Potent virucidal effect of pheophorbide a and pyropheophorbide a on enveloped viruses

Membrane-Active Singlet Oxygen Photogenerators as a Paradigm for Broad-Spectrum Antivirals: The Case of Halogenated (BOron)-DIPYrromethenes

Enveloped viruses, such as flaviviruses and coronaviruses, are pathogens of significant medical concern that cause severe infections in humans. Some photosensitizers are known to possess virucidal activity against enveloped viruses, targeting their lipid bilayer. Here we report a series of halogenated difluoroboron-dipyrromethene (BODIPYs) photosensitizers with strong virus-inactivating activity. Our structure-activity relationship analysis revealed that BODIPY scaffolds with a heavy halogen atom demonstrate significant efficacy against both tick-borne encephalitis virus (TBEV; Flaviviridae family) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; Coronaviridae family) along with high singlet oxygen quantum yields. Moreover, select compounds also inactivated other enveloped viruses, such as herpes simplex virus type 1 and monkeypox virus. The nature and length of the alkyl side chain notably influenced the virus-inactivating activity of BODIPY molecules. Furthermore, molecular dynamics studies highlighted the critical importance of the positioning of the chromophore moiety within the lipid bilayer. As membrane-targeting photosensitizers, BODIPYs interact directly with virus particles, causing damage to the viral envelope membranes. Thus, TBEV pretreated with BODIPY was completely noninfective for lab mice. Consequently, BODIPY-based photosensitizers hold potential either as broad-spectrum virus-inactivating antivirals against a variety of phylogenetically unrelated enveloped viruses or as potent inactivators of viruses for the development of vaccines for preventing life-threatening emerging viral diseases.

Antiviral activity of the water extract and ethanol extract of Sorbus commixta against influenza A virus in vitro

Although vaccines and antivirals are currently available, influenza virus infections continually present major threats to human health. Due to genetic diversity and variability of influenza viruses, the development of new antiviral agents against the virus remains as a considerable challenge. In this study, we evaluated the antiviral activity of the water extract and ethanol extract of Sorbus commixta Hedl. (SCH), widely used as a medical herb, against influenza A viruses and identified molecular mechanisms for the antiviral activity. The water extract and ethanol extract of SCH demonstrated virucidal activity against influenza A virus at the noncytotoxic concentrations. In addition, cytopathic effect reduction assay and GFP fluorescence image analysis suggest that SCH extracts have inhibitory activity on multiple stages during influenza virus life cycle. Mechanisms studies showed that SCH extracts inhibited the biological functions of influenza viral surface hemagglutinin and neuraminidase proteins that play critical roles in the viral entry and release steps. SCH extracts not only prevented the receptor binding of influenza viral HA to the cellular receptors but also inhibited the HA-mediated membrane fusion. In addition, SCH extracts suppressed the enzyme activity of the viral neuraminidase. The results together suggest that SCH extracts contain antiviral natural compounds that inhibit multiple influenza viral proteins including the viral surface proteins. Our findings suggest that SCH extracts could be promising resources for the development of novel antiviral agents against influenza A viruses.

Development and Investigation of a Nanoemulgel Formulated from Tunisian Opuntia ficus-indica L. Seed Oil for Enhanced Wound Healing Activity

The aim of this study is to develop a nanoemulgel encapsulating a Tunisian Prickly Pear (Opuntia ficus-indica L.) seed oil (PPSO) to assess, for the first time, the in vivo efficacy of this nanoformulation on wound healing. Phytocompounds of this oil have been reported in the literature as having powerful pharmacological activities. However, it remains poorly exploited due to low bioavailability. A nanoemulsion (NE) was designed by determining the required hydrophilic-lipophilic balance (HLB) and subsequently characterized. The mean droplet size was measured at 56.46 ± 1.12 nm, with a polydispersity index (PDI) of 0.23 ± 0.01 using dynamic light scattering. The zeta potential was -31.4 ± 1.4 mV, and the morphology was confirmed and assessed using transmission electron microscopy (TEM). These characteristics align with the typical properties of nanoemulsions. The gelification process resulted in the formation of a nanoemulgel from the optimum nanoemulsion. The high wound healing efficiency of the nanoemulgel was confirmed compared to that of a medicinally marketed cream. The outcomes of this research contribute valuable insights, for the first time, into the potential therapeutic applications of PPSO and its innovative pharmaceutical formulation for wound healing.

The photoactivated antifungal activity and possible mode of action of sodium pheophorbide a on Diaporthe mahothocarpus causing leaf spot blight in Camellia oleifera

Introduction

Sodium pheophorbide a (SPA) is a natural plant-derived photosensitizer, with high photoactivated antifungal activity against some phytopathogenic fungi. However, its fungicidal effect on Diaporthe mahothocarpus, a novel pathogen that causes Camellia oleifera leaf spot blight, is unclear.

Methods

In the present study, we explored its inhibitory effects on spore germination and mycelial growth of D. mahothocarpus. Then we determined its effects on the cell membrane, mycelial morphology, redox homeostasis, and cell death through bioassay. Finally, RNA-seq was used further to elucidate its mode of action at the transcriptional level.

Results

We found that SPA effectively inhibited the growth of D. mahothocarpus, with half-maximal effective concentrations to inhibit mycelial growth and spore germination of 1.059 and 2.287 mg/mL, respectively. After 1.0 mg/mL SPA treatment, the conductivity and malondialdehyde content of D. mahothocarpus were significantly increased. Scanning electron microscopy and transmission electron microscopy indicated that SPA significantly affected the morphology and ultrastructure of D. mahothocarpus hyphae, revealing that SPA can destroy the mycelial morphology and cell structure, especially the cell membrane of D. mahothocarpus. Furthermore, transcriptome analysis revealed that SPA significantly suppressed the expression of genes involved in morphology, cell membrane permeability, and oxidative stress. Then, we also found that SPA significantly promoted the accumulation of reactive oxygen species (ROS) in of D. mahothocarpus, while it decreased the content of reduced glutathione, inhibited the enzyme activities of superoxide dismutase and catalase, and exacerbated DNA damage. Annexin V-FITC/PI staining also confirmed that 1.0 mg/mL SPA could significantly induce apoptosis and necrosis.

Discussion

Generally, SPA can induce ROS-mediated oxidative stress and cell death, thus destroying the cell membrane and hyphal morphology, and ultimately inhibiting mycelial growth, which indicates that SPA has multiple modes of action, providing a scientific basis for the use of SPA as an alternative plant-derived photoactivated fungicide against C. oleifera leaf spot blight.

Natural chlorophyll: a review of analysis methods, health benefits, and stabilization strategies

Chlorophyll (Chl) is a natural pigment, widely distributed ranging from photosynthetic prokaryotes to higher plants, with an annual yield of up to 1.2 billion tons worldwide. Five types of Chls are observed in nature, that can be distinguished and identified using spectroscopy and mass spectrometry. Chl is also used in the food industry owing to its bioactivities, including obesity prevention, inflammation reduction, viral infection inhibition, anticancer effects, anti-oxidation, and immunostimulatory properties. It has great potential of being applied as a colorant and dietary supplement in the food industry. However, Chl is unstable under various enzymatic, acidic, heat, and light conditions, which limit its application. Although some strategies, such as aggregation with other food components, microencapsulation, and metal cation replacement, have been proposed to overcome these limitations, they are still not enough to facilitate its widespread application. Therefore, stabilization strategies and bioactivities of Chl need to be expected to expand its application in various fields, thereby aiding in the sustainable development of mankind.

Galdieria sulphuraria: An Extremophilic Alga as a Source of Antiviral Bioactive Compounds

In the last decades, the interest in bioactive compounds derived from natural sources including bacteria, fungi, plants, and algae has significantly increased. It is well-known that aquatic or terrestrial organisms can produce, in special conditions, secondary metabolites with a wide range of biological properties, such as anticancer, antioxidant, anti-inflammatory, and antimicrobial activities. In this study, we focused on the extremophilic microalga Galdieria sulphuraria as a possible producer of bioactive compounds with antiviral activity. The algal culture was subjected to organic extraction with acetone. The cytotoxicity effect of the extract was evaluated by the 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The antiviral activity was assessed through a plaque assay against herpesviruses and coronaviruses as enveloped viruses and poliovirus as a naked one. The monolayer was treated with different concentrations of extract, ranging from 1 µg/mL to 200 µg/mL, and infected with viruses. The algal extract displayed strong antiviral activity at non-toxic concentrations against all tested enveloped viruses, in particular in the virus pre-treatment against HSV-2 and HCoV-229E, with IC₅₀ values of 1.7 µg/mL and IC₉₀ of 1.8 µg/mL, respectively. However, no activity against the non-enveloped poliovirus has been detected. The inhibitory effect of the algal extract was confirmed by the quantitative RT-PCR of viral genes. Preliminary chemical profiling of the extract was performed using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS), revealing the enrichment in primary fatty acid amides (PFAA), such as oleamide, palmitamide, and pheophorbide A. These promising results pave the way for the further purification of the mixture to explore its potential role as an antiviral agent.

Characterization of Neochloris oleoabundans under Different Cultivation Modes and First Results on Bioactivity of Its Extracts against HCoV-229E Virus

Microalgae are proposed in several biotechnological fields because of their ability to produce biomass enriched in high-value compounds according to cultivation conditions. Regarding the health sector, an emerging area focuses on natural products exploitable against viruses. This work deals with the characterization of the green microalga Neochloris oleoabundans cultivated under autotrophic and mixotrophic conditions as a source of whole aqueous extracts, tested as antivirals against HCoV-229E (Coronaviridae family). Glucose was employed for mixotrophic cultures. Growth and maximum quantum yield of photosystem II were monitored for both cultivations. Algae extracts for antiviral tests were prepared using cultures harvested at the early stationary phase of growth. Biochemical and morphological analyses of algae indicated a different content of the most important classes of bioactive compounds with antiviral properties (lipids, exo-polysaccharides, and total phenolics, proteins and pigments). To clarify which phase of HCoV-229E infection on MRC-5 fibroblast cells was affected by N. oleoabundans extracts, four conditions were tested. Extracts gave excellent results, mainly against the first steps of virus infection. Notwithstanding the biochemical profile of algae/extracts deserves further investigation, the antiviral effect may have been mainly promoted by the combination of proteins/pigments/phenolics for the extract derived from autotrophic cultures and of proteins/acidic exo-polysaccharides/lipids in the case of mixotrophic ones.

Opuntia spp. in Human Health: A Comprehensive Summary on Its Pharmacological, Therapeutic and Preventive Properties. Part 2

Plants of the genus Opuntia spp are widely distributed in Africa, Asia, Australia and America. Specifically, Mexico has the largest number of wild species; mainly O. streptacantha, O. hyptiacantha, O. albicarpa, O. megacantha and O. ficus-indica. The latter being the most cultivated and domesticated species. Its main bioactive compounds include pigments (carotenoids, betalains and betacyanins), vitamins, flavonoids (isorhamnetin, kaempferol, quercetin) and phenolic compounds. Together, they favor the different plant parts and are considered phytochemically important and associated with control, progression and prevention of some chronic and infectious diseases. Part 1 collected information on its preventive actions against atherosclerotic cardiovascular diseases, diabetes and obesity, hepatoprotection, effects on human infertility and chemopreventive capacity. Now, this second review (Part 2), compiles the data from published research (in vitro, in vivo, and clinical studies) on its neuroprotective, anti-inflammatory, antiulcerative, antimicrobial, antiviral potential and in the treatment of skin wounds. The aim of both reviews is to provide scientific evidences of its beneficial properties and to encourage health professionals and researchers to expand studies on the pharmacological and therapeutic effects of Opuntia spp.

A photoactivable natural product with broad antiviral activity against enveloped viruses including highly pathogenic coronaviruses

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has highlighted the need for broad-spectrum antivirals against coronaviruses (CoVs). Here, pheophorbide a (Pba) was identified as a highly active antiviral molecule against human CoV-229E after bioguided fractionation of plant extracts. The antiviral activity of Pba was subsequently shown for SARS-CoV-2 and Middle East respiratory syndrome coronavirus (MERS-CoV), and its mechanism of action was further assessed, showing that Pba is an inhibitor of coronavirus entry by directly targeting the viral particle. Interestingly, the antiviral activity of Pba depends on light exposure, and Pba was shown to inhibit virus-cell fusion by stiffening the viral membrane, as demonstrated by cryoelectron microscopy. Moreover, Pba was shown to be broadly active against several other enveloped viruses and reduced SARS-CoV-2 and MERS-CoV replication in primary human bronchial epithelial cells. Pba is the first described natural antiviral against SARS-CoV-2 with direct photosensitive virucidal activity that holds potential for COVID-19 therapy or disinfection of SARS-CoV-2-contaminated surfaces.

SARS-CoV-2 Fears Green: The Chlorophyll Catabolite Pheophorbide A Is a Potent Antiviral

SARS-CoV-2 pandemic is having devastating consequences worldwide. Although vaccination advances at good pace, effectiveness against emerging variants is unpredictable. The virus has displayed a remarkable resistance to treatments and no drugs have been proved fully effective against COVID-19. Thus, despite the international efforts, there is still an urgent need for new potent and safe antivirals against SARS-CoV-2. Here, we exploited the enormous potential of plant metabolism using the bryophyte Marchantia polymorpha L. and identified a potent SARS-CoV-2 antiviral, following a bioactivity-guided fractionation and mass-spectrometry approach. We found that the chlorophyll derivative Pheophorbide a (PheoA), a porphyrin compound similar to animal Protoporphyrin IX, has an extraordinary antiviral activity against SARS-CoV-2, preventing infection of cultured monkey and human cells, without noticeable cytotoxicity. We also show that PheoA targets the viral particle, interfering with its infectivity in a dose- and time-dependent manner. Besides SARS-CoV-2, PheoA also displayed a broad-spectrum antiviral activity against enveloped RNA viral pathogens such as HCV, West Nile, and other coronaviruses. Our results indicate that PheoA displays a remarkable potency and a satisfactory therapeutic index, which together with its previous use in photoactivable cancer therapy in humans, suggest that it may be considered as a potential candidate for antiviral therapy against SARS-CoV-2.

Evaluation of Microalgae Antiviral Activity and Their Bioactive Compounds

During the last year, science has been focusing on the research of antivirally active compounds overall after the SARS-CoV-2 pandemic, which caused a great amount of deaths and the downfall of the economy in 2020. Photosynthetic organisms such as microalgae are known to be a reservoir of bioactive secondary metabolites; this feature, coupled with the possibility of achieving very high biomass levels without excessive energetic expenses, make microalgae worthy of attention in the search for new molecules with antiviral effects. In this work, the antiviral effects of microalgae against some common human or animal viruses were considered, focusing our attention on some possible effects against SARS-CoV-2. We summed up the data from the literature on microalgae antiviral compounds, from the most common ones, such as lectins, polysaccharides and photosynthetic pigments, to the less known ones, such as unidentified proteins. We have discussed the effects of a microalgae-based genetic engineering approach against some viral diseases. We have illustrated the potential antiviral benefits of a diet enriched in microalgae.

Sodium pheophorbide a controls cherry tomato gray mold (Botrytis cinerea) by destroying fungal cell structure and enhancing disease resistance-related enzyme activities in fruit

Sodium pheophorbide a (SPA) is a natural photosensitizer. The present study investigated the antifungal activity and mechanism of SPA against Botrytis cinerea in vitro and in vivo. Its inhibitory effect was studied on the spore germination and mycelial growth of B. cinerea. The effects of SPA on cell wall integrity, cell membrane permeability, and mycelial morphology of B. cinerea were also determined. Additionally, how SPA effected B. cinerea in vivo was evaluated using cherry tomato fruit. The results showed that SPA effectively inhibited the spore germination and mycelial growth of B. cinerea under light conditions (4000 lx). SPA significantly affected both cell wall integrity and cell membrane permeability (P < .05). In addition, SEM analysis suggested that B. cinerea treated with SPA (12.134 mg/mL) showed abnormal mycelial morphology, including atrophy, collapse, flattening, and mycelial wall dissolution. In vivo tests showed that SPA could increase the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) significantly (P < .05); however, SPA had no significant effect on phenylalanine ammonia lyase (PAL) activity. In short, SPA could destroy the fungal cell structure and enhance disease resistance-related enzyme activity in cherry tomatoes, thereby controlling cherry tomato gray mold.

The seafood Musculus senhousei shows anti-influenza A virus activity by targeting virion envelope lipids

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Pyropheophorbide a (PPa) was isolated from the seafood of M. senhousei.

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PPa shows a potent activity against a broad panel of influenza A viral strains.

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The mechanism of PPa is to block the entry of virus in the early stage of infection.

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The target of PPa may be that of lipid bilayer of the enveloped viruses.

Marine environments are known to be a new source of structurally diverse bioactive molecules. In this paper, we identified a porphyrin derivative of Pyropheophorbide a (PPa) from the mussel Musculus senhousei (M. senhousei) that showed broad anti-influenza A virus activity in vitro against a panel of influenza A viral strains. The analysis of the mechanism of action indicated that PPa functions in the early stage of virus infection by interacting with the lipid bilayer of the virion, resulting in an alteration of membrane-associated functions, thereby blocking the entry of enveloped viruses into host cells. In addition, the anti-influenza A virus activity of PPa was further assessed in mice infected with the influenza A virus. The survival rate and mean survival time of mice were apparently prolonged compared with the control group which was not treated with the drug. Therefore, PPa and its derivatives may represent lead compounds for controlling influenza A virus infection.

Antioxidant activity, carotenoids, chlorophylls and mineral composition from leaves of Pallenis spinosa: an Algerian medicinal plant

Background

Plant and medicinal herbs are important sources of bioactive compounds and minerals that can play a role in preventing various diseases and they are considered a factor indispensable for the proper functioning of the human body.

Methods

We investigated the content of carotenoids and chlorophylls of leaves fromPallenis spinosa(P. spinosa), as well as their antioxidant activity and mineral composition then, we optimized the solvent extraction for the recovery of total carotenoids and chlorophylls using spectrophotometric method. Finally, we tested the antioxidant activity of the optimized extract by three assays (DPPH, ABTS and FRAP) and we determined the mineral composition by Emission Spectrometer Induced Couple Plasma (ICP).

Results

Carotenoid (CART), chlorophylls (CHLa + b), chlorophyll a (CHLA), chlorophyll b (CHLB) contents were about 36.337 ± 0.312; 347.769 ± 6.326; 224.286 ± 5.601; 123.483 ± 1.339 mg/100 g dw, respectively. We revealed an interesting antioxidant capacity by the tested extract (DPPH: 127.522 ± 1.406 mmol ET/Kgdw, ABTS: 104.827 ± 1.222 mmol ET/Kgdwand FRAP 71.89 ± 0.495 ± 0.994 mmol ET/Kgdw). Carotenoids and chlorophylls content correlate positively with the antioxidant activity ofP. spinosaleaves extract (r=0.646–0.986). Eight minerals have been detected (Mg, Ca, P, Fe, Mn, Zn, Cu and Cr), Mg and Ca being the predominant ones (6479.32 ± 48.33 and 3851.88 ± 130.63 mg/Kg, respectively).

Conclusions

These results have shown thatP. spinosaleaves are a good source of carotenoids and chlorophylls with a potent antioxidant potential with high amount of minerals.

Sodium pheophorbide a has photoactivated fungicidal activity against Pestalotiopsis neglecta

Sodium pheophorbide a (SPA) is a natural photosensitizer. To explore its antifungal activity and mechanism, we studied its inhibitory effects on spore germination and mycelial growth of Pestalotiopsis neglecta. We used sorbitol, 2-thiobarbituric acid (TBA) and electron microscopy to determine its effects on cell wall integrity, cell membrane lipid peroxidation and mycelial morphology. Finally, the effects of SPA on enzyme activity in mycelia were determined. The results showed that SPA effectively inhibited spore germination and mycelial growth of P. neglecta under light conditions (4000 lx, 24 h). Scanning electron microscopy (SEM) revealed that SPA treatment resulted in a roughened, twisted and knotted mycelial surface and abnormal mycelial growth. SPA influenced cell wall integrity, and the content of MDA, a cell membrane lipid peroxidation product was significantly increased (P < 0.05). SPA also significantly inhibited SOD, POD and PG activity, but enhanced PPO activity (P < 0.05). In conclusion, SPA may have potential to become a biological pesticide.

Anti-HIV Activity of Ocimum labiatum Extract and Isolated Pheophytin-a

Ocimum plants are traditionally used to manage HIV/AIDS in various African countries. The effects of Ocimum labiatum extract on HIV-1 protease (PR) and reverse transcriptase (RT) is presented here along with characterization of an identified bioactive compound, achieved through ¹H- and 13C-NMR. The extract's effect on HIV-1 replication was assessed by HIV-1 p24 antigen capture. Cytotoxicity of samples was evaluated using tetrazolium dyes and real-time cell electronic sensing (RT-CES). Ocimum labiatum inhibited HIV-1 PR with an IC50 value of 49.8 ± 0.4 μg/mL and presented weak inhibition (21%) against HIV-1 RT. The extract also reduced HIV-1 replication in U1 cells at a non-cytotoxic concentration (25 μg/mL). The CC50 value of the extract in U1 cells was 42.0 ± 0.13 μg/mL. The HIV-1 PR inhibiting fraction was purified using prep-HPLC and yielded a chlorophyll derivative, pheophytin-a (phy-a). Phy-a inhibited HIV-1 PR with an IC50 value of 44.4 ± 1.5 μg/mL (51 ± 1.7 μM). The low cytotoxicity of phy-a in TZM-bl cells was detected by RT-CES and the CC50 value in U1 cells was 51.3 ± 1.0 μg/mL (58.9 ± 1.2 μM). This study provides the first in vitro evidence of anti-HIV activity of O. labiatum and isolated phy-a, supporting further investigation of O. labiatum for lead compounds against HIV-1.

Seasonal variation of pheophorbide a and flavonoid in different organs of two Carpinus species and its correlation with immunosuppressive activity

The genus Carpinus of Betulaceae is the most widely distributed in the European landscape. This study reports a comparative study based on the pheophorbide a and flavonoid content from the two main species of the genus Carpinus, Carpinus betulus and Carpinus turczaninowii, respectively, in Nanjing, China. The pheophorbide a and flavonoid content depends on the organ, species, and season. HPLC analysis showed that the pheophorbide a and flavonoid levels were the highest in May and June, respectively, from the leaves of C. betulus 'Fastigiata.' In contrast, the content of pheophorbide a and flavonoid in the stems of C. betulus 'Fastigiata' or in other species was low. The immunosuppressive effects of the ethyl acetate extracts and methanol extracts from the two Carpinus species were also evaluated. The ethyl acetate extracts of C. betulus 'Fastigiata' in May and the methanol extracts of C. betulus 'Fastigiata' in June showed better immunosuppressive activity than in other seasons, which coincided with the content of pheophorbide a and flavonoid, respectively. Our findings indicated that C. betulus 'Fastigiata' can serve as a medicinal plant against inflammation because of its pheophorbide a and flavonoid content.

Natural plant essential oils do not inactivate non-enveloped enteric viruses

The application of plant essential oils (EOs) (hyssop and marjoram) was evaluated for inactivation of non-enveloped viruses using murine norovirus and human adenovirus as models. No significant reduction of virus titres (TCID(50)) was observed when EOs were used at different temperatures and times.