A History and Analysis of Antiviral Medicinal Plants
The three plant species share similarities as to their location and characteristics. The three plant species were all collected within the United States and have samples that are housed in the UCLA Herbarium. Based on materia medica and research, scientists have found historical and modern-day evidence that these plants offer antiviral, antioxidant, anti-microbial, and anti-inflammatory properties. All of these plants have a long history of usage for a variety of ailments. For example, the water extract of Eclipta prostrata contains “one of the most inhibitory [activities] against HIV-1 integrase” (“Antiviral Plant Extracts”). Several compounds have been extracted from the plant with coumestan derivatives like wedelolactone showing particular antibacterial effects (Timalsina & Devkota). Other chemicals like saponins, phenolic acids, and flavonoids show some promise for the other uses of Eclipta prostrata. The plant is prepared in several ways, mainly involving a tea, decoction, or extract of the leaves, roots, or the whole plant (Jahan et al.). Another plant that shares antiviral properties, was collected in the United States, and has records stored in the UCLA herbarium is Astragalus nuttallii var. nuttallii. More specifically, the leaves of Astragalus nuttallii var. nuttallii are used in homeopathic treatments aimed at body rejuvenation. Therapies containing astragalus nuttallii var. nuttallii leaves can address weakness and fainting (“Astragalus menziesii- astragalus nuttallii leaf liquid,” 2018; “Astragalus menziesii- astragalus nuttallii leaf pellet,” 2020). The Chinese have used Astragalus plant roots to stave off disease, enhance immunity, lower blood pressure, and kill bacteria in humans for at least two millennia (Jiang et al., 2015). Currently, Astragalus roots are used to treat cancer, anemia, heart disease, colds, and diabetes (Mount Sinai, n.d.). The third species of plants that have historically exhibited antiviral properties is Sambucus canadensis. Its berries are edible and can serve as a source of vitamin C, an essential antioxidant that helps the body form proteins necessary for growth and survival. The inner and root bark can be used as a diuretic, emetic, and laxative, while the leaves and flowers are used as an antiseptic. Additionally, elderberry juice contains high levels of anthocyanins, a class of flavonoids which is known for its antiviral properties.
Despite the similarities between these three aforementioned plants, their individual therapies differ, especially in the production process. While treatments containing Sambucus canadensis are being developed into marketable products for widespread use, those containing Eclipta prostrata have specific uses in the various regions in which they are found. For example, the leaves and juice of Eclipta prostrata are used in a remedy for snakebites in Brazil and in Ayurvedic medicine on the Indian subcontinent. It’s notable that the flowers are rarely used compared to the leaves, shoots, and juice of the plant. Eclipta prostrata is traditionally consumed as a decoction or tea of certain parts of the plant. Meanwhile, therapies made from Astragalus nuttallii var. nuttallii leaves have not been evaluated or approved for use by the Food and Drug Administration “Astragalus menziesii- astragalus nuttallii leaf liquid,” 2018; “Astragalus menziesii- astragalus nuttallii leaf pellet,” 2020).
The three plant species differ somewhat in their origins, herbal preparations, and phytocompounds. Eclipta prostrata can be found within the United States but most of its range is found within humid, tropical areas such as India, China, Brazil, and Southeast Asia. Astragalus nuttallii var. nuttallii however is found only along the California coast (Calflora, n.d.). Sambucus canadensis lives across North and South America. Furthermore, these plants differ greatly in their structure. Astragalus nuttallii var nuttallii is a small perennial plant with compound leaves and purple flowers (“Astragalus Nuttallii, Nuttall's Milkvetch,” n.d.). Eclipta prostrata is a summer annual with purplish stems and small white flowers. Eclipta prostrata grows to less than 2 feet tall and stays close to the ground. On the other hand, Sambacus canadensis is a woody deciduous shrub or small tree and can grow between 9 and 12 feet tall. While Eclipta prostrata and Sambacus canadensis have whole leaves, Astragalus nuttallii var nuttallii leaves are made of smaller leaves – likely an adaptation to an environment with high levels of sun exposure. Eclipta prostrata has wedelolactones, flavinoids, and phenolic acids while the juices of the fruit of Sambucus canadensis contain anthocyanins, which are known for having antiviral properties. Astragalus nuttallii var. nuttallii have Astragalosides II and IV, saponins, and flavonoids, which are all “immunologically active” compounds (Hong et al., 2011, 6-7). Even with these differences in physical appearance, compounds, and taxonomy, these plants have separately evolved to possess antiviral properties.
Eclipta prostrata, Sambucus canadensis, and Astragalus nuttallii var. nuttallii are all examples of plants whose medicinal uses will likely have significant implications in a world dominated by synthetic compounds whose efficacy is waning by the day. All species have antiviral properties that can treat common ailments. The juice and leaves of Eclipta prostrata are most commonly concocted to treat hepatic/liver ailments (i.e., hepatitis, jaundice), gastrointestinal illnesses, and wound infections. Most notably, it is also used to kill and inhibit the growth of disease-carrying vectors like mosquitos. Sambucus canadensis can treat headaches, kidney problems and mucous congestion in addition to weakening influenza viruses A and B. Astragalus nuttallii var. nuttallii leaves can increase energy levels, while astragalus roots can treat colds and certain kinds of cancer (Mount Sinai, n.d.).
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