Pomegranate peel extract polyphenols attenuate the SARS-CoV-2 S-glycoprotein binding ability to ACE2 Receptor: In silico and in vitro studies

Phytomedical compounds as promising therapeutic agents for COVID-19 targeting angiotensin-converting enzyme 2: a review

AIMS

The aim of the present review was to highlight natural product investigations in silico and in vitro to find plants and chemicals that inhibit or stimulate angiotensin-converting enzyme 2 (ACE-2).

BACKGROUND

The global reduction of incidents and fatalities attributable to infections with SARS-CoV-2 is one of the most public health problems. In the absence of specific therapy for coronavirus disease 2019 (COVID-19), phytocompounds generated from plant extracts may be a promising strategy worth further investigation, motivating researchers to evaluate the safety and anti-SARS-CoV-2 effectiveness of these ingredients.

OBJECTIVE

To review phytochemicals in silico for anti-SARS-CoV-2 activity and to assess their safety and effectiveness in vitro and in vivo.

METHODS

The present review was conducted using various scientific databases and studies on anti-SARS-CoV-2 phytochemicals were analyzed and summarized. The results obtained from the in silico screening were subjected to extraction, isolation, and purification. The in vitro studies on anti-SarcoV-2 were also included in this review. In addition, the results of this research were interpreted, analyzed, and documented on the basis of the bibliographic information obtained.

RESULTS

This review discusses recent research on using natural remedies to cure or prevent COVID-19 infection. The literature analysis shows that the various herbal preparations (extracts) and purified compounds can block the replication or entrance of the virus directly to carry out their anti-SARS-CoV-2 effects. It is interesting to note that certain items can prevent SARS-CoV-2 from infecting human cells by blocking the ACE-2 receptor or the serine protease TMPRRS2. Moreover, natural substances have been demonstrated to block proteins involved in the SARS-CoV-2 life cycle, such as papain- or chymotrypsin-like proteases.

CONCLUSION

The natural products may have the potential for use singly or in combination as alternative drugs to treat/prevent COVID-19 infection, including blocking or stimulating ACE-2. In addition, their structures may provide indications for the development of anti-SARS-CoV-2 drugs.

Therapeutic Potential of Pomegranate Extract for Women's Reproductive Health and Breast Cancer

Pomegranate extract has potential benefits for women's reproductive health, including fertility enhancement, menstrual cycle regulation, pregnancy support, and polycystic ovary syndrome (PCOS) treatment. It possesses antioxidant properties, reducing oxidative stress and improving fertility. Pomegranate extract may help regulate hormonal imbalances and promote regular menstrual cycles. The extract's rich nutrient profile supports placental development and fetal growth and may reduce the risk of preterm birth. Additionally, pomegranate extract shows promise in improving insulin sensitivity and reducing inflammation and oxidative damage in PCOS. Some studies suggest its potential anticancer properties, particularly against breast cancer. However, further research, including human clinical trials, is necessary to establish its effectiveness and safety. The current evidence is limited and primarily based on in vitro studies, animal studies, and clinical trials. This review provides a comprehensive summary of the benefits of pomegranate extract for women's reproductive health and breast cancer, serving as a reference for future research.

Long COVID as a disease of accelerated biological aging: An opportunity to translate geroscience interventions

It has been four years since long COVID-the protracted consequences that survivors of COVID-19 face-was first described. Yet, this entity continues to devastate the quality of life of an increasing number of COVID-19 survivors without any approved therapy and a paucity of clinical trials addressing its biological root causes. Notably, many of the symptoms of long COVID are typically seen with advancing age. Leveraging this similarity, we posit that Geroscience-which aims to target the biological drivers of aging to prevent age-associated conditions as a group-could offer promising therapeutic avenues for long COVID. Bearing this in mind, this review presents a translational framework for studying long COVID as a state of effectively accelerated biological aging, identifying research gaps and offering recommendations for future preclinical and clinical studies.

A Repurposed Drug Interferes with Nucleic Acid to Inhibit the Dual Activities of Coronavirus Nsp13

The recent pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) highlighted a critical need to discover more effective antivirals. While therapeutics for SARS-CoV-2 exist, its nonstructural protein 13 (Nsp13) remains a clinically untapped target. Nsp13 is a helicase responsible for unwinding double-stranded RNA during viral replication and is essential for propagation. Like other helicases, Nsp13 has two active sites: a nucleotide binding site that hydrolyzes nucleoside triphosphates (NTPs) and a nucleic acid binding channel that unwinds double-stranded RNA or DNA. Targeting viral helicases with small molecules, as well as the identification of ligand binding pockets, have been ongoing challenges, partly due to the flexible nature of these proteins. Here, we use a virtual screen to identify ligands of Nsp13 from a collection of clinically used drugs. We find that a known ion channel inhibitor, IOWH-032, inhibits the dual ATPase and helicase activities of SARS-CoV-2 Nsp13 at low micromolar concentrations. Kinetic and binding assays, along with computational and mutational analyses, indicate that IOWH-032 interacts with the RNA binding interface, leading to displacement of nucleic acid substrate, but not bound ATP. Evaluation of IOWH-032 with microbial helicases from other superfamilies reveals that it is selective for coronavirus Nsp13. Furthermore, it remains active against mutants representative of observed SARS-CoV-2 variants. Overall, this work provides a new inhibitor for Nsp13 and provides a rationale for a recent observation that IOWH-032 lowers SARS-CoV-2 viral loads in human cells, setting the stage for the discovery of other potent viral helicase modulators.

Cistus incanus: a natural source of antimicrobial metabolites

The discovery of natural molecules with antimicrobial properties has become an urgent need for the global treatment of bacterium and virus infections. Cistus incanus, a Mediterranean shrub species, represents a valuable source of phytochemicals with an interesting wide-spectrum antimicrobial potential. In this study, we analysed the spectrum of molecules composing a commercial hydroalcoholic extract of C. incanus finding ellagitannins as the most abundant. The effect of the extract and its main constituents (gallic acid, ellagic acid and punicalin) was assessed as co-treatment during viral (HSV-1, HCoV-229E, SARS-CoV-2) and bacterial infection (Staphylococcus aureus and Escherichia coli) of cells and as pre-treatment before virus infections. The results indicated a remarkable antiviral activity of punicalin against SARS-CoV-2 by pre-treating both the viral and the host cells, and a major sensitivity of S. aureus to the C. incanus extract compared to E. coli. The present study highlights broad antimicrobial potential of C. incanus extract.

Plant-derived compounds as potential leads for new drug development targeting COVID-19

COVID-19, which was first identified in 2019 in Wuhan, China, is a respiratory illness caused by a virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although some patients infected with COVID-19 can remain asymptomatic, most experience a range of symptoms that can be mild to severe. Common symptoms include fever, cough, shortness of breath, fatigue, loss of taste or smell and muscle aches. In severe cases, complications can arise including pneumonia, acute respiratory distress syndrome, organ failure and even death, particularly in older adults or individuals with underlying health conditions. Treatments for COVID-19 include remdesivir, which has been authorised for emergency use in some countries, and dexamethasone, a corticosteroid used to reduce inflammation in severe cases. Biological drugs including monoclonal antibodies, such as casirivimab and imdevimab, have also been authorised for emergency use in certain situations. While these treatments have improved the outcome for many patients, there is still an urgent need for new treatments. Medicinal plants have long served as a valuable source of new drug leads and may serve as a valuable resource in the development of COVID-19 treatments due to their broad-spectrum antiviral activity. To date, various medicinal plant extracts have been studied for their cellular and molecular interactions, with some demonstrating anti-SARS-CoV-2 activity in vitro. This review explores the evaluation and potential therapeutic applications of these plants against SARS-CoV-2. This review summarises the latest evidence on the activity of different plant extracts and their isolated bioactive compounds against SARS-CoV-2, with a focus on the application of plant-derived compounds in animal models and in human studies.

Chemical Composition of Rosemary (Rosmarinus officinalis L.) Extract and Its Inhibitory Effects on SARS-CoV-2 Spike Protein-ACE2 Interaction and ACE2 Activity and Free Radical Scavenging Capacities

This study evaluated the chemical composition of rosemary water extract (RWE) and its influence on mechanisms by which the SARS-CoV-2 virus enters into cells as a potential route for reducing the risk of COVID-19 disease. Compounds in RWE were identified using UHPLC-MS/MS. The inhibitory effect of RWE was then evaluated on binding between the SARS-CoV-2 spike protein (S-protein) and ACE2 and separately on ACE2 activity/availability. Additionally, total phenolic content (TPC) and free radical scavenging capacities of RWE against HO•, ABTS•+, and DPPH• were assessed. Twenty-one compounds were tentatively identified in RWE, of which tuberonic acid hexoside was identified for the first time in rosemary. RWE dose of 33.3 mg of rosemary equivalents (RE)/mL suppressed the interaction between S-protein and ACE2 by 72.9%, while rosmarinic and caffeic acids at 3.3 μmol/mL suppressed the interaction by 36 and 55%, respectively. RWE at 5.0, 2.5, and 0.5 mg of RE/mL inhibited ACE2 activity by 99.5, 94.5, and 68.6%, respectively, while rosmarinic acid at 0.05 and 0.01 μmol/mL reduced ACE2 activity by 31 and 8%, respectively. RWE had a TPC value of 72.5 mg GAE/g. The results provide a mechanistic basis on which rosemary may reduce the risk of SARS-CoV-2 infection and the development of COVID-19.

In-vitro and computational analysis of Urolithin-A for anti-inflammatory activity on Cyclooxygenase 2 (COX-2)

Cyclooxygenase 2 (COX-2) participates in the inflammation process by converting arachidonic acid into prostaglandin G2 which increases inflammation, pain and fever. COX-2 has an active site and a heme pocket and blocking these sites stops the inflammation. Urolithin A is metabolite of ellagitannin produced from humans and animals gut microbes. In the current study, Urolithin A showed good pharmacokinetic properties. Molecular docking of the complex of Urolithin A and COX-2 revealed the ligand affinity of -7.97 kcal/mol with the ligand binding sites at TYR355, PHE518, ILE517 and GLN192 with the 4-H bonds at a distance of 2.8 Å, 2.3 Å, 2.5 Å and 1.9 Å. The RMSD plot for Urolithin A and COX-2 complex was observed to be constant throughout the duration of dynamics. A total of 3 pair of hydrogen bonds was largely observed on average of 3 simulation positions for dynamics duration of 500 ns. The MMPBSA analysis showed that active site amino acids had a binding energy of -22.0368 kJ/mol indicating that throughout the simulation the protein of target was bounded by Urolithin A. In-silico results were validated by biological assays. Urolithin A strongly revealed to exhibit anti-inflammatory effect on COX-2 with an IC50 value of 44.04 µg/mL. The anti-inflammatory capability was also depicted through reduction of protein denaturation that showed 37.6 ± 0.1 % and 43.2 ± 0.07 % reduction of protein denaturation for BSA and egg albumin respectively at 500 µg/mL. The present study, suggests Urolithin A to be an effective anti-inflammatory compound for therapeutic use.

Fruit waste: a current perspective for the sustainable production of pharmacological, nutraceutical, and bioactive resources

Fruits are crucial components of a balanced diet and a good source of natural antioxidants, that have proven efficacy in various chronic illnesses. Various kinds of waste generated from fruit industries are considered a global concern. By utilizing this fruit waste, the international goal of "zero waste" can be achieved by sustainable utilization of these waste materials as a rich source of secondary metabolites. Moreover, to overcome this waste burden, research have focused on recovering the bioactive compounds from fruit industries and obtaining a new strategy to combat certain chronic diseases. The separation of high-value substances from fruit waste, including phytochemicals, dietary fibers, and polysaccharides which can then be used as functional ingredients for long-term health benefits. Several novel extraction technologies like ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE) could provide an alternative approach for successful extraction of the valuable bioactives from the fruit waste for their utilization as nutraceuticals, therapeutics, and value-added products. Most of these waste-derived secondary metabolites comprise polyphenols, which have been reported to have anti-inflammatory, insulin resistance-treating, cardiovascular disease-maintaining, probiotics-enhancing, or even anti-microbial and anti-viral capabilities. This review summarizes the current knowledge of fruit waste by-products in pharmacological, biological, and probiotic applications and highlights several methods for identifying efficacious bioactive compounds from fruit wastes.

Pomegranate-specific natural compounds as onco-preventive and onco-therapeutic compounds: Comparison with conventional drugs acting on the same molecular mechanisms

Pomegranate, scientifically known as Punica granatum, has been a traditional medicinal remedy since ancient times. Research findings have shown that using pomegranate extracts can positively affect a variety of signaling pathways, including those involved in angiogenesis, inflammation, hyperproliferation, cellular transformation, the beginning stages of tumorigenesis, and lastly, a reduction in the final stages of metastasis and tumorigenesis. This is due to the fact that pomegranate extracts are rich in polyphenols, which are known to inhibit the activity of certain signaling pathways. In the United States, cancer is the second biggest cause of death after heart disease. The number of fatalities caused by cancer in the United States escalates yearly. Altering one's diet, getting involved in regular physical activity, and sustaining a healthy body weight are three easy steps an individual may follow to lower their cancer risk. Simply garnishing one's diet with vegetables and fruits has the potential to avert at least 20% of all cancer diagnoses and around 200,000 deaths caused by cancer each year. Vegetables, fruits, and other dietary constituents, such as minerals and phytochemicals, are currently being researched for their potential to prevent cancer. It is being done because they are safe, have minimal toxicity, possess antioxidant properties, and are universally accepted as dietary supplements. Ancient civilizations used the fruit of pomegranate (Punica granatum L.) to prevent and cure a number of diseases. The anti-tumorigenic, anti-inflammatory and anti-proliferative qualities of pomegranate have been shown in studies with the fruit, juice, extract, and oil of the pomegranate. Pomegranate has the capacity to affect several signaling pathways, which implies that it may have the potential to be employed not only as a chemopreventive agent but also as a chemotherapeutic drug. This article elaborates on some recent preclinical and clinical research which shows that pomegranate seems to have a role in the prevention and treatment of a number of cancers, including but not limited to breast, bladder, skin, prostate, colon, and lung cancer, among others.

An Overview of the Health Benefits, Extraction Methods and Improving the Properties of Pomegranate

Pomegranate (Punica granatum L.) is a polyphenol-rich edible food and medicinal plant of ancient origin, containing flavonols, anthocyanins, and tannins, with ellagitannins as the most abundant polyphenols. In the last decades, its consumption and scientific interest increased, due to its multiple beneficial effects. Pomegranate is a balausta fruit, a large berry surrounded by a thick colored peel composed of exocarp and mesocarp with edible arils inside, from which the pomegranate juice can be produced by pressing. Seeds are used to obtain the seed oil, rich in fatty acids. The non-edible part of the fruit, the peel, although generally disposed as a waste or transformed into compost or biogas, is also used to extract bioactive products. This review summarizes some recent preclinical and clinical studies on pomegranate, which highlight promising beneficial effects in several fields. Although further insight is needed on key aspects, including the limited oral bioavailability and the role of possible active metabolites, the ongoing development of suitable encapsulation and green extraction techniques enabling the valorization of waste pomegranate products point to the great potential of pomegranate and its bioactive constituents as dietary supplements or adjuvants in therapies of cardiovascular and non-cardiovascular diseases.

Pomegranate Peel Extract Attenuates Isoprenaline-Induced Takotsubo-like Myocardial Injury in Rats

Takotsubo syndrome (TTS) is an acute heart failure syndrome characterised by catecholamine-induced oxidative tissue damage. Punica granatum, a fruit-bearing tree, is known to have high polyphenolic content and has been proven to be a potent antioxidant. This study aimed to investigate the effects of pomegranate peel extract (PoPEx) pre-treatment on isoprenaline-induced takotsubo-like myocardial injury in rats. Male Wistar rats were randomised into four groups. Animals in the PoPEx(P) and PoPEx + isoprenaline group (P + I) were pre-treated for 7 days with 100 mg/kg/day of PoPEx. On the sixth and the seventh day, TTS-like syndrome was induced in rats from the isoprenaline(I) and P + I groups by administering 85 mg/kg/day of isoprenaline. PoPEx pre-treatment led to the elevation of superoxide dismutase and catalase (p < 0.05), reduced glutathione (p < 0.001) levels, decreased the thiobarbituric acid reactive substances (p < 0.001), H₂O₂, O₂^- (p < 0.05), and NO₂^- (p < 0.001), in the P + I group, when compared to the I group. In addition, a significant reduction in the levels of cardiac damage markers, as well as a reduction in the extent of cardiac damage, was found. In conclusion, PoPEx pre-treatment significantly attenuated the isoprenaline-induced myocardial damage, primarily via the preservation of endogenous antioxidant capacity in the rat model of takotsubo-like cardiomyopathy.

Chewable tablet with herbal extracts and propolis arrests Wuhan and Omicron variants of SARS-CoV-2 virus

Prevention of COVID-19 is of paramount importance for public health. Some natural extracts might have the potential to suppress COVID-19 infection. Therefore, this study aimed to design a standardised, efficient, and safe chewable tablet formulation (with propolis and three herbal extracts) for possible prevention against two variants (Wuhan B.1.36 and Omicron BA.1.1) of SARS-CoV-2 virus and other viral infections. Green tea, bilberry, dried pomegranate peel, and propolis extracts were selected for this purpose. Cytotoxicity and antiviral activity of each component, as well as the developed chewable tablet, were examined against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus using Vero E6 cells with the xCELLigence real-time cell analyser-multiple plates system. Anti-inflammatory and analgesic activities, as well as mutagenicity and anti-mutagenicity of the chewable tablet were also analysed. Compared to the control, it was observed that the chewable tablet at concentrations of 110 and 55 µg/mL had antiviral activity rates of 101% and 81%, respectively, for the Wuhan variant and 112% and 35%, respectively, for the Omicron variant. The combination of herbal extracts with propolis extract were synergically more effective (∼7-fold higher) than that of individual extract. The present work suggests that a combination of herbal extracts with propolis at suitable concentrations can effectively be used as a food supplement for the prevention of both variants of the SARS-CoV-2 virus in the oral cavity (the first entry point of the SARS-CoV-2 virus).

Anti-COVID-19 Potential of Ellagic Acid and Polyphenols of Punica granatum L

Pomegranate (Punica granatum L.) is a rich source of polyphenols, including ellagitannins and ellagic acid. The plant is used in traditional medicine, and its purified components can provide anti-inflammatory and antioxidant activity and support of host defenses during viral infection and recovery from disease. Current data show that pomegranate polyphenol extract and its ellagitannin components and metabolites exert their beneficial effects by controlling immune cell infiltration, regulating the cytokine secretion and reactive oxygen and nitrogen species production, and by modulating the activity of the NFκB pathway. In vitro, pomegranate extracts and ellagitannins interact with and inhibit the infectivity of a range of viruses, including SARS-CoV-2. In silico docking studies show that ellagitannins bind to several SARS-CoV-2 and human proteins, including a number of proteases. This warrants further exploration of polyphenol-viral and polyphenol-host interactions in in vitro and in vivo studies. Pomegranate extracts, ellagitannins and ellagic acid are promising agents to target the SARS-CoV-2 virus and to restrict the host inflammatory response to viral infections, as well as to supplement the depleted host antioxidant levels during the stage of recovery from COVID-19.

Anticancer Effect of Pomegranate Peel Polyphenols against Cervical Cancer

Polyphenols are a broad group of bioactive phytochemicals with powerful antioxidant, anti-inflammatory, immunomodulatory, and antiviral activities. Numerous studies have demonstrated that polyphenol extracts obtained from natural sources can be used for the prevention and treatment of cancer. Pomegranate peel extract is an excellent source of polyphenols, such as punicalagin, punicalin, ellagic acid, and caffeic acid, among others. These phenolic compounds have antineoplastic activity in in vitro models of cervical cancer through the regulation of cellular redox balance, induction of apoptosis, cell cycle arrest, and modulation of different signaling pathways. The current review summarizes recent data from scientific reports that address the anticancer activity of the predominant polyphenol compounds present in PPE and their different mechanisms of action in cervical cancer models.

The Synthesis of Urolithins and their Derivatives and the Modes of Antitumor Action

Urolithins are microbial metabolites derived from berries and pomegranate fruits, which display anti-inflammatory, anti-oxidative, and anti-aging activities. There are eight natural urolithins (urolithin A-E, M5, M6 and M7), which have been isolated by now. Structurally, urolithins are phenolic compounds and belong to 6H-dibenzo [b,d] pyran-6-one. They have drawn considerable attention because of their vast range of biological activities and health benefits. Recent studies also suggest that they possess anti-SARS-CoV-2 and anticancer effects. In this article, the recent advances in the synthesis of urolithins and their derivatives from 2015 to 2021 are reviewed. To improve or overcome the solubility and metabolism stability issues, the modifications of urolithins are mainly centered on the hydroxy group and lactone group, and some compounds have been found to display promising results and the potential for further study. The possible modes of antitumor action of urolithin are also discussed. Several signaling pathways, including PI3K-Akt, Wnt/β-catenin pathways, and multiple receptors (aryl hydrocarbon receptor, estrogen and androgen receptors) and enzymes (tyrosinase and lactate dehydrogenase) are involved in the antitumor activity of urolithins.

Pomegranate Pomace Extract with Antioxidant, Anticancer, Antimicrobial, and Antiviral Activity Enhances the Quality of Strawberry-Yogurt Smoothie

Valorizing the wastes of the food industry sector as additives in foods and beverages enhances human health and preserves the environment. In this study, pomegranate pomace (PP) was obtained from the company Schweppes and exposed to the production of polyphenols and fiber-enriched fractions, which were subsequently included in a strawberry-yogurt smoothie (SYS). The PP is rich in carbohydrates and fibers and has high water-absorption capacity (WAC) and oil-absorption capacity (OAC) values. The LC/MS phenolic profile of the PP extract indicated that punicalagin (199 g/L) was the main compound, followed by granatin B (60 g/L) and pedunculagin A (52 g/L). Because of the high phenolic content of PP extract, it (p ≤ 0.05) has high antioxidant activity with SC50 of 200 µg/mL, besides scavenging 95% of DPPH radicals compared to ascorbic acid (92%); consequently, it reduced lung cancer cell lines' viability to 86%, and increased caspase-3 activity. Additionally, it inhibited the growth of pathogenic bacteria and fungi i.e., L. monocytogenes, P. aeruginosa, K. pneumonia, A. niger, and C. glabrata, in the 45-160 µg/mL concentration range while killing the tested isolates with 80-290 µg/mL concentrations. These isolates were selected based on the microbial count of spoiled smoothie samples and were identified at the gene level by 16S rRNA gene sequence analysis. The interaction between Spike and ACE2 was inhibited by 75.6%. The PP extract at four levels (0.4, 0.8, 1.2, and 1.4 mg/mL) was added to strawberry-yogurt smoothie formulations. During 2 months storage at 4 °C, the pH values, vitamin C, and total sugars of all SYS decreased. However, the decreases were gradually mitigated in PP-SYS because of the high phenolic content in the PP extract compared to the control. The PP-SYS3 and PP-SYS4 scored higher in flavor, color, and texture than in other samples. In contrast, acidity, fat, and total soluble solids (TSS) increased at the end of the storage period. High fat and TSS content are observed in PP-SYS because of the high fiber content in PP. The PP extract (1.2 and 1.6 mg/mL) decreases the color differences and reduces harmful microbes in PP-SYS compared to the control. Using pomegranate pomace as a source of polyphenols and fiber in functional foods enhances SYS's physiochemical and sensory qualities.

Punica granatum Peel and Leaf Extracts as Promising Strategies for HSV-1 Treatment

Punica granatum is a rich source of bioactive compounds which exhibit various biological effects. In this study, pomegranate peel and leaf ethanolic crude extracts (PPE and PLE, respectively) were phytochemically characterized and screened for antioxidant, antimicrobial and antiviral activity. LC-PDA-ESI-MS analysis led to the identification of different compounds, including ellagitannins, flavonoids and phenolic acids. The low IC₅₀ values, obtained by DPPH and FRAP assays, showed a noticeable antioxidant effect of PPE and PLE comparable to the reference standards. Both crude extracts and their main compounds (gallic acid, ellagic acid and punicalagin) were not toxic on Vero cells and exhibited a remarkable inhibitory effect on herpes simplex type 1 (HSV-1) viral plaques formation. Specifically, PPE inhibited HSV-1 adsorption to the cell surface more than PLE. Indeed, the viral DNA accumulation, the transcription of viral genes and the expression of viral proteins were significantly affected by PPE treatment. Amongst the compounds, punicalagin, which is abundant in PPE crude extract, inhibited HSV-1 replication, reducing viral DNA and transcripts accumulation, as well as proteins of all three phases of the viral replication cascade. In contrast, no antibacterial activity was detected. In conclusion, our findings indicate that Punica granatum peel and leaf extracts, especially punicalagin, could be a promising therapeutic candidate against HSV-1.

Bioactive natural products in COVID-19 therapy

The devastating COVID-19 pandemic has caused more than six million deaths worldwide during the last 2 years. Effective therapeutic agents are greatly needed, yet promising magic bullets still do not exist. Numerous natural products (cordycepin, gallinamide A, plitidepsin, telocinobufagin, and tylophorine) have been widely studied and play a potential function in treating COVID-19. In this paper, we reviewed published studies (from May 2021 to April 2022) relating closely to bioactive natural products (isolated from medicinal plants, animals products, and marine organisms) in COVID-19 therapy in vitro to provide some essential guidance for anti-SARS-CoV-2 drug research and development.

Punicalagin as an allosteric NSP13 helicase inhibitor potently suppresses SARS-CoV-2 replication in vitro

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) helicase NSP13 plays a conserved role in the replication of coronaviruses and has been identified as an ideal target for the development of antiviral drugs against SARS-CoV-2. Here, we identify a novel NSP13 helicase inhibitor punicalagin (PUG) through high-throughput screening. Surface plasmon resonance (SPR)-based analysis and molecular docking calculation reveal that PUG directly binds NSP13 on the interface of domains 1A and 2A, with a K_D value of 21.6 nM. Further biochemical and structural analyses suggest that PUG inhibits NSP13 on ATP hydrolysis and prevents it binding to DNA substrates. Finally, the antiviral studies show that PUG effectively suppresses the SARS-CoV-2 replication in A549-ACE2 and Vero cells, with EC₅₀ values of 347 nM and 196 nM, respectively. Our work demonstrates the potential application of PUG in the treatment of coronavirus disease 2019 (COVID-19) and identifies an allosteric inhibition mechanism for future drug design targeting the viral helicases.

In Silico and In Vitro Studies of Alchemilla viridiflora Rothm-Polyphenols' Potential for Inhibition of SARS-CoV-2 Internalization

Since the outbreak of the COVID-19 pandemic, it has been obvious that virus infection poses a serious threat to human health on a global scale. Certain plants, particularly those rich in polyphenols, have been found to be effective antiviral agents. The effectiveness of Alchemilla viridiflora Rothm. (Rosaceae) methanol extract to prevent contact between virus spike (S)-glycoprotein and angiotensin-converting enzyme 2 (ACE2) and neuropilin-1 (NRP1) receptors was investigated. In vitro results revealed that the tested samples inhibited 50% of virus-receptor binding interactions in doses of 0.18 and 0.22 mg/mL for NRP1 and ACE2, respectively. Molecular docking studies revealed that the compounds from A. viridiflora ellagitannins class had a higher affinity for binding with S-glycoprotein whilst flavonoid compounds more significantly interacted with the NRP1 receptor. Quercetin 3-(6″-ferulylglucoside) and pentagalloylglucose were two compounds with the highest exhibited interfering potential for selected target receptors, with binding energies of −8.035 (S-glycoprotein) and −7.685 kcal/mol (NRP1), respectively. Furthermore, computational studies on other SARS-CoV-2 strains resulting from mutations in the original wild strain (V483A, N501Y-K417N-E484K, N501Y, N439K, L452R-T478K, K417N, G476S, F456L, E484K) revealed that virus internalization activity was maintained, but with different single compound contributions.

Multifaceted role of plant derived small molecule inhibitors on replication cycle of sars-cov-2

Introduction

Coronavirus disease 2019 (COVID-19) is an illness caused by the new coronavirus severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). It has affected public health and the economy globally. Currently approved vaccines and other drug candidates could be associated with several drawbacks which urges developing alternative therapeutic approaches.

Aim

To provide a comprehensive review of anti-SARS-CoV-2 activities of plants and their bioactive compounds.

Methods

Information was gathered from diverse bibliographic platforms such as PubMed, Google Scholar, and ClinicalTrials.gov registry.

Results

The present review highlights the potential roles of crude extracts of plants as well as plant-derived small molecules in inhibiting SARS-CoV-2 infection by targeting viral or host factors essential for viral entry, polyprotein processing, replication, assembly and release. Their anti-inflammatory and antioxidant properties as well as plant-based therapies that are under development in the clinical trial phases-1 to 3 are also covered.

Conclusion

This knowledge could further help understanding SARS-CoV-2 infection and anti-viral mechanisms of plant-based therapeutics.

Urolithins: The Colon Microbiota Metabolites as Endocrine Modulators: Prospects and Perspectives

Selective estrogen receptor modulators (SERMs) have been used in hormone related disorders, and their role in clinical medicine is evolving. Tamoxifen and raloxifen are the most commonly used synthetic SERMs, and their long-term use are known to create side effects. Hence, efforts have been directed to identify molecules which could retain the beneficial effects of estrogen, at the same time produce minimal side effects. Urolithins, the products of colon microbiota from ellagitannin rich foodstuff, have immense health benefits and have been demonstrated to bind to estrogen receptors. This class of compounds holds promise as therapeutic and nutritional supplement in cardiovascular disorders, osteoporosis, muscle health, neurological disorders, and cancers of breast, endometrium, and prostate, or, in essence, most of the hormone/endocrine-dependent diseases. One of our findings from the past decade of research on SERMs and estrogen modulators, showed that pomegranate, one of the indirect but major sources of urolithins, can act as SERM. The prospect of urolithins to act as agonist, antagonist, or SERM will depend on its structure; the estrogen receptor conformational change, availability and abundance of co-activators/co-repressors in the target tissues, and also the presence of other estrogen receptor ligands. Given that, urolithins need to be carefully studied for its SERM activity considering the pleotropic action of estrogen receptors and its numerous roles in physiological systems. In this review, we unveil the possibility of urolithins as a potent SERM, which we are currently investigating, in the hormone dependent tissues.

Polyphenols and their potential role to fight viral diseases: An overview

Fruits, vegetables, spices, and herbs are a potential source of phenolic acids and polyphenols. These compounds are known as natural by-products or secondary metabolites of plants, which are present in the daily diet and provide important benefits to the human body such as antioxidant, anti-inflammatory, anticancer, anti-allergic, antihypertensive and antiviral properties, among others. Plentiful evidence has been provided on the great potential of polyphenols against different viruses that cause widespread health problems. As a result, this review focuses on the potential antiviral properties of some polyphenols and their action mechanism against various types of viruses such as coronaviruses, influenza, herpes simplex, dengue fever, and rotavirus, among others. Also, it is important to highlight the relationship between antiviral and antioxidant activities that can contribute to the protection of cells and tissues of the human body. The wide variety of action mechanisms of antiviral agents, such as polyphenols, against viral infections could be applied as a treatment or prevention strategy; but at the same time, antiviral polyphenols could be used to produce natural antiviral drugs. A recent example of an antiviral polyphenol application deals with the use of hesperidin extracted from Citrus sinensis. The action mechanism of hesperidin relies on its binding to the key entry or spike protein of SARS-CoV-2. Finally, the extraction, purification and recovery of polyphenols with potential antiviral activity, which are essential for virus replication and infection without side-effects, have been critically reviewed.

Polyethylene Films Containing Plant Extracts in the Polymer Matrix as Antibacterial and Antiviral Materials

Low density polyethylene (LDPE) films covered with active coatings containing mixtures of rosemary, raspberry, and pomegranate CO₂ extracts were found to be active against selected bacterial strains that may extend the shelf life of food products. The coatings also offer antiviral activity, due to their influence on the activity of Φ6 bacteriophage, selected as a surrogate for SARS-CoV-2 particles. The mixture of these extracts could be incorporated into a polymer matrix to obtain a foil with antibacterial and antiviral properties. The initial goal of this work was to obtain active LDPE films containing a mixture of CO₂ extracts of the aforementioned plants, incorporated into an LDPE matrix via an extrusion process. The second aim of this study was to demonstrate the antibacterial properties of the active films against Gram-positive and Gram-negative bacteria, and to determine the antiviral effect of the modified material on Φ6 bacteriophage. In addition, an analysis was made on the influence of the active mixture on the polymer physicochemical features, e.g., mechanical and thermal properties, as well as its color and transparency. The results of this research indicated that the LDPE film containing a mixture of raspberry, rosemary, and pomegranate CO₂ extracts incorporated into an LDPE matrix inhibited the growth of Staphylococcus aureus. This film was also found to be active against Bacillus subtilis. This modified film did not inhibit the growth of Escherichia coli and Pseudomonas syringae cells; however, their number decreased significantly. The LDPE active film was also found to be active against Φ6 particles, meaning that the film had antiviral properties. The incorporation of the mixture of CO₂ extracts into the polymer matrix affected its mechanical properties. It was observed that parameters describing mechanical properties decreased, although did not affect the transition of LDPE significantly. Additionally, the modified film exhibited barrier properties towards UV radiation. Modified PE/CO₂ extracts films could be applied as a functional food packaging material with antibacterial and antiviral properties.

Simultaneous process optimization of ultrasound-assisted extraction of polyphenols and ellagic acid from pomegranate (Punica granatum L.) flowers and its biological activities

This study was designed to optimize the extraction rate of total polyphenols and ellagic acid from pomegranate flowers. Single factors were investigated for liquid-to-material ratio (5-25), ethanol concentration (20%-60%), sonication time (5-60 min), and sonication power (150-500 W). The level range of the Box-Bokhen design was determined with respect to the single-factor results. The components of each index were normalized using the entropy weighting method for obtaining the comprehensive evaluation value. Under the actual conditions, the final optimization results were 17 for liquid-to-material ratio, 43% for ethanol concentration, 10 min for ultrasonic time, and 300 W for ultrasonic power. The extracts obtained under optimal conditions were tested for the inhibition of Streptococcus mutans and its biofilm, and results showed that pomegranate flowers exerted some inhibitory effects on the bacterium. Phosphomolybdenum and FRAP assays were used, and DPPH, ABTS, and O^2- radical scavenging tests were conducted, indicating that pomegranate flower extracts have good antioxidant capacity.

Polyethylene Films Coated with Antibacterial and Antiviral Layers Based on CO2 Extracts of Raspberry Seeds, of Pomegranate Seeds and of Rosemary

The main goal of the work was to create an internal coating based on super critical CO2 extracts of raspberry seeds, pomegranate seeds and rosemary that could be active against chosen bacterial strains. Additionally, the synergistic effect of these substances in the coating were then analysed. The next goal of the work was to demonstrate the antiviral activity of the coatings against phi6 bacteriophage particles (airborne viruses surrogate). The results of the study indicated that three coatings containing a mixture of extracts showed bacteriolytic activity against S. aureus cells and bacteriostatic activity against E. coli and B. subtilis strains. Two coatings showed bacteriolytic activity against a P. syringae strain. As a result of the experiments, a synergistic effect was noted in the active additives/compounds in the coatings. These coatings may be used as internal coatings for packaging films to extend the shelf life of selected food products. All seven coatings may also be used as external coatings with antiviral activity, as these coatings demonstrated significant effects on the phi6 phage, selected as a surrogate for airborne viruses, e.g., coronaviruses. It could be concluded that coatings I–VII will also show antiviral effects on SARS-CoV-2 particles.