Plant plasma membrane aquaporins in natural vesicles as potential stabilizers and carriers of glucosinolates

Brassica oleracea L. var. italica Aquaporin Reconstituted Proteoliposomes as Nanosystems for Resveratrol Encapsulation

Aquaporins (AQPs), membrane proteins responsible for facilitating water transport, found in plant membrane vesicles (MV), have been related to the functionality and stability of MV. We focused on AQPs obtained from broccoli, as they show potential for biotechnological applications. To gain further insight into the role of AQPs in MV, we describe the heterologous overexpression of two broccoli AQPs (BoPIP1;2 and BoPIP2;2) in Pichia pastoris, resulting in their purification with high yield (0.14 and 0.99 mg per gram cells for BoPIP1;2 and BoPIP2;2). We reconstituted AQPs in liposomes to study their functionality, and the size of proteoliposomes did not change concerning liposomes. BoPIP2;2 facilitated water transport, which was preserved for seven days at 4 °C and at room temperature but not at 37 °C. BoPIP2;2 was incorporated into liposomes to encapsulate a resveratrol extract, resulting in increased entrapment efficiency (EE) compared to conventional liposomes. Molecular docking was utilized to identify binding sites in PIP2s for resveratrol, highlighting the role of aquaporins in the improved EE. Moreover, interactions between plant AQP and human integrin were shown, which may increase internalization by the human target cells. Our results suggest AQP-based alternative encapsulation systems can be used in specifically targeted biotechnological applications.

Membrane Vesicles for Nanoencapsulated Sulforaphane Increased Their Anti-Inflammatory Role on an In Vitro Human Macrophage Model

At present, there is a growing interest in finding new non-toxic anti-inflammatory drugs to treat inflammation, which is a key pathology in the development of several diseases with considerable mortality. Sulforaphane (SFN), a bioactive compound derived from Brassica plants, was shown to be promising due to its anti-inflammatory properties and great potential, though its actual clinical use is limited due to its poor stability and bioavailability. In this sense, the use of nanocarriers could solve stability-related problems. In the current study, sulforaphane loaded into membrane vesicles derived from broccoli plants was studied to determine the anti-inflammatory potential in a human-macrophage-like in vitro cell model under both normal and inflammatory conditions. On the one hand, the release of SFN from membrane vesicles was modeled in vitro, and two release phases were stabilized, one faster and the other slower due to the interaction between SFN and membrane proteins, such as aquaporins. Furthermore, the anti-inflammatory action of sulforaphane-loaded membrane vesicles was demonstrated, as a decrease in interleukins crucial for the development of inflammation, such as TNF-α, IL-1β and IL-6, was observed. Furthermore, these results also showed that membrane vesicles by themselves had anti-inflammatory properties, opening the possibility of new lines of research to study these vesicles, not only as carriers but also as active compounds.

Nanoencapsulation of sulforaphane in broccoli membrane vesicles and their in vitro antiproliferative activity

CONTEXT

The development of nanocarriers of plant origin, such as plant cell membranes, has recently been investigated. Also, plant bioactive compounds as sulforaphane (SFN) from broccoli have recognized antioxidant or anticancer properties.

OBJECTIVE

To investigate the capacity of membrane vesicles from broccoli (BM-vesicles) to encapsulate SFN and their application in the cancer cell line.

MATERIALS AND METHODS

Physicochemical analysis was carried out to characterize BM-vesicles through different approaches: dynamic light scattering, transmission electron microscopy, stopped-flow analysis, and proteomic analysis. They were applied at different concentrations (BM-vesicles at 0.04-0.00315% of protein and SFN at 5, 25, and 100 µM) in SK-MEL-28 cells during 24 h for studying cytotoxicity and gene expression.

RESULTS

The entrapment efficiency was 41%. The anticancer activity tested in cells showed a decrease in proliferation when SFN in BM-vesicles was utilized. Expression patterns when SFN was applied in an encapsulated form showed a reduction of cancer markers and an increase of AQP3. Also, the metabolism of SFN occurred inside of cells, and higher SFN penetrated when it was encapsulated.

DISCUSSION

The results showed that encapsulated SFN was better absorbed by melanoma cells providing metabolism products and a reduction of cancer molecular markers. Also aquaporin, AQP3 was pointed to as an important marker since it appeared to play a key role in homeostasis due to the importance of water transport in biological processes.

CONCLUSION

These results indicate that SFN and SFN encapsulated in BM-vesicles have a high activity for the inhibition of melanocyte development. Therefore, BM-vesicles could serve as nanocarriers for drugs.

Structure based virtual screening of natural product molecules as glycosidase inhibitors

Objective of the present investigation comprised of the application of in silico methods to discover novel natural product (NP) based potential inhibitors for carbohydrate mediated diseases. Structure based drug design studies (molecular docking and structure based pharmacophore analysis)  were carried out on a series of natural product compounds to identify significant bioactive molecules to inhibit α-mannosidase (I and II) and β-galactosidase enzymes. Furthermore, protein ligand interaction fingerprint analysis, molecular dynamics simulations and molecular access system (MACCS) fingerprint analysis were performed to understand the binding behaviors of the studied molecules. The results derived from these analyses showed that the identified compounds exhibit significant binding interactions with the active site residues. The compounds, NP-51, NP-81 and NP-165 have shown significant docking score against the studied enzymes (α-mannosidases-I, α-mannosidases-II and β-galactosidases). The fingerprint studies showed that the presence of rings (aromatic or aliphatic) with sulfur atoms, nitrogen atoms, methyl groups, etc. have favorable effects on the α-mannosidase II inhibitory activity. However, the presence of halogen atoms substituted in the molecules have reduced inhibitory ability against α-mannosidase II. The compound, NP-165 has significant activity against both enzymes (α-mannosidases and β-galactosidases). These studies accomplished that the compounds identified through in silico methodologies can be used to develop semisynthetic derivatives of the glycosidase inhibitors and can be screened for the treatment of different carbohydrate mediated diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-021-00115-9.

The therapeutic triad of extracellular vesicles: As drug targets, as drugs, and as drug carriers

Rapidly growing interest in the study of extracellular vesicles (EVs) has led to the accumulation of evidence on their critical roles in various pathologies, as well as opportunities to design novel therapeutic EV-based applications. Efficiently exploiting the constantly expanding knowledge of the biology and function of EVs requires a deep understanding of the various possible strategies of using EVs for therapeutic purposes. Accordingly, in the present work, we have narrowed the broad therapeutic potential of EVs and consider the similarities and differences of various strategies as we articulate three major aspects (i.e., a triad) of their therapeutic uses: (i) EVs as drug targets, whereby we discuss therapeutic targeting of disease-promoting EVs; (ii) EVs as drugs, whereby we consider the natural medicinal properties of EVs and the available options for their optimization; and (iii) EVs as drug carriers, whereby we highlight the advantages of EVs as vehicles for efficacious drug delivery of natural compounds. Finally, after conducting a comprehensive review of the latest literature on each of these aspects, we outline opportunities, limitations, and potential solutions.

The Influence of Red Cabbage Extract Nanoencapsulated with Brassica Plasma Membrane Vesicles on the Gut Microbiome of Obese Volunteers

The aim of the study was to evaluate the influence of the red cabbage extracts on the bioaccessibility of their isothiocyanates, and their effect on the intestinal microbiota using a dynamic model of human digestion treated with the gut microbiome of obese adults. The elicitation of red cabbage plants with methyl jasmonate (MeJA) duplicated the content of glucosinolates (GSLs) in the plant organs used for elaborating the encapsulated formula. The use of plasma membrane vesicles, according to a proper methodology and technology, showed a high retention of sulforaphane (SFN) and indol-3-carbinol (I3C) over the course of the 14-day digestion study. The microbiome was scarcely affected by the treatments in terms of microbiota composition or the Bacteroidetes/Firmicutes ratio, but a 3 to 4-fold increase was observed in the production of butyric acid with the encapsulated extract treatment. Based on our pilot red cabbage extract study, the consumption of this extract, mainly encapsulated, may play a potential role in the management of obesity in adults.

Nanoencapsulation of Pomegranate Extract to Increase Stability and Potential Dermatological Protection

Pomegranate extract (PG-E) has been reported to exert a protective effect on the skin due to its antioxidant activity. Ingredients rich in phenolic compounds are unstable in extract solutions, and, therefore, the use of a suitable nanosystem to encapsulate this type of extract could be necessary in different biotechnological applications. Thus, we investigated the capacity of Brassica oleracea L. (cauliflower) inflorescence vesicles (CI-vesicles) to encapsulate PG-E and determined the stability and the antioxidant capacity of the system over time. In addition, the protective effect against UV radiation and heavy metals in HaCaT cells was also tested. The CI-vesicles had an entrapment efficiency of around 50%, and accelerated stability tests did not show significant changes in the parameters tested. The results for the HaCaT cells showed the non-cytotoxicity of the CI-vesicles containing PG-E and their protection against heavy metals (lead acetate and mercuric chloride) and UV-B radiation through a reduction of oxidative stress. The reduction of the percentage of deleted mtDNA (mtDNA4977, "common deletion") in UV-treated HaCaT cells due to the presence of CI-vesicles containing PG-E indicated the mechanism of protection. Therefore, the effects of CI-vesicles loaded with PG-E against oxidative stress support their utilization as natural cosmeceuticals to protect skin health against external damage from environmental pollution and UV radiation.

Plasma membrane vesicles from cauliflower meristematic tissue and their role in water passage

BACKGROUND

Cauliflower (Brassica oleracea L. var. botrytis) inflorescences are composed mainly of meristematic tissue, which has a high cellular proliferation. This considerable cellular density makes the inflorescence an organ with a large proportion of membranes. However, little is known about the specific role of the lipid and protein composition of the plasma membrane present in this organ.

RESULTS

In this work, we analyzed the lipids and proteins present in plasma membrane from two different stages of development of cauliflower inflorescence and compared them with leaf plasma membrane. For this purpose, plasma membrane vesicles were obtained by centrifugation for each sample and the vesicular diameter and osmotic permeability (Pf) were analyzed by dynamic light scattering and the stopped-flow technique, respectively. In addition, fatty acids and sterols were analyzed by gas chromatography and HPLC. The protein composition of the inflorescences and leaves was characterized by HPLC-ESI-QTOF-MS and the data obtained were compared with Brassicaceae proteins present in the UniProt database in relation to the presence of aquaporins determined by western blot analysis. The highest Pf value was found in 90 day inflorescences-derived plasma membrane vesicles (61.4 ± 4.14 μms- 1). For sterols and fatty acids, the concentrations varied according to the organ of origin. The protein profile revealed the presence of aquaporins from the PIP1 and PIP2 subfamilies in both inflorescences and leaves.

CONCLUSION

This study shows that the composition of the sterols, the degree of unsaturation of the fatty acids, and the proteins present in the membranes analyzed give them high functionality for water passage. This represents an important addition to the limited information available in this field.

Detergent Resistant Membrane Domains in Broccoli Plasma Membrane Associated to the Response to Salinity Stress

Detergent-resistant membranes (DRMs) microdomains, or “raft lipids”, are key components of the plasma membrane (PM), being involved in membrane trafficking, signal transduction, cell wall metabolism or endocytosis. Proteins imbibed in these domains play important roles in these cellular functions, but there are few studies concerning DRMs under abiotic stress. In this work, we determine DRMs from the PM of broccoli roots, the lipid and protein content, the vesicles structure, their water osmotic permeability and a proteomic characterization focused mainly in aquaporin isoforms under salinity (80 mM NaCl). Based on biochemical lipid composition, higher fatty acid saturation and enriched sterol content under stress resulted in membranes, which decreased osmotic water permeability with regard to other PM vesicles, but this permeability was maintained under control and saline conditions; this maintenance may be related to a lower amount of total PIP1 and PIP2. Selective aquaporin isoforms related to the stress response such as PIP1;2 and PIP2;7 were found in DRMs and this protein partitioning may act as a mechanism to regulate aquaporins involved in the response to salt stress. Other proteins related to protein synthesis, metabolism and energy were identified in DRMs independently of the treatment, indicating their preference to organize in DMRs.

Plant plasma membrane vesicles interaction with keratinocytes reveals their potential as carriers

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Broccoli root vesicles showed stability and high entrapment efficiency.

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Nanoencapsulation with membrane vesicles provide an efficient system for keratinocytes cell delivery.

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Effectivity is probed by penetrating in skin layers.

During the last few years, membrane vesicles (as exovesicles) have emerged as potential nanocarriers for therapeutic applications. They are receiving attention due to their proteo-lipid nature, size, biocompatibility and biodegradability. In this work, we investigated the potential use of isolated root plasma membrane vesicles from broccoli plants as nanocarriers. For that, the entrapment efficiency and integrity of the vesicles were determined. Also, the delivery of keratinocytes and penetrability through skin were studied. The results show that the broccoli vesicles had high stability, in relation to their proteins, and high entrapment efficiency. Also, the interaction between the vesicles and keratinocytes was proven by the delivery of an encapsulated fluorescent product into cells and by the detection of plant proteins in the keratinocyte plasma membrane, showing the interactions between the membranes of two species of distinct biological kingdoms. Therefore, these results, together with the capacity of brassica vesicles to cross the skin layers, detected by fluorescent penetration, enable us to propose a type of nanocarrier obtained from natural plant membranes for use in transdermal delivery.

Potential inhibitors of the enzyme acetylcholinesterase and juvenile hormone with insecticidal activity: study of the binding mode via docking and molecular dynamics simulations

Models validation in QSAR, pharmacophore, docking and others can ensure the accuracy and reliability of future predictions in design and selection of molecules with biological activity. In this study, pyriproxyfen was used as a pivot/template to search the database of the Maybridge Database for potential inhibitors of the enzymes acetylcholinesterase and juvenile hormone as well. The initial virtual screening based on the 3D shape resulted in 2000 molecules with Tanimoto index ranging from 0.58 to 0.88. A new reclassification was performed on the overlapping of positive and negative charges, which resulted in 100 molecules with Tanimoto's electrostatic score ranging from 0.627 to 0.87. Using parameters related to absorption, distribution, metabolism and excretion and the pivot molecule, the molecules selected in the previous stage were evaluated regarding these criteria, and 21 were then selected. The pharmacokinetic and toxicological properties were considered and for 12 molecules, the DEREK software not fired any alert of toxicity, which were thus considered satisfactory for prediction of biological activity using the Web server PASS. In the molecular docking with insect acetylcholinesterase, the Maybridge3_002654 molecule had binding affinity of -11.1 kcal/mol, whereas in human acetylcholinesterase, the Maybridge4_001571molecule show in silico affinity of -10.2 kcal/mol, and in the juvenile hormone, the molecule MCULE-8839595892 show in silico affinity value of -11.6 kcal/mol. Subsequent long-trajectory molecular dynamics studies indicated considerable stability of the novel molecules compared to the controls.AbbreviationsQSARquantitative structure-activity relationshipsPASSprediction of activity spectra for substancesCommunicated by Ramaswamy H. Sarma.

Anxiolytic effects of Formononetin in an inflammatory pain mouse model

Chronic pain is commonly accompanied with anxiety disorder, which complicates treatment. In this study, we investigated the analgesic and anxiolytic effects of Formononetin (FMNT), an active component of traditional Chinese medicine red clover (Trifolium pratense L.) that is capable of protecting neurons from N-methyl-D-aspartate (NMDA)-evoked excitotoxic injury, on mice suffering from complete Freund’s adjuvant (CFA)-induced chronic inflammatory pain. The results show that FMNT administration significantly reduces anxiety-like behavior but does not affect the nociceptive threshold in CFA-injected mice. The treatment reverses the upregulation of NMDA, GluA1, and GABA_A receptors, as well as PSD95 and CREB in the basolateral amygdala (BLA). The effects of FMNT on NMDA receptors and CREB binding protein (CBP) were further confirmed by the potential structure combination between these compounds, which was analyzed by in silico docking technology. FMNT also inhibits the activation of the NF-κB signaling pathway and microglia in the BLA of mice suffering from chronic inflammatory pain. Therefore, the anxiolytic effects of FMNT are partially due to the attenuation of inflammation and neuronal hyperexcitability through the inhibition of NMDA receptor and CBP in the BLA.

The use of biovesicles to improve the efficiency of Zn foliar fertilization

Foliar fertilization is becoming very popular since it is highly efficient, minimizes contamination, and is target oriented. However, the low mobility of several nutrients and low penetration through the leaf cuticle should be addressed, to establish an efficient leaf applied fertilizer. During the last few years, nanotechnologies - such as nanocarriers - have been studied with regard to improving the penetration and delivery of compounds. This work describes the use of membrane vesicles obtained from Brassica oleracea L. as nanobiocarriers of Zn and the evaluation of their potential as a foliar fertilizer, also in Brassica. The results show a high Zn encapsulation efficiency and high delivery into protoplasts. Also, the foliar fertilization experiments demonstrated a very effective system of Zn nanofertilization.

The Expanding Role of Vesicles Containing Aquaporins

In animals and plants, membrane vesicles containing proteins have been defined as key for biological systems involving different processes such as trafficking or intercellular communication. Docking and fusion of vesicles to the plasma membrane occur in living cells in response to different stimuli, such as environmental changes or hormones, and therefore play an important role in cell homeostasis as vehicles for certain proteins or other substances. Because aquaporins enhance the water permeability of membranes, their role as proteins immersed in vesicles formed of natural membranes is a recent topic of study. They regulate numerous physiological processes and could hence serve new biotechnological purposes. Thus, in this review, we have explored the physiological implications of the trafficking of aquaporins, the mechanisms that control their transit, and the proteins that coregulate the migration. In addition, the importance of exosomes containing aquaporins in the cell-to-cell communication processes in animals and plants have been analyzed, together with their potential uses in biomedicine or biotechnology. The properties of aquaporins make them suitable for use as biomarkers of different aquaporin-related diseases when they are included in exosomes. Finally, the fact that these proteins could be immersed in biomimetic membranes opens future perspectives for new biotechnological applications.

Identification of chemically diverse GABAA agonists as potential anti-epileptic agents using structure-guided virtual screening, ADMET, quantum mechanics and clinical validation through off-target analysis

Development of resistance against existing anti-epileptic drugs has alarmed the scientific innovators to find novel potential chemical starting points for the treatment of epilepsy and GABA_A inhibition is a promising drug target strategy against epilepsy. The crystal structure of a subtype-selective β3-homopentameric ligand-gated ion channel of GABA_A receptor has been used for the first time for screening the Asinex library for discovery of GABA_A agonists as potential anti-epileptic agents. Co-crystallized ligand established the involvement of part of the β7-β8 loop (Glu155 and Tyr157) and β9-β10 loop (Phe200 and Tyr205) residues as the crucial amino acids in effective binding, an essential feature, being hydrogen bond or ionic interaction with Glu155 residue. Top ranked hits were further subjected to binding energy estimation, ADMET analysis and ligand efficiency matric calculations as consecutive filters. About 19 compounds qualifying all parameters possessed interaction of one positively charged group with Glu155 with good CNS drug-like properties. Simulation studies were performed on the apo protein, its complex with co-crystallized ligand and the best hit qualifying all screening parameters. The best hit was also analyzed using Quantum mechanical studies, off-target analysis and hit modification. The off-target analysis emphasized that these agents did not have any other predicted side-effects.

The current limits in virtual screening and property prediction

Beyond finding inhibitors that show high binding affinity to the respective target, there is the challenge of optimizing their properties with respect to metabolic and toxicological issues, as well as further off-target effects. To reduce the experimental effort of synthesizing and testing actual substances in corresponding assays, virtual screening has become an indispensable toolbox in preclinical development. The scope of application covers the prediction of molecular properties including solubility, metabolic liability and binding to antitargets, such as the hERG channel. Furthermore, prediction of binding sites and drugable targets are emerging aspects of virtual screening. Issues involved with the currently applied computational models including machine learning algorithms are outlined, such as limitations to the accuracy of prediction and overfitting.

Plasma membrane aquaporins mediates vesicle stability in broccoli

The use of in vitro membrane vesicles is attractive because of possible applications in therapies. Here we aimed to compare the stability and functionality of plasma membrane vesicles extracted from control and salt-treated broccoli. The impact of the amount of aquaporins was related to plasma membrane osmotic water permeability and the stability of protein secondary structure. Here, we describe for first time an increase in plant aquaporins acetylation under high salinity. Higher osmotic water permeability in NaCl vesicles has been related to higher acetylation, upregulation of aquaporins, and a more stable environment to thermal denaturation. Based on our findings, we propose that aquaporins play an important role in vesicle stability.

Environment sensitive fluorescent analogue of biologically active oxazoles differentially recognizes human serum albumin and bovine serum albumin: Photophysical and molecular modeling studies

An environment sensitive fluorophore, 4-(5-(4-(dimethylamino)phenyl)oxazol-2-yl)benzoic acid (DMOBA), that closely mimics biologically active 2,5-disubstituited oxazoles has been designed to probe two homologous serum proteins, human serum albumin (HSA) and bovine serum albumin (BSA) by means of photophysical and molecular modeling studies. This fluorescent analogue exhibits solvent polarity sensitive fluorescence due to an intramolecular charge transfer in the excited state. In comparison to water, the steady state emission spectra of DMOBA in BSA is characterized by a greater blue shift (~10nm) and smaller Stokes' shift (~5980cm^-1) in BSA than HSA (Stokes'shift~6600cm^-1), indicating less polar and more hydrophobic environment of the dye in the former than the latter. The dye-protein binding interactions are remarkably stronger for BSA than HSA which is evident from higher value of the association constant for the DMOBA-BSA complex (K_a~5.2×10⁶M^-1) than the DMOBA-HSA complex (K_a~1.0×10⁶M^-1). Fӧrster resonance energy transfer studies revealed remarkably less efficient energy transfer (8%) between the donor tryptophans in BSA and the acceptor DMOBA dye than that (30%) between the single tryptophan moiety in HSA and the dye, which is consistent with a much larger distance between the donor (tryptophan)-acceptor (dye) pair in BSA (34.5Å) than HSA (25.4Å). Site specific competitive binding assays have confirmed on the location of the dye in Sudlow's site II of BSA and in Sudlow's site I of HSA, respectively. Molecular modeling studies have shown that the fluorescent analogue is tightly packed in the binding site of BSA due to strong steric complementarity, where, binding of DMOBA to BSA is primarily dictated by the van der Waals and hydrogen bonding interactions. In contrast, in HSA the steric complementarity is less significant and binding is primarily guided by polar interactions and van der Waals interactions appear to be less significant in the formation of the HSA-DMOBA complex. Electrostatic interactions contribute significantly in the binding of DMOBA to HSA (-2.09kcal/mol) compared to BSA (-0.47kcal/mol). Electrostatic surface potential calculation reveals that the DMOBA binding site within HSA is highly charged compared to BSA.

Mutual Interactions between Aquaporins and Membrane Components

In recent years, a number of studies have been focused on the structural evaluation of protein complexes in order to get mechanistic insights into how proteins communicate at the molecular level within the cell. Specific sites of protein-aquaporin interaction have been evaluated and new forms of regulation of aquaporins described, based on these associations. Heterotetramerizations of aquaporin isoforms are considered as novel regulatory mechanisms for plasma membrane (PIPs) and tonoplast (TIPs) proteins, influencing their intrinsic permeability and trafficking dynamics in the adaptive response to changing environmental conditions. However, protein-protein interaction is an extensive theme that is difficult to tackle and new methodologies are being used to study the physical interactions involved. Bimolecular fluorescence complementation and the identification of cross-linked peptides based on tandem mass spectra, that are complementary to other methodologies such as heterologous expression, co-precipitation assays or confocal fluorescence microscopy, are discussed in this review. The chemical composition and the physical characteristics of the lipid bilayer also influence many aspects of membrane aquaporins, including their functionality. The molecular driving forces stabilizing the positions of the lipids around aquaporins could define their activity, thereby altering the conformational properties. Therefore, an integrative approach to the relevance of the membrane-aquaporin interaction to different processes related to plant cell physiology is provided. Finally, it is described how the interactions between aquaporins and copolymer matrixes or biological compounds offer an opportunity for the functional incorporation of aquaporins into new biotechnological advances.