Quercetin as a Promising Antiprotozoan Phytochemical: Current Knowledge and Future Research Avenues

Despite tremendous advances in the prevention and treatment of infectious diseases, only few antiparasitic drugs have been developed to date. Protozoan infections such as malaria, leishmaniasis, and trypanosomiasis continue to exact an enormous toll on public health worldwide, underscoring the need to discover novel antiprotozoan drugs. Recently, there has been an explosion of research into the antiprotozoan properties of quercetin, one of the most abundant flavonoids in the human diet. In this review, we tried to consolidate the current knowledge on the antiprotozoal effects of quercetin and to provide the most fruitful avenues for future research. Quercetin exerts potent antiprotozoan activity against a broad spectrum of pathogens such as Leishmania spp., Trypanosoma spp., Plasmodium spp., Cryptosporidium spp., Trichomonas spp., and Toxoplasma gondii. In addition to its immunomodulatory roles, quercetin disrupts mitochondrial function, induces apoptotic/necrotic cell death, impairs iron uptake, inhibits multiple enzymes involved in fatty acid synthesis and the glycolytic pathways, suppresses the activity of DNA topoisomerases, and downregulates the expression of various heat shock proteins in these pathogens. In vivo studies also show that quercetin is effective in reducing parasitic loads, histopathological damage, and mortality in animals. Future research should focus on designing effective drug delivery systems to increase the oral bioavailability of quercetin. Incorporating quercetin into various nanocarrier systems would be a promising approach to manage localized cutaneous infections. Nevertheless, clinical trials are needed to validate the efficacy of quercetin in treating various protozoan infections.

Maternal rat prenatal and neonatal treatment with pequi pulp reduces anxiety and lipid peroxidation in brain tissue of rat offspring at adolescence

The Pequi fruit (Caryocar Brasiliense cambess), typical of the Brazilian cerrado or savannah, is a source of essential fatty acids, carotenoids, and phenolic compounds. The aim of this study was to analyze the effects of consuming this fruit on anxiety behavior and lipid peroxidation in the brains of rats whose mothers were treated (by gavage) during pregnancy and lactation with Pequi fruit (pulp or nuts) at 2000 mg/kg of body weight. Anxiety parameters were assessed using the open field (OF), elevated plus maze (EPM), and light/dark box (LDB) tests. The brain was removed to measure malondialdehyde (MDA) levels. Data were analyzed using One-way Anova (p < 0.05). In the OF, the animals in the pulp group presented more time spent in the central area (20.37 ± 0.73 vs Control: 12.51 ± 0.39; Nuts: 8.28 ± 0.40) and increased locomotion (159.7 ± 6.10) compared to the other groups (Control: 127.3 ± 5.54; Nuts: 139.08 ± 6.57). In the EPM, the pulp group entered into the open arms (8.57 ± 0.36) and stayed more time in the central area (19.44 ± 1.17) compared to the Nuts group (7.14 ± 0.34; 13.00 ± 1.57). In the LDB the pulp group entered more (8.00 ± 0.42 vs Control: 7.16 ± 0.16 and Nuts: 7.42 ± 0.75) and stayed longer in the clear light side (92.18 ± 6.42) than all the other groups (Control: 71.44 ± 3.53; Nuts: 80.57 ± 6.50), respectively. Pulp group presented lower MDA in the brain (55.34 ± 3.04) compared to Control (72.06 ± 4.66) and Nuts (66.57 ± 2.45). We conclude that Pequi pulp consumption during pregnancy and lactation reduces lipid peroxidation in brain tissue and induces anxiolytic-like behavior in rat offspring. These effects were not observed in the Pequi nuts group.

The Association between Malaria and β-Carotene Levels: A Systematic Review and Meta-Analysis

BACKGROUND

β-Carotene, which is a prominent carotenoid with notable antioxidant properties, may play a role in countering the oxidative stresses induced by malaria. The association between β-carotene levels and malaria is not yet fully understood, prompting this systematic review and meta-analysis.

METHODS

A rigorous search of databases, including Nursing and Allied Health Premium, EMBASE, MEDLINE, Ovid, PubMed, Scopus, and Google Scholar, was undertaken to collate studies that focused on β-carotene levels in malaria patients. The selected studies underwent critical appraisal, followed by data extraction for a meta-analysis.

RESULTS

Of the 2498 records initially identified, 10 were deemed suitable for synthesis. A considerable number of these studies indicated a pronounced reduction in β-carotene levels among malaria patients in contrast with uninfected individuals. The meta-analysis, encompassing 421 malaria patients and 240 uninfected controls, revealed a significant correlation between reduced β-carotene levels and malaria (p < 0.01, Hedges's g: -1.26, 95% CI: -2.00-(-0.53), I2: 93.86%, seven studies).

CONCLUSIONS

The conducted systematic review and meta-analysis corroborated the correlation between lower β-carotene levels and malaria. The intricate relationship between malaria and β-carotene merits deeper exploration. A comprehensive understanding of this association might pave the way for innovative therapeutic approaches leveraging the antioxidant attributes of β-carotene to combat malaria-induced oxidative stress.

Optimization and multiple in vitro activity potentials of carotenoids from marine Kocuria sp. RAM1

Marine pigmented bacteria are a promising natural source of carotenoids. Kocuria sp. RAM1 was isolated from the Red Sea Bohadschia graeffei collected from Marsa Alam, Egypt, and used for carotenoids production. The extracted carotenoids were purified by thin-layer chromatography (TLC). The characteristic UV absorbance of the three purified fractions gave us an inkling of what the purified pigments were. The chemical structures were confirmed by nuclear magnetic resonance spectroscopy (NMR) and LC-ESI-QTOF-MS/MS. The three different red pigments were identified as two C₅₀-carotenoids, namely bisanhydrobacterioruberin and trisanhydrobacterioruberin, in addition to 3,4,3',4'-Tetrahydrospirilloxanthin (C₄₂-carotenoids). Kocuria sp. RAM1 carotenoids were investigated for multiple activities, including antimicrobial, anti-inflammatory, antioxidant, anti-HSV-1, anticancer, antidiabetic and wound healing. These new observations suggest that Kocuria sp. RAM1 carotenoids can be used as a distinctive natural pigment with potent properties.

Hepatoprotective Effect of Opuntia robusta Fruit Biocomponents in a Rat Model of Thioacetamide-Induced Liver Fibrosis

Liver fibrosis is a chronic disease associated with oxidative stress that has a great impact on the population mortality. Due to their antioxidant capacity, we evaluated the protective effect of Opuntia robusta fruit (Or) on liver fibrosis. A nutraceutical characterization of Or was performed and a model of fibrosis was induced with thioacetamide (TAA) in Wistar rats. Aminotransferases, reduced glutathione (GSH) and histopathology were evaluated. Or contained 436.5 ± 57 mg of Betacyanins equivalents/L., 793 mg of catechin equivalents (CAE)/100 g for flavonoids, 1118 mg of gallic acid equivalents (GAE)/100 g for total phenols, 141.14 mg/100 g for vitamin C and 429.9 μg/100 g for vitamin E. The antioxidant capacity of Or was: 2.27 mmol of Trolox® equivalents (TE)/L (DPPH), 62.2 ± 5.0 μmol TE/g (ABTS•+), 80.2 ± 11.7 μmol TE/g (FRAP), 247.9 ± 15.6 µmol TE/g (AAPH) and 15.0% of H2O2 elimination. An increase (p < 0.05) of aminotransferases and a decrease (p < 0.05) of hepatic GSH was observed in the TAA group compared to the control and the concomitant groups. Histopathology showed changes in the normal architecture of the liver treated with TAA compared to the concomitant treatments. Or contains bioactive components with antioxidant capacity, which can reduce fibrotic liver damage.

Comparative performance evaluation of chitosan based polymeric microspheres and nanoparticles as delivery system for bacterial β-carotene derived from Planococcus sp. TRC1

β-carotene is a natural compound with immense healthcare benefits. To overcome insolubility and lack of stability which restricts its application, in this study, β-carotene from Planococcus sp. TRC1 was entrapped into formulations of chitosan‑sodium alginate microspheres (MF1, MF2 and MF3) and chitosan nanoparticles (NF1, NF2 and NF3). The maximum entrapment efficiency (%) and loading capacity (%) were 80.6 ± 4.28 and 26 ± 3.05 (MF2) and 92.1 ± 3.44 and 41.86 ± 4.65 (NF2) respectively. Korsmeyer-Peppas model showed best fit with release, revealing non-Fickian diffusion. Thermal and UV treatment exhibited higher activation energy (kJ/mol), 17.76 and 15.57 (MF2) and 37.03 and 19.33 (NF2) compared to free β-carotene (3.7 and 3.9), uncovering enhanced stability. MF2 and NF2 revealed swelling index (%) 721 ± 1.7 and 18.1 ± 1.5 (pH 6.8) and particle size 69.5 ± 3.2 μm and 92 ± 2.5 nm respectively. FESEM, FT-IR, XRD and DSC depicted spherical morphology, intactness of functional groups and masking of crystallinity. The IC₅₀ (μg ml^-1) values for antioxidant and anticancer (A-549) activities were 33.1 ± 1.7, 45.1 ± 2.8, 39.3 ± 2.9 and 31.3 ± 1.7, 27.9 ± 2.4, 25.3 ± 2.2 for β-carotene, MF2 and NF2 respectively with no significant cytotoxicity on HEK-293 cells and RBCs (p > 0.05). This comparative study of microspheres and nanoparticles may allow the diverse applications of an unconventional bacterial β-carotene with promising stability and efficacies.

Dermocosmetic applications of microalgal pigments

Among photosynthetic microorganisms, Cyanobacteria and Microalgae species have been highly studied thank to their high value-added compounds for several industrial applications. Thus, their production is increasing in the last decade to produce raw material for cosmetics. In fact, the daily routine includes the use of cosmetics and sunscreens to protect against the environmental changes, mainly the increment of ultraviolet (UV) radiation rate with a consequent skin damage and premature aging due to this overexposure. As it is well discussed, chemical UV filters are extensively incorporated into sunscreens formulas; however, they can induce allergenic reactions as well. For these reasons, some pigments derived from microalgae, such as astaxanthin, lutein, β-carotene as well as other biocompounds are now well described in the literature as well as biotechnologically manufactured as natural ingredients to be incorporated into skin care products with multifunctional benefits even for sunscreen purposes. Hence, this investigation summarizes the recent studies about the main pigments from photosynthetic microorganisms' biomasses as well as their uses in dermocosmetics with novel attributes, such as anti-aging agents, makeups, skin lightening and whitening, among others.

Cannabidiol modulation of oxidative stress and signalling

Cannabidiol (CBD), one of the primary non-euphoric components in the Cannabis sativa L. plant, has undergone clinical development over the last number of years as a therapeutic for patients with Lennox-Gastaut syndrome and Dravet syndromes. This phytocannabinoid demonstrates functional and pharmacological diversity, and research data indicate that CBD is a comparable antioxidant to common antioxidants. This review gathers the latest knowledge regarding the impact of CBD on oxidative signalling, with focus on the proclivity of CBD to regulate antioxidants and control the production of reactive oxygen species. CBD is considered an attractive therapeutic agent for neuroimmune disorders, and a body of literature indicates that CBD can regulate redox function at multiple levels, with a range of downstream effects on cells and tissues. However, pro-oxidant capacity of CBD has also been reported, and hence caution must be applied when considering CBD from a therapeutic standpoint. Such pro- and antioxidant functions of CBD may be cell- and model-dependent and may also be influenced by CBD dose, the duration of CBD treatment and the underlying pathology.

A Comprehensive Overview of Colon Cancer- A Grim Reaper of the 21st Century

A few decades ago, the incidence of colorectal cancer (CRC) was low and is now the fourth in the list of deadly cancers producing nearly a million deaths annually. A population that is aging along with risk factors such as smoking, obesity, sedentary lifestyle with little or no physical activity, and non-healthy food habits of developed countries can increase the risk of colorectal cancer. The balance in gut microbiota and the metabolites produced during bacterial fermentation within the host plays a significant role in regulating intestinal diseases as well as colorectal cancer development. Recent progress in the understanding of illness resulted in multiple treatment options such as surgery, radiation, and chemotherapy, including targeted therapy and multitherapies. The treatment plan for CRC depends on the location, stage and grade of cancer as well as genomic biomarker tests. Despite all the advancements made in the genetic and molecular aspects of the disease, the knowledge seems inadequate as the drug action as well as the wide variation in drug response did not appear strongly correlated with the individual molecular and genetic characteristics, which suggests the requirement of comprehensive molecular understanding of this complex heterogeneous disease. Furthermore, multitherapies or a broad spectrum approach, which is an amalgamation of the various promising as well as effective therapeutic strategies that can tackle heterogeneity and act on several targets of the disease, need to be validated in clinical studies. The latest treatment options have significantly increased the survival of up to three years in the case of advanced disease. The fact that colorectal cancer is developed from a polypoid precursor, as well as the symptoms of the disease that occur at an advanced stage, underlines how screening programs can help early detection and decrease mortality as well as morbidity from CRC.

Multitarget protection of Pterospartum tridentatum phenolic-rich extracts against a wide range of free radical species, antidiabetic activity and effects on human colon carcinoma (Caco-2) cells

Pterospartum tridentatum is an edible endemic plant common in Portugal. Its flowers are used in culinary and are part of the popular medicine owing to its therapeutic properties. In this study, P. tridentatum flower infusion and hydroethanolic extracts were characterized concerning their phenolic composition and biological potential. By high-performance liquid chromatography method coupled to a diode array detector analysis were detected 13 phenolics. Genistein was the major one. Concerning the biological potential, the hydroethanolic extract was the most active against 2,2-diphenyl-1-picrylhydrazyl^● and also as α-glucosidase inhibitor, while the infusion proved to be a remarkable free radical scavenger. Concerning human epithelial colorectal adenocarcinoma (Caco-2) cells, it was observed that both extracts displayed dose-dependent cytotoxicity on the viability of Caco-2 cells, presenting cytotoxic selectivity for these cancer cells when compared to the NHDF normal cell line. Additionally, they also showed protective effects against oxidative stress induced by tert-butyl hydroperoxide on Caco-2 cells. The obtained results suggest that these extracts may be interesting to enrich nutraceutical, pharmaceutical and food industries; however, more studies need to be done for their inclusion in pharmaceutical preparations and/or food additives. PRACTICAL APPLICATION: Pterospartum tridentatum is an endemic plant commonly used in folk medicine due to its depurative and hypoglycaemic properties. For this reason, we decided to determine the phenolic content of infusion and hydroethanolic extracts of P. tridentatum and their biological potential. The obtained results proved that P. tridentatum extracts are a rich source of bioactive compounds and possess great antioxidant and antidiabetic activities, ability to protect human erythrocytes against oxidative damage, inhibiting hemolysis, hemoglobin oxidation, and lipid peroxidation, and to interfere with Caco-2 cells growth and to protect these cells when subject to tert-butyl hydroperoxide oxidative stress conditions.

Recovery and identification bioactive peptides from protein isolate of Spirulina platensis and their in vitro effectiveness against oxidative stress-induced erythrocyte hemolysis

BACKGROUND

Spirulina platensis is recognized as one of the most nutritious foods, containing a high protein content of up to 70%. Meanwhile, he interest in using natural protein resources to develop bioactive peptides is steadily increasing. Therefore, this study released the bioactive peptides from S. platensis by enzymatic hydrolysis using pepsin (1:3000 U g^-1 ), and their amino acid sequences were determined by de novo sequencing. On this basis, the antioxidant activities of synthesized bioactive peptides were comprehensively evaluated by 2,2'-azinobis-3-ethylbenzothiazolin-6-sulfonic acid assay, 1,1-diphenyl-2-picryhydrazyl assay, and cell hemolysis assay induced by 2,2'-azobis-(2-amidino-propane) dihydrochloride (AAPH).

RESULTS

The degree of hydrolysis and recovery percentage of pepsin hydrolysis were 172 and 825 g kg^-1 respectively, and FFEFF (P1: m/z 736.4, 8%), EYFDALA (P2: m/z 828.4, relative intensity 18.5%), and VTAPAASVAL (P3: m/z 899.5, relative intensity 17.3%) were purified and identified. P2 possessed an excellent radical scavenging activity compared with P1, P3, and vitamin C, which was contributed to by its high β-sheet conformation and specific amino acid compositions. Moreover, P2 significantly attenuated AAPH-induced oxidative hemolysis of erythrocytes and protected the erythrocytes, because it reduced the formation of malondialdehyde and increased the enzyme activities of superoxide dismutase, catalase, and glutathione peroxidase in erythrocytes.

CONCLUSION

This study provided insights into the potential antioxidant function of the synthesized peptides originated from the bioactive peptides of S. platensis proteins, which would contribute to the development of natural antioxidant from new protein resources. © 2020 Society of Chemical Industry.

β-Carotene and its physiological metabolites: Effects on oxidative status regulation and genotoxicity in in vitro models

Carotenoids are ubiquitously distributed in nature, β-carotene being the most frequently found carotenoid in the human diet. In the human body, β-carotene is absorbed, distributed and metabolized by enzymatic and/or non-enzymatic oxidant cleavage into several metabolites. Despite the broadly accepted biological value of β-carotene, it has also been considered a double-edged sword, mainly due to its potential antioxidant versus pro-oxidant behaviour. In this sense, the aim of this work was to scrutinize the antioxidant or pro-oxidant potential of β-carotene and its metabolites, namely trans-β-apo-8'-carotenal and β-ionone. Several parameters were evaluated in this study, viz. their effects on reactive species production, both in human whole blood and neutrophils; their effects on lipid peroxidation, in the absence and presence of peroxynitrite anion (ONOO^-) or hydrogen peroxide (H₂O₂), using a synaptosomal model; and finally, their putative genotoxic effects in the human hepatic HepG2 cell line. In general, depending on the cellular model and conditions tested, β-carotene and its metabolites revealed antioxidant effects to varying degrees without significant pro-oxidant or genotoxic effects.

Marine Bacteria versus Microalgae: Who Is the Best for Biotechnological Production of Bioactive Compounds with Antioxidant Properties and Other Biological Applications?

Natural bioactive compounds with antioxidant activity play remarkable roles in the prevention of reactive oxygen species (ROS) formation. ROS, which are formed by different pathways, have various pathological influences such as DNA damage, carcinogenesis, and cellular degeneration. Incremental demands have prompted the search for newer and alternative resources of natural bioactive compounds with antioxidant properties. The marine environment encompasses almost three-quarters of our planet and is home to many eukaryotic and prokaryotic microorganisms. Because of extreme physical and chemical conditions, the marine environment is a rich source of chemical and biological diversity, and marine microorganisms have high potential as a source of commercially interesting compounds with various pharmaceutical, nutraceutical, and cosmeceutical applications. Bacteria and microalgae are the most important producers of valuable molecules including antioxidant enzymes (such as superoxide dismutase and catalase) and antioxidant substances (such as carotenoids, exopolysaccharides, and bioactive peptides) with various valuable biological properties and applications. Here, we review the current knowledge of these bioactive compounds while highlighting their antioxidant properties, production yield, health-related benefits, and potential applications in various biological and industrial fields.

Asperyellone pretreatment protects HaCaT cells from UVB irradiation induced oxidative damages: Assessment under in vitro and in vivo conditions and at molecular level

The present study explores the UVB protective role of Asperyellone (AY), a secondary metabolite of Aspergillus niger strain AN01. The in vitro UVB protective efficacy of AY was studied using the Human Epidermal keratinocytes cells (HaCaT) cell line. The results suggest the appreciable scavenging of UVB-induced reactive oxygen species in the AY-pretreated cells compared with UVB control. Experimental results on the antioxidant enzymes (Catalase, SOD, LPO, and GPx) profile, histochemical, and molecular analyses support the UVB protective effect of AY in HaCaT cells. Further, the in vivo UVB protective efficacy of AY was studied using animal models and compared with that of commercially available UVB protective agents. Physical, biochemical, and molecular analyses of skin samples emphasized the UVB protective role of AY. Thus, the important beneficial effects of AY have been explored in the present study.

Exploring the Valuable Carotenoids for the Large-Scale Production by Marine Microorganisms

Carotenoids are among the most abundant natural pigments available in nature. These pigments have received considerable attention because of their biotechnological applications and, more importantly, due to their potential beneficial uses in human healthcare, food processing, pharmaceuticals and cosmetics. These bioactive compounds are in high demand throughout the world; Europe and the USA are the markets where the demand for carotenoids is the highest. The in vitro synthesis of carotenoids has sustained their large-scale production so far. However, the emerging modern standards for a healthy lifestyle and environment-friendly practices have given rise to a search for natural biocompounds as alternatives to synthetic ones. Therefore, nowadays, biomass (vegetables, fruits, yeast and microorganisms) is being used to obtain naturally-available carotenoids with high antioxidant capacity and strong color, on a large scale. This is an alternative to the in vitro synthesis of carotenoids, which is expensive and generates a large number of residues, and the compounds synthesized are sometimes not active biologically. In this context, marine biomass has recently emerged as a natural source for both common and uncommon valuable carotenoids. Besides, the cultivation of marine microorganisms, as well as the downstream processes, which are used to isolate the carotenoids from these microorganisms, offer several advantages over the other approaches that have been explored previously. This review summarizes the general properties of the most-abundant carotenoids produced by marine microorganisms, focusing on the genuine/rare carotenoids that exhibit interesting features useful for potential applications in biotechnology, pharmaceuticals, cosmetics and medicine.

Lycopene-rich extract from red guava (Psidium guajava L.) displays cytotoxic effect against human breast adenocarcinoma cell line MCF-7 via an apoptotic-like pathway

This study investigated a lycopene-rich extract from red guava (LEG) for its chemical composition using spectrophotometry, mass spectrometry, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), and computational studies. The cytotoxic activity of LEG and the underlying mechanism was studied in human breast adenocarcinoma cells (MCF-7), murine fibroblast cells (NIH-3T3), BALB/c murine peritoneal macrophages, and sheep blood erythrocytes by evaluating the cell viability with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and flow cytometry. Spectrophotometry analysis showed that LEG contained 20% of lycopene per extract dry weight. Experimental and theoretical ATR-FTIR suggests the presence of lycopene, whereas MS/MS spectra obtained after fragmentation of the molecular ion [M]+• of 536.4364 show fragment ions at m/z 269.2259, 375.3034, 444.3788, and 467.3658, corroborating the presence of lycopene mostly related to all-trans configuration. Treatment with LEG (1600 to 6.25μg/mL) for 24 and 72h significantly affected the viability of MCF-7 cells (mean half maximal inhibitory concentration [IC50]=29.85 and 5.964μg/mL, respectively) but not NIH-3T3 cells (IC50=1579 and 911.5μg/mL, respectively). Furthermore LEG at concentrations from 800 to 6.25μg/mL presented low cytotoxicity against BALB/c peritoneal macrophages (IC50≥800μg/mL) and no hemolytic activity. LEG (400 and 800μg/mL) caused reduction in the cell proliferation and induced cell cycle arrest, DNA fragmentation, modifications in the mitochondrial membrane potential, and morphologic changes related to granularity and size in MCF-7 cells; however, it failed to cause any significant damage to the cell membrane or display necrosis or traditional apoptosis. In conclusion, LEG was able to induce cytostatic and cytotoxic effects on breast cancer cells probably via induction of an apoptotic-like pathway.

Chemopreventive effects of some popular phytochemicals on human colon cancer: a review

The present review summarizes (1) the epidemiology and etiology of colon cancer, (2) generalized cancer chemoprotective mechanisms, and (3) the chemopreventive properties of some popular phytochemicals as well as some phytochemicals developed by our research group recently.

Chronic consumption of quercetin reduces erythrocytes oxidative damage: Evaluation at resting and after eccentric exercise in humans

The polyphenolic flavonoid quercetin has been shown to be a powerful antioxidant, in vitro and in murine models. However, its effect on redox status has been poorly examined in humans, particularly in combination with strenuous exercise. We hypothesized that quercetin supplementation would beneficially affect redox homeostasis in healthy individuals undergoing eccentric exercise. To test this hypothesis, the effects of chronic consumption of quercetin on glutathione system (reduced, oxidized, and reduced to oxidized glutathione ratio), oxidative damage [thiobarbituric acid reactive substances (TBARs)], antioxidant enzymatic network (catalase, glutathione peroxidase, superoxide dismutase) and resistance to lysis, were investigated in erythrocytes, a traditional model widely used to study the effects of oxidative stress as well as the protective effects of antioxidants. In a two weeks controlled, randomized, crossover, intervention trial, 14 individuals ingested 2 caps (1 g/d) of quercetin or placebo. Blood samples were collected before, after 2 weeks of supplementation and after a bout of eccentric exercise. Quercetin, reduced significantly erythrocytes lipid peroxidation levels and the susceptibility to hemolysis induced by the free radical generator AAPH, while no differences in antioxidant enzyme activities and glutathione homeostasis were found between the two groups. After a single bout of eccentric exercise, quercetin supplementation improved redox status as assessed by reduced/oxidized glutathione ratio analysis and reduced TBARs levels both in erythrocytes and plasma. In conclusion, our study provides evidences that chronic quercetin supplementation has antioxidant potential prior to and after a strenuous eccentric exercise thus making the erythrocytes capable to better cope with an oxidative insult.

Effect of yeast biomass with high content of carotenoids on erythrocyte deformability, NO production and Na,K-ATPase activity in healthy and LPS treated rats

Measurements of red blood cell (RBC) deformability together with estimation of NO-synthase activity and Na,K-ATPase activity were used for characterization of RBC functionality in rats subjected to single dose of Escherichia coli lipopolysaccharides (LPS) at a dose of 1 mg/kg. We hypothesized that LPS might initiate a malfunction of RBC. We also investigated the potential effect of carotenoids (10 mg/kg/day) produced in red yeast biomass of Rhodotorula glutinis on RBC in LPS-challenged rats. LPS significantly reduced the deformability of RBC (by 14%) together with decrease of NO-synthase activity by 20%. Daily supplementation of carotenoids for 10 days attenuated the LPS-induced injury, as observed by 22% increase of RBC deformability and 23% increase of NO-synthase activity. The activity of Na,K-ATPase was also improved probably due to increased number of active enzyme molecules as indicated by 66% enhancement of Vmax value, hence maintaining the activity of erythrocyte Na,K-ATPase to the level even higher as compared with healthy control animals. It may be concluded that administration of yeast biomass with high content of carotenoids resulted in advanced function of erythrocytes as concerns their ability to squeeze through narrow capillaries of the circulation, better intrinsic production of NO and improvement of intracellular homeostasis of sodium.

Nicotine alkaloids as antioxidant and potential protective agents against in vitro oxidative haemolysis

The capacity of eleven nicotine alkaloids to reduce oxidative stress was investigated. In order to provide a structure-activity relationships analysis, new nicotine derivatives with a substituent introduced into the pyrrolidine ring were synthesized and investigated together with nicotine and its known analogs. All newly synthesized compounds were characterized by (1)H, (13)C NMR and EI-MS technique. The antioxidant properties of nicotine, its known analogs and newly produced derivatives, were evaluated by various antioxidant assays such 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH(•)) scavenging, ferrous ions (Fe(2+)) chelating activity and total reducing ability determination by Fe(3+) → Fe(2+) transformation assay. The protective effects of all compounds tested against 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH) and tert-butyl hydroperoxide (t-BuOOH)-induced oxidative haemolysis and morphological injury of human erythrocytes, were estimated in vitro. The results showed that nicotine alkaloids exhibited various antiradical efficacy and antioxidant activity in a structure- and a dose-dependent manner. In addition, the capacity of nicotine alkaloids to protect erythrocytes from AAPH- and t-BuOOH-induced oxidative haemolysis, was dependent on its incubation time with cells. Our findings showed that chemical and biological investigations conducted simultaneously can provide comprehensive knowledge concerning the antioxidant potential of nicotine alkaloids. This knowledge can be helpful in better understanding the properties of nicotine alkaloids under oxidative stress conditions.

Quality assessment and antiplasmodial activity of West African Cochlospermum species

The present study focuses on development of phytochemical methods for quality assessment of two West-African Cochlospermum species (Cochlospermum planchonii and Cochlospermum tinctorium) traditionally used for malaria treatment in Burkina Faso. Antimalarial activity of preparations from dried rhizomes (decoction) was tested against the chloroquine-sensitive Plasmodium strain 3D7 using the histidine-rich protein II (HRP2) drug susceptibility assay and compared with extract preparations using organic solvents of different polarity. Two main apocarotenoids were isolated from rhizomes of C. planchonii and unambiguously identified as dihydrocochloxanthine and cochloxanthine by spectroscopic methods. Comparative HPLC analyses of thirty-nine (39) samples from markets and from collections in natural habitats of both species showed a high variability in the accumulation of cochloxanthines and related carotenoids which were proven to be characteristic for rhizomes of both species and generally absent in leaves. Furthermore, content of total phenolics and antioxidant activities (DPPH and FRAP) as well as haemolytic activity of various extracts was tested. The HPLC method presented here was validated and provides a good separation of both compounds including 10 minor carotenoids. Extracts from both species and pure cochloxanthine offered pronounced antioxidant activities and weak haemolytic activity while, in contrast, dihydrocochloxanthine had a strong haemolytic effect at the highest concentration analysed. However, cochloxanthine as well as dihydrocochloxanthine showed erythroprotective effects against the haemolytic activity of the reference saponin. Moderate antiplasmodial activity between 16 and 63 μg/ml were observed with all tested extracts, and lower IC50 values were obtained with pure dihydrocochloxanthine (IC50=6.9 μg/ml), cochloxanthine (IC50=6.8 μg/ml), the DCM fraction (IC50=2.4 μg/ml) and the ethyl acetate fraction (IC50=11.5μg/ml) derived from a methanolic extract of C. planchonii. This study shows a major variability of carotenoid content and antiplasmodial activity of both C. planchonii and C. tinctorium. The high haemolytic activity of dihydrocochloxanthine (at 100 μg/ml) should be considered as a selection criterion for choosing species phenotypes for treatment.

Production of carotenoids by microalgae: achievements and challenges

Carotenoids are a wide group of lipophylic isoprenoids synthesized by all photosynthetic organisms and also by some non-photosynthetic bacteria and fungi. Animals, which cannot synthesize carotenoids de novo, must include them in their diet to fulfil essential provitamin, antioxidant, or colouring requirements. Carotenoids are indispensable in light harvesting and energy transfer during photosynthesis and in the protection of the photosynthetic apparatus against photooxidative damage. In this review, we outline the factors inducing carotenoid accumulation in microalgae, the knowledge acquired on the metabolic pathways responsible for their biosynthesis, and the recent achievements in the genetic engineering of this pathway. Despite the considerable progress achieved in understanding and engineering algal carotenogenesis, many aspects remain to be elucidated. The increasing number of sequenced microalgal genomes and the data generated by high-throughput technologies will enable a better understanding of carotenoid biosynthesis in microalgae. Moreover, the growing number of industrial microalgal species genetically modified will allow the production of novel strains with enhanced carotenoid contents.

Carotenoids from Haloarchaea and Their Potential in Biotechnology

The production of pigments by halophilic archaea has been analysed during the last half a century. The main reasons that sustains this research are: (i) many haloarchaeal species possess high carotenoids production availability; (ii) downstream processes related to carotenoid isolation from haloarchaea is relatively quick, easy and cheap; (iii) carotenoids production by haloarchaea can be improved by genetic modification or even by modifying several cultivation aspects such as nutrition, growth pH, temperature, etc.; (iv) carotenoids are needed to support plant and animal life and human well-being; and (v) carotenoids are compounds highly demanded by pharmaceutical, cosmetic and food markets. Several studies about carotenoid production by haloarchaea have been reported so far, most of them focused on pigments isolation or carotenoids production under different culture conditions. However, the understanding of carotenoid metabolism, regulation, and roles of carotenoid derivatives in this group of extreme microorganisms remains mostly unrevealed. The uses of those haloarchaeal pigments have also been poorly explored. This work summarises what has been described so far about carotenoids production by haloarchaea and their potential uses in biotechnology and biomedicine. In particular, new scientific evidence of improved carotenoid production by one of the better known haloarchaeon (Haloferax mediterranei) is also discussed.

The Amazonian fruit Byrsonima crassifolia effectively scavenges reactive oxygen and nitrogen species and protects human erythrocytes against oxidative damage

A hydrophilic extract of murici (Byrsonima crassifolia), a fruit native to the North and Northeast regions of Brazil, was evaluated in relation to its phenolic composition and in vitro antioxidant potential against some physiologically relevant reactive oxygen and nitrogen species. Additionally, the protective effect of murici extract against peroxyl radical (ROO)-induced toxicity to human erythrocytes was also determined. The major phenolic compound, determined by HPLC-DAD-MSⁿ, was quercetin (2.72±0.35μg/mL). The extract was able to scavenge ROO (0.30±0.04μmoltroloxequivalent/mg), hypochlorous acid (IC₅₀=10.0±0.1μg/mL), hydroxyl radical (IC₅₀=7±1μg/mL) and peroxynitrite anion (IC₅₀=21.0±0.6μg/mL and 17.0±1.6μg/mL, respectively, in absence and presence of NaHCO₃). Human erythrocytes were subjected to oxidative damage, but murici extract was not able to inhibit hemolysis, even at the highest tested concentration. On the other hand, the extract inhibited hemoglobin oxidation (IC₅₀=271±44μg/mL), lipid peroxidation (1000μg/mL) by 48±5%, depletion of glutathione (100μg/mL) by 49±2% and formation of its oxidized form (100μg/mL) by 96±4%.