Tylosema esculentum (Marama) Tuber and Bean Extracts Are Strong Antiviral Agents against Rotavirus Infection

Ammi-visnaga extract; a novel phyto-antiviral agent against bovine rotavirus

The spread of bovine rotavirus has a great impact on animal productivity, milk products, and human public health. Thus, this study aimed to develop a novel, effective and accessible Phyto-antiviral treatment made from methanolic Ammi-visnaga seed extract against rotavirus infection. Rotaviruses were isolated from raw milk and cottage cheese samples randomly collected from Cairo and Qalubia governorates. They were all identified serologically, however, only three of them were both biologically and molecularly confirmed. The methanolic extract derived from Khella seeds (MKSE) was chemically analyzed with mass chromatography. The cellular toxicity of MKSE was tested on Caco-2 cells and its antiviral activity against one of the isolated bovine rotaviruses (BRVM1) was tested by both the cytopathic inhibition assay and the plaque reduction assay. Our results showed that 17.3% of the total collected 150 dairy samples were bovine rotavirus antigen positive. Three representatives of them were phylogenetically identified to be included in group A based on a 379 bp coat protein gene. Visnagin, Benzopyran, Khellin, and Benzenepropanoic acid were the major active components found in the MKSE. The maximum non-toxic concentration of MKSE was 5 µg/mL and the CC50 value was 417 µg/mL. The MKSE exhibited in-vitro antiviral activity against BRVM1 indicated by inhibition of the viral cytopathic effect (SI = 204.5, IP = 98%), causing a 1.5 log decrease in BVRM1 TCID50 and reducing the viral plaques count by the percentage of 93.14% at MNTC (5 ug/ml). In conclusion, our study showed that bovine rotavirus represents a severe health problem that needs attention in Egypt, and it supports using MKSE as a potential natural anti-rotavirus agent.

Medicinal plants: Treasure for antiviral drug discovery

The pandemic of viral diseases like novel coronavirus (2019-nCoV) prompted the scientific world to examine antiviral bioactive compounds rather than nucleic acid analogous, protease inhibitors, or other toxic synthetic molecules. The emerging viral infections significantly associated with 2019-nCoV have challenged humanity's survival. Further, there is a constant emergence of new resistant viral strains that demand novel antiviral agents with fewer side effects and cell toxicity. Despite significant progress made in immunization and regenerative medicine, numerous viruses still lack prophylactic vaccines and specific antiviral treatments that are so often influenced by the generation of viral escape mutants. Of importance, medicinal herbs offer a wide variety of therapeutic antiviral chemotypes that can inhibit viral replication by preventing viral adsorption, adhering to cell receptors, inhibiting virus penetration in the host cell, and competing for pathways of activation of intracellular signals. The present review will comprehensively summarize the promising antiviral activities of medicinal plants and their bioactive molecules. Furthermore, it will elucidate their mechanism of action and possible implications in the treatment/prevention of viral diseases even when their mechanism of action is not fully understood, which could serve as the base for the future development of novel or complementary antiviral treatments.

The Impact of Genetic Changes during Crop Domestication

Humans have domesticated hundreds of plant and animal species as sources of food, fiber, forage, and tools over the past 12,000 years, with manifold effects on both human society and the genetic structure of the domesticated species. The outcomes of crop domestication were shaped by selection driven by human preferences, cultivation practices, and agricultural environments, as well as other population genetic processes flowing from the ensuing reduction in effective population size. It is obvious that any selection imposes a reduction of diversity, favoring preferred genotypes, such as nonshattering seeds or increased palatability. Furthermore, agricultural practices greatly reduced effective population sizes of crops, allowing genetic drift to alter genotype frequencies. Current advances in molecular technologies, particularly of genome sequencing, provide evidence of human selection acting on numerous loci during and after crop domestication. Population-level molecular analyses also enable us to clarify the demographic histories of the domestication process itself, which, together with expanded archaeological studies, can illuminate the origins of crops. Domesticated plant species are found in 160 taxonomic families. Approximately 2500 species have undergone some degree of domestication, and 250 species are considered to be fully domesticated. The evolutionary trajectory from wild to crop species is a complex process. Archaeological records suggest that there was a period of predomestication cultivation while humans first began the deliberate planting of wild stands that had favorable traits. Later, crops likely diversified as they were grown in new areas, sometimes beyond the climatic niche of their wild relatives. However, the speed and level of human intentionality during domestication remains a topic of active discussion. These processes led to the so-called domestication syndrome, that is, a group of traits that can arise through human preferences for ease of harvest and growth advantages under human propagation. These traits included reduced dispersal ability of seeds and fruits, changes to plant structure, and changes to plant defensive characteristics and palatability. Domestication implies the action of selective sweeps on standing genetic variation, as well as new genetic variation introduced via mutation or introgression. Furthermore, genetic bottlenecks during domestication or during founding events as crops moved away from their centers of origin may have further altered gene pools. To date, a few hundred genes and loci have been identified by classical genetic and association mapping as targets of domestication and postdomestication divergence. However, only a few of these have been characterized, and for even fewer is the role of the wild-type allele in natural populations understood. After domestication, only favorable haplotypes are retained around selected genes, which creates a genetic valley with extremely low genetic diversity. These “selective sweeps” can allow mildly deleterious alleles to come to fixation and may create a genetic load in the cultivated gene pool. Although the population-wide genomic consequences of domestication offer several predictions for levels of the genetic diversity in crops, our understanding of how this diversity corresponds to nutritional aspects of crops is not well understood. Many studies have found that modern cultivars have lower levels of key micronutrients and vitamins. We suspect that selection for palatability and increased yield at domestication and during postdomestication divergence exacerbated the low nutrient levels of many crops, although relatively little work has examined this question. Lack of diversity in modern germplasm may further limit our capacity to breed for higher nutrient levels, although little effort has gone into this beyond a handful of staple crops. This is an area where an understanding of domestication across many crop taxa may provide the necessary insight for breeding more nutritious crops in a rapidly changing world.

In vitro screening for antiviral activity of Turkish plants revealing methanolic extract of Rindera lanata var. lanata active against human rotavirus

Background

Human rotavirus (HRoV) is the leading cause of severe gastroenteritis in infants and children under the age of five years. No specific antiviral drug is available for HRoV infections and the treatment of viral diarrhea is mainly based on rehydration and zinc treatment. In this study, we explored medicinal plants endemic to Turkey flora as a source of anti-HRoV compunds.

Methods

We performed an antiviral screening on Ballota macrodonta, Salvia cryptantha and Rindera lanata extracts by focus reduction assay. The extract with the highest selectivity index (SI) was selected; its antiviral activity was further confirmed against other HRoV strains and by virus yield reduction assay. The step of viral replicative cycle putatively inhibited was investigated by in vitro assays.

Results

The methanolic extract of R. lanata (Boraginaceae) showed the most favourable selectivity index. This extract exhibited a dose-dependent inhibitory activity against three different HRoV strains (EC₅₀ values ranging from 5.8 μg/ml to 25.5 μg/ml), but was inactive or barely active against other RNA viruses, namely human rhinovirus and respiratory syncytial virus. The R. lanata extract targets the early steps of HRoV infection, likely by hampering virus penetration into the cells.

Conclusion

These results make the R. lanata methanolic extract a promising starting material for a bioguided-fractionation aimed at identifying anti-HRoV compounds. Further work is required to isolate the active principle and assess its clinical potential.

Medicinal plants and natural molecules with in vitro and in vivo activity against rotavirus: A systematic review

BACKGROUND

Rotaviruses can cause life-threatening health disorders, such as severe dehydrating gastroenteritis and diarrhea in children. Vaccination is the main preventive strategy to reduce rotavirus diarrhea and the severity of episodes, but vaccines are not fully effective and new episodes may occur, even in vaccinated children. The WHO recommends oral rehydration therapy and zinc supplementation for rotavirus-induced diarrhea management. There is little preclinical evidence to support the use of phytotherapeutics in the management of rotaviral infections.

PURPOSE

We aim to review the use of medicinal plants and natural molecules in the management of rotavirus infections in experimental studies.

METHODS

Articles, published in the English language between 1991 and 2016, were retrieved from PubMed, Scopus and Web of Science using relevant keywords. The scientific literature mainly focusing on plant natural products with therapeutic efficacies against experimental models of rotavirus, were identified and tabulated. In addition, an assessment of the reliability of animal experiments was determined under ``Risk of Bias'' criteria.

CHAPTERS

After an initial search and a revision of the inclusion criteria, 41 reports satisfied the objectives of the study. 36 articles were found concerning the anti-rotaviral potential in rotavirus infected cell lines. Among the active secondary metabolites screened for rotavirus inhibition, the polyphenols of flavonoid structure had acquired the highest number of studies in our survey, compared to phenolic acids, stilbenoids, tannins, pectins, terpenoids and flavonoid glycosides. Also, many phytochemicals reduced the efficacy of viral capsid proteins foremost to their elimination and improved the tendency of host-cell inhibiting virus absorption or by prevention of viral replication. Furthermore, five in vivo studies reported that herbs, as well its components, reduced the duration and severity of diarrhea in mice and piglets. The anti-rotavirus efficacy were highlighted based on improvements in reduction on liquid stool, fecal virus shedding, small intestinal histology, levels of inflammation related cytokines and signaling receptors. However, the quality of the experiments in animal studies contained certain types of bias in terms of how they were conducted and reported.

CONCLUSION

We identified and summarized studies on medicinal plants and natural molecules having anti-rotavirus activity in order to further future developments of cures for rotavirus gastroenteritis.

In vitro Antiviral Activity of Rubia cordifolia Aerial Part Extract against Rotavirus

The root of Rubia cordifolia has been used traditionally as a hemostatic agent, while the aerial part of the plant consisting of leaf and stem is known to exhibit anti-diarrheal properties and has been widely used as a remedy in many parts of China. As rotavirus is one of the most commonly associated diarrhea-causing pathogen, this study aims to investigate the anti-rotaviral effect of R. cordifolia aerial part (RCAP). The cytotoxicity of RCAP toward MA-104 cells was evaluated using the WST-8 assay. Colloidal gold method and real time polymerase chain reaction (qPCR) assay were used to confirm the findings of the antiviral assay. Then, 4',6-diamidino-2-phenylindole (DAPI) staining method was subsequently used to investigate the mode of death among the cells. And the representative components of aqueous extract were isolated and identified. It was shown that both the viability of MA-104 cells and the viral load were reduced with increasing concentration of the extract. DAPI staining showed that virus-induced apoptosis was the cause of the low cell viability and viral load, an effect which was accelerated with incubation in the aqueous herbal extract. The major compounds postulated to exhibit this activity were isolated from the aqueous herbal extract and identified to be compounds Xanthopurpurin and Vanillic Acid. This study showed that RCAP extract effectively inhibited rotavirus multiplication by promoting virus-induced apoptosis in MA-104 cells.

Therapeutic and Prophylactic Potential of Morama (Tylosema esculentum): A Review

Tylosema esculentum (morama) is a highly valued traditional food and source of medicine for the San and other indigenous populations that inhabit the arid to semi-arid parts of Southern Africa. Morama beans are a rich source of phenolic acids, flavonoids, certain fatty acids, non-essential amino acids, certain phytosterols, tannins and minerals. The plant's tuber contains griffonilide, behenic acid and starch. Concoctions of extracts from morama bean, tuber and other local plants are frequently used to treat diarrhoea and digestive disorders by the San and other indigenous populations. Information on composition and bioactivity of phytochemical components of T. esculentum suggests that the polyphenol-rich extracts of the bean testae and cotyledons have great potential as sources of chemicals that inhibit infectious microorganisms (viral, bacterial and fungal, including drug-resistant strains), offer protection against certain non-communicable diseases and promote wound healing and gut health. The potential antinutritional properties of a few morama components are also highlighted. More research is necessary to reveal the full prophylactic and therapeutic potential of the plant against diseases of the current century. Research on domestication and conservation of the plant offers new hope for sustainable utilisation of the plant.

Inhibitory Effect of a Hot-Water Extract of Leaves of Japanese Big-Leaf Magnolia (Magnolia obovata) on Rotavirus-Induced Diarrhea in Mouse Pups

The leaf of Japanese big-leaf magnolia (Magnolia obovata Thunb.) has long been used as a natural packaging material for traditional foods in Japan. However, many of the physiological functions of the leaves against oral infection and resultant illness remain unclear. The aim of the present study was to investigate the effects of a hot-water extract of the leaves of Magnolia obovata on diarrhea induced by rotavirus (RV), a major cause of acute diarrhea. RV strain SA11 was mixed with the M. obovata leaf extract and inoculated orally to neonatal BALB/c mouse pups. Simultaneous inoculation of SA11 with the extract significantly decreased the incidence of diarrhea. In addition, the extract significantly inhibited cytopathic effects and mRNA expression of viral proteins in SA11-infected MA104 cells. Two flavonoid glycosides, quercitrin and rutin, were strongly suggested to be major anti-RV agents in the extract by serial solvent extraction and reversed-phase HPLC-ESI-MS analysis. Our results suggest that the hot-water extract of M. obovata leaves can be used as a medicine or food additive to prevent and ameliorate RV-induced diarrhea in individuals that may have difficulty in benefitting from the RV vaccines.

Anti-rotavirus effects by combination therapy of stevioside and Sophora flavescens extract

Anti-rotaviral activities of Sophora flavescens extract (SFE) and stevioside (SV) from Stevia rebaudiana Bertoni either singly or in various combinations were examined in vitro and in vivo using a porcine rotavirus G5[P7] strain. Combination of SFE and SV inhibited in vitro virus replication more efficiently than each single treatment. In the piglet model, SV had no effect on rotavirus enteritis, whereas SFE improved but did not completely cure rotaviral enteritis. Interestingly, combination therapy of SFE and SV alleviated diarrhea, and markedly improved small intestinal lesion score and fecal virus shedding. Acute toxicity tests including the piglet lethal dose 50, and body weight, organ weight and pathological changes for the combination therapy did not show any adverse effect on the piglets. These preliminary data suggest that the combination therapy of SV and SFE is a potential curative medication for rotaviral diarrhea in pigs. Determination of the efficacy of this combination therapy in other species including humans needs to be addressed in the future.

Extract of Scutellaria baicalensis inhibits dengue virus replication

BACKGROUND

Scutellaria baicalensis (S. baicalensis) is one of the traditional Chinese medicinal herbs that have been shown to possess many health benefits. In the present study, we evaluated the in vitro antiviral activity of aqueous extract of the roots of S. baicalensis against all the four dengue virus (DENV) serotypes.

METHODS

Aqueous extract of S. baicalensis was prepared by microwave energy steam evaporation method (MEGHE™), and the anti-dengue virus replication activity was evaluated using the foci forming unit reduction assay (FFURA) in Vero cells. Quantitative real-time polymerase chain reaction (qRT-PCR) assay was used to determine the actual dengue virus RNA copy number. The presence of baicalein, a flavonoid known to inhibit dengue virus replication was determined by mass spectrometry.

RESULTS

The IC(50) values for the S. baicalensis extract on Vero cells following DENV adsorption ranged from 86.59 to 95.19 μg/mL for the different DENV serotypes. The IC(50) values decreased to 56.02 to 77.41 μg/mL when cells were treated with the extract at the time of virus adsorption for the different DENV serotypes. The extract showed potent direct virucidal activity against extracellular infectious virus particles with IC(50) that ranged from 74.33 to 95.83 μg/mL for all DENV serotypes. Weak prophylactic effects with IC(50) values that ranged from 269.9 to 369.8 μg/mL were noticed when the cells were pre-treated 2 hours prior to virus inoculation. The concentration of baicalein in the S. baicalensis extract was ~1% (1.03 μg/gm dried extract).

CONCLUSIONS

Our study demonstrates the in vitro anti-dengue virus replication property of S. baicalensis against all the four DENV serotypes investigated. The extract reduced DENV infectivity and replication in Vero cells. The extract was rich in baicalein, and could be considered for potential development of anti-DENV therapeutics.

An evaluation of the inhibitory effects against rotavirus infection of edible plant extracts

Background

Rotaviruses are the single most important cause of severe diarrhea in young children worldwide. The developments of specific, potent and accessible antiviral treatments that restrain rotavirus infection remain important to control rotavirus disease.

Methods

150 plant extracts with nutritional applications were screened in vitro on MA-104 cells for their antiviral activity against rhesus rotavirus (RRV). One extract (Aspalathus linearis (Burm.f.) R.Dahlgren) was also tested for its effect on the loss of transepithelial resistance (TER) of Caco-2 cells caused by simian rotavirus (SA-11) infection.

Results

Aqueous extracts of Nelumbo nucifera Gaertn. fruit, Urtica dioica L. root, Aspalathus linearis (Burm.f.) R.Dahlgren leaves, Glycyrrhiza glabra L. root and Olea europaea L. leaves were found to have strong significant antiviral activity with a 50% inhibitory concentration (IC50) < 300 μg/ml. The pure compound 18ß-glycyrrhetinic acid from Glycyrrhiza glabra was found to have the strongest antiviral activity (IC50 46 μM), followed by luteolin and vitexin from Aspalathus linearis (IC50 respectively 116 μM and 129 μM) and apigenin-7-O-glucoside from Melissa officinalis (IC50 150 μM). A combination of Glycyrrhiza glabra L. + Nelumbo nucifera Gaertn. and Urtica dioica L. + Nelumbo nucifera Gaertn. showed synergy in their anti-viral activities. Aspalathus linearis (Burm.f.) R.Dahlgren showed no positive effect on the maintenance of the TER.

Conclusions

These results indicate that nutritional intervention with extracts of Nelumbo nucifera Gaertn., Aspalathus linearis (Burm.f.) R.Dahlgren, Urtica dioica L., Glycyrrhiza glabra L. and Olea europaea L. might be useful in the treatment of diarrhea caused by rotavirus infection.