In vitro antiherpetic and antirotaviral activities of a sulfate prepared from Mimosa scabrella galactomannan

Phytochemistry and Diverse Pharmacology of Genus Mimosa: A Review

The genus Mimosa belongs to the Fabaceae family and comprises almost 400 species of herbs, shrubs and ornamental trees. The genus Mimosa is found all over the tropics and subtropics of Asia, Africa, South America, North America and Australia. Traditionally, this genus has been popular for the treatment of jaundice, diarrhea, fever, toothache, wound healing, asthma, leprosy, vaginal and urinary complaints, skin diseases, piles, gastrointestinal disorders, small pox, hepatitis, tumor, HIV, ulcers and ringworm. The review covered literature available from 1959 to 2020 collected from books, scientific journals and electronic searches, such as Science Direct, Web of Science and Google scholar. Various keywords, such as Mimosa, secondary metabolites, medicines, phytochemicals and pharmacological values, were used for the data search. The Mimosa species are acknowledged to be an essential source of secondary metabolites with a wide-ranging biological functions, and up until now, 145 compounds have been isolated from this genus. Pharmacological studies showed that isolated compounds possess significant potential, such as antiprotozoal, antimicrobial, antiviral, antioxidant, and antiproliferative as well as cytotoxic activities. Alkaloids, chalcones, flavonoids, indoles, terpenes, terpenoids, saponins, steroids, amino acids, glycosides, flavanols, phenols, lignoids, polysaccharides, lignins, salts and fatty esters have been isolated from this genus. This review focused on the medicinal aspects of the Mimosa species and may provide a comprehensive understanding of the prospective of this genus as a foundation of medicine, supplement and nourishment. The plants of this genus could be a potential source of medicines in the near future.

Antiviral Strategies Using Natural Source-Derived Sulfated Polysaccharides in the Light of the COVID-19 Pandemic and Major Human Pathogenic Viruses

Only a mere fraction of the huge variety of human pathogenic viruses can be targeted by the currently available spectrum of antiviral drugs. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has highlighted the urgent need for molecules that can be deployed quickly to treat novel, developing or re-emerging viral infections. Sulfated polysaccharides are found on the surfaces of both the susceptible host cells and the majority of human viruses, and thus can play an important role during viral infection. Such polysaccharides widely occurring in natural sources, specifically those converted into sulfated varieties, have already proved to possess a high level and sometimes also broad-spectrum antiviral activity. This antiviral potency can be determined through multifold molecular pathways, which in many cases have low profiles of cytotoxicity. Consequently, several new polysaccharide-derived drugs are currently being investigated in clinical settings. We reviewed the present status of research on sulfated polysaccharide-based antiviral agents, their structural characteristics, structure-activity relationships, and the potential of clinical application. Furthermore, the molecular mechanisms of sulfated polysaccharides involved in viral infection or in antiviral activity, respectively, are discussed, together with a focus on the emerging methodology contributing to polysaccharide-based drug development.

Are Structurally Modified Galactomannan Derivatives Biologically Active?

Galactomannans are versatile macromolecules with broad industrial potential. The influence of changes in the chemical structures and respective bioactivities of these polysaccharides have been extensively studied. The derivatives obtained by sulfation, complexation, and phosphorylation are the most studied biological properties in galactomannans. The derivatives obtained have shown several pharmacological activities such as antiviral, antimicrobial, anticoagulant, fibrinolytic, chemopreventive, anticancer, antioxidant, chondroprotective, analgesic, immunomodulatory, and antileishmanial. Considering the relevance of these studies, we aim to provide an overview of studies that apply galactomannan modification or derivatization strategies to improve their properties for applications in the biomedical area. We identified the success of most modified galactomannans for pharmacological purposes. However, some studies found loss of bioactivity of the original polysaccharide after chemical changes to its original structures.

Promising alternative gum: Extraction, characterization, and oxidation of the galactomannan of Cassia fistula

Galactomannan extracted from Cassia fistula seed endosperm present little data related to the its structural characterization. This study reports the chemical characterization of the galactomannan from Cassia fistula (CF) and their oxidized derivatives. The extracted CF presented a yield of 26.5% (w/w) and the intrinsic viscosity [η] was 9.73 dL/g. 1D and 2D nuclear magnetic resonance spectroscopy (NMR) confirmed that the polysaccharide has a backbone of 4-linked β-D-mannose units, and contains galactose units as pending groups. These galactose units are linked to the central core through a (1→6) linkage and the galactomannan presented Man/Gal ratio of 3.1/1. The galactomannan from Cassia fistula presents low cytotoxicity in Vero cells with a CC₅₀ > 1000 μg/ml. The properties of CF resemble other commercially important galactomannans such as Locust bean gum. Three oxidized derivatives of CF were produced by periodate oxidation, which were carefully characterized by different structural techniques. It was observed that as the degree of oxidation increased, there was an increase in the Man/Gal ratio and a reduction in molar mass and viscosity. The polialdehyde produced may be explored as a versality material to react with amine group of the protein and amined polysaccharide to produce biomaterials.

A comparative study of sulfated tara gum: RSM optimization and structural characterization

Interest in galactomannans and its derivatives as a functional health supplement is growing based on physicochemical properties. In this work, the optimized conditions of sulfated tara gum (STG) with a maximum DS of 0.66 by box-behnken design (BBD) were obtained as following: ratio of chlorosulfonic acid/pyridine 3:1, reaction time 4 h and reaction temperature 40 °C. The structure features of STG such as the degree of substitution (DS), substitution position, weight average molar mass (M_W), monosaccharide components and chain conformation were investigated. Decreasing of M_W, the increasing of Z-average radius of gyration (〈S²〉_Z^1/2) and specific volume for gyration (SV_g) were obtained by SEC-MALLS. In addition, the structural properties of four sulfated galactomannans were comparatively investigated and analyzed based on our earlier reports of sulfated fenugreek gum, guar gum and locust bean gum. A conclusion was drown that higher galactose branch could enhance steric hindrance, which was inferred as one of the significant factors for the derivatization efficiency, thus affecting the DS, M_W and conformational transition of sulfated galactomannans. This study will provide valuable information for further research on the comparison of bioactivities and medical application of galactomannans family.

The Combination of Dimorphandra gardneriana Galactomannan and Mangiferin Inhibits Herpes Simplex and Poliovirus

BACKGROUND

Herpes simplex virus (HSV) and poliovirus (PV) are both agents of major concern in the public health system. It has been shown that Dimorphandra gardneriana galactomannans can be used as solubilizer vehicles in the manufacturing of medicine. Mangiferin is the major constituent of Mangifera indica and presents multiple medicinal and biological activities.

OBJECTIVE

This study assayed the effect of D. gardneriana galactomannan combined with mangiferin (DgGmM) against HSV-1 and PV-1.

METHODS

The DgGmM cytotoxicity was evaluated by the colorimetric MTT method and the antiviral activity by plaque reduction assay, immunofluorescence and polymerase chain reaction (PCR), in HEp-2 cells.

RESULTS

The DgGmM showed a 50% cytotoxic concentration (CC50) > 2000 µg/mL. The 50% inhibitory concentrations (IC50) for HSV-1 and PV-1 were, respectively, 287.5 µg/mL and 206.2 µg/mL, with selectivity indexes (SI) > 6.95 for the former and > 9.69 for the latter. The DgGmM time-ofaddition protocol for HSV-1 showed a maximum inhibition at 500 µg/mL, when added concomitantly to infection and at the time 1 h post-infection (pi). While for PV-1, for the same protocol, the greatest inhibition, was also observed concomitantly to infection at 500 μg/mL and at the times 4 h and 8 h pi. The inhibition was also demonstrated by the decrease of fluorescent cells and/or the inhibition of specific viral genome.

CONCLUSION

These results suggested that the DgGmM inhibited HSV-1 and PV-1 replication, with low cytotoxicity and high selectivity and, therefore, represents a potential candidate for further studies on the control of herpes and polio infections.

Antiviral effect of <em>Archidendron pauciflorum</em> leaves extract to hepatitis C virus: An <em>in vitro</em> study in JFH-1 strain

Background: Hepatitis C virus (HCV) is a leading cause of chronic liver diseases. Drug resistance to the regimen is also increasing. Hence, there is a need for new anti-HCV agents that are less toxic and more efficacious. The aim of this study is to evaluate the  possibility of A. pauciflorum extracts can be a antiviral drug.Methods: Huh-7it cells were infected with the HCV genotype 2a strain JFH-I in the presence of methanol extracts of Archidenron pauciflorum. The methanol extract further partition used n-hexane, ethyl acetate, n-butanol, and water showed in which butanol extracts exerted the strongest IC50 (6.3 g/ml). Further, the butanol fraction was fractionated and yielded into 13 fractions.Results: The methanol extract of the leaves of A. pauciflorum exhibited concentration dependent inhibition against the JFH1 strain of HCV genotype 2a with an IC50 is 72.5 μg/ml. The butanol fraction exhibited the highest anti-HCV activity with an IC50 is 6.3 μg/ml. The butanol fraction was fractionated which yielded 13 fractions. Fractions 5 and 13 exhibited high anti-HCV activities with IC50 is 5.0 μg/ml and 8.5 μg/ml and a time-of-addition study demonstrated that fraction 5 inhibited viral infection at the post-entry step, whereas fraction 13 primarily inhibited the viral entry step.Conclusion: The extract A. pauciflorum can be used as a herbal-based antiviral drug.

Chemically sulfated natural galactomannans with specific antiviral and anticoagulant activities

Naturally occurring galactomannans were sulfated to give sulfated galactomannans with degrees of substitution of 0.7-1.4 per sugar unit and molecular weights of M¯n=0.6×10(4)-2.4×10(4). Sulfated galactomannans were found to have specific biological activities in vitro such as anticoagulant, anti-HIV and anti-Dengue virus activities. The biological activities were compared with those of standard dextran and curdlan sulfates, which are polysaccharides with potent antiviral activity and low cytotoxicity. It was found that sulfated galactomannans had moderate to high anticoagulant activity, 13.4-36.6unit/mg, compared to that of dextran and curdlan sulfates, 22.7 and 10.0unit/mg, and high anti-HIV and anti-Dengue virus activities, 0.04-0.8μg/mL and 0.2-1.1μg/mL, compared to those curdlan sulfates, 0.1μg/mL, respectively. The cytotoxicity on MT-4 and LCC-MK2 cells was low. Surface plasmon resonance (SPR) of sulfated galactomannans revealed strong interaction with poly-l-lysine as a model compound of virus proteins, and suggested that the specific biological activities might originate in the electrostatic interaction of negatively charged sulfate groups of sulfated galactomannans and positively charged amino groups of surface proteins of viruses. These results suggest that sulfated galactomannans effectively prevented the infection of cells by viruses and the degree of substitution and molecular weights played important roles in the biological activities.

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.

Antiviral and Antioxidant Activities of Sulfated Galactomannans from Plants of Caatinga Biome

Dengue represents a serious social and economic public health problem; then trying to contribute to improve its control, the objective of this research was to develop phytoterapics for dengue treatment using natural resources from Caatinga biome. Galactomannans isolated from Adenanthera pavonina L., Caesalpinia ferrea Mart., and Dimorphandra gardneriana Tull were chemically sulfated in order to evaluate the antioxidant, and antiviral activities and the role in the inhibition of virus DENV-2 in Vero cells. A positive correlation between the degree of sulfation, antioxidant and antiviral activities was observed. The sulfated galactomannans showed binding to the virus surface, indicating that they interact with DENV-2. The sulfated galactomannans from C. ferrea showed 96% inhibition of replication of DENV-2 followed by D. gardneriana (94%) and A. pavonina (77%) at 25 µg/mL and all sulfated galactomannans also showed antioxidant activity. This work is the first report of the antioxidant and antiviral effects of sulfated galactomannans against DENV-2. The results are very promising and suggest that these sulfated galactomannans from plants of Caatinga biome act in the early step of viral infection. Thus, sulfated galactomannans may act as an entry inhibitor of DENV-2.

Antiviral effect of sulfated Chuanmingshen violaceum polysaccharide in chickens infected with virulent Newcastle disease virus

Newcastle disease virus (NDV) belonging to the Paramyxovirinae subfamily is one of the most devastating pathogens in poultry. Although vaccines are widely applied to control the infection, outbreaks of Newcastle disease (ND) repeatedly happen. Currently, there are no alternative control measures available for ND. In the present study, we found that sulfated Chuanmingshen violaceum polysaccharide (sCVPS) were potent inhibitors of NDV in specific pathogen free chickens infected with a virulent strain. With sCVPS treatment, the survival rate increased by almost 20% and virus titers in test organs, including brain, lung, spleen and thymus, were significantly decreased. The sCVPS also exhibited the ability to prevent viral transmission by reducing the amount of virus shed in saliva and feces. Higher concentrations of interferon α and γ in serum were detected in chickens treated with sCVPS, indicating that one of the antiviral mechanisms may be attributed to the property of immunoenhancement. Histopathological examination showed that sCVPS could alleviate the tissue lesions caused by NDV infection. These results suggest that sCVPS are expected to be a new alternative control measure for NDV infection and further studies could be carried out to evaluate the antiviral activity of sCVPS against other paramyxoviruses.

Antiviral Activity of Sulfated Polysaccharide of Adenanthera pavonina against Poliovirus in HEp-2 Cells

Adenanthera pavonina, popularly known as red-bead tree, carolina, pigeon's eye, and dragon's eye, is a plant traditionally used in Brazil for the treatment of several diseases. The present study aimed at evaluating the activity of sulfated polysaccharide from the Adenanthera pavonina (SPLSAp) seeds against poliovirus type 1 (PV-1) in HEp-2 cell cultures. The SPLSAp presented a cytotoxic concentration (CC₅₀) of 500 μg/mL in HEp-2 cell cultures, evaluated by the dimethylthiazolyl-diphenyltetrazolium bromide method (MTT). The SPLSAp exhibited a significant antiviral activity, with a 50% inhibitory concentration (IC₅₀) of 1.18 µg/mL, determined by plaque reduction assay and a high selectivity index (SI) of 423. The maximum inhibition (100%) of PV replication was found when the SPLSAp treatment was concomitant with viral infection (time 0 h), at all tested concentrations. The maximal inhibition was also found when the SPLSAp was used 1 h and 2 h postinfection, albeit at 50 μg/mL and 100 μg/mL. Therefore, we demonstrated that the SPLSAp inhibited PV growth. We also suggested that SPLSAp inhibited PV in more than one step of the replication, as the mechanism of antiviral action. We, therefore, selected the compound as a potential candidate for further development towards the control of the infection.