Lipophilic ester and amide derivatives of rosmarinic acid protect cells against H2O2-induced DNA damage and apoptosis: The potential role of intracellular accumulation and labile iron chelation

Development of a novel apigenin prodrug programmed for alkaline-phosphatase instructed self-inhibition to combat cancer

Elevated levels of alkaline phosphatase (ALP) in the tumor microenvironment (TME) are a hallmark of cancer progression and thus inhibition of ALP could serve as an effective approach against cancer. Herein, we developed a novel prodrug approach to tackle cancer that bears self-inhibiting alkaline phosphatase-responsiveness properties that can enhance at the same time the solubility of the parent compound. To probe this novel concept, we selected apigenin as the cytotoxic agent since we first unveiled, that it directly interacts and inhibits ALP activity. Consequently, we rationally designed and synthesized, using a self-immolative linker, an ALP responsive apigenin-based phosphate prodrug, phospho-apigenin. Phospho-apigenin markedly increased the stability of the parent compound apigenin. Furthermore, the prodrug exhibited enhanced antiproliferative effect in malignant cells with elevated ALP levels, compared to apigenin. This recorded potency of the developed prodrug was further confirmed in vivo where phospho-apigenin significantly suppressed by 52.8% the growth of PC-3 xenograft tumors.Communicated by Ramaswamy H. Sarma.

Rosmarinic acid liposomes suppress ferroptosis in ischemic brain via inhibition of TfR1 in BMECs

BACKGROUND

Iron deposition and ferroptosis are involved in ischemic stroke injury, but the choice of drugs for treatment is limited.

PURPOSE

To investigate the potential neuroprotective effects of Rosmarinic acid (RosA) encapsulated within nanoliposomes (RosA-LIP) on ischemic stroke.

METHODS

Wild-type (WT) and TfR1EC cKO (specific knockout of the TfR1 gene in BMECs) mice used to establish a dMCAO model, with simultaneous administration of RosA-LIP (20 mg/kg/d, i.p.) or RosA (20 mg/kg/d, i.p.).

RESULTS

The successful synthesis of RosA-LIP resulted in enhanced stability and precise delivery in both the serum and brain. The administration of RosA-LIP effectively mitigated ischemia-induced behavioral abnormalities and pathological damage. RosA-LIP inhibited ferroptosis by ameliorating mitochondrial abnormalities, increasing GPX4 levels, and decreasing ACSL4/LPCAT3/Lox-dependent lipid peroxidation. RosA-LIP effectively improved blood‒brain barrier (BBB) permeability, increased tight junctions (TJs) protein expression and reduced iron levels in ischemic tissue and brain microvascular endothelial cells (BMECs) by modulating FPN1 and TfR1 levels. Furthermore, RosA-LIP suppressed TfR1 to attenuate ACSL4/LPCAT3/Lox-mediated ferroptosis in TfR1EC cKO mice subjected to dMCAO.

CONCLUSION

RosA-LIP effectively increased the brain level of RosA and protected against ferroptosis through the regulation of TfR1 in BMECs.

Exploiting the beneficial effects of Salvia officinalis L. extracts in human health and assessing their activity as potent functional regulators of food microbiota

Salvia officinalis L. has attracted scientific and industrial interest due to its pharmacological properties. However, its detailed phytochemical profile and its correlation with beneficial effects in the human microbiome and oxidative stress remained elusive. To unveil this, S. officinalis was collected from the region of Epirus and its molecular identity was verified with DNA barcoding. Phytochemical profile for both aqueous and ethanol-based extracts was determined by high-pressure liquid chromatography-tandem mass spectrometry and 103 phytochemicals were determined. The effect of S. officinalis extracts as functional regulators of food microbiota by stimulating the growth of Lacticaseibacillus rhamnosus strains and by suppressing evolution of pathogenic bacteria was verified. Furthermore, we recorded that both extracts exhibited a significant cellular protection against H2O2-induced DNA damage. Finally, both extracts exhibited strong inhibitory effect towards LDL oxidation. This study provides a comprehensive characterization of S. officinalis on its phytochemical components as also its potential impact in human microbiome and oxidative stress.

Rosmarinic Acid Protects Skin Keratinocytes from Particulate Matter 2.5-Induced Apoptosis

Background: The exposure of the human skin to particulate matter 2.5 (PM2.5) results in adverse health outcomes, such as skin aging, wrinkle formation, pigment spots, and atopic dermatitis. It has previously been shown that rosmarinic acid (RA) can protect keratinocytes from ultraviolet B radiation by enhancing cellular antioxidant systems and reducing oxidative damage; however, its protective action against the adverse effects of PM2.5 on skin cells remains unclear. Therefore, in this study, we explored the mechanism underlying the protective effects of RA against PM2.5-mediated oxidative stress in HaCaT keratinocytes. Methods: HaCaT keratinocytes were pretreated with RA and exposed to PM2.5. Thereafter, reactive oxygen species (ROS) production, protein carbonylation, lipid peroxidation, DNA damage, and cellular apoptosis were investigated using various methods, including confocal microscopy, western blot analysis, and flow cytometry. Results: RA significantly inhibited PM2.5-induced lipid peroxidation, protein carbonylation, DNA damage, increases in intracellular Ca2+ level, and mitochondrial depolarization. It also significantly attenuated PM2.5-induced apoptosis by downregulating Bcl-2-associated X, cleaved caspase-9, and cleaved caspase-3 protein levels, while upregulating B-cell lymphoma 2 protein level. Further, our results indicated that PM2.5-induced apoptosis was associated with the activation of the mitogen-activated protein kinase (MAPK) signaling pathway and that MAPK inhibitors as well as RA exhibited protective effects against PM2.5-induced apoptosis. Conclusion: RA protected HaCaT cells from PM2.5-induced apoptosis by lowering oxidative stress.

The dual face of microglia (M1/M2) as a potential target in the protective effect of nutraceuticals against neurodegenerative diseases

The pathophysiology of different neurodegenerative illnesses is significantly influenced by the polarization regulation of microglia and macrophages. Traditional classifications of macrophage phenotypes include the pro-inflammatory M1 and the anti-inflammatory M2 phenotypes. Numerous studies demonstrated dynamic non-coding RNA modifications, which are catalyzed by microglia-induced neuroinflammation. Different nutraceuticals focus on the polarization of M1/M2 phenotypes of microglia and macrophages, offering a potent defense against neurodegeneration. Caeminaxin A, curcumin, aromatic-turmerone, myricetin, aurantiamide, 3,6'-disinapoylsucrose, and resveratrol reduced M1 microglial inflammatory markers while increased M2 indicators in Alzheimer's disease. Amyloid beta-induced microglial M1 activation was suppressed by andrographolide, sulforaphane, triptolide, xanthoceraside, piperlongumine, and novel plant extracts which also prevented microglia-mediated necroptosis and apoptosis. Asarone, galangin, baicalein, and a-mangostin reduced oxidative stress and pro-inflammatory cytokines, such as interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha in M1-activated microglia in Parkinson's disease. Additionally, myrcene, icariin, and tenuigenin prevented the nod-like receptor family pyrin domain-containing 3 inflammasome and microglial neurotoxicity, while a-cyperone, citronellol, nobiletin, and taurine prevented NADPH oxidase 2 and nuclear factor kappa B activation. Furthermore, other nutraceuticals like plantamajoside, swertiamarin, urolithin A, kurarinone, Daphne genkwa flower, and Boswellia serrata extracts showed promising neuroprotection in treating Parkinson's disease. In Huntington's disease, elderberry, curcumin, iresine celosia, Schisandra chinensis, gintonin, and pomiferin showed promising results against microglial activation and improved patient symptoms. Meanwhile, linolenic acid, resveratrol, Huperzia serrata, icariin, and baicalein protected against activated macrophages and microglia in experimental autoimmune encephalomyelitis and multiple sclerosis. Additionally, emodin, esters of gallic and rosmarinic acids, Agathisflavone, and sinomenine offered promising multiple sclerosis treatments. This review highlights the therapeutic potential of using nutraceuticals to treat neurodegenerative diseases involving microglial-related pathways.

Isolation of Anti-SARS-CoV-2 Natural Products Extracted from Mentha canadensis and the Semi-synthesis of Antiviral Derivatives

Traditional herbal medicine offers opportunities to discover novel therapeutics against SARS-CoV-2 mutation. The dried aerial part of mint (Mentha canadensis L.) was chosen for bioactivity-guided extraction. Seven constituents were isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS). Syringic acid and methyl rosmarinate were evaluated in drug combination treatment. Ten amide derivatives of methyl rosmarinate were synthesized, and the dodecyl (13) and 3-ethylphenyl (19) derivatives demonstrated significant improvement in the anti-SARS-CoV-2 plaque reduction assay, achieving IC50 of 0.77 and 2.70 μM, respectively, against Omicron BA.1 as compared to methyl rosmarinate's IC50 of 57.0 μM. Spike protein binding and 3CLpro inhibition assays were performed to explore the viral inhibition mechanism. Molecular docking of compounds 13 and 19 to 3CLpro was performed to reveal potential interaction. In summary, natural products with anti-Omicron BA.1 activity were isolated from Mentha canadensis and derivatives of methyl rosmarinate were synthesized, showing 21- to 74-fold improvement in antiviral activity against Omicron BA.1.

Oxidative Stress-Induced Cellular Senescence: Is Labile Iron the Connecting Link?

Cellular senescence, a cell state characterized by a generally irreversible cell cycle arrest, is implicated in various physiological processes and a wide range of age-related pathologies. Oxidative stress, a condition caused by an imbalance between the production and the elimination of reactive oxygen species (ROS) in cells and tissues, is a common driver of cellular senescence. ROS encompass free radicals and other molecules formed as byproducts of oxygen metabolism, which exhibit varying chemical reactivity. A prerequisite for the generation of strong oxidizing ROS that can damage macromolecules and impair cellular function is the availability of labile (redox-active) iron, which catalyzes the formation of highly reactive free radicals. Targeting labile iron has been proven an effective strategy to counteract the adverse effects of ROS, but evidence concerning cellular senescence is sparse. In the present review article, we discuss aspects of oxidative stress-induced cellular senescence, with special attention to the potential implication of labile iron.

New Aspect of Composition and Biological Properties of Glechoma hederacea L. Herb: Detailed Phytochemical Analysis and Evaluation of Antioxidant, Anticoagulant Activity and Toxicity in Selected Human Cells and Plasma In Vitro

It is known that phenolic compounds can alleviate the negative impact of oxidative stress and modulate hemostasis. However, the effect of extracts and phenolics from Glechoma hederacea L. on the biomarkers of these processes is not well documented. The aim of our study was to investigate the in vitro protective effects of one extract and three fractions (20, 60, and 85% fraction) from G. hederacea L. on oxidative stress and hemostasis. Phytochemical analysis showed that aerial parts of G. hederacea L. are rich in both phenolic acids (such as rosmarinic acid, neochlorogenic acid, and chlorogenic acid) and flavonoids (mainly rutin and glycoside derivatives of apigenin, quercetin, and luteolin). We observed that the 85% fraction (at three concentrations: 5, 10, and 50 μg/mL) inhibited protein carbonylation. Moreover, the extract and 85% fraction (at the concentration of 50 μg/mL) could reduce lipid peroxidation. All fractions and the extract were very effective at decreasing H2O2-induced DNA damage in PBM cells. The 85% fraction had the strongest protective potential against DNA oxidative damage. We also observed that the extract and fractions decreased PBM cell viability to a maximum of 65% after 24 h incubation. Our results indicate that the 85% fraction showed the strongest antioxidant potential. The main component of the 85% fraction was apigenin (26.17 ± 1.44 mg/g), which is most likely responsible for its strong antioxidant properties.

Rosmarinic acid ameliorates skin inflammation and pruritus in allergic contact dermatitis by inhibiting mast cell-mediated MRGPRX2/PLCγ1 signaling pathway

BACKGROUND

Allergic contact dermatitis (ACD) is one of the most common dermatoses, which has high disease burden and quality of life impairment. Anti-histamine is not effective in a part of the ACD patients. Thus, the discovery of novel antipruritic therapy is of highly demand.

OBJECTIVE

In this study, we investigated the anti-pruritic effects of rosmarinic acid (RA) and explored the underlying mechanism.

METHOD

SPF Balb/c mice were randomly divided into control group, ACD model group, RA group (1.0 mg/kg) and loratadine (LORA) group (1.5 mg/kg). Back epidermal thickness was recorded. H&E staining was used for pathological observation. Mast cell degranulation was assessed by toluidine blue staining. ELISA assay was employed to detect cytokines levels. Cortistatin-14 (CST-14) and Mas-related G protein-coupled receptor X2 (MRGPRX2) expression was detetcted by RT-PCR and western blot. Molecular docking assay was used to predict the affinity of RA and MRGPRX2. Surface plasmon resonance (SPR) assay was used to verify structure affinity of RA and MRGPRX2.

RESULTS

RA treatment significantly decreased epidermal keratinization and inflammatory cell infiltration in ACD mouse model. Administration of RA significantly reduced secretion of histamine, IL-13, and mRNA expression of CST-14. Furthermore, RA treatment increased mRNA expression of MRGPRX2. In addition, Molecular docking results predict that RA has a good affinity with MRGPRX2. RA displayed a structure affinity (K_D = 8.89 × 10^-4) with MRGPRX2 by SPR. RA inhibited CST-14 and Compound 48/80 (C48/80)-induced mast cell activation via MRGPRX2-PLCγ1-PKC-NF-κB signaling pathway.

CONCLUSION

RA exhibits anti-pruritic and anti-inflammatory effects in ACD mice by inhibiting MRGPRX2-PLCγ1-PKC-NF-κB signaling pathway. RA might emerge as a potential drug for the treatment of pruritus and skin inflammation in the setting of ACD.

Enhancement of oral bioavailability and anti-colitis effect of luteolin-loaded polymer micelles with RA (rosmarinic acid)-SS-mPEG as carrier

OBJECTIVE

Polymer micelles were prepared (L-RSPMs) with luteolin and synthetic RA-SS-mPEG polymeric material before evaluation of their anti-inflammatory effect on 2, 4, 6-trinitro-benzene-sulfonic acid (TNBS)-induced ulcerative colitis (UC) model in rats.

METHODS

The synthetic RA-SS-mPEG was characterized with NMR spectroscopy, before preparation of luteolin-coated RA-SS-mPEG polymer micelles. The in vitro characterization and evaluation of the formulation were accomplished, couple with its pharmacokinetic parameters. The levels of PEG2, MDA, CRP and GSH, as well as concentrations of TNF-α, IL1-β, IL-6 and IL-10 in serum and colon tissue were detected via ELISA kit. The degree of colon injury and inflammation was evaluated via histopathologic examination.

RESULTS

L-RSPMs displayed small average droplet size (133.40 ± 4.52 nm), uniformly dispersed (PDI: 0.163 ± 0.011), good stability, slow release and enhanced solubility. We observed 353.28% increase in the relative bioavailability of L-RSPMs compared to free luteolin, while the half-life of the micelle was extended by 6.16h. Compared to model (M) group, luteolin (low and high doses) and L-RSPMs (low and high doses) significantly reduced levels of MDA, PEG2, CRP, TNF-α, IL-6 and IL-1β in colon tissue and serum of colitic rats but dose dependently increased IL-10 and SOD levels (p < 0.01). Histopathologic examination of colon showed that luteolin (low and high doses) and L-RSPMs (low and high doses) improved colonic inflammation in colitic rats to varying degrees compared to M group.

CONCLUSION

L-RSPMs could improve TNBS-induced colon inflammation by enhancing bioavailability, promoting antioxidant effects and regulating cytokine release, which may become a potential agent for UC treatment in clinical settings.

Phenethyl Ester of Gallic Acid Ameliorates Experimental Autoimmune Encephalomyelitis

Gallic acid is a phenolic acid present in various plants, nuts, and fruits. It is well known for its anti-oxidative and anti-inflammatory properties. The phenethyl ester of gallic acid (PEGA) was synthesized with the aim of increasing the bioavailability of gallic acid, and thus its pharmacological potential. Here, the effects of PEGA on encephalitogenic cells were examined, and PEGA was found to modulate the inflammatory activities of T cells and macrophages/microglia. Specifically, PEGA reduced the release of interleukin (IL)-17 and interferon (IFN)-γ from T cells, as well as NO, and IL-6 from macrophages/microglia. Importantly, PEGA ameliorated experimental autoimmune encephalomyelitis, an animal model of chronic inflammatory disease of the central nervous system (CNS)-multiple sclerosis. Thus, PEGA is a potent anti-inflammatory compound with a perspective to be further explored in the context of CNS autoimmunity and other chronic inflammatory disorders.

Banxia-Houpu decoction diminishes iron toxicity damage in heart induced by chronic intermittent hypoxia

CONTEXT

Obstructive sleep apnoea (OSA) causes chronic intermittent hypoxia (CIH), which results in mitochondrial dysfunction and generates reactive oxygen species (ROS) in the heart. Excessive free iron could accelerate oxidative damage, which may be involved in this process. Banxia-Houpu decoction (BHD) was reported to improve the apnoea hypopnoea index in OSA patients, but the specific mechanism was still unclear.

OBJECTIVE

To investigate whether BHD could reduce CIH-induced heart damage by regulating iron metabolism and mitochondrial function.

MATERIALS AND METHODS

C57BL/6N mice were randomly divided into control, CIH and BHD groups. Mice were exposed to CIH (21 - 5% O2, 20 times/h, 8 h/d) and administered BHD (3.51, 7.01 and 14.02 g/kg, intragastrically) for 21 d. Cardiac and mitochondrial function, iron levels, apoptosis and mitophagy were determined.

RESULTS

BHD (7.01 g/kg) significantly improved cardiac dysfunction, pathological change and mitochondrial structure induced by CIH. BHD increased the Bcl-2/Bax ratio (1.4-fold) and inhibited caspase 3 cleavage in CIH mice (0.45-fold). BHD activated mitophagy by upregulating Parkin (1.94-fold) and PINK1 (1.26-fold), inhibiting the PI3K-AKT-mTOR pathway. BHD suppressed ROS generation by decreasing NOX2 (0.59-fold) and 4-HNE (0.83-fold). BHD reduced the total iron in myocardial cells (0.72-fold) and mitochondrial iron by downregulating Mfrn2 (0.81-fold) and MtFt (0.78-fold) proteins, and upregulating ABCB8 protein (1.33-fold). Rosmarinic acid, the main component of Perilla Leaf in BHD, was able to react with Fe2+ and Fe3+ in vitro.

DISCUSSION AND CONCLUSIONS

These findings encourage the use of BHD to resist cardiovascular injury and provide the theoretical basis for clinical treatment in OSA patients.

Combined administration of membrane-permeable and impermeable iron-chelating drugs attenuates ischemia/reperfusion-induced hepatic injury

BACKGROUND

The underlying pathophysiological mechanisms of hepatic ischemia-reperfusion (I/R) injury have not been completely elucidated. However, it is well known that oxidative stress, caused by a burst of reactive oxygen species (ROS) production during the reperfusion phase, plays a crucial role. A growing body of evidence indicates that the intracellular availability of free iron represents a requirement for ROS-induced adverse effects, as iron catalyzes the generation of highly reactive free radicals. The aim of this study was to examine whether a combination of iron chelators with varying lipophilicity could offer enhanced protection against I/R by diminishing the conversion of weak oxidants, like H₂O₂, to extremely reactive ones such as hydroxyl radicals (HO^.).

METHODS

HepG2 cells (hepatocellular carcinoma cell line) were exposed to oxidative stress conditions after pre-treatment with the iron chelators desferrioxamine (DFO) and deferiprone (DFP) alone or in combination. Labile iron pool was estimated using the calcein-acetoxymethyl ester (calcein-AM) method and DNA damage with the comet assay. We subsequently used a rabbit model (male New Zealand white rabbits) of hepatic I/R-induced injury to investigate, by measuring biochemical (ALT, ALT, ALP, γGT) and histological parameters, whether this may be true for in vivo conditions.

RESULTS

The combination of a membrane-permeable iron chelator (DFP) with a strong membrane-impermeable one (DFO) raises the level of protection in both hepatic cell lines exposed to oxidative stress conditions and hepatic I/R rabbit model.

CONCLUSIONS

Our results show that combinations of iron chelators with selected lipophilicity and iron-binding properties may represent a valuable strategy to protect against tissue damage during reperfusion after a period of ischemia.

Phenethyl ester of rosmarinic acid attenuates autoimmune responses during type 1 diabetes development in mice

AIMS

Rosmarinic acid (RA) is a polyphenol that occurs in plants of the Lamiaceae family. Phenethyl ester of RA (PERA), a novel RA derivative, has been developed and evaluated in vivo in an animal model of type 1 diabetes (T1D).

METHODS

T1D was induced in male C57BL/6 mice using multiple low doses of streptozotocin (STZ) administered intraperitoneally for 5 consecutive days. Intraperitoneal administration of PERA (2.5 mg/kg bw) began from the first STZ injection and continued for 20 days.

KEY FINDINGS

PERA-treated mice exhibited lower incidence of T1D (monitored up to 38 days from the disease induction), and fluorescent histochemical analysis showed that their pancreatic islets expressed more insulin. PERA treatment significantly down-regulated the proportions of CD11b+ and CD11c+ myeloid cells in the immune cell infiltrates in the pancreatic islets early during T1D pathogenesis (on day 9 after T1D induction), while on day 15, PERA significantly reduced the proportions of CD11c+, CD8+, Th1 and Th17 cells. Simultaneously, it was found that the cells from the pancreatic infiltrates of PERA-treated mice produced significantly less reactive oxygen species than cells from the control group.

SIGNIFICANCE

These findings suggest that PERA efficiently prevented T1D development in mice. Interestingly, PERA attenuated the inflammatory process in the islets through temporally specific interference with the innate and adaptive immune response and therefore shows great promise for further clinical evaluation as a novel T1D therapeutic.

919 syrup inhibits ROS-mediated leptin-induced anorexia by activating PPARγ and improves gut flora abnormalities

BACKGROUND

Women with postpartum psychiatric disorders are prone to severe anorexia. Clinical studies have revealed the efficacy of 919 syrup, a traditional Chinese medicine mixture against postpartum illnesses, such as in regulating maternal mood and improving postpartum anorexia.

AIM

This study investigated the mechanisms through which 919 syrup improved anorexia induced by postpartum stress, focussing on the combined peroxisome proliferator-activated receptor gamma (PPARγ) and leptin signalling pathway, and its effects on the structure of the gut flora.

METHODS

Mice were randomly divided into five groups-control group, immobilisation stressed (IS) group (normal saline), pioglitazone (Piog; western medicine control) group, 919 syrup low-dose (TJD; 13.5 g/kg) group, and 919 syrup high-dose (TJG; 27.0 g/kg) group. The control group was housed normally. The other groups received IS for 3 h daily for 21 days. The treatments were initiated following the first postnatal day and were administered by gastric gavage. All mice were sacrificed under anaesthesia on postnatal day 22. Blood, hypothalamus, stomach, and faecal specimens were collected. Gene and protein expression levels of components of the PPARγ-leptin signalling pathway in the serum, hypothalamus, and stomach were determined. Immunofluorescence staining for proopiomelanocortin (POMC), phosphorylated signal transducer and activator of transcription 3 (pSTAT3), and leptin was performed to observe their spatial distributions in the hypothalamus and stomach. 16s rRNA gene sequencing and bioinformatics analysis of fecal specimens were performed.

RESULTS

After IS, postpartum mice showed significantly reduced appetite and body weight, accompanied by abnormalities in the structure of the gut flora. Treatment with 919 syrup (27.0 g/kg) downregulated malondialdehyde and upregulated catalase, glutathione peroxidase, and superoxide dismutase by activating PPARγ, thereby affecting the expression of leptin signalling pathway components (leptin, leptin receptor, pSTAT3, POMC, and cocaine and amphetamine-related transcript and neuropeptide Y), and modulated the gut flora in stressed mice.

CONCLUSION

919 syrup improved appetite in mice with postnatal stress by activating PPARγ to induce crosstalk with the leptin signalling pathway, this mechanism was similar to that of PPARγ agonists. 919 syrup also improved gut flora structure, and the changes in the relative abundances of the gut flora strongly correlated with the expression levels of PPARγ and leptin pathway components.

Caffeic Acid Phenyl Ester (CAPE) Protects against Iron-Mediated Cellular DNA Damage through Its Strong Iron-Binding Ability and High Lipophilicity

Caffeic acid phenethyl ester (CAPE) and its structurally-related caffeic acid (CA), ferulic acid (FA) and ethyl ferulate (EF) are constituents of honeybee propolis that have important pharmacological activities. This study found that CAPE—but not CA, FA, and EF—could effectively prevent cellular DNA damage induced by overloaded iron through decreasing the labile iron pool (LIP) levels in HeLa cells. Interestingly, CAPE was found to be more effective than CA in protecting against plasmid DNA damage induced by Fe(II)–H₂O₂ or Fe(III)–citrate–ascorbate-H₂O₂ via the inhibition of hydroxyl radical (•OH) production. We further provided more direct and unequivocal experimental evidences for the formation of inactive CAPE/CA–iron complexes. CAPE was found to have a stronger iron-binding ability and a much higher lipophilicity than CA. Taken together, we propose that the esterification of the carboxylic moiety with phenethyl significantly enhanced the iron-binding ability and lipophilicity of CAPE, which is also responsible for its potent protection against iron-mediated cellular DNA damage. A study on the iron coordination mechanism of such natural polyphenol antioxidants will help to design more effective antioxidants for the treatment and prevention of diseases caused by metal-induced oxidative stress, as well as help to understand the structure–activity relationships of these compounds.

Implication of Dietary Iron-Chelating Bioactive Compounds in Molecular Mechanisms of Oxidative Stress-Induced Cell Ageing

One of the prevailing perceptions regarding the ageing of cells and organisms is the intracellular gradual accumulation of oxidatively damaged macromolecules, leading to the decline of cell and organ function (free radical theory of ageing). This chemically undefined material known as "lipofuscin," "ceroid," or "age pigment" is mainly formed through unregulated and nonspecific oxidative modifications of cellular macromolecules that are induced by highly reactive free radicals. A necessary precondition for reactive free radical generation and lipofuscin formation is the intracellular availability of ferrous iron (Fe2+) ("labile iron"), catalyzing the conversion of weak oxidants such as peroxides, to extremely reactive ones like hydroxyl (HO•) or alcoxyl (RO•) radicals. If the oxidized materials remain unrepaired for extended periods of time, they can be further oxidized to generate ultimate over-oxidized products that are unable to be repaired, degraded, or exocytosed by the relevant cellular systems. Additionally, over-oxidized materials might inactivate cellular protection and repair mechanisms, thus allowing for futile cycles of increasingly rapid lipofuscin accumulation. In this review paper, we present evidence that the modulation of the labile iron pool distribution by nutritional or pharmacological means represents a hitherto unappreciated target for hampering lipofuscin accumulation and cellular ageing.

Rosmarinic acid attenuates obesity and obesity-related inflammation in human adipocytes

Chronic low-grade inflammation is a hallmark of obesity and its related metabolic disorders. At the same time signaling from pro-inflammatory factors such as transforming growth factor beta (TGF-β) or interleukin 17A (IL-17A) are proposed as crucial for the commitment of fibroblast progenitor cells towards adipogenic differentiation. Modulation of inflammation during adipogenic differentiation is incompletely explored as a potential approach to prevent metabolic disorders. Rosmarinic acid (RA) is a caffeic acid derivative known for its anti-inflammatory effects. Experimental studies of its activity on adipogenic factors or in vivo obesity models are, however, controversial and hence insufficient. Here, we investigated the anti-adipogenic action of RA in human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes. Gene expression levels of key players in adipogenesis and lipid metabolism were assessed. Furthermore, a molecular mechanism of action was proposed. The most prominent effect was found on the translation of C/EBPα, PPARγ and adiponectin, as well as on the modulation of TGF1B and IL17A. Interestingly, involvement of NRF2 signaling was identified upon RA treatment. In summary, our findings indicate that RA prevents inflammation and excessive lipid accumulation in human adipocytes. Data from the molecular analysis demonstrate that RA has potential for treatment of obesity and obesity-related inflammation.

Enhancement of glioblastoma multiforme therapy through a novel Quercetin-Losartan hybrid

Glioblastoma multiforme (GBM) is the most common and aggressive primary malignant brain tumor. Maximal surgical resection followed by radiotherapy and concomitant chemotherapy with temozolomide remains the first-line therapy, prolonging the survival of patients by an average of only 2.5 months. There is therefore an urgent need for novel therapeutic strategies to improve clinical outcomes. Reactive oxygen species (ROS) are an important contributor to GBM development. Here, we describe the rational design and synthesis of a stable hybrid molecule tethering two ROS regulating moieties, with the aim of constructing a chemopreventive and anticancer chemical entity that retains the properties of the parent compounds. We utilized the selective AT₁R antagonist losartan, leading to the inhibition of ROS levels, and the antioxidant flavonoid quercetin. In GBM cells, we show that this hybrid retains the binding potential of losartan to the AT₁R through competition-binding experiments and simultaneously exhibits ROS inhibition and antioxidant capacity similar to native quercetin. In addition, we demonstrate that the hybrid is able to alter the cell cycle distribution of GBM cells, leading to cell cycle arrest and to the induction of cytotoxic effects. Last, the hybrid significantly and selectively reduces cancer cell proliferation and angiogenesis in primary GBM cultures with respect to the isolated parent components or their simple combination, further emphasizing the potential utility of the current hybridization approach in GBM.

Bioinspired tailoring of fluorogenic thiol responsive antioxidant precursors to protect cells against H2O2-induced DNA damage

Natural antioxidants, like phenolic acids, possess a unique chemical space that can protect cellular components from oxidative stress. However, their polar carboxylic acid chemotype reduces full intracellular antioxidant potential due to limited diffusion through biological membranes. Here, we have designed and developed a new generation of hydrophobic turn-on fluorescent antioxidant precursors that upon penetration of the cell membrane, reveal a more polar and more potent antioxidant core and simultaneously become fluorescent allowing their intracellular tracking. Their activation is stimulated by polarity alteration by sensing intracellular signals and specifically biothiols. In our design, the carboxylic group of phenolic acids that originally restricts cell entrance is derivatized and conjugated through Copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) to a coumarin derivative that its fluorescence properties are quenched with a biothiol activatable element. This more hydrophobic precursor readily penetrates cell membrane and once inside the cell the antioxidant core is revealed upon sensing glutathione, its fluorescence is restored in a turn-on manner and the generation of a more polar character traps the molecule inside the cell. This turn-on fluorescent antioxidant precursor that can be applied to phenolic acids, was developed for rosmarinic acid and the conjugate was named as RCG. The selectivity and responsiveness of RCG towards the most abundant biothiols was monitored through a variety of biophysical techniques including UV-Vis, fluorescence and NMR spectroscopy. The electrochemical behavior and free radical scavenging capacity of the precursor RCG and the active compound (RC) was evaluated and compared with the parent compound (rosmarinic acid) through cyclic voltammetry and EPR spectroscopy, respectively. The stability of the newly synthesized bioactive conjugate RC was found significantly higher than the parent rosmarinic acid when exposed to oxygen. Cell uptake experiments were conducted and revealed the internalization of RCG. The degree of intracellular DNA protection offered by RCG and its active drug (RC) on exposure to H₂O₂ was also evaluated in Jurkat cells.

Chemical characterisation and quantification of the major constituents in the Chinese herbal formula Jian-Pi-Yi-Shen pill by UPLC-Q-TOF-MS/MS and HPLC-QQQ-MS/MS

INTRODUCTION

Jian-Pi-Yi-Shen pill (JPYSP) is a Chinese medicine formula developed for the treatment of anaemic patients with chronic kidney disease (CKD).

OBJECTIVE

To investigate the chemical profile of JPYSP in the treatment of renal anaemia.

METHODS

A method coupling ultra-performance liquid chromatography with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) was established to characterise the chemical constituents present in JPYSP. Subsequently, a high-performance liquid chromatography method coupled with triple-quadrupole tandem mass spectrometry (HPLC-QQQ-MS/MS) was developed to quantify the major constituents from the identified compounds related to the treatment of CKD and anaemia.

RESULTS

A total of 71 compounds were tentatively identified from JPYSP, including saponins, flavonoids, sesquiterpenoids, coumarins, phenylpropanoids, anthranones, anthraquinones, tannins, phenolic acids and others. Amongst them, 12 compounds (i.e. astragaloside IV, calycosin, calycosin 7-O-glucoside, salvianolic acid A, rosmarinic acid, rhein, liquiritin, formononetin, atractylenolide I, dioscin, tanshinone IIA, and acteoside) were further quantified simultaneously by HPLC-QQQ-MS/MS.

CONCLUSION

The newly developed approach is suitable for the chemical profiling analysis and quality control of JPYSP, and could lead to additional pharmacodynamic studies involving the components of JPYSP.

Gd-Complex of a Rosmarinic Acid Conjugate as an Anti-Inflammatory Theranostic Agent via Reactive Oxygen Species Scavenging

Rosmarinic acid (RosA), an important polyphenol, is known for its antioxidant and anti-inflammatory activities. However, its application in theranostics has been rarely reported. Therefore, a new single-molecule anti-inflammatory theranostic compound containing RosA would be of great interest. A gadolinium (Gd) complex of 1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid (DO3A) and RosA (Gd(DO3A-RosA)(H₂O)) was synthesized and examined for use as a single-molecule theranostic agent. Its kinetic stability is comparable to that of clinically used macrocyclic magnetic resonance imaging contrast agents. In addition, its relaxivity is higher than that of structurally analogous Gd-BT-DO3A. This agent was evaluated for inflammatory targeting magnetic resonance contrast and showed strong and prolonged enhancement of imaging in inflamed tissues of mice. The theranostic agent also possesses antioxidant and anti-inflammatory activities, as evidenced by reactive oxygen species scavenging, superoxide dismutase activity, and inflammatory factors. The novel RosA-conjugated Gd complex is a promising theranostic agent for the imaging of inflamed tissues, as well as for the treatment of inflammation and oxidative stress.

Charting the structural and thermodynamic determinants in phenolic acid natural product - cyclodextrin encapsulations

Cyclodextrins are pliable platforms that have served to optimize the pharmaceutic profile of numerous compounds and to enhance the stability of natural food additives. Caffeic and rosmarinic acid are natural products with proven health benefits, though their full therapeutic potential has not been exploited. To enhance their pharmaceutic profile, we developed cyclodextrin-based formulates and unveiled their thermodynamic and structural principles. The complexes' stoichiometry was determined by ESI-MS. Solid-state and liquid NMR spectroscopy revealed the interactions and the topographical location of the caffeic and rosmarinic acid inside the cyclodextrin cavity. The theoretically analyzed HP-β-CD's degree of substitution (DS) of caffeic and rosmarinic acids can explain the intensities obtained by 2D NOESY experiments. The thermodynamics and the affinity of the complexes were evaluated through isothermal titration calorimetry. In addition, the rosmarinic and caffeic acids as, also, their complexes showed considerable antimicrobial activity against common food spoilage and pathogenic bacteria. The generated data could provide the basis to understand the structural and thermodynamic determinants implicated in natural products - CD recognition and to develop platforms for the optimization of their pharmaceutical and stability profiles in order to be utilized as safe and stable natural antimicrobial food additives.Communicated by Ramaswamy H. Sarma.

Implications of Oxidative Stress and Cellular Senescence in Age-Related Thymus Involution

The human thymus is a primary lymphoepithelial organ which supports the production of self-tolerant T cells with competent and regulatory functions. Paradoxically, despite the crucial role that it exerts in T cell-mediated immunity and prevention of systemic autoimmunity, the thymus is the first organ of the body that exhibits age-associated degeneration/regression, termed “thymic involution.” A hallmark of this early phenomenon is a progressive decline of thymic mass as well as a decreased output of naïve T cells, thus resulting in impaired immune response. Importantly, thymic involution has been recently linked with cellular senescence which is a stress response induced by various stimuli. Accumulation of senescent cells in tissues has been implicated in aging and a plethora of age-related diseases. In addition, several lines of evidence indicate that oxidative stress, a well-established trigger of senescence, is also involved in thymic involution, thus highlighting a possible interplay between oxidative stress, senescence, and thymic involution.

Synthesis of Rosmarinic Acid Amides as Antioxidative and Hypoglycemic Agents

Type 2 diabetes mellitus (T2DM) is an important metabolic disorder for which there is an urgent need for new antidiabetic drugs. α-Glucosidase inhibition is an established protocol for T2DM therapy. Because hyperglycemia causes oxidative tissue damage, the development of agents with both α-glucosidase inhibition and antioxidant activity from natural or natural-derived polyphenols such derivatives of rosmarinic acid (RA) represents an attractive therapeutic option. We report a study on amides 1-10 derived from RA and their evaluation for yeast α-glucosidase inhibition and antioxidant activity (DPPH and ORAC tests). All amides showed higher inhibitory activity than that of RA, were by far more potent than the antidiabetic drug acarbose, and proved to be effective antioxidants. A molecular docking study displayed significant binding interactions of RA amides with the active site of α-glucosidase. This in silico optimization study led to the design and synthesis of amides 9 (IC50 = 42.3 μM) and 10 (IC50 = 35.2 μM), showing the most potent α-glucosidase inhibition and good antioxidative properties. A kinetic study showed that 10 acts as a mixed type inhibitor.

Rosmarinic acid alleviates cardiomyocyte apoptosis via cardiac fibroblast in doxorubicin-induced cardiotoxicity

Cardiomyocyte apoptosis is a key event in the process of doxorubicin (DOX)-induced cardiotoxicity. Our previous study found that rosmarinic acid (RA) could attenuate pressure overload-induced cardiac dysfunction via cardiac fibroblasts (CFs), however its effect in DOX-induced cardiotoxicity remains unknown. In the present study, mice were subjected to a single intraperitoneal injection of DOX (15mg/kg) to generate DOX-induced cardiotoxicity. Histological examination, echocardiography, and molecular markers were used to evaluate the effects of RA. Neonatal rat cardiomyocytes (CMs) and CFs were used to verify the protective effect of RA in vitro. Conditioned medium derived from RA-treated CFs were prepared to illustrate the effect of RA on paracrine interplay between CFs and CMs. We found that RA significantly alleviated DOX-induced cardiomyocyte apoptosis and cardiac dysfunction in vivo, which, however, had almost negligible beneficial effect on DOX directly induced cardiomyocyte apoptosis in vitro. Mechanistically, CFs-derived Fas L was responsible for DOX-induced cardiomyocyte apoptosis, and RA treatment could decrease Fas L expression in CFs and its release to the conditioned medium by suppressing nuclear factor of activated T cells (NFAT) activation and metalloproteinase 7 (MMP7) expression, and exerted the anti-apoptotic effect on CMs via CFs. Ionomycin, and activator of NFAT, abrogated RA-mediated protective effect on cardiomyocyte apoptosis and cardiac dysfunction. In summary, RA alleviated cardiomyocyte apoptosis by inhibiting the expression and release of Fas L in CFs via a paracrine manner, moreover, NFAT as well as MMP7 inhibition were responsible for the suppression of Fas L. RA could be a powerful new therapeutic agent to mitigate cardiomyocyte apoptosis, thereby improving DOX-induced cardiotoxicity.