Antiviral activity-guided fractionation from Araucaria angustifolia leaves extract

Application of Cyclic Diaryliodonium Salts in the Synthesis of Axially Chiral Natural Product Analogues

The application of cyclic diaryliodonium salts in the synthesis of bioactive natural product analogues was demonstrated. Axially chiral biaryls were obtained via the enantioselective ring opening of cyclic diaryliodonium salts. Regioselective borylation was key in accessing both enantiomers of a biphenol key intermediate in eight steps overall. 8,8″-Amino biflavones were synthesized, their bioactivity profiled, and the eutomer identified. The structure-activity relationship was probed.

Modular Approach for the Synthesis and Bioactivity Profiling of 8,8'-Biflavones

In this work, we report the scalable and modular synthesis of a library of 55 monomeric and dimeric flavonoids including 14 8,8'-biflavones. The sterically demanding tetra-ortho-substituted axis of an acetophenone dimer key intermediate was constructed in a regioselective manner using Fe-mediated oxidative coupling. This step was systematically optimized and performed on up to multigram scale. The biological activities of this compound library were evaluated, including cytotoxicity against healthy and malignant human cell lines, antimicrobial activity against the apicomplexan parasite Toxoplasma gondii, and antioxidant capacity. A marked increase in activity for the 8,8'-dimeric structures compared to that of their monomeric counterparts was observed. Several biflavones were identified with high selectivity indices (low cytotoxicity and high antiprotozoal activity), showing that this class of natural products may serve as lead structures for further investigations.

Chemical Profiling of Significant Antioxidant and Phytotoxic Microwave-Extracted Essential Oil from Araucaria heterophylla Resin

Due to the various hazards of using synthetic chemical compounds in pharmaceutics, agriculture, and industry, scientists and researchers do their best to explore and assess new green natural compounds from natural resources with potent activity. The essential oil (EO) from the resin collected from Araucaria heterophylla Salisb. was extracted by the microwave technique and chemically characterized via GC-MS analysis. Furthermore, the extract EO was assessed for its antioxidant and phytotoxic activities. The EO has 33 compounds, mainly terpenes (98.23%), and the major compounds were α-pinene (62.57%), β-pinene (6.60%), germacrene D (5.88%), and β-caryophyllene (3.56%). The extracted EO showed substantial antioxidant activity, where it showed IC50 values of 142.42 and 118.03 mg L−1 for DPPH and ABTS, respectively. On the other hand, the EO revealed considerable phytotoxicity against the weed Chenopodium murale, where the EO showed IC50 values of 304.0, 230.1, and 147.1 mg L−1, for seed germination, seedling shoot growth, and seedling root growth, respectively. Moreover, the EO showed the same pattern of allelopathic inhibition against the weed Sonchus oleraceus, where it showed IC50 values of 295.7, 224.5, and 106.1 mg L−1, for seed germination, seedling shoot growth, and seedling root growth, respectively. The present study showed that the extraction technique affects the constituents of the EO, particularly the quantitative composition. The EO of A. heterophylla resin also revealed considerable antioxidant and phytotoxic activity against weeds. Therefore, it can be considered a promising natural resource that could be integrated into the weed management approach. However, further study is recommended for deep characterization of their authentic compounds and evaluation of their mode of action(s) on a wide spectrum of weeds.

Tackling the Future Pandemics: Broad-Spectrum Antiviral Agents (BSAAs) Based on A-Type Proanthocyanidins

A-type proanthocyanidins (PAC-As) are plant-derived natural polyphenols that occur as oligomers or polymers of flavan-3-ol monomers, such as (+)-catechin and (-)-epicatechin, connected through an unusual double A linkage. PAC-As are present in leaves, seeds, flowers, bark, and fruits of many plants, and are thought to exert protective natural roles against microbial pathogens, insects, and herbivores. Consequently, when tested in isolation, PAC-As have shown several biological effects, through antioxidant, antibacterial, immunomodulatory, and antiviral activities. PAC-As have been observed in fact to inhibit replication of many different human viruses, and both enveloped and non-enveloped DNA and RNA viruses proved sensible to their inhibitory effect. Mechanistic studies revealed that PAC-As cause reduction of infectivity of viral particles they come in contact with, as a result of their propensity to interact with virion surface capsid proteins or envelope glycoproteins essential for viral attachment and entry. As viral infections and new virus outbreaks are a major public health concern, development of effective Broad-Spectrum Antiviral Agents (BSAAs) that can be rapidly deployable even against future emerging viruses is an urgent priority. This review summarizes the antiviral activities and mechanism of action of PAC-As, and their potential to be deployed as BSAAs against present and future viral infections.

Oral and Topical Anti-Inflammatory and Antipyretic Potentialities of Araucaria bidiwillii Shoot Essential Oil and Its Nanoemulsion in Relation to Chemical Composition

Different parts of Araucaria bidiwillii (bunya pin) trees, such as nuts, seeds, bark, and shoots, are widely used in cooking, tea, and traditional medicines around the world. The shoots essential oil (EO) has not yet been studied. Herein, the chemical profile of A. bidiwillii shoots EO (ABSEO) was created by GC–MS analysis. Additionally, the in vivo oral and topical anti-inflammatory effect against carrageenan-induced models, as well as antipyretic potentiality of ABSEO and its nanoemulsion were evaluated. Forty-three terpenoid components were identified and categorized as mono- (42.94%), sesqui- (31.66%), and diterpenes (23.74%). The main compounds of the ABSEO were beyerene (20.81%), α-pinene (16.21%), D-limonene (14.22%), germacrene D (6.69%), β-humulene (4.14%), and sabinene (4.12%). The ABSEO and its nanoemulsion exhibited significant inflammation suppression in carrageenan-induced rat paw edema model, in both oral (50 and 100 mg/kg) and topical (5% in soyabean oil) routes, compared to the control and reference drugs groups. All the results demonstrated the significant inflammation reduction via the inflammatory cytokines (IL-1β and IL8), nitrosative (NO), and prostaglandin E2 (PGE2) supported by the histopathological studies and immunohistochemical assessment of MMP-9 and NF-κβ levels in paw tissues. Moreover, the oral administration of ABSEO and its nanoemulsion (50 and 100 mg/kg) exhibited antipyretic activity in rats, demonstrated by the inhibition of hyperthermia induced by intramuscular injection of brewer’s yeast. These findings advised that the use of ABSEO and its nanoemulsion against numerous inflammatory and hyperthermia ailments that could be attributed to its active constituents.

Conifers Phytochemicals: A Valuable Forest with Therapeutic Potential

Conifers have long been recognized for their therapeutic potential in different disorders. Alkaloids, terpenes and polyphenols are the most abundant naturally occurring phytochemicals in these plants. Here, we provide an overview of the phytochemistry and related commercial products obtained from conifers. The pharmacological actions of different phytochemicals present in conifers against bacterial and fungal infections, cancer, diabetes and cardiovascular diseases are also reviewed. Data obtained from experimental and clinical studies performed to date clearly underline that such compounds exert promising antioxidant effects, being able to inhibit cell damage, cancer growth, inflammation and the onset of neurodegenerative diseases. Therefore, an attempt has been made with the intent to highlight the importance of conifer-derived extracts for pharmacological purposes, with the support of relevant in vitro and in vivo experimental data. In short, this review comprehends the information published to date related to conifers' phytochemicals and illustrates their potential role as drugs.

Phytochemical constituents, antimicrobial and antioxidant activities of Kumaun Himalayan Hoop Pine bark extract

The chemical composition of the methanol extract obtained from Araucaria cunninghamii Sweet. bark was determined by GC-MS analysis with its antioxidant and antibacterial potential, for the first time. A total of 73 compounds were identified and the extract was strongly characterised by Viridiflorene; Androstan-17-one, 3-ethyl-3-hydroxy-, (5α)-; 8-Isopropenyl-1,3,3,7-tetramethyl-bicyclo[5.1.0]oct-5-en-2-one; 3,6,9-Triethyl-3,6,9-trimethyl-tetracyclo[6.1.0.0 ∼ 2,4∼.0 ∼ 5,7∼]-nonane; Longifolenaldehyde; (-)-Caryophyllen-(I1); 2-hydroxymethyl-5-furfural; Methyl commate B; 3-Ethyl-3-hydroxyandrostan-17-one; 3-Hydroxybenzoic acid as the main components (55.39%). A. cunninghamii extract presents IC₅₀, 53.52 µg/mL and 65.29 µg/mL using DPPH and H₂O₂ scavenging assay, respectively. The antibacterial activity of the extract was evaluated for eight microorganisms showed that the extract had a remarkable inhibitory potential with a mean zone diameter of inhibition ranging from 09 to 21 mm. The methanol extract of A. cunninghamii showed significant antibacterial activity against X. campestris (21 mm, ZOI) with MIC and MBC values 15.6 and 31.25 µg/mL, respectively.

Phytochemistry, Chemotaxonomy, and Biological Activities of the Araucariaceae Family-A Review

In this review article, the phytochemistry of the species belonging to the Araucariaceae family is explored. Among these, in particular, it is given a wide overview on the phytochemical profile of Wollemia genus, for the first time. In addition to this, the ethnopharmacology and the general biological activities associated to the Araucariaceae species are singularly described. Lastly, the chemotaxonomy at the genus and family levels is described and detailed.

Identification of bilobetin metabolites, in vivo and in vitro, based on an efficient ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry strategy

Bilobetin, a natural compound extracted from Ginkgo biloba, has various pharmacological activities such as antioxidation, anticancer, antibacterial, antifungal, anti-inflammatory, antiviral, and promoting osteoblast differentiation. However, few studies have been conducted and there are no reports on its metabolites owing to its low content in nature. In addition, it has been reported to have potential liver and kidney toxicity. Therefore, this study aimed to identify the metabolites of bilobetin in vitro and in vivo. Bilobetin was incubated with liver microsomes to determine metabolites in vitro, and faeces and urine were collected after oral administration to rats to determine metabolites in vivo. After the samples were processed, they were measured using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. As a result, a total of 21 and 9 metabolites were detected in vivo and in vitro, respectively. Demethylation, demethylation and loss of water, demethylation and hydrogenation, demethylation and glycine conjugation, oxidation, methylation, oxidation and methylation, and hydrogenation were the main metabolic pathways. This study is the first to identify the metabolites of bilobetin and provides a theoretical foundation for the safe use of bilobetin in clinical application and the development of new drugs.

In vitro antioxidant properties of the biflavonoid agathisflavone

Purpose

Free radicals are considered as the causative agents of a variety of acute and chronic pathologies. Natural antioxidants have drawn attention of the researchers in recent years for their ability to scavenge free radicals with minimal or even no side effects. This study evaluates the antioxidant capacity of agathisflavone, a naturally occurring biflavonoid by a number of in vitro methods.

Methods

Agathisflavone was subjected to DPPH, ABTS, OH and NO radical scavenging assay, reducing potential and inhibition of lipid peroxidation (TBARS) test using trolox as a standard.

Results

Agathisflavone showed concentration-dependent antioxidant activity against all types of free radicals used in this study. The antioxidant capacity, reducing potential and inhibition of lipid peroxidation showed by agathisflavone were comparable to that of trolox.

Conclusion

Agathisflavone exhibited antioxidant capacity, which suggests considering this biflavonoid for the use in the prevention and/or treatment of diseases precipitated by oxidative stress.

Strychnos pseudoquina A. St. Hil.: a Brazilian medicinal plant with promising in vitro antiherpes activity

AIMS

To investigate the anti-HSV and anti-inflammatory effects of a standardized ethyl acetate extract (SEAE) prepared with the stem bark of Strychnos pseudoquina, along with two isolated compounds: quercetin 3-O-methyl ether (3MQ) and strychnobiflavone (SBF).

METHODS AND RESULTS

The mechanisms of action were evaluated by different methodological strategies. SEAE and SBF affected the early stages of viral infection and reduced HSV-1 protein expression. Both flavonoids elicited a concentration-dependent inhibition of monocyte chemoattractant protein-1 (MCP-1), whereas 3MQ reduced the chemokine release more significantly than SBF. Conversely, both compounds stimulated the production of the cytokines TNF-α and IL-1-β in LPS-stimulated cells, especially at the intermediate and the highest tested concentrations.

CONCLUSIONS

SEAE and SBF interfered with various steps of HSV replication cycle, mainly adsorption, postadsorption and penetration, as well as with β and γ viral proteins expression; moreover, a direct inactivation of viral particles was observed. Besides, both flavonoids inhibited MCP-1 selectively, a feature that may be beneficial for the development of new anti-HSV agents.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results indicated that the samples present anti-HSV and anti-inflammatory activities, at different levels, which is an interesting feature since cold and genital sores are accompanied by an inflammation process.

Chemical constituents of the leaves of Campylospermum elongatum

The leaves of Campylospermum elongatum have furnished the cyano-glycoside (lithospermoside), nine isomeric biflavonoid derivatives among which five are I3–II6 linked (robustaflavone; 4′-O-methyl robustaflavone; 4′,4″′-di-O-methyl robustaflavone; 7,4′,4″-tri-O-methyl robustaflavone; 4′,7″-di-O-methyl robustaflavone) and four I3–II8 linked (amentoflavone; 7-O-methyl amentoflavone; 7,7″-di-O-methyl amentoflavone; 7, 4′,7″-tri-O-methyl amentoflavone) and a flavone glycoside, 4″-O-methyl-7-O-β-d-galactosylapigenin. All structures were established from a complete spectroscopic analysis (MS, IR, 1D, and 2D NMR, including HSQC, HMBC, and NOESY) as well as by comparing the obtained spectroscopic data with literature. This is the first report on the characterization of 4′-O-methyl-7-O-β-d-galactosylapigenin from the genus campylospermum and thus has important chemotaxonomic implications.

Antiherpetic Plants: A Review of Active Extracts, Isolated Compounds, and Bioassays

Herpes simplex is a disease that is widely distributed throughout the world. It is caused by herpes simplex virus type 1 (HSV-1) and simplex virus type 2 (HSV-2). The drugs of choice for treatment are acyclovir (ACV), Penciclovir (PCV) and other guanine analogues, which have the same mechanism of action. However, due to the constant increase of ACV-resistant strains in immunocompromised patients, it is necessary to find new treatment alternatives. It has been shown that natural products are a good alternative for the treatment of these diseases as well as being an excellent source of compounds with anti-herpetic activity, which may be useful for the development of new drugs and act through a mechanism of action different from ACV and PCV. This paper compiles reports on extracts and compounds isolated from plants that have anti-herpetic activity. We present an analysis of the solvents most widely used for extraction from plants as well as cells and commonly used methods for evaluating cytotoxic and anti-herpetic activity. Families that have a higher number of plants with anti-herpetic activity are evaluated, and we also highlight the importance of studies of mechanisms of action of extracts and compounds with anti-herpetic activity.

Antioxidant and Antigenotoxic Activities of the Brazilian Pine Araucaria angustifolia (Bert.) O. Kuntze

Polyphenols are natural products with recognized potential in drug discovery and development. We aimed to evaluate the polyphenolic profile of Araucaria angustifolia bracts, and their ability to scavenge reactive species. The antioxidant and antigenotoxic effects of A. angustifolia polyphenols in MRC5 human lung fibroblast cells were also explored. The total polyphenol extract of A. angustifolia was determined by the Folin–Ciocalteu reagent and the chemical composition was confirmed by HPLC. Reactive oxygen species’ scavenging ability was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and superoxide dismutase- and catalase-like activities. The protective effect of the extract in MRC5 cells was carried out by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method and the determination of oxidative lipids, protein, and DNA (alkaline and enzymatic comet assay) damage. Total phenolic content of the A. angustifolia extract was 1586 ± 14.53 mg gallic acid equivalents/100 g of bracts. Catechin, epicatechin, quercetin, and apigenin were the major polyphenols. The extract was able to scavenge DPPH radicals and exhibited potent superoxide dismutase and catalase-like activities. Moreover, A. angustifolia extract significantly protected MRC5 cells against H₂O₂-induced mortality and oxidative damage to lipids, proteins, and DNA. Therefore, A. angustifolia has potential as a source of bioactive chemical compounds.

Antiviral activity of the Lippia graveolens (Mexican oregano) essential oil and its main compound carvacrol against human and animal viruses

Mexican oregano (Lippia graveolens) is a plant found in Mexico and Central America that is traditionally used as a medicinal herb. In the present study, we investigated the antiviral activity of the essential oil of Mexican oregano and its major component, carvacrol, against different human and animal viruses. The MTT test (3–4,5-dimethythiazol-2yl)-2,5-diphenyl tetrazolium bromide) was conducted to determine the selectivity index (SI) of the essential oil, which was equal to 13.1, 7.4, 10.8, 9.7, and 7.2 for acyclovir-resistant herpes simplex virus type 1 (ACVR-HHV-1), acyclovir-sensitive HHV-1, human respiratory syncytial virus (HRSV), bovine herpesvirus type 2 (BoHV-2), and bovine viral diarrhoea virus (BVDV), respectively. The human rotavirus (RV) and BoHV-1 and 5 were not inhibited by the essential oil. Carvacrol alone exhibited high antiviral activity against RV with a SI of 33, but it was less efficient than the oil for the other viruses. Thus, Mexican oregano oil and its main component, carvacrol, are able to inhibit different human and animal viruses in vitro. Specifically, the antiviral effects of Mexican oregano oil on ACVR-HHV-1 and HRSV and of carvacrol on RV justify more detailed studies.

Effects of Ilex paraguariensis A. St. Hil. (yerba mate) on herpes simplex virus types 1 and 2 replication

The antiherpes effects of the crude extract obtained from Ilex paraguariensis leaves (yerba mate) and their purified fractions were investigated. The most active fraction was selected and assayed to determine the viral multiplication steps upon which it acted. In order to detect the major components of this fraction, thin layer chromatography (TLC) analysis was performed. The antiviral activity was evaluated against HSV-1 and HSV-2 by a viral plaque number reduction assay (IC(50) ) and the cytotoxicity by a MTT assay (CC(50) ). According to the obtained results, all tested samples showed antiherpes activity at noncytotoxic concentrations, and the ethyl acetate fraction was the most active (SI = CC(50) /IC(50)  = 188.7 and 264.7 for HSV-1 and HSV-2, respectively). The results also demonstrated that this fraction exerts antiviral activity by the reduction of viral infectivity, the inhibition of virus entry into cells and cell-to-cell virus spread, as well as by the impaired levels of ICP27, ICP4, gD and gE proteins of HSV-1. The TLC analysis showed that this fraction contains monodesmosidic triterpenoid saponins, matesaponin-1 (a bidesmosidic one), caffeic and chlorogenic acids and rutin, which suggests that they could act synergistically and be responsible for the detected antiherpes activity.

In vitro antiherpes effects of a C-glycosylflavonoid-enriched fraction of Cecropia glaziovii Sneth

AIMS

To investigate the in vitro antiherpes effects of the crude aqueous extract obtained from Cecropia glaziovii leaves and their related fractions, the n-butanol fraction (n-BuOH) and the C-glycosylflavonoid-enriched fraction (MeOH(AMB)), and to determine the viral multiplication step(s) upon which this C-glycosylflavonoid-enriched fraction acts.

METHODS AND RESULTS

The antiviral activity was evaluated against human herpes virus types 1 and 2 (HHV-1, HHV-2) by plaque reduction assay. The mode of action of the most active fraction was investigated by a set of assays, and the results demonstrated that MeOH(AMB) fraction exerts anti-herpes action by the reduction of viral infectivity (only against HHV-2); by the inhibition of virus entry into cells; by the inhibition of cell-to-cell virus spread as well as by the impaired levels of envelope proteins of HHV-1. The high-performance liquid chromatography (HPLC)-photo-diode array (PDA) analysis showed that the C-glycosylflavonoids are the major constituents of this fraction.

CONCLUSIONS

These data showed that the MeOH(AMB) fraction has an antiviral activity against HHV types 1 and 2. The C-glycosylflavonoids are the major constituents of this fraction, which suggests that they could be one of the compounds responsible for the detected anti-herpes activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The MeOH(AMB) fraction can be regarded as a phytopharmaceutical candidate for the treatment of herpetic infections.