αS1-Casein-Loaded Proteo-liposomes as Potential Inhibitors in Amyloid Fibrillogenesis: In Vivo Effects on a C. elegans Model of Alzheimer's Disease.

According to the amyloid hypothesis, in the early phases of Alzheimer's disease (AD), small soluble prefibrillar aggregates of the amyloid ß-peptide (Aß) interact with neuronal membranes, causing neural impairment. Such highly reactive and toxic species form spontaneously and transiently in the amyloid building pathway. A therapeutic strategy consists of the recruitment of these intermediates, thus preventing aberrant interaction with membrane components (lipids and receptors), which in turn may trigger a cascade of cellular disequilibria. Milk αs1-Casein is an intrinsically disordered protein that is able to inhibit Aß amyloid aggregation in vitro, by sequestering transient species. In order to test αs1-Casein as an inhibitor for the treatment of AD, it needs to be delivered in the place of action. Here, we demonstrate the use of large unilamellar vesicles (LUVs) as suitable nanocarriers for αs1-Casein. Proteo-LUVs were prepared and characterized by different biophysical techniques, such as multiangle light scattering, atomic force imaging, and small-angle X-ray scattering; αs1-Casein loading was quantified by a fluorescence assay. We demonstrated on a C. elegans AD model the effectiveness of the proposed delivery strategy in vivo. Proteo-LUVs allow efficient administration of the protein, exerting a positive functional readout at very low doses while avoiding the intrinsic toxicity of αs1-Casein. Proteo-LUVs of αs1-Casein represent an effective proof of concept for the exploitation of partially disordered proteins as a therapeutic strategy in mild AD conditions.

Isolation of Extracellular Vesicles From Microalgae: A Renewable and Scalable Bioprocess.

Extracellular vesicles (EVs) play a crucial role as potent signal transducers among cells, with the potential to operate cross-species and cross-kingdom communication. Nanoalgosomes are a subtype of EVs recently identified and isolated from microalgae. Microalgae represent a natural bioresource with the capacity to produce several secondary metabolites with a broad range of biological activities and commercial applications. The present study highlights the upstream and downstream processes required for the scalable production of nanoalgosomes from cultures of the marine microalgae Tetraselmis chuii. Different technical parameters, protocols, and conditions were assessed to improve EVs isolation by tangential flow filtration (TFF), aiming to enhance sample purity and yield. The optimization of the overall bioprocess was enhanced by quality control checks operated through robust biophysical and biochemical characterizations. Further, we showed the possibility of recycling by TFF microalgae cells post-EVs isolation for multiple EV production cycles. The present results highlight the potential of nanoalgosome production as a scalable, cost-effective bioprocess suitable for diverse scientific and industrial exploitations.

Extracellular Vesicles From Microalgae: Uptake Studies in Human Cells and Caenorhabditis elegans.

Extracellular vesicles (EVs) are lipid membrane nano-sized vesicles secreted by various cell types for intercellular communication, found in all kingdoms of life. Nanoalgosomes are a subtype of EVs derived from microalgae with a sustainable biotechnological potential. To explore the uptake, distribution and persistence of nanoalgosomes in cells and living organisms, we separated them from a culture of the chlorophyte Tetraselmis chuii cells by tangential flow filtration (TFF), labelled them with different lipophilic dyes and characterized their biophysical attributes. Then we studied the cellular uptake of labelled nanoalgosomes in human cells and in C. elegans, demonstrating that they enter the cells through an energy dependent mechanism and are localized in the cytoplasm of specific cells, where they persist for days. Our data confirm that nanoalgosomes are actively uptaken in vitro by human cells and in vivo by C. elegans cells, supporting their exploitation as potential nanocarriers of bioactive compounds for theranostic applications.

Nanoalgosomes: Introducing extracellular vesicles produced by microalgae.

Cellular, inter-organismal and cross kingdom communication via extracellular vesicles (EVs) is intensively studied in basic science with high expectation for a large variety of bio-technological applications. EVs intrinsically possess many attributes of a drug delivery vehicle. Beyond the implications for basic cell biology, academic and industrial interests in EVs have increased in the last few years. Microalgae constitute sustainable and renewable sources of bioactive compounds with a range of sectoral applications, including the formulation of health supplements, cosmetic products and food ingredients. Here we describe a newly discovered subtype of EVs derived from microalgae, which we named nanoalgosomes. We isolated these extracellular nano-objects from cultures of microalgal strains, including the marine photosynthetic chlorophyte Tetraselmis chuii, using differential ultracentrifugation or tangential flow fractionation and focusing on the nanosized small EVs (sEVs). We explore different biochemical and physical properties and we show that nanoalgosomes are efficiently taken up by mammalian cell lines, confirming the cross kingdom communication potential of EVs. This is the first detailed description of such membranous nanovesicles from microalgae. With respect to EVs isolated from other organisms, nanoalgosomes present several advantages in that microalgae are a renewable and sustainable natural source, which could easily be scalable in terms of nanoalgosome production.

BBIT20 inhibits homologous DNA repair with disruption of the BRCA1-BARD1 interaction in breast and ovarian cancer.

BACKGROUND AND PURPOSE: Advances in the treatment of triple-negative breast and ovarian cancer remain challenging. In particular, resistance to the available therapy, by restoring or overexpressing the DNA repair machinery, has often been reported. New strategies to improve the therapeutic outcomes of these cancers are needed. Herein, we disclose the dregamine 5-bromo-pyridin-2-ylhydrazone (BBIT20), a natural monoterpene indole alkaloid derivative, as an inhibitor of homologous DNA repair. EXPERIMENTAL APPROACH: To unveil BBIT20 antitumour activity and underlying molecular mechanism of action, two-dimensional (2D) and three-dimensional (3D) cell cultures, patient-derived cell lines and xenograft mouse models were used. KEY RESULTS: BBIT20 disrupted the BRCA1-BARD1 interaction, triggering nuclear-to-cytoplasmic BRCA1 translocation, cell cycle arrest and downregulation of homologous DNA repair-related genes and proteins, with subsequent enhancement of DNA damage, reactive oxygen species generation and apoptosis, in triple-negative breast and ovarian cancer cells. BBIT20 also displayed pronounced antitumour activity in patient-derived cells and xenograft mouse models of ovarian cancer, with low toxicity in non-malignant cells and undetectable side effects in mice. Additionally, it did not induce resistance in triple-negative breast and ovarian cancer and displayed marked synergistic effects with cisplatin and olaparib (a poly [ADP-ribose] polymerase inhibitor), on 2D and 3D models of these cancer cells. CONCLUSION AND IMPLICATIONS: These findings add an inhibitor of the BRCA1-BARD1 interaction to the list of DNA-damaging agents. Importantly, either as a single agent or in combination therapy, BBIT20 reveals great potential in the personalized treatment of aggressive and resistant cancers, particularly triple-negative breast and advanced ovarian cancer.

Lyophilized extracts from vegetable flours as valuable alternatives to purified oxygenases for the synthesis of oxylipins.

In this work, the whole aqueous extracts of soybean flour and oat flour have been used as valuable alternatives to purified oxygenase enzymes for the preparation of oxylipins derived from (5Z,8Z,11Z,14Z,17Z)-eicosapentaenoic acid (EPA). The lipoxygenase activity in the aqueous extracts of soybean (Glycine max. L.) flour was monitored with linoleic acid as substrate and compared with the commercially available purified enzyme (LOX-1). Oat flour extracts (Avena sativa L.) were evaluated for their peroxygenase activity by comparing different enzyme preparations in the epoxidation of methyl oleate. It was found that lyophilization of the aqueous extracts from these vegetable flours offers advantages in terms of enzyme stability, reproducibility and applicability to preparative organic synthesis. The lyophilized enzyme preparations were tested for the oxyfunctionalization of EPA and the formed products were isolated in satisfactory yields. In the presence of lyophilized extract from soybean, EPA gave 15S-hydroxy-(5Z,8Z,11Z,13E,17Z)-eicosapentaenoic acid in enantiopure form as exclusive product. Peroxygenase from oat flour was less selective and catalyzed the formation of different epoxides of EPA. However, the biocatalyzed epoxidation of EPA under controlled conditions allowed to obtain optically active (17R,18S)-epoxy-(5Z,8Z,11Z,14Z)-eicosatetraenoic acid (65% ee) as the main monoepoxide, among the five possible ones.

Monoterpene indole alkaloid azine derivatives as MDR reversal agents.

Aiming at generating a library of bioactive indole alkaloid derivatives as multidrug resistance (MDR) reversers, two epimeric indole alkaloids (1 and 2) were submitted to chemical transformations, giving rise to twenty-four derivatives (5-28), bearing new aromatic or aliphatic azine moieties. The structure of the compounds was established by 1D and 2D NMR (COSY, HMBC, HMQC and NOESY) experiments. Two different strategies were employed for assessing their anti-MDR potential, namely through the evaluation of their activity as inhibitors of typical MDR ABC transporters overexpressed by cell transfection, such as ABCB1 (P-gp), ABCC1 (MRP1), and ABCG2 (BCRP), or by evaluating their ability as collateral sensitivity (CS) agents in cells overexpressing MRP1. A considerable MDR reversing activity was observed for compounds bearing the aromatic azine moiety. The strongest and most selective P-gp inhibition was found for the epimeric azines 5 and 6, bearing a para-methylbenzylidene moiety. Instead, compounds 17 and 18 that possess a di-substituted benzylidene portion with methoxy and hydroxyl groups, selectively inhibited MRP1 drug-efflux. None of these compounds inhibited BCRP. Compounds 5, 6 and 18 were further investigated in drug combination experiments, which corroborated their anti-MDR potential. Moreover, it was observed that compound 12, with an aromatic azine moiety, and compounds 23-26, sharing a new aliphatic substituent, displayed a CS activity, selectively killing MRP1-overexpressing cells. Among these last compounds, it could be established that addition of 19, 23 and 25 to MRP1-overexpressing cells led to glutathione depletion triggering cell death through apoptosis.

Evaluation of Marine Microalga Diacronema vlkianum Biomass Fatty Acid Assimilation in Wistar Rats.

Diacronema vlkianum is a marine microalgae for which supposed health promoting effects have been claimed based on its phytochemical composition. The potential use of its biomass as health ingredient, including detox-shakes, and the lack of bioavailability studies were the main concerns. In order to evaluate the microalgae-biomass assimilation and its health-benefits, single-dose (CD1-mice) studies were followed by 66-days repeated-dose study in Wistar rats with the highest tested single-dose of microalgae equivalent to 101 mg/kg eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA). Microalgae-supplementation modulated EPA and docosapentaenoic acid enrichment at arachidonic acid content expenditure in erythrocytes and liver, while increasing EPA content of heart and adipose tissues of rats. Those fatty acid (FA) changes confirmed the D. vlkianum-biomass FA assimilation. The principal component analyses discriminated brain from other tissues, which formed two other groups (erythrocytes, liver, and heart separated from kidney and adipose tissues), pointing to a distinct signature of FA deposition for the brain and for the other organs. The improved serum lipid profile, omega-3 index and erythrocyte plasticity support the cardiovascular benefits of D. vlkianum. These results bolster the potential of D. vlkianum-biomass to become a "heart-healthy" food supplement providing a safe and renewable source of bioavailable omega-3 FA.

Dregamine and tabernaemontanine derivatives as ABCB1 modulators on resistant cancer cells.

Dregamine (1) and tabernaemontanine (2), two epimeric monoterpene indole alkaloids isolated in large amount from the roots of the African plant Tabernaemontana elegans, were derivatized, yielding ten imine derivatives, as previously described (3-12). In the present study, aiming at increasing the pool of analogues for establishing structure-activity relationships (SAR), compounds 1 and 2 were further submitted to several chemical transformations, yielding thirteen new derivatives (13-25). Their structures were assigned by spectroscopic methods, including 1D and 2D NMR experiments. Compounds 1-25 were evaluated for their effects on the reversion of multidrug resistance (MDR) in cancer cells mediated by P-glycoprotein (P-gp/ABCB1), through combination of functional and chemosensitivity assays, using a human ABCB1-transfected mouse T-lymphoma cell model. SAR analysis showed that different substituents at C-3 and at the indole nitrogen led to different ABCB1 modulatory effects. When compared to the parent compounds, a remarkable enhancement in MDR reversal activity was found for derivatives sharing a new aromatic moiety. Thus, the strongest ability as MDR reversers, and a manifold activity when compared to verapamil, was found for compound 8, the epimeric compounds 9 and 10, and compound 15, bearing pyrazine, bromo-pyridine, and methoxybenzyloxycarbonyl moieties, respectively. In drug combination assays, all compounds tested were revealed to interact synergistically with doxorubicin. Collectively, the results indicate that some of these derivatives may be promising leads for overcoming MDR in cancer.

Vobasinyl-Iboga Alkaloids from Tabernaemontana elegans: Cell Cycle Arrest and Apoptosis-Inducing Activity in HCT116 Colon Cancer Cells.

Phytochemical investigation of the roots of the African medicinal plant Tabernaemontana elegans led to the isolation of three new (1-3) and two known (4 and 5) bisindole alkaloids of the vobasinyl-iboga type. The structures of 1-3 were assigned by spectroscopic methods, mainly using 1D and 2D NMR experiments. All of the isolated compounds were evaluated for their cytotoxicity against HCT116 colon and HepG2 liver carcinoma cells by the MTS metabolism assay. Compounds 1-3 and 5 were found to be cytotoxic to HCT116 colon cancer cells, displaying IC50 values in the range 8.4 to >10 µM. However, the compounds did not display significant cytotoxicity against HepG2 cancer cells. The cytotoxicity of compounds 1-3 and 5 was corroborated using a lactate dehydrogenase assay. Hoechst staining and nuclear morphology assessment and caspase-3/7 activity assays were also performed for investigating the activity of compounds 1-3 and 5 as apoptosis inducers. The induced inhibition of proliferation of HCT116 cells by compounds 1 and 2 was associated with G1 phase arrest, while compounds 3 and 5 induced G2/M cell cycle arrest. These results showed that the new vobasinyl-iboga alkaloids 1-3 and compound 5 are strong inducers of apoptosis and cell cycle arrest in HCT116 colon cancer cells.

(3'R)-hydroxytabernaelegantine C: A bisindole alkaloid with potent apoptosis inducing activity in colon (HCT116, SW620) and liver (HepG2) cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Tabernaemontana elegans Stapf. (Apocynaceae) is a medicinal plant traditionally used in African countries to treat cancer. AIMS OF THE STUDY: To discover new apoptosis inducing lead compounds from T. elegans and provide scientific validation of the ethnopharmacological use of this plant. MATERIALS AND METHODS: Through fractionation, (3'R)-hydroxytaberanelegantine C (1), a vobasinyl-iboga bisindole alkaloid, was isolated from a cytotoxic alkaloid fraction of the methanol extract of T. elegans roots. Its structure was identified by spectroscopic methods, mainly 1D and 2D NMR experiments. Compound 1 was evaluated for its ability to induce apoptosis in HCT116 and SW620 colon and HepG2 liver carcinoma cells. The cell viability of compound 1 was evaluated by the MTS and lactate dehydrogenase (LDH) assays. Induction of apoptosis was analyzed through Guava ViaCount assay, by flow cytometry, caspase-3/7 activity assays and evaluation of nuclear morphology by Hoechst staining. To determine the molecular pathways elicited by 1 exposure, immunoblot analysis was also performed. RESULTS: (3'R)-hydroxytaberanelegantine C (1) displayed strong apoptosis induction activity as compared to 5-fluorouracil (5-FU), the most used anticancer agent in colorectal cancer treatment. In the MTS assay, compound 1 exhibited IC50 values similar or lower than 5-FU in the three cell lines tested. The IC50 value of 1 was also calculated in CCD18co normal human colon fibroblasts. The lactate dehydrogenase assay showed increased LDH release by compound 1, and the Guava ViaCount assay revealed that 1 significantly increased the incidence of apoptosis to a further extent than 5-FU. Moreover, the induction of apoptosis was corroborated by evaluation of nuclear morphology by Hoechst staining and caspase-3/7 activity assays of 1 treated cells. As expected, in immunoblot analysis, compound 1 treatment led to poly(ADP-ribose) polymerase cleavage. This was accompanied by decreased anti-apoptotic proteins Bcl-2 and XIAP steady state levels in all three cancer cell lines tested. CONCLUSIONS: Compound 1 showed remarkable induction of apoptosis in HCT116, SW620 and HepG2 cells. Together, the results suggest that compound 1 is a promising lead structure for inducing apoptosis.

Monoterpene indole alkaloid hydrazone derivatives with apoptosis inducing activity in human HCT116 colon and HepG2 liver carcinoma cells.

The derivatization of dregamine (1) and tabernaemontanine (2), two epimeric monoterpene indole alkaloids isolated from the methanol extract of the roots of Tabernaemontana elegans, with several hydrazines and hydroxylamine gave rise to ten new derivatives (3-12). Their structures were assigned by spectroscopic methods, including 2D NMR experiments. The compounds were tested for their ability to induce apoptosis in HCT116 colon and HepG2 liver cancer cells. Firstly, the cytotoxicity of all compounds (1-12) was evaluated in both cell lines by the MTS assay. The most active compounds (6, 9, 10) along with 1 and 2 were further investigated for their apoptosis induction capability by Guava ViaCount flow cytometry assays, nuclear morphology evaluation by Hoechst staining, and caspase-3/7 activity assays. Compounds 9 and 10 showed promising apoptosis induction profile, displaying higher activities than 5-fluorouracil, the mainstay in colon cancer treatment.

Diterpenes from Euphorbia piscatoria: synergistic interaction of Lathyranes with doxorubicin on resistant cancer cells.

Four new diterpenes were isolated from the methanolic extract of Euphorbia piscatoria, two ent-abietanes (1, 2) and two lathyrane-type macrocyclic diterpenes (3, 4), along with three known diterpenes (5-7). Their structures were characterized by spectroscopic methods, mainly 1D and 2D NMR ((1)H, (13)C, DEPT, COSY, HMBC, HMQC, and NOESY) experiments. Compound 2, with an unusual structure, might be considered intermediate in the biosynthesis of ent-abietane α,ß-unsaturated lactones, commonly found in Euphorbia species. Therefore, a possible biogenetic pathway is proposed. The MDR reversal potential of macrocyclic diterpenes 3-5 was evaluated through a drug combination assay, using the L5178Y mouse T lymphoma cell line transfected with the human MDR1 gene. Compounds 3-5 were able to enhance, synergistically, the antiproliferative activity of doxorubicin (combination indexes < 0.5). Moreover, compounds 1-6 were also assessed for their antiproliferative activity on human MDR cancer cell models, namely gastric, pancreatic, and colon. Weak antiproliferative activity was observed for compounds 1 (IC50 = 66.02 ± 7.10 µM) and 4 (IC50 = 39.51 ± 3.82 µM) on the MDR gastric cell line.

Macrocyclic diterpenes resensitizing multidrug resistant phenotypes.

Herein, collateral sensitivity effect was exploited as a strategy to select effective compounds to overcome multidrug resistance in cancer. Thus, eleven macrocyclic diterpenes, namely jolkinol D (1), isolated from Euphorbia piscatoria, and its derivatives (2-11) were evaluated for their activity on three different Human cancer entities: gastric (EPG85-257), pancreatic (EPP85-181) and colon (HT-29) each with a variant selected for resistance to mitoxantrone (EPG85-257RN; EPP85-181RN; HT-29RN) and one to daunorubicin (EPG85-257RD; EPP85-181RD; HT-29RD). Jolkinol D (1) and most of its derivatives (2-11) exhibited significant collateral sensitivity effect towards the cell lines EPG85-257RN (associated with P-glycoprotein overexpression) and HT-29RD (altered topoisomerase II expression). The benzoyl derivative, jolkinoate L (8) demonstrated ability to target different cellular contexts with concomitant high antiproliferative activity. These compounds were previously assessed as P-glycoprotein modulators, at non-cytotoxic doses, on MDR1-mouse lymphoma cells. A regression analysis between the antiproliferative activity presented herein and the previously assessed P-glycoprotein modulatory effect showed a strong relation between the compounds that presented both high P-glycoprotein modulation and cytotoxicity.