E3 ubiquitin ligases and plant innate immunity

In yeast and in animals the ubiquitin-proteasome system (UPS) is responsible for removing or modifying most abnormal peptides and also short-lived cellular regulators. The UPS therefore influences many processes such as the cell cycle, signal transduction, transcription, and stress responses including defence. In recent years, similar regulatory roles have been identified in plants. In Arabidopsis, mutations in the ubiquitin-proteasome pathway block development, circadian rhythms, photomorphogenesis, floral homeosis, hormone responses, senescence, and pathogen invasion. Plants have evolved an armoury of defence mechanisms that allow them to counter infection. These encompass both basal responses, triggered by recognition of conserved pathogen-associated molecular patterns, and pathogen-specific responses, mediated via pathogen- and plant-specific gene-for-gene recognition events. The role of E3 ubiquitin ligases in mediating plant defence signalling is reviewed and examples where pathogens impinge on the host's ubiquitination machinery acting as molecular mimics to undermine defence are also highlighted.

BTB-BACK Domain Protein POB1 Suppresses Immune Cell Death by Targeting Ubiquitin E3 ligase PUB17 for Degradation

Hypersensitive response programmed cell death (HR-PCD) is a critical feature in plant immunity required for pathogen restriction and prevention of disease development. The precise control of this process is paramount to cell survival and an effective immune response. The discovery of new components that function to suppress HR-PCD will be instrumental in understanding the regulation of this fundamental mechanism. Here we report the identification and characterisation of a BTB domain E3 ligase protein, POB1, that functions to suppress HR-PCD triggered by evolutionarily diverse pathogens. Nicotiana benthamiana and tobacco plants with reduced POB1 activity show accelerated HR-PCD whilst those with increased POB1 levels show attenuated HR-PCD. We demonstrate that POB1 dimerization and nuclear localization are vital for its function in HR-PCD suppression. Using protein-protein interaction assays, we identify the Plant U-Box E3 ligase PUB17, a well established positive regulator of plant innate immunity, as a target for POB1-mediated proteasomal degradation. Using confocal imaging and in planta immunoprecipitation assays we show that POB1 interacts with PUB17 in the nucleus and stimulates its degradation. Mutated versions of POB1 that show reduced interaction with PUB17 fail to suppress HR-PCD, indicating that POB1-mediated degradation of PUB17 U-box E3 ligase is an important step for negative regulation of specific immune pathways in plants. Our data reveals a new mechanism for BTB domain proteins in suppressing HR-PCD in plant innate immune responses.

The Role of Epac in Cancer Progression

Cancer continues to be a prime contributor to global mortality. Despite tremendous research efforts and major advances in cancer therapy, much remains to be learned about the underlying molecular mechanisms of this debilitating disease. A better understanding of the key signaling events driving the malignant phenotype of cancer cells may help identify new pharmaco-targets. Cyclic adenosine 3',5'-monophosphate (cAMP) modulates a plethora of biological processes, including those that are characteristic of malignant cells. Over the years, most cAMP-mediated actions were attributed to the activity of its effector protein kinase A (PKA). However, studies have revealed an important role for the exchange protein activated by cAMP (Epac) as another effector mediating the actions of cAMP. In cancer, Epac appears to have a dual role in regulating cellular processes that are essential for carcinogenesis. In addition, the development of Epac modulators offered new routes to further explore the role of this cAMP effector and its downstream pathways in cancer. In this review, the potentials of Epac as an attractive target in the fight against cancer are depicted. Additionally, the role of Epac in cancer progression, namely its effect on cancer cell proliferation, migration/metastasis, and apoptosis, with the possible interaction of reactive oxygen species (ROS) in these phenomena, is discussed with emphasis on the underlying mechanisms and pathways.

The hypertensive potential of estrogen: An untold story

Cardiovascular disease (CVD) is the major cause of morbidity and mortality worldwide. The implication of estrogen in this disease has been extensively studied. While the vast majority of published research argue for a cardioprotective role of estrogen in vascular inflammation such as in atherosclerosis, the role of estrogen in hypertension remains far from being resolved. The vasorelaxant effect of estrogen has already been well-established. However, emerging evidence supports a vasoconstrictive potential of this hormone. It has been proposed that the microenvironment dictates the effect of estrogen-induced type 1 nitric oxide synthase-1 (nNOS) on vasotone. Indeed, depending on nNOS product, nitric oxide or superoxide, estrogen can induce vasodilation or vasoconstriction, respectively. In this review, we discuss the evidence supporting the vasorelaxant effects of estrogen, and the molecular players involved. Furthermore, we shed light on recent reports revealing a vasoconstrictive role of estrogen, and speculate on the underlying signaling pathways. In addition, we identify certain factors that can account for the discrepant estrogenic effects. This review emphasizes a yin-yang role of estrogen in regulating blood pressure.

Marjoram Relaxes Rat Thoracic Aorta Via a PI3-K/eNOS/cGMP Pathway

Despite pharmacotherapeutic advances, cardiovascular disease (CVD) remains the primary cause of global mortality. Alternative approaches, such as herbal medicine, continue to be sought to reduce this burden. Origanum majorana is recognized for many medicinal values, yet its vasculoprotective effects remain poorly investigated. Here, we subjected rat thoracic aortae to increasing doses of an ethanolic extract of Origanum majorana (OME). OME induced relaxation in a dose-dependent manner in endothelium-intact rings. This relaxation was significantly blunted in denuded rings. N(ω)-nitro-l-arginine methyl ester (L-NAME) or 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ) significantly reduced the OME-induced vasorelaxation. Cyclic guanosine monophosphate (cGMP) levels were also increased by OME. Moreover, wortmannin or LY294002 significantly reduced OME-induced vasorelaxation. Blockers of ATP-sensitive or Ca²⁺-activated potassium channels such as glibenclamide or tetraethylamonium (TEA), respectively, did not significantly affect OME-induced relaxation. Similarly, verapamil, a Ca²⁺ channel blocker, indomethacin, a non-selective cyclooxygenase inhibitor, and pyrilamine, a H1 histamine receptor blocker, did not significantly modulate the observed relaxation. Taken together, our results show that OME induces vasorelaxation via an endothelium-dependent mechanism involving the phosphoinositide 3-kinase (PI3-K)/ endothelial nitric oxide (NO) synthase (eNOS)/cGMP pathway. Our findings further support the medicinal value of marjoram and provide a basis for its beneficial intake. Although consuming marjoram may have an antihypertensive effect, further studies are needed to better determine its effects in different vascular beds.

Origanum syriacum L. Attenuates the Malignant Phenotype of MDA-MB231 Breast Cancer Cells

Breast cancer is the leading cause of cancer-related deaths among women. Among breast cancer types, triple negative breast cancer (TNBC) is the most aggressive, and is resistant to hormonal and chemotherapeutic treatments. As such, alternative approaches that may provide some benefit in fighting this debilitating pathology are critically needed; hence the utilization of herbal medicine. Origanum syriacum L., one of the most regularly consumed plants in the Mediterranean region, exhibits antiproliferative effect on several cancer cell lines. However, whether this herb modulates the malignant phenotype of TNBC remains poorly investigated. Here, we show that in MDA-MB-231, a TNBC cell line, Origanum syriacum L. aqueous extract (OSE) inhibited cellular viability, induced autophagy determined by the accumulation of lipidized LC3 II, and triggered apoptosis. We also show that OSE significantly promoted homotypic cell-cell adhesion while it decreased cellular migration, adhesion to fibronectin, and invasion of MDA-MB-231 cells. This was supported by decreased activity of focal adhesion kinase (FAK), reduced α2 integrin expression, and downregulation of secreted PgE2, MMP2 and MMP-9, in OSE-treated cells. Finally, we also show that OSE significantly inhibited angiogenesis and downregulated the level of nitric oxide (NO) production. Our findings demonstrate the ability of OSE to attenuate the malignant phenotype of the MDA-MB-231 cells, thus presenting Origanum syriacum L. as a promising potential source for therapeutic compounds for TNBC.

Ethanolic extract of Origanum syriacum L. leaves exhibits potent anti-breast cancer potential and robust antioxidant properties

Background: Breast cancer (BC) is the second most common cancer overall. In women, BC is the most prevalent cancer and the leading cause of cancer-related mortality. Triple-negative BC (TNBC) is the most aggressive BC, being resistant to hormonal and targeted therapies. Hypothesis/Purpose: The medicinal plant Origanum syriacum L. is a shrubby plant rich in bioactive compounds and widely used in traditional medicine to treat various diseases. However, its therapeutic potential against BC remains poorly investigated. In the present study, we screened the phytochemical content of an ethanolic extract of O. syriacum (OSEE) and investigated its anticancer effects and possible underlying mechanisms of action against the aggressive and highly metastatic human TNBC cell line MDA-MB-231. Methods: MTT, trans-well migration, and scratch assays were used to assess cell viability, invasion, or migration, respectively. Antioxidant potential was evaluated in vitro using the DPPH radical-scavenging assay and levels of reactive oxygen species (ROS) were assessed in cells in culture using DHE staining. Aggregation assays were used to determine cell-cell adhesion. Flow cytometry was used to analyze cell cycle progression. Protein levels of markers of apoptosis (BCL-2, pro-Caspase3, p53), proliferation (p21, Ki67), cell migration, invasion, or adhesion (FAK, E-cadherin), angiogenesis (iNOS), and cell signaling (STAT3, p38) were determined by immunoblotting. A chorioallantoic Membrane (CAM) assay evaluated in ovo angiogenesis. Results: We demonstrated that OSEE had potent radical scavenging activity in vitro and induced the generation of ROS in MDA-MB-231 cells, especially at higher OSEE concentrations. Non-cytotoxic concentrations of OSEE attenuated cell proliferation and induced G₀/G₁ cell cycle arrest, which was associated with phosphorylation of p38 MAPK, an increase in the levels of tumor suppressor protein p21, and a decrease of proliferation marker protein Ki67. Additionally, only higher concentrations of OSEE were able to attenuate inhibition of proliferation induced by the ROS scavenger N-acetyl cysteine (NAC), indicating that the anti-proliferative effects of OSEE could be ROS-dependent. OSEE stimulated apoptosis and its effector Caspase-3 in MDA-MB-231 cells, in correlation with activation of the STAT3/p53 pathway. Furthermore, the extract reduced the migration and invasive properties of MDA-MB-231 cells through the deactivation of focal adhesion kinase (FAK). OSEE also reduced the production of inducible nitric oxide synthase (iNOS) and inhibited in ovo angiogenesis. Conclusion: Our findings reveal that OSEE is a rich source of phytochemicals and has robust anti-breast cancer properties that significantly attenuate the malignant phenotype of MD-MB-231 cells, suggesting that O. syriacum may not only act as a rich source of potential TNBC therapeutics but may also provide new avenues for the design of novel TNBC drugs.

Origanum syriacum Phytochemistry and Pharmacological Properties: A Comprehensive Review

Herbal medicine has been gaining special interest as an alternative choice of treatment for several diseases, being generally accessible, cost-effective and safe, with fewer side-effects compared to chemically synthesized medicines. Over 25% of drugs worldwide are derived from plants, and surveys have shown that, when available, herbal medicine is the preferred choice of treatment. Origanum syriacum (Lamiaceae) is a widely used medicinal plant in the Middle East, both as a home and a folk remedy, and in the food and beverage industry. Origanum syriacum contains numerous phytochemical compounds, including flavonoids, phenols, essential oils, and many others. Because of its bioactive compounds, O. syriacum possesses antioxidant, antimicrobial, and antiparasitic capacities. In addition, it can be beneficial in the treatment of various diseases such as cancer, neurodegenerative disorders, and peptic ulcers. In this review, the chemical compositions of different types of extracts and essential oils from this herb will first be specified. Then, the pharmacological uses of these extracts and essential oils in various contexts and diseases will be discussed, putting emphasis on their efficacy and safety. Finally, the cellular and molecular mechanisms of O. syriacum phytochemicals in disease treatment will be described as a basis for further investigation into the plant's pharmacological role.

Biotransformation of contraceptive drug desogestrel with Cunninghamella elegans, and anti-inflammatory activity of its metabolites

Biotransformation of an orally active contraceptive drug, desogestrel (1), with Cunninghamella elegans yielded a new metabolite, 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-17β-ol-3,6-dione (2), along with five known metabolites, i.e., 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-3β,6β,17β-triol (3), 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-6β,17β-diol-3-one (4), 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-17β-ol-3-one (5), 13β-ethyl-11-epoxy-18,19-dinor-17α-pregn-4-en-20-yn-17β-ol-3-one (6), and 13β-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-10β,17β-diol-3-one (7). The structure of new metabolite 2 was elucidated by using ¹H-, ¹³C-, and 2D-NMR, EI-, and HREI-MS, IR, and UV spectroscopic data. Compounds 1-7 were evaluated for anti-inflammatory activities, i.e., inhibition of T-cell proliferation, and pro-inflammatory cytokine (TNF-α). Compounds 1 (IC₅₀ = 1.12 ± 0.03 µg/mL), 2 (IC₅₀ = 1.15 ± 0.05 µg/mL), 3 (IC₅₀ = 1.15 ± 0.05 µg/mL), 4 (IC₅₀ = 1.40 ± 0.03 µg/mL), 5 (IC₅₀ = 1.78 ± 0.08 µg/mL), and 6 (IC₅₀ = 1.36 ± 0.07 µg/mL) were identified as potent inhibitors of T-cells proliferation, in comparison to the standard drug, prednisolone (IC₅₀ = 3.51 ± 0.03 µg/mL). Compound 7 (IC₅₀ = 6.18 ± 0.04 µg/mL) showed a good activity. In addition, substrate 1 (IC₅₀ ≤ 1 µg/mL), and its metabolites 2 (IC₅₀ = 4.1 ± 0.60 µg/mL), and 6 (IC₅₀ = 6.8 ± 0.8 µg/mL) also showed a potent inhibition of pro-inflammatory cytokine (TNF-α) production, as compared to the standards drug, pentoxifilline (IC₅₀ = 94.8 ± 2.1 µg/mL). Whereas compounds 3 (IC₅₀ = 57.9 ± 7.6 µg/mL), and 5 (IC₅₀ = 27.2 ± 6.8 µg/mL) showed a moderate inhibition of TNF-α production, while compounds 4 and 7 showed no inhibition. Compounds 1-7 were found to be non-cytotoxic to 3T3 normal cell line (mouse fibroblast).

Ziziphus nummularia: A Comprehensive Review of Its Phytochemical Constituents and Pharmacological Properties

Ziziphus nummularia, a small bush of the Rhamnaceae family, has been widely used in traditional folk medicine, is rich in bioactive molecules, and has many reported pharmacological and therapeutic properties. Objective: To gather the current knowledge related to the medicinal characteristics of Z. nummularia. Specifically, its phytochemical contents and pharmacological activities in the treatment of various diseases such as cancer, diabetes, and cardiovascular diseases, are discussed. Methods: Major scientific literature databases, including PubMed, Scopus, ScienceDirect, SciFinder, Chemical Abstracts, Medicinal and Aromatic Plants Abstracts, Henriette’s Herbal Homepage, Dr. Duke’s Phytochemical and Ethnobotanical Databases, were searched to retrieve articles related to the review subject. General web searches using Google and Google scholar were also utilized. The search period covered articles published between 1980 and the end of October 2021.The search used the keywords ‘Ziziphus nummularia’, AND (‘phytochemical content’, ‘pharmacological properties, or activities, or effects, or roles’, ‘anti-inflammatory’, ‘anti-drought’, ‘anti-thermal’, ‘anthelmintic’, ‘antidiabetic’,’ anticancer’, ‘anticholinesterase’, ‘antimicrobial’, ‘sedative’, ‘antipyretic’, ‘analgesic’, or ‘gastrointestinal’). Results: This plant is rich in characteristic alkaloids, especially cyclopeptide alkaloids such as nummularine-M. Other phytochemicals, including flavonoids, saponins, glycosides, tannins, and phenolic compounds, are also present. These phytochemicals are responsible for the reported pharmacological properties of Z. nummularia, including anti-inflammatory, antioxidant, antimicrobial, anthelmintic, antidiabetic, anticancer, analgesic, and gastrointestinal activities. In addition, Z. nummularia has anti-drought and anti-thermal characteristics. Conclusion: Research into the phytochemical and pharmacological properties of Z. nummularia has demonstrated that this plant is a rich source of novel bioactive compounds. So far, Z. nummularia has shown a varied pharmacological profile (antioxidant, anticancer, anti-inflammatory, and cardioprotective), warranting further research to uncover the therapeutic potential of the bioactives of this plant. Taken together, Z. nummularia may represent a new potential target for the discovery of new drug leads.

Liposome-based nanocapsules for the controlled release of dietary curcumin: PDDA and silica nanoparticle-coated DMPC liposomes enhance the fluorescence efficiency and anticancer activity of curcumin

Nanosystems with various compositions and biological properties are being extensively investigated for drug and gene delivery applications. Many nanotechnology methods use novel nanocarriers, such as liposomes, in therapeutically targeted drug delivery systems. However, liposome matrices suffer from several limitations, including drug leakage and instability. Therefore, the surface modification of liposomes by coating them or adding polymers has advanced their application in drug delivery. Hence, the prevention of drug release from the liposome bilayers was the main focus of this work. For this purpose, liposomes were synthesized according to a thin film hydration method by applying various surface modifications. Three different nanocapsules, N1, N2, and N3, were prepared using 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), poly(diallyldimethylammonium)chloride (PDAA) polymer, and silica nanoparticles. PDDA and silica nanoparticles were coated on the surface of liposomes using a layer-by-layer assembly method, completely encapsulating curcumin into the core of the liposome. Fluorescence spectroscopy, TGA, DLS, XRD, SEM, and zeta potential methods were used to characterize the prepared nanocapsules. Interestingly, the fluorescence of curcumin showed a blue shift and the fluorescence efficiency was extraordinarily enhanced ∼25-, ∼54-, and ∼62-fold in the N1, N2, and N3 nanocapsules, respectively. Similarly, encapsulation efficiency, drug loading, and the anticancer activity of dietary curcumin were investigated for the different types of DMPC nanocapsules. The drug efficiencies of the liposomes were established according to the release of curcumin from the liposomes. The results showed that the release of curcumin from the nanocapsules decreased as the number of layers at the surface of the liposomes increased. The release of curcumin follows the Higuchi model; thus, a slow rate of diffusion is observed when a number of layers is added. The better encapsulation and higher anti-cancer activity of curcumin were also observed when more layers were added, which is due to electrostatic interactions inhibiting curcumin from being released.

In Vitro Evaluation of Biological and Anticancer Activities Exhibited by Five Varieties of Vitis vinifera L

Vitis vinifera commonly known as grapevine is one of the most important fruit crops worldwide. Its cultivation started more than 7000 years ago in the Near East, and over the millennia was followed by the development of thousands of cultivars that were further selected and characterized for specific purposes. Its important pharmacological value and its richness in phytoconstituents were the triggers to perform this project. Seven extracts were prepared from five different V. vinifera varieties (V. vinifera 'Black Pearl' (BP), V. vinifera 'Red Glob' (RG), V. vinifera 'Crimson' (CR), V. vinifera 'Beitamouni' (BE) and V. vinifera 'Superior' (SU)) by separating the pulp from the seeds, followed by methanolic extraction. The phytochemical analysis showed that red colored grapes (RE, BP and CR), the seeds from V. vinifera 'Black Pearl' and V. vinifera 'Red Globe' contain higher amounts of primary and secondary metabolites such as polyphenols, anthocyanins and reducing sugars. In addition to their richness in phytoconstituents, these varieties/seeds possess an important antioxidant activity. The results of the cell viability assays showed that the red varieties have a potential anticancer activity against Capan-2 pancreatic cancer and MDA-MB231(TNBC) breast cancer cell lines, with the greatest promise when combined with the seeds.