Insights into the properties of the two enantiomers of trans-δ-viniferin, a resveratrol derivative: antioxidant activity, biochemical and molecular modeling studies of its interactions with hemoglobin

"Novel chemo-enzymatic synthesis, structural elucidation and first antiprotozoal activity profiling of the atropoisomeric dimers of trans-8-Hydroxycalamenene"

Leishmaniasis and malaria are two debilitating protozoan diseases affecting millions globally, particularly in tropical and subtropical regions. Current therapeutic options face significant challenges due to emerging drug-resistant strains, necessitating the discovery of novel antiprotozoal agents. This study explores, for the first time, the antiprotozoal potential of calamenenes and their dimers, naturally occurring sesquiterpenes found in essential oils, through a novel chemo-enzymatic synthesis approach. Using the laccase from Trametes versicolor, atropoisomeric dimers of (-)- and (+)-8-trans-hydroxycalamenene were synthesized from commercially available (-)- and (+)-menthol. Structural elucidation was achieved via 2D-NMR spectroscopy, electronic circular dichroism, and DFT calculations. In vitro profiling against Leishmania spp and drug-resistant Plasmodium falciparum revealed that calamenene dimers exhibited significantly higher antiprotozoal activity compared to their monomeric counterparts, highlighting the potential of dimeric terpenoids as promising antiprotozoal agents. This work lays the foundation for developing novel antimalarial drugs based on calamenene scaffolds, encouraging further interactome studies to optimize their pharmacological properties.

Medicinal herbal remedies in neurodegenerative diseases: an update on antioxidant potential

It has been widely documented that medicinal herbal remedies are effective, have fewer side effects than conventional medicine, and have a synergistic effect on health collaborations in the fight against complicated diseases. Traditional treatments for neurological problems in ancient times sometimes involved the use of herbal remedies and conventional methods from East Asian countries including India, Japan, China, and Korea. We collected and reviewed studies on plant-derived neuroprotective drugs and tested them in neurotoxic models. Basic research, preclinical and clinical transgene research can benefit from in silico, in vitro, and in vivo investigations. Research, summaries of the extracts, fractions, and herbal ingredients were compiled from popular scientific databases, which were then examined according to origin and bioactivity. Given the complex and varied causes of neurodegeneration, it may be beneficial to focus on multiple mechanisms of action and a neuroprotection approach. This approach aims to prevent cell death and restore function to damaged neurons, offering promising strategies for preventing and treating neurodegenerative diseases. Neurodegenerative illnesses can potentially be treated with natural compounds that have been identified as neuroprotective agents. To gain deeper insights into the neuropharmacological mechanisms underlying the neuroprotective and therapeutic properties of naturally occurring antioxidant phytochemical compounds in diverse neurodegenerative diseases, this study aims to comprehensively review such compounds, focusing on their modulation of apoptotic markers such as caspase, Bax, Bcl-2, and proinflammatory markers. In addition, we delve into a range of efficacies of antioxidant phytochemical compounds as neuroprotective agents in animal models. They reduce the oxidative stress of the brain and have been shown to have anti-apoptotic effects. Many researches have demonstrated that plant extracts or bioactive compounds can fight neurodegenerative disorders. Herbal medications may offer neurodegenerative disease patients' new treatments. This may be a cheaper and more culturally appropriate alternative to standard drugs for millions of people with age-related NDDs.

Studies on the Oxidation of Aromatic Amines Catalyzed by Trametes versicolor Laccase

The bio-oxidation of a series of aromatic amines catalyzed by T. versicolor laccase has been investigated exploiting either commercially available nitrogenous substrates [(E)-4-vinyl aniline and diphenyl amine] or ad hoc synthetized ones [(E)-4-styrylaniline, (E)-4-(prop-1-en-1-yl)aniline and (E)-4-(((4-methoxyphenyl)imino)methyl)phenol]. At variance to their phenolic equivalents, the investigated aromatic amines were not converted into the expected cyclic dimeric structures under T. versicolor catalysis. The formation of complex oligomeric/polymeric or decomposition by-products was mainly observed, with the exception of the isolation of two interesting but unexpected chemical skeletons. Specifically, the biooxidation of diphenylamine resulted in an oxygenated quinone-like product, while, to our surprise, in the presence of T. versicolor laccase (E)-4-vinyl aniline was converted into a 1,2-substited cyclobutane ring. To the best of our knowledge, this is the first example of an enzymatically triggered [2 + 2] olefin cycloaddition. Possible reaction mechanisms to explain the formation of these products are also reported.

Scavengome of an antioxidant

The term "scavengome" refers to the chemical space of all the metabolites that may be formed from an antioxidant upon scavenging reactive oxygen or nitrogen species (ROS/RNS). This chemical space covers a wide variety of free radical metabolites with drug discovery potential. It is very rich in structures representing an increased chemical complexity as compared to the parent antioxidant: a wide range of unusual heterocyclic structures, new CC bonds, etc. may be formed. Further, in a biological environment, this increased chemical complexity is directly translated from the localized conditions of oxidative stress that determines the amounts and types of ROS/RNS present. Biomimetic oxidative chemistry provides an excellent tool to model chemical reactions between antioxidants and ROS/RNS. In this chapter, we provide an overview on the known metabolites obtained by biomimetic oxidation of a few selected natural antioxidants, i.e., a stilbene (resveratrol), a pair of hydroxycinnamates (caffeic acid and methyl caffeate), and a flavonol (quercetin), and discuss the drug discovery perspectives of the related chemical space.

Chiroptical and potential in vitro anti-inflammatory properties of viniferin stereoisomers from grapevine (Vitis vinifera L.)

Determination of stereochemistry and enantiomeric excess in chiral natural molecules is a research of great interest because enantiomers can exhibit different biological activities. Viniferin stilbene dimers are natural molecules present in grape berries and wine but also, in larger amount, in stalks of grapevine. Four stereoisomers of viniferin stilbene dimers (7aS,8aS)-E-ε-viniferin (1a), (7aR,8aR)-E-ε-viniferin (1b), (7aS,8aR)-E-ω-viniferin (2a), and (7aR,8aS)-E-ω-viniferin (2b) were isolated from grapevine stalks of Cabernet Sauvignon, Merlot and Sauvignon Blanc, using a combination of centrifugal partition chromatography (CPC), preparative and chiral HPLC. The structure elucidation of these molecules was achieved by NMR whereas the absolute configurations of the four stereoisomers were investigated by vibrational circular dichroism spectroscopy in combination with density functional theory (DFT) calculations. This study unambiguously established the (+)-(7aS,8aS) and (+)-(7aR,8aS) configurations for E-ε-viniferin and E-ω-viniferin, respectively. Finally, we show that Cabernet Sauvignon provided the quasi enantiopure (+)-(7aS,8aS)-E-ε-viniferin compound which presents the best anti-inflammatory and anti-oxidant activities.

Highly Efficient Bioconversion of trans-Resveratrol to δ-Viniferin Using Conditioned Medium of Grapevine Callus Suspension Cultures

δ-Viniferin is a resveratrol dimer that possesses potent antioxidant properties and has attracted attention as an ingredient for cosmetic and nutraceutical products. Enzymatic bioconversion and plant callus and cell suspension cultures can be used to produce stilbenes such as resveratrol and viniferin. Here, δ-viniferin was produced by bioconversion from trans-resveratrol using conditioned medium (CM) of grapevine (Vitis labruscana) callus suspension cultures. The CM converted trans-resveratrol to δ-viniferin immediately after addition of hydrogen peroxide (H₂O₂). Peroxidase activity and bioconversion efficiency in CM increased with increasing culture time. Optimized δ-viniferin production conditions were determined regarding H₂O₂ concentration, incubation time, temperature, and pH. Maximum bioconversion efficiency reached 64% under the optimized conditions (pH 6.0, 60 °C, 30 min incubation time, 6.8 mM H₂O₂). In addition, in vitro bioconversion of trans-resveratrol was investigated using CM of different callus suspension cultures, showing that addition of trans-resveratrol and H₂O₂ to the CM led to production of δ-viniferin via extracellular peroxidase-mediated oxidative coupling of two molecules of trans-resveratrol. We thus propose a simple and low-cost method of δ-viniferin production from trans-resveratrol using CM of plant callus suspension cultures, which may constitute an alternative approach for in vitro bioconversion of valuable molecules.

Implication of COVID-19 on Erythrocytes Functionality: Red Blood Cell Biochemical Implications and Morpho-Functional Aspects

Several diseases (such as diabetes, cancer, and neurodegenerative disorders) affect the morpho-functional aspects of red blood cells, sometimes altering their normal metabolism. In this review, the hematological changes are evaluated, with particular focus on the morphology and metabolic aspects of erythrocytes. Changes in the functionality of such cells may, in fact, help provide important information about disease severity and progression. The viral infection causes significant damage to the blood cells that are altered in size, rigidity, and distribution width. Lower levels of hemoglobin and anemia have been reported in several studies, and an alteration in the concentration of antioxidant enzymes has been shown to promote a dangerous state of oxidative stress in red blood cells. Patients with severe COVID-19 showed an increase in hematological changes, indicating a progressive worsening as COVID-19 severity progressed. Therefore, monitored hematological alterations in patients with COVID-19 may play an important role in the management of the disease and prevent the risk of a severe course of the disease. Finally, monitored changes in erythrocytes and blood, in general, may be one of the causes of the condition known as Long COVID.

Colorectal Adenocarcinoma Cell Culture in a Microfluidically Controlled Environment with a Static Molecular Gradient of Polyphenol

To study the simultaneous effect of the molecular gradient of polyphenols (curcumin, trans-resveratrol, and wogonin) and biological factors released from tumor cells on apoptosis of adjacent cells, a novel microfluidic system was designed and manufactured. The small height/volume of microfluidic culture chambers and static conditions allowed for establishing the local microenvironment and maintaining undisturbed concentration profiles of naturally secreted from cells biochemical factors. In all trials, we observe that these conditions significantly affect cell viability by stimulating cell apoptosis at lower concentrations of polyphenols than in traditional multiwell cultures. The observed difference varied between 20.4-87.8% for curcumin, 11.0-37.5% for resveratrol, and 21.7-62.2% for wogonin. At low concentrations of polyphenols, the proapoptotic substances released from adjacent cells, like protein degradation products, significantly influence cell viability. The mean increase in cell mortality was 38.3% for microfluidic cultures. Our research has also confirmed that the gradient microsystem is useful in routine laboratory tests in the same way as a multiwell plate and may be treated as its replacement in the future. We elaborated the new repetitive procedures for cell culture and tests in static gradient conditions, which may become a gold standard of new drug investigations in the future.

Overexpression of VlPRX21 and VlPRX35 genes in Arabidopsis plants leads to bioconversion of trans-resveratrol to δ-viniferin

Stilbenes, including resveratrol and viniferins, a small family of polyphenols, are considered the most important phytoalexin group in Vitis species. In a previous study, we found that co-treatment of methyl jasmonate (MJ) and stevioside (STE) resulted in enhanced extracellular production of viniferins in grapevine cell suspension cultures. Thus, to further understand the mechanisms of viniferin production in grapevine cell cultures, we performed transcriptome analysis and isolated seven candidates of grapevine peroxidase genes (VlAPX6, VlGPX5, VlPRX13, VlPRX21, VlPRX35, VlPRX40, and VlPRX50). Bioconversion of trans-resveratrol to δ-viniferin was examined using crude protein extracts isolated from agroinfiltration-based transient expression of VlPRXs in Nicotiana benthamiana. In addition, we found that crude protein extracts from VlPRX21-, VlPRX35-, and VlPRX40-overexpressing (OX) transgenic Arabidopsis plants led to the conversion of trans-resveratrol to δ-viniferin. We found that in vitro experiments with crude protein extracts from VlPRX21-OX and VlPRX35-OX Arabidopsis plants catalyzed the dimerization of trans-resveratrol to δ-viniferin. Our results suggest that VlPRX21 and VlPRX35 encode functional grapevine class III peroxidases and catalyze the oxidative dimerization of trans-resveratrol to form δ-viniferin in grapevine.

Biocatalysis with Laccases: An Updated Overview

Laccases are multicopper oxidases, which have been widely investigated in recent decades thanks to their ability to oxidize organic substrates to the corresponding radicals while producing water at the expense of molecular oxygen. Besides their successful (bio)technological applications, for example, in textile, petrochemical, and detoxifications/bioremediations industrial processes, their synthetic potentialities for the mild and green preparation or selective modification of fine chemicals are of outstanding value in biocatalyzed organic synthesis. Accordingly, this review is focused on reporting and rationalizing some of the most recent and interesting synthetic exploitations of laccases. Applications of the so-called laccase-mediator system (LMS) for alcohol oxidation are discussed with a focus on carbohydrate chemistry and natural products modification as well as on bio- and chemo-integrated processes. The laccase-catalyzed Csp2-H bonds activation via monoelectronic oxidation is also discussed by reporting examples of enzymatic C-C and C-O radical homo- and hetero-couplings, as well as of aromatic nucleophilic substitutions of hydroquinones or quinoids. Finally, the laccase-initiated domino/cascade synthesis of valuable aromatic (hetero)cycles, elegant strategies widely documented in the literature across more than three decades, is also presented.

Structure-based virtual screening to identify novel carnitine acetyltransferase activators

Carnitine acetyltransferase (CAT) is an attractive therapeutic target against fibrosis. We have identified few CAT activators through structure-based virtual screening followed by molecular dynamics simulations for assessment of the binding mode. A set of 10,000 drug-like molecules properly filtered from an initial chemical library of 13 M commercially available compounds were docked into the active site. Virtual hits were selected for in vitro experimental testing to validate the computational findings and the stability of the predicted complexes was evaluated by molecular dynamics simulations. Applied protocol led to the identification of three hit compounds showing promising activity, which can serve as potential scaffolds for further structural optimization. This is the first report of successful discovery of CAT activators through the use of structure-based virtual screening.

Resveratrol mitigates hypercholesterolemia exacerbated hyperthermia in chronically heat-stressed rats

BACKGROUND AND AIM

Hypercholesterolemia (HC) is the major leading cause of cardiovascular disease worldwide. Such atherogenic aberration deeply impacts blood circulation. Resveratrol (R) is a polyphenol that has received attention as a hypolipidemic, antioxidant, and vascular agility advocate. Efficient blood redistribution is a key element in mammalian thermoregulation. We hypothesized that R treatment may aid in mitigating hyperthermic responses under both acute and chronic heat stress (HS) conditions in HC male rats.

MATERIALS AND METHODS

All rats were initially fitted with miniaturized thermologgers to measure core body temperature (T_core). With a 2 × 2 factorial arrangement, four groups were randomly allotted, in which half of the animals ingested an HC diet (C+), while the other half ingested a control (C-) diet, throughout the whole study duration of 35 days. Seven rats from each dietary treatment, however, received R (R+; 13 mg/kg BW/day), while the rest received normal saline (R-) for 5 continuous days. All animals were maintained at thermoneutrality (TN; ambient temperature; T_a=23.15±0.04°C) for a period of 30 continuous days (days 0-29). On day 29, an acute HS (HS; T_a=35.86±0.37°C; for 9 nocturnal h) was imposed. Then, from day 29, a chronic HS protocol (T_a=32.28±1.00°C) was maintained until the past day of the trial (day 34), after which blood samples were drawn for analyses of platelet (PL) count, total antioxidant activity (TAO), total cholesterol (TC), triglycerides (TGs), and lipid peroxidation (LP).

RESULTS

Switching animals from TN to HS resulted in abrupt rises in T_core. The HC diet induced a significant (p<0.01) hyperlipidemia over the control of diet-consuming rats. Interestingly, the hyperthermic response to acute HS was highly pronounced in the rats consuming the C- diet, while the C+ diet exacerbated the chronic HS-induced hyperthermia. Despite failure to improve TAO in the C+ diet, R+ treatment caused a marked (p<0.05) decline in nighttime - hyperthermia in C+ rats, likely by enhancing blood flow to extremities (for heat dissipation) as delineated by drastic downregulations of C+ related rises in PL, TC, TG, and LP (HC diet by R+ interaction; p<0.03).

CONCLUSION

The hyperthermic response in C- groups was attributed to higher amount of feed intake than those consuming the C+ diet. Yet, the R+ improvement of thermoregulation in the C+ group was likely related to enhancement of vascular hemodynamics. Resveratrol intake mitigated chronic HS-evoked hyperthermia in rats. Such an approach is worthy to follow-up in other mammals and humans.

Chemo-enzymatic synthesis of (E)-2,3-diaryl-5-styryl-trans-2,3-dihydrobenzofuran-based scaffolds and their in vitro and in silico evaluation as a novel sub-family of potential allosteric modulators of the 90 kDa heat shock protein (Hsp90)

Herein we propose a facile, versatile and selective chemo-enzymatic synthesis of substituted (E)-2,3-diaryl-5-styryl-trans-2,3-dihydrobenzofurans based on the exploitation of the laccase-mediated oxidative (homo)coupling of (E)-4-styrylphenols. Thanks to this novel synthetic strategy, a library of benzofuran-based potential allosteric activators of the Heat shock protein 90 (Hsp90) was easily prepared. Moreover, considering their structural analogies to previously reported allosteric modulators, the sixteen new compounds synthesized in this work were tested in vitro for their potential stimulatory action on the ATPase activity of the molecular chaperone Hsp90. Combining experimental and computational results, we propose a mechanism of action for these compounds, and expand the structure-activity relationship (SAR) information available for benzofuran-based Hsp90 activators.

Strategic Syntheses of Vine and Wine Resveratrol Derivatives to Explore their Effects on Cell Functions and Dysfunctions

Trans-resveratrol, the most well-known polyphenolic stilbenoid, is found in grapes and accordingly in wine and it is considered to be beneficial for human health, especially towards the aging-linked cell alterations by providing numerous biological activities, such as anti-oxidant, antitumoral, antiviral, anti-inflammatory, neuroprotective, and platelet anti-aggregation properties. Although trans-resveratrol is a promising molecule, it cannot be considered as a drug, due to its weak bio-availability and fast metabolism. To overcome these weaknesses, several research teams have undertaken the synthesis of innovative trans-resveratrol derivatives, with the aim to increase its solubility in water and pharmacological activities towards cell targets. The aim of this review is to show the chronological evolution over the last 25 years of different strategies to develop more efficient trans-resveratrol derivatives towards organism physiology and, therefore, to enhance various pharmacological activities. While the literature on the development of new synthetic derivatives is impressive, this review will focus on selected strategies regarding the substitution of trans-resveratrol phenyl rings, first with hydroxy, methoxy, and halogen groups, and next with functionalized substituents. The effects on cell functions and dysfunctions of interesting resveratrol analogs will be addressed in this review.

Preliminary Study on the In vitro and In vivo Effects of Asparagopsis taxiformis Bioactive Phycoderivates on Teleosts

Several compounds from marine organisms have been studied for their potential use in aquaculture. Among the red algae, Asparagopsis taxiformis is considered one of the most promising species for the production of bioactive metabolites with numerous proposed applications. Here, the in vitro antibacterial activity, the easy handling and the absence of adverse effects on marine fish species are reported. Depending on the seasonal period of sampling, ethanol extracts of A. taxiformis exhibited significantly different inhibitory activity against fish pathogenic bacteria. The extract obtained in late spring showed strong antibacterial activity against Aeromonas salmonicida subsp. salmonicida, Vibrio alginolyticus, and V. vulnificus, and moderate activity against Photobacterium damselae subsp. damselae, P. damselae subsp. piscicida, V. harveyi and V. parahaemolyticus. Sea bass and gilthead sea bream were fed with pellets supplied with the alga and algal extracts. The absence of undesired effects on fish was demonstrated. Hematological and biochemical investigations allowed to confirm that the whole alga and its extracts could be proposed for a future application in aquaculture.