AYURVEDIC ANTIVIRAL AGENTS: OVERVIEW OF MEDICINAL PLANTS PERSPECTIVE

AYURVEDIC ANTIVIRAL AGENTS: OVERVIEW OF MEDICINAL PLANTS PERSPECTIVE

Ranu Choudhary *, Laxmikant Borse and Anil Jadhav

Department of Quality Assurance, Sandip Institute of Pharmaceutical Sciences, Mahiravani, Nasik, Maharashtra, India.

ABSTRACT: In recent years, it has been reported that many herbal plants contain antiviral agents which combat a human disease that is caused by pathogenic viruses. The natural products which are obtained from plants as antiviral agents against viruses have gone through researches to check the efficacy and potentials of the herbal products in the prevention of viral disorders. On the basis of randomized controlled studies and in-vivo studies, and in-vitro studies, some agents are utilized all across the globe. Progressively numerous studies on therapy of antivirals have been increased. Though, efficacy remains disputable for antiviral drugs that are employed for viral disorders. The viral diseases are challenging for the health of people around the world cause significant increase in mortality and enhance crises. There are many synthetic antiviral drugs that have a large number of side effects and have narrow therapeutic window range, while in the other hand herbal formulations have minimized side effects. The advantages of herbal formulation over synthetic drugs encourage us to devise and expand new herbal moieties against the emerging viral infections. The medicinal plants contain phytochemicals that have antiviral properties. In this paper, the activity of antiviral agents from medicinal plants which have importance in Ayurveda, are discussed along with their source.

Keywords: Medicinal plants, Antiviral agents, Ttherapeutic window range, Viral infections, Phytochemicals, Ayurveda

INTRODUCTION: Viral diseases are more threatening to public health day by day. Many numbers of viral diseases have been reported from different regions of the world ¹. The therapeutic potentials of medicinal plants recapped by various research programs ². For humans, plants are the crucial source of medicine. Day by day the demand for traditional medicine is increased. To achieve the health goals it is important to use the traditional medicines as per World Health Organisation. There is about at least 35000 species of plants which are used for the purpose of medicine.

About 700 herbal products are described along with their clinical effects and properties. Fifty categories of the herbs have been described according to their clinical effect as anti-inflammatory, antiviral, antiasthmatic, antihelminthic, antipyretic, anti-emetic, antipruritic, antidiarrhea, sedative, anti-epileptic, haemostatic, analgesic, haemopoietic, promoter of strength, semen and sperm, voice, complexion, wound healing etc. ³.

For primary health care, millions of people depend on the medicinal plant, but it is not limited to that; it is also for improvement of livelihood and generation of income ⁴. Herbal formulations are the basic foundation in many traditional medicinal systems worldwide wide ⁵. The active natural ingredients of higher plants have been studied for their potency against viruses on the basis of Siddha and Ayurveda traditional system of medicine; these studies revealed the virus’s e.g., feline immuno-deficiency virus, coxsackievirus, herpes simplex virus, influenza virus, respiratory syncytial virus, par influenza virus, etc. The medicinal plants contain several of the phytochemicals constituents, which are responsible for their property to treat diseases.

Among them, some have antiviral properties. Nowadays, people demanding alternative medicines other than conventional medicine shown by a recent survey in developing countries.

What is a Virus: A virus is an infectious agent or parasite of small size that itself reproduces. Viruses are called a link between living and nonliving. The multiplication of viruses occurs only in living cells such as plant cells, animal cells, and bacterial cells ⁶.

The genetic material of viruses is DNA or RNA. The genome is encompassed within the protein sheath called a capsid. The genetic material may be double or single-stranded. Capsids of viruses are regular arrays of one or a few types of protein. Almost every ecosystem has viruses.

A non-bacterial pathogen infecting tobacco plants was described by Dmitri Wanovsky's 1892 article. Tobacco Mosaic virus was discovered by Martinus Beijerink in 1898 ⁷.

Emerging Pathogenic Viruses: The public threat of emerging viruses is increasing day by day. The viral diseases are very dangerous; hence the scientists are continuously involved in the researches for the discoveries of antivirals for curing the new pandemics. Nowadays, coronavirus is spreading increasingly, which is of unknown origin.

Newly Emerging Viruses are given as below:

Coronavirus: Coronavirus is a single stranded RNA virus. The coronavirus is included in coronaviridae family. In humans, it causes a common cold, and complications that include pneumonia and SARS can occur ⁸.

Ebola Virus: The Ebola virus’s transferral occurs from the wild animals and in the humans by human to human transmission. It is Ebola hemorrhagic fever which causes fatal illness in humans. Ebola virus is a member of the filoviridae family.

West Nile Virus: It is an example of a mosquito-borne zoonotic virus caused by a change in the climate. It belongs to the family of Flaviviridae and is transmitted by mosquitoes.

Nipah Virus: It was first revealed in April 1999 in Malaysia on the pigfarm. It caused the outbreak of respiratory and neurological diseases. Symptoms of encephalitis in humans and respiratory in pigs were observed in outbreak ⁷.

Sin Nombre Virus: Sin Nombre virus is related to Hantavirus. The symptoms of the Hantavirus pulmonary syndrome (HPS) are fever, cough, headache, pulmonary edema, and death at the end. SNV belongs to the genus of Hantavirus of the family Bunyaviridae.

The reservoir of SNV infection is rodent carrier (the deer mouse); the inhalation of virus-contaminated deer mouse excretion is the mode of transmission of SNV about 66 ⁷. percent fatality rate of SNV induced HPS reported in the United States.

SARS-coronavirus (SARS): It is caused by SARS-CoV. It is viral respiratory disease. In bats high probability of SARS-CoV is originated on the basis of phylogenetic analysis and in humans it spreads directly or indirectly via animals held in the Chinese market. 8273 cases and 775 deaths were reported in China in the middle of November 2002 & July 2003.

MERS-Corona Virus: MERS-CoV is a novel coronavirus. In 2012 in Saudi Arabia, it was isolated out of a patient who suffered from acute Pneumonia. The fatality rate of MERS - CoV is higher than SARS-CoV up to 30%. 1084 cases and 439 deaths were reported in March 2015. Through dromedary camel MERS-CoV spreads from bats to human here is the list of major zoonotic viruses ^{7, 8}.

Natural Antiviral Agents: Natural antiviral agents are obtained from the medicinal plants which are described in Ayurveda along with their antiviral properties.

The extraction of the parts of medicinal plants gives the crude antiviral agents later; these crude products can be purified by using purification techniques such as chromatography ⁹.

These are obtained as active phytochemicals, including polyphenols, terpenoids, coumarins, alkaloids, phytosterols, glycosides, flavonoids, saponins, sulphides, lignans etc. ^{9, 10}.

Some antiviral agents from medicinal plants, including their mechanism of action, are explained in Table 2 ^{3, 4, 6, 11}.

TABLE 1: LIST OF MAJOR ZOONOTIC VIRUSES ^{7, 8}:

TABLE 2: ANTIVIRAL AGENTS FROM MEDICINAL PLANTS, INCLUDING THEIR MECHANISM OF ACTION ON THE VIRUS

N/A=Not Available, HIV=Human Immunodeficiency Virus, HSV=Herpes Simplex Virus, EBR=Epstein Barr Virus, RSV=Respiratory Syncytial Virus.

Mechanism of Action of the Antivirals Obtained from Plants: The natural antiviral agents obtain from plants as phytochemicals ⁹. This phyto-chemicals acts on the virus during the infection of the host cell by the virus & inhibits further viral infection. The infection of the host cell by virus involves the following steps refer Fig. 1. The first step is the adsorption of the virus on the surface of the host cell. This occurs due to the interaction of glycoprotein present on the surface of the virus with a transmembrane receptor on host cell surface.

• After adsorption, penetration of virus through cell wall occurs.
• Then the uncoating of the virus involves the deliverance of genetic material.
• This delivered genetic material integrates, or it may remain exist in the nucleus with the host's genetic material, and this interferes with replication, transcription, and translation processes and protein synthesis occurs.
• These proteins assemble and form virions and release by the process of exocytosis ³.

The natural antiviral drugs can act on different steps as given above and inhibit viral replication in viral synthesis. The adsorption of virus on the surface of host cell in first step. Inhibition of these step occurs by natural agents such as Quercetin, epigallocatechine-3-gallate, Ajoene, allicin tannin such as prodelphinidin B-2, 3, 3’-di-O-gallate etc. ^{6, 12} penetration through a cell wall is inhibited by apigenin, ursolicacid, lectins, lignin-carbohydrate complex etc ⁴. After uncoating, the early enzymes and gene products are formed for control of nucleic acid synthesis. This step is inhibited by antiviral agents such as calanolide a, inophyllum, etc ^{4, 13}. Which inhibit the reverse transcriptase enzyme. The inhibition of transcription, translation, DNA replication process can be done by Triterpene saponin, glycyrrhizic acid, meliacarpin, vasicine, scopadulcic acid, acid polysaccharides, quercetin and its derivatives, meliacarpin, scopadulcic acid B etc ^{12, 13}. The viral neuraminase resonsible for release of virus from host cell, this neuraminase is inhibited by with aferin. One more recognised mechanism of action of opposing viruses carrying DNA as genome is the demolition of coating of virus facilitated by natural antivirus such as anthraquinones like aloe emodin.

FIG. 1: MECHANISM OF ACTION OF ANTIVIRALS OBTAINED FROM PLANT SOURCE

CONCLUSION: Keeping in view it has been concluded that in Ayurveda, many of the medicinal plants contain similar phytochemicals that are responsible for their antiviral property.

The enzymes which are essential for viral replication are targeted by phytochemicals procured from plants and acts on different stages of viral replication. The mechanism to target the virus of many phytoconstituents has not been discovered yet. The discoveries & researches on these phytochemicals for their mechanisms to target the viruses are in progress throughout the globe. In this era of emerging viral infections, new bioactive moieties should be discovered. The medicinal plants are taken as a source for a finding of new antiviral agents with potent antiviral activity than conventional antiviral compounds.

ACKNOWLEDGEMENTS: I acknowledge support from my guide Dr. Laxmikant Borse and co-guide Dr. Anil Jadhav.

CONFLICTS OF INTEREST: The author declares no conflicts of interest.

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    How to cite this article:

    Choudhary R, Borse L and Jadhav A: Ayurvedic antiviral agents: overview of medicinal plants perspective. Int J Pharm Sci & Res 2021; 12(12):6214-20. doi: 10.13040/IJPSR.0975-8232.12(12).6214-20.

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