As a result of many people turning to medicinal plants, such as guinea hen weed, bissy and papaya leaves, for assistance with the management of their Chikungunya virus (CHIKV) symptoms, against which conventional medicines seem to have little answers, many individuals are curious to know the scientific potential of medicinal plants in dealing with viral diseases.

It is for this reason that, based on a variety of requests, I have provided this article, based on scientific evidence, which is for information only.

For centuries, medicinal plants have been widely included in traditional folklore medicine in the Caribbean, and indeed all over the world. People tend to go for more of these plant-based remedies due to limited accessibility and high cost of pharmaceuticals.

Although many of the herbal medicines are used, they lack standardisation and often there is little or no proof of efficacy, appropriate dosage and potential toxicity. Additionally, there may be health problems associated with contamination of the herbs by reptiles, rodents and insects.

Nevertheless, plants have been recognised to have the ability to synthesise a wide variety of chemical compounds that can be used to perform important human biological functions, such as medications for a variety of ailments.

In Jamaica, for example, several plants have, over the years, been used to treat a wide range of illnesses such as diarrhoea, diabetes, fevers, coughs, wounds, among several others. It is this type of lead information that our Bio-Tech Institute sometimes evaluates for the scientific evidence of efficacy and safety.

In a global context, there is mounting hard, scientific evidence that proves the potential and actual medicinal properties of some of these plants. Over 12,000 chemical compounds have so far been isolated from a number of medicinal plants and it is estimated that only 10 per cent have so far been scientifically evaluated.

Compared with other bioactivity from medicinal plants, the antiviral potentials are relatively limited. Scientific studies have identified only a few plants that have the potential for treating viruses. An attempt will be made to identify some plants of international and clinical scientific repute, with the potential to provide antiviral medicines.

For convenience, the plants will be divided into two groups: (I) Global and (II) Caribbean/Jamaican:

(I) Global Plants

American ginseng (Panax quinquefolius) is a herbaceous perennial plant, commonly used as Chinese or herbal medicine. It is native to eastern North America, and is also cultivated in various places in Asia and particularly China. Randomised, double-blind, placebo-controlled clinical trials have shown it can prevent both colds and flu.

Studies show that a liquid extract from Elderberry (Sambucus nigra) displayed an inhibitory effect on the propagation of human pathogenic influenza viruses. Different parts of the plant were also found to have antiviral effects against the influenza virus.

The activity of Elderberry against other viral infections, including HIV and herpes, has also been studied. It was found to significantly reduce the infectivity of HIV strains in laboratory tests and to completely inhibit the replication of four strains of herpes simplex virus, including two strains resistant to the drug acyclovir (Zovirax).

Extracts of the Echinacea plant (E. purpurea), native to North America, from the roots and flowering parts of the plant have been shown in several clinical trials to be effective in reducing the severity and duration of symptoms in patients with common cold, upper respiratory tract infection and viral bronchitis.

Scientific research on the Olive plant (Olea europaea), found in Mediterranean countries, has shown that the leaves contain a bitter substance called Oleuropein, and is a potent inhibitor of a wide range of viruses in laboratory tests.

The calcium salt of Elenoic acid destroyed all of the viruses it was tested against, including influenza, herpes, polio and coxsackie viruses.

Green tea (Camellia sinensis), extensively consumed in Chinese folklore practices, contains a group of flavonoids called catechins, which appear to inhibit viral infections, such as HIV, herpes simplex and hepatitis B virus.

The infamous St John’s wort (Hypericum perforatum) found in Europe and Australia has revealed that it also has antiviral activity against influenza, herpes simplex, and HIV.

(II) Caribbean/Jamaican Herbs

Coming closer to home, garlic (Allium sativum) is not only known for its medicinal properties, but it is a common food ingredient. In laboratory studies, garlic was found to possess a wide variety of antiviral properties.

This antiviral activity is due to its hundreds of beneficial compounds, which work together (synergistically) to deliver its effects. Laboratory tests show that garlic’s antiviral activity is against the cold virus, various strains of influenza viruses and herpes simplex virus types I and II.

Recently, colleagues from the Bio-Tech R&D Institute and the University of Maryland, Institute of Human Virology found that bioactive chemicals from our own Lignum vitae plant (Guiacum Officinale) has demonstrated significant bioactivity against HIV and is now regarded as a potential antiviral drug candidate.

And, only a few weeks ago, the public was informed about guinea hen weed (Petivera alliacea) and its anti-HIV potential. It has joined Lignum vitae in this limited, yet special group of plants, with the potential to fight HIV. These two Jamaican plants are being further tested against other types of viruses and will be reported on in due course.

Finally, it might be of interest to note that a new pharmaceutical drug, ZMapp, is now being used to treat the dreaded Ebola virus.

As we are all now recognising, viral infections are serious issues, which have severe social and economic implications. We need to be responsible and research and develop whatever products we can to fight these diseases, in the same way that we are fighting cancer.

Notably, we must remember Taxol, derived from the Hew tree, and the anticancer compounds vincristine and vinblastine, from our own Vinca rosea (Ram Goat Roses) for their major anticancer properties and the wealth they have created for those who dared to research and develop these plant-based drugs.

In laboratory studies, garlic was found to possess a wide variety of antiviral properties. (PHOTO: Donovan Govan/Wikimedia Commons)