The country’s medical experts and chemists have identified at least 10 medicinal plants that possess phytochemicals with potential anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) activities, and have immunomodulatory properties that may strengthen one’s immune system against coronavirus disease (COVID-19).
In a 17-page review paper published in the October 2021 issue of the Philippine Journal of Science (PJS), Dr. Fabian M. Dayrit of the Ateneo de Manila University (AdMU); Armando M. Guidote Jr. of the Philippine Institute of Pure and Applied Chemistry (PIPAC), Dr. Nina Gloriani, head of the Department of Science and Technology’s (DOST) Vaccine Expert Panel, and six other experts said the 10 plants were selected from 100 of the best-studied medicinal plants with antiviral and immunomodulatory properties from three volumes of the “Encyclopedia of Philippine Medicinal Plants.”
“These are the Philippine medicinal plants with the highest number of botanical, pharmacological, and phytochemical publications, and with the longest history of documented use,” they said.
These plants were the following:
Allium spp. bulbs (bawang)
Andrographis paniculata (Burm.f.) Nees leaves (sinta)
Cocos nucifera L. oil (niyog)
Euphorbia hirta L. leaves (tawa-tawa)
Euphorbia neriifolia L. leaves (sorosoro),
Moringa oleifera Lam. leaves (malunggay)
Ocimum basilica L. leaves (balanoy)
Piper nigrum L. seeds (paminta)
Vitex negundo L. leaves (lagundi),
Zingiber officinale Roscoe rhizome (luya)
“The general antiviral and specific anti-SARS-CoV-2 activities and immunomodulatory properties of the phytochemicals that these plants contained were searched. While many compounds assessed individually using in vitro and in silico techniques suggest potential anti-SARS-CoV-2 or immunomodulatory effects, this review sought to identify the medicinal plants which contain these compounds and which, based on literature, have the best potential application against COVID-19,” read the review paper, entitled “ Philippine Medicinal Plants with Potential Immunomodulatory and Anti-SARS-CoV-2 Activities.”
The experts clarified that the objective of their paper is not to analyze the immunomodulatory and antiviral mechanisms of COVID-19, but to recommend the medicinal plants in the country that can be used in clinical studies against COVID-19 based on their phytochemical constituents.
“While medicinal plants are recognised for particular benefits, their effective and safe use against COVID-19 needs to be carefully studied to avoid conflicting outcomes,” they said.
They said only a few medicinal plants have actually undergone clinical trials against COVID. “It is hoped that this review will help identify those which have scientific evidence to be considered.”
Herbal immunomodulators were described as plants that can stimulate or suppress the innate or adaptive responses of immune system.
“Medicinal plants are multi-component agents that are able to modulate the complex immune system to defend itself against viral infections rather than directly act against the virus,” the experts explained.
They noted that the phytochemical constituents which have been identified in medicinal plants that exhibit favourable immunomodulatory properties include anthraquinones, flavonoids, terpenoids, alkaloids, polyphenolics, polysaccharides, proteins, fatty acids, and sulfur-containing compounds.
“Among these compound classes, the flavonoids and their glycosides have the highest number of documented cases.”
The experts likewise cited that many of the identified medicinal plants also have beneficial effects against comorbidities that are known risk factors for COVID-19.
These include A. sativum (bawang), and A. paniculata (sinta) for cardiovascular disease, chronic kidney disease, chronic respiratory disease, and diabetes mellitus; C. nucifera, and Z. officinale for chronic kidney disease, chronic respiratory disease, and diabetes mellitus; E. hirta (tawa-tawa) and O. basilicum (balanoy) for cardiovascular disease, chronic respiratory disease, and diabetes mellitus; E neriifolia (sorosoro) for chronic respiratory disease; M. oleifera (malunggay) for cardiovascular disease, and chronic kidney disease; and P. nigrum (paminta) and V. negundo (lagundi) for chronic respiratory disease, and diabetes mellitus.
“These are important additional benefits that are not found in many drug candidates,” the group said.
They recommended the implementation of a strategy based on prioritized plant sources, “given the urgent need for a response to the COVID-19 pandemic.”
“The plant sources should have a good safety margin, are available and affordable, and contain identified active constituents that can be standardised accordingly. However, it is important that clinical studies be done on standardised plant preparations."
Also involved the review paper were Sheriah Laine M. de Paz-Silava of the University of the Philippines (UP) Manila, Irene M. Villaseñor of UP Diliman, Rene Angelo S. Macahig of Andrew Moore and Associates Ltd., Singapore; Mario A. Tan of University of Santo Tomas; and Isidro C. Sia of the Integrative Medicine for Alternative Healthcare Systems (INAM) Philippines Inc.
The PJS is the country’s oldest peer-reviewed scientific journal. The first PJS issue was published in 1906.
The scientific journal is published by the Department of Science and Technology- Science and Technology Information Institute (DOST-STII).