Antioxidant Activity and Biocompatibility of Fructo-Polysaccharides Extracted from a Wild Species of Ornithogalum from Lebanon

P. Oliveira MB, Carpena M, Prieto MA. Therapeutic and Preventive Potential of Plant-Derived Antioxidant Nutraceuticals

Oxidative stress and its relation to the onset of several chronic diseases have been increasingly highlighted in recent years. In parallel, there has been an increasing interest in the antioxidant properties of phytochemicals. Phytochemicals are products of plant secondary metabolism, including structural polysaccharides, unsaturated fatty acids, pigments (chlorophylls, carotenoids, and anthocyanins), or phenolic compounds. Phytochemicals can be obtained from lower and higher plants, their fruits, and even from macro- or microalgae. Their diverse structural features are linked to different beneficial effects through various molecular mechanisms, contributing to disease prevention. Beyond antioxidant activity, many phytochemicals also display anti-inflammatory, antidiabetic, anti-obesity, and neuroprotective effects, which can be intertwined. Beyond these, other natural antioxidants can also be obtained from animal, fungal, and bacterial sources. Thus, a wide range of antioxidants have the potential to be used as nutraceuticals with chemopreventive effects on the onset of various diseases related to antioxidant stress. Given their enormous structural and sourcing diversity, the present work provides an updated insight into the therapeutic and preventive potential of plant-derived antioxidants and nutraceuticals.

Extraction methods, structural diversity and potential biological activities of Artemisia L. polysaccharides (APs): A review

The extraction and structural characterization of polysaccharides are challenging in plants with overlapping distributions such as Artemisia, the plant genus producing antimalarial drug artemisinin discovered by the Nobel Prize 2015 winning Professor Tu You-you. The diversity in Artemisia polysaccharides (APs) is due to difference in extraction methods leading to different bioactivities. In spite of that, APs utilization is decelerated due to lack of a review portraying current advancements. This review delivers data on extraction, structural characterization and bioactivities of APs with emphasis on mechanisms of action and structure-function relationships. Outcomes indicated that various polysaccharides in 16 Artemisia species were reported and comprehensively described. The common methods for preparing APs were hot water and microwave assisted extractions with maximum yield. Maximum plant parts used to extract APs include leaves, aerial part, whole plant and seeds. The APs presented varying molecular weight, monosaccharide composition, carbohydrates, proteins, uronic acids and phenolic content with around 20 bioactivities. Data on structure-function relationships indicated that the bioactivities of APs are highly correlated with the differences in Mw and monosaccharide's type. While Artemisia species discussed here are the most studied species for their polysaccharides, other Artemisia species may offer unique polysaccharides with distinct biological properties; hence, the future research could focus on expanding the scope of species studied. Broader investigations are also needed specifically on the structure-function relationships of APs with the elucidation of impact of unknown factors on their efficacy.

Characterization and Antioxidant Activity of Polysaccharides From Agaricus bisporus by Gradient Ethanol Precipitation

In this present work, the polysaccharides from Agaricus bisporus were extracted and fractioned with gradient ethanol precipitation method for the first time. Five fractions (ABP40, ABP50, ABP60, ABP70, and ABP80) were obtained with ethanol concentrations of 40%, 50%, 60%, 70%, and 80%, respectively, and their characteristics and antioxidant activities in vitro were investigated. The five fractions presented significant differences in total sugar, protein, and uronic acid content, with a marked discrepancy in the molar ratio of the monosaccharide composition. The molecular weights of the polysaccharides decreased with increasing ethanol concentration. Compared to the other four fractions, ABP70, which has the highest uronic acid content, showed more conspicuous radical-scavenging activities against hydroxyl (89.9 ± 0.33%) and DPPH radicals (80.1 ± 0.01%). Moreover, it was found that the total sugar content and antioxidant activities of polysaccharides increased with the extension of precipitation time, with the highest antioxidant activities at 24 h. Therefore, ABP70, precipitated for 24 h, may have a potential application value for the development of antioxidants. This study provides valuable information for the further commercial applications of polysaccharides from Agaricus bisporus.

Response surface methodology-based optimisation of chitin production and its antioxidant activity from Aspergillusniger

- In this study, we focused on isolating fungi capable of producing extracellular chitin, a critical component of fungal cell walls. Aspergillus niger was chosen as the candidate, and we aimed to optimise chitin production. Initially, one variable at a time (OVAT) method was used to enhance chitin yield under the best fermentation conditions. Subsequently, the Plackett-Burman design was employed to identify the key medium components influencing chitin production. These factors were then fine-tuned using the Central Composite Design, resulting in the optimal concentrations of dipotassium hydrogen phosphate (0.7 mg/l), calcium chloride (0.5 mg/l), thymine hydrochloride (0.5 mg/l), and pH (4), as confirmed by ANOVA. The application of response surface methodology (RSM) led to a remarkable improvement in chitin yield, increasing it from 1.14 g/l to an impressive 4.42 g/l, a substantial 3.34-fold enhancement compared to unoptimized conditions. Additionally, we explored the antioxidant activity of the produced chitin, revealing its promising properties with a scavenging activity ranging from 32% to 55% at concentrations of 1-2 mg/ml, surpassing the control. In conclusion, our study successfully optimized chitin production from Aspergillus niger and demonstrated the remarkable antioxidant potential of the produced chitin, highlighting its significance in various applications.

Antioxidant Activities of Natural Polysaccharides and Their Derivatives for Biomedical and Medicinal Applications

Many chronic diseases such as Alzheimer's disease, diabetes, and cardiovascular diseases are closely related to in vivo oxidative stress caused by excessive reactive oxygen species (ROS). Natural polysaccharides, as a kind of biomacromolecule with good biocompatibility, have been widely used in biomedical and medicinal applications due to their superior antioxidant properties. In this review, scientometric analysis of the highly cited papers in the Web of Science (WOS) database finds that antioxidant activity is the most widely studied and popular among pharmacological effects of natural polysaccharides. The antioxidant mechanisms of natural polysaccharides mainly contain the regulation of signal transduction pathways, the activation of enzymes, and the scavenging of free radicals. We continuously discuss the antioxidant activities of natural polysaccharides and their derivatives. At the same time, we summarize their applications in the field of pharmaceutics/drug delivery, tissue engineering, and antimicrobial food additives/packaging materials. Overall, this review provides up-to-date information for the further development and application of natural polysaccharides with antioxidant activities.

Molecular Characterization and Biocompatibility of Exopolysaccharide Produced by Moderately Halophilic Bacterium Virgibacillus dokdonensis from the Saltern of Kumta Coast

The use of natural polysaccharides as biomaterials is gaining importance in tissue engineering due to their inherent biocompatibility. In this direction, the present study aims to explore the structure and biocompatibility of the EPS produced by Virgibacillus dokdonensis VITP14. This marine bacterium produces 17.3 g/L of EPS at 96 h of fermentation. The EPS was purified using ion exchange and gel permeation chromatographic methods. The porous web-like structure and elemental composition (C, O, Na, Mg, P, S) of the EPS were inferred from SEM and EDX analysis. AFM analysis revealed spike-like lumps with a surface roughness of 84.85 nm. The zeta potential value of −10 mV indicates the anionic nature of the EPS. Initial molecular characterization showed that the EPS is a heteropolysaccharide composed of glucose (25.8%), ribose (18.6%), fructose (31.5%), and xylose (24%), which are the monosaccharide units in the HPLC analysis. The FTIR spectrum indicates the presence of functional groups/bonds typical of EPSs (O-H, C-H, C-O-H, C-O, S=O, and P=O). The polymer has an average molecular weight of 555 kDa. Further, NMR analysis revealed the monomer composition, the existence of two α- and six β-glycosidic linkages, and the branched repeating unit as → 1)[α-D-Xylp-(1 → 2)-α-D-Glcp-(1 → 6)-β-D-Glcp-(1 → 5)]-β-D-Frup-(2 → 2)[β-D-Xylp-(1 → 4)]-β-D-Xylp-(1 → 6)-β-D-Fruf-(2 → 4)-β-D-Ribp-(1 →. The EPS is thermally stable till 251.4 °C. X-ray diffraction analysis confirmed the semicrystalline (54.2%) nature of the EPS. Further, the EPS exhibits significant water solubility (76.5%), water-holding capacity (266.8%), emulsifying index (66.8%), hemocompatibility (erythrocyte protection > 87%), and cytocompatibility (cell viability > 80% on RAW264.7 and keratinocyte HaCaT cells) at higher concentrations and prolongs coagulation time in APTT and PT tests. Our research unveils the significant biocompatibility of VITP14 EPS for synthesizing a variety of biomaterials.

The Nanostructured lipid carrier gel of Oroxylin A reduced UV-induced skin oxidative stress damage

Oxidative stress damage caused by sun exposure damages the appearance and function of the skin, which is one of the essential inducements of skin aging and even leads to skin cancer. Oroxylin A (OA) is a flavonoid with excellent antioxidant activity and has protective effects against photoaging induced by UV irradiation. However, the strong barrier function of the skin stratum corneum prevents transdermal absorption of the drug, which limits the application of OA in dermal drug delivery. Studies have shown that nanostructured lipid carriers (NLC) can promote not only transdermal absorption of drugs but also increase drug stability and control drug release efficiency, which has broad prospects for clinical applications. In this paper, NLC loaded with OA (OA-NLC) was prepared in order to improve the skin permeability and stability of OA. In vitro studies revealed that OA-NLC had better therapeutic effects than OA solution (OA-Sol) in the cellular model of UVB radiation. OA-Sol and OA-NLC were immobilized in a hydrogel matrix to facilitate application to the dorsal skin of mice. It was found that OA-NLC-gel showed significant antioxidant and anti-apoptotic activity compared to OA-Sol-gel, which was able to protect against skin damage in mice after UV radiation. These results suggest that OA-NLC can improve the deficiencies of OA in skin delivery and show better resistance to UV-induced oxidative damage. The application of OA-NLC to skin delivery systems has good prospects and deserves further development and investigation.

Correlations between rheological and mechanical properties of fructo-polysaccharides extracted from Ornithogalum billardieri as biobased adhesive for biomedical applications

Polysaccharides are extracted from Ornithogalum by maceration using different ultrasound (US) treatment times (0%US, 50%US, 100%US), and under optimized extraction conditions (OP%US). The total carbohydrates content (TCC) and proteins content of the extracts were determined. Data show that the extraction parameters significantly influence the extracts composition. Rheological measurements allowed determining the liquid, intermediate and gel states of the extract's solutions. The adhesion strength of the solutions was evaluated on paper and polylactide (PLA) substrates to evaluate their potential as environmentally friendly adhesive. OP%US presents the highest adhesion strength (1418.3 kPa) on paper, and is further tested on pork skin substrates. The adhesion strength is higher on skin/paper (870 kPa) than on skin/skin (411 kPa) substrate due to the capillary force of paper which allows penetration of adhesive into the micropores of paper. The correlation between rheological properties and adhesion strength indicates that the adhesion strength strongly depends on the state of adhesives and the substrate type. SEM analyses show that higher adhesion strength (intermediate and gel states) involves both cohesive and adhesive failure, whereas only adhesive failure is observed in liquid state on PLA substrates. Therefore, these polysaccharides extracts could be very promising as tissue adhesive in medical applications.

Design, Synthesis and Characterization of [G10a]-Temporin SHa Dendrimers as Dual Inhibitors of Cancer and Pathogenic Microbes

As the technologies for peptide synthesis and development continue to mature, antimicrobial peptides (AMPs) are being widely studied as significant contributors in medicinal chemistry research. Furthermore, the advancement in the synthesis of dendrimers’ design makes dendrimers wonderful nanostructures with distinguishing properties. This study foregrounds a temporin SHa analog, [G10a]-SHa, and its dendrimers as globular macromolecules possessing anticancer and antibacterial activities. These architectures of temporin SHa, named as [G10a]-SHa, its dendrimeric analogs [G10a]₂-SHa and [G10a]₃-SHa, and [G10a]₂-SHa conjugated with a polymer molecule, i.e., Jeff-[G10a]₂-SHa, were synthesized, purified on RP-HPLC and UPLC and fully characterized by mass, NMR spectroscopic techniques, circular dichroism, ultraviolet, infrared, dynamic light scattering, and atomic force microscopic studies. In pH- and temperature-dependent studies, all of the peptide dendrimers were found to be stable in the temperature range up to 40–60 °C and pH values in the range of 6–12. Biological-activity studies showed these peptide dendrimers possessed improved antibacterial activity against different strains of both Gram-positive and Gram-negative strains. Together, these dendrimers also possessed potent selective antiproliferative activity against human cancer cells originating from different organs (breast, lung, prostate, pancreas, and liver). The high hemolytic activity of [G10a]₂-SHa and [G10a]₃-SHa dendrimers, however, limits their use for topical treatment, such as in the case of skin infection. On the contrary, the antibacterial and anticancer activities of Jeff-[G10a]₂-SHa, associated with its low hemolytic action, make it potentially suitable for systemic treatment.

Antioxidant activity of sulfated Porphyra yezoensis polysaccharides and their regulating effect on calcium oxalate crystal growth

The nucleation, growth and aggregation of calcium oxalate (CaOx) crystals and the oxidative damage of renal tubular epithelial cells are the key factors to induce kidney stones. In this study, degraded Porphyra yezoensis polysaccharide (PYP0) with 14.14% sulfate group (-OSO₃^-) content was modified via the sulfur trioxide-pyridine method to obtain three kinds of sulfated P. yezoensis polysaccharides (PYPs), namely, PYPS1, PYPS2, and PYPS3, with -OSO₃^- group contents of 17.11%, 20.28%, and 27.14% respectively. Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR analyses showed that the -OSO₃^- groups replaced the hydroxyl groups at the C2, C4, and C6 positions on (1 → 3)-linked β-D-galactose, the basic structural skeleton unit of PYP0. The antioxidant activity of the PYPSs increased after sulfation, and their scavenging capacity for OH and DPPH free radicals was enhanced with the increase in their -OSO₃^- group content. Calcium oxalate (CaOx) crystal growth experiments showed that sulfated PYPs promoted the conversion of the thermodynamically stable and sharp CaOx monohydrate (COM) crystals into the thermodynamically unstable and round CaOx dihydrate crystals. With the increase in the -OSO₃^- group content of the polysaccharides, the concentration of soluble Ca²⁺ ions in the supernatant increased and the amount of CaOx precipitate decreased. PYPs were nontoxic to human kidney proximal tubular epithelial cells (HK-2) and could protect HK-2 from oxidative damage caused by nano-COM and reduce the level of reactive oxygen species in cells. PYPS3, which had the highest degree of sulfation, had the best protective capability. The results of this work showed that sulfation improved the biological activity of PYPs. This study could provide inspiration for the development of new drugs for the prevention and treatment of kidney stones.

Development and evaluation studies of Corylin loaded nanostructured lipid carriers gel for topical treatment of UV-induced skin aging

We prepared nanostructured lipid carriers (NLC) to promote skin permeation of Corylin so that it can increase its effect on photoaging. Corylin-NLCs were prepared and characterized based on morphology, particle size, zeta potentials, FTIR and DSC. In vitro, we assess the cytotoxicity and lactate dehydrogenase (LDH) of HaCaT cells irradiated by UVB. Expression of antioxidant enzymes was evaluated by commercial kits. The effects of Corylin-NLC on apoptosis were confirmed by flow cytometry and western blotting. In vivo, we use UV irradiated mouse as the oxidative stress model to assess the therapeutic effect of Corylin loaded NLC gel. We identified the Corylin-NLCs can significantly suppress the LDH release, decrease MDA content, increase in CAT, SOD, GSH-Px activity, increase the expression of Bcl-2/Bax protein and reduce the expression of cleaved caspase-3/caspase-3 protein on UVB induced HaCaT cells. The histopathological lesions were significantly improved and observably decreased MDA level, increase in antioxidant enzymes activity in serum of mice by pretreatment of Corylin-NLCs gel. Overall, this study proposes a promising strategy for improving the therapeutic efficacy of photoaging.

Antioxidants: Classification, Natural Sources, Activity/Capacity Measurements, and Usefulness for the Synthesis of Nanoparticles

Natural extracts are the source of many antioxidant substances. They have proven useful not only as supplements preventing diseases caused by oxidative stress and food additives preventing oxidation but also as system components for the production of metallic nanoparticles by the so-called green synthesis. This is important given the drastically increased demand for nanomaterials in biomedical fields. The source of ecological technology for producing nanoparticles can be plants or microorganisms (yeast, algae, cyanobacteria, fungi, and bacteria). This review presents recently published research on the green synthesis of nanoparticles. The conditions of biosynthesis and possible mechanisms of nanoparticle formation with the participation of bacteria are presented. The potential of natural extracts for biogenic synthesis depends on the content of reducing substances. The assessment of the antioxidant activity of extracts as multicomponent mixtures is still a challenge for analytical chemistry. There is still no universal test for measuring total antioxidant capacity (TAC). There are many in vitro chemical tests that quantify the antioxidant scavenging activity of free radicals and their ability to chelate metals and that reduce free radical damage. This paper presents the classification of antioxidants and non-enzymatic methods of testing antioxidant capacity in vitro, with particular emphasis on methods based on nanoparticles. Examples of recent studies on the antioxidant activity of natural extracts obtained from different species such as plants, fungi, bacteria, algae, lichens, actinomycetes were collected, giving evaluation methods, reference antioxidants, and details on the preparation of extracts.

Syntrophy of Crypthecodinium cohnii and immobilized Zymomonas mobilis for docosahexaenoic acid production from sucrose-containing substrates

Marine heterotrophic dinoflagellate Crypthecodinium cohnii is an aerobic oleaginous microorganism that accumulates intracellular lipid with high content of 4,7,10,13,16,19-docosahexaenoic acid (DHA), a polyunsaturated ω-3 (22:6) fatty acid with multiple health benefits. C. cohnii can grow on glucose and ethanol, but not on sucrose or fructose. For conversion of sucrose-containing renewables to C. cohnii DHA, we investigated a syntrophic process, involving immobilized cells of ethanologenic bacterium Zymomonas mobilis for fermenting sucrose to ethanol. The non-respiring, NADH dehydrogenase-deficient Z. mobilis strain Zm6-ndh, with high ethanol yield both under anaerobic and aerobic conditions, was taken as the genetic background for inactivation of levansucrase (sacB). SacB mutation eliminated the levan-forming activity on sucrose. The double mutant Zm6-ndh-sacB cells were immobilized in Ca alginate, and applied for syntrophic conversion of sucrose to DHA of C. cohnii, either taking the ethanol-containing fermentation medium from the immobilized Z. mobilis for feeding to the C. cohnii fed-batch culture, or directly coculturing the immobilized Zm6-ndh-sacB with C. cohnii on sucrose. Both modes of cultivation produced C. cohnii CCMP 316 biomass with DHA content around 2-3 % of cell dry weight, corresponding to previously reported results for this strain on glucose.