant status of chickens, infected with Eimeria acervulina. Our results proved the ameliorating role of CuZn(OH)(3)Cl (0.170 g per kg food) against Eimeria acervulina-induced oxidative damage in infected chickens.

Dynamic studies of nitrophenols adsorption on perfil in a fixed-bed column: application of single and two resistance model

The mechanism of 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) adsorption on perfil-natural mineral taken from Bulgarian deposits, in a fixed-bed column was investigated. The single component experiments were conducted at constant initial sorbate concentration, volumetric flow rate, temperature and pH. The effect of adsorbent bed depth (Z 1, 2, 3, 6 cm) and sorbate nature on the adsorption capacity, mass transfer parameters and mechanisms was studied. The equilibrium behaviour of the system 4-NP-perfil was described by Langmuir, Freundlich and Redlich-Peterson models. The single resistance Thomas model, including Reynolds-Richards and Walter solutions, and the two-resistance Arnold model were applied for mathematical modeling of the experimental data. The comparative analyses indicated that external mass transfer was the rate limiting mechanism during the initial adsorption stages, while intraparticle diffusion was dominant in the middle and high concentration ranges. The effect of axial dispersion on the dynamics of adsorption was evaluated.

Dynamic studies of nitrophenols sorption on perfil in a fixed-bed column

The adsorption of two substituted nitrophenols, namely 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP), from aqueous solutions onto perfil was studied using a fixed bed column. The theoretical solid diffusion control (SDC) model describing single solute adsorption in a fixed bed based on the Linear Driving Force (LDF) kinetic model was successfully applied to the investigated systems. The model parameters of solid diffusion coefficient, DS, axial dispersion coefficient, DL, and external mass transfer coefficient, kf, for the investigated systems were estimated by the means of a best fit approach. Some deviations were found between the predicted and the experimental data which reflect the fact that the assumptions of the model were not quite fulfilled for these experiments. It is necessary to adjust the values of the solid diffusion coefficient, the axial dispersion coefficient and the external mass transfer coefficient in order to obtain a satisfactory agreement between the simulated and the experimental breakthrough curves. A Biot number was used as an indicator for the intarparticle diffusion. The Biot number was found to decrease with the increase of bed depth, indicating that the film resistance increased or the intraparticle diffusion resistance decreased.

Comparative modelling of mono- and dinitrophenols sorption on yellow bentonite from aqueous solutions

Equilibrium removal of three substituted nitrophenols, namely 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP), by adsorption on yellow bentonite was tested. The batch kinetic data are described by the pseudo-first order, pseudo-second order, and intraparticle diffusion models. Results show that chemisorption processes could be rate limiting in the sorption step. The adsorption equilibrium was modelled by the Langmuir and Freundlich equations. The Langmuir model better represents the equilibrium isotherm data for 2-NP, 4-NP, and 2,4-DNP uptake on yellow bentonite. 4-NP is adsorbed in larger amounts than the disubstituted nitrophenol. Uptake of nitrophenols increases in the order 2-NP < 2,4-DNP < 4-NP.

A phase II trial with new triptorelin sustained release formulations in prostatic carcinoma

OBJECTIVES

The objectives were to assess if a single intramuscular (i.m.) injection of the GnRH agonist triptorelin, as pamoate Sustained Release (RS) 11.25 mg, was able to induce pharmacological castration and to maintain the plasma testosterone levels in the castrate range (< 1.735 nmol/l) up to 3 months in prostatic carcinoma.

METHODS

Two different formulations of triptorelin pamoate 11.25 mg were assessed in 2 groups of 10 patients suffering from prostatic carcinoma. Each patient received one i.m. injection of triptorelin pamoate SR 11.25 mg. Triptorelin and testosterone levels were measured over 3 months. Pain, micturition difficulties, performance status, local and general tolerance, and the occurrence of adverse events were evaluated.

RESULTS

Both formulations were able to induce castration levels (<1.735 nmol/l) of testosterone within 3 to 4 weeks post-injection, and to maintain levels below 1.735 nmol/l till the end of 3rd month. The bioavailability of one formulation (DLGSD-3-95-21) tended to be greater. This may explain the quicker onset of castration and the slight better maintenance of low testosterone levels during the 3rd month observed with this formulation. In terms of clinical end-points, the local tolerance of both formulations was excellent. No serious adverse events were recorded except transient hot flushes in 2 cases and slight bone pain in one.

CONCLUSION

Triptorelin pamoate 11.25 mg given in microgranules is a 3-month sustained-release administration form which appears to be safe and effective in advanced prostatic carcinoma. Based on the findings of this study, the formulation with greater bioavailability (DLGSD-3-95-21) was selected as formulation of choice to be used for clinical treatments and further clinical investigation.