Are There Herbs That May Kill Viruses?

I love herbal medicine. At the onset of 2020 health crisis I wondered: “Do I know of herbs growing in Croatia that may be able to cure viral infections?” I did some research and, among many, I came up with these two herbs:

  • Rockrose (bušin in Croatian, or Cistus spp.)
  • Olive Leaf (list masline in Croatian, or Olea Europea leaf)

Apparently, the list does not stop there. I’ve discovered that many herbs that grow in Croatia expressed anti-viral activity. I will, however, focus on these two in this article.

Does Herbal Medicine Really Work?

I’ve been interested in herbal medicine since my childhood. My first knowledge of herbs I got from my grandfather. He would always have pockets full of seeds that he would plant everywhere.

When he came to visit us, he would come with paper bags filled with strange dry herbs. And he knew how to use them.

This knowledge is becoming rare today. We resort to all kinds of pills and capsules to alleviate our symptoms.

Interestingly, though, modern science is becoming increasingly aware of this ancient wisdom. Scientific papers investigate the medicinal properties of herbs that were attributed healing powers by the traditional medicine. Surprisingly or not, in many cases they have confirmed the ancient findings.

The health crisis of 2020 has created anxiety and fear. Especially since the proven cure was absent. Many tried to provide a solution and search for possible therapies.

Which plant would kill a virus? Well, traditional herbal remedies were usually prepared by people who were unaware of the existence of viruses. However, they noted some positive effects that herbs had on actual symptoms. Inadvertently or not, they got it right!

I was motivated to do my personal research and compare the traditional knowledge with the findings of modern medicine. I was looking for herbs that may provide protection against or even cure viral infections.

I have found some interesting information on plants and herbs that virtually grow in my backyard, all over the island of Čiovo in Croatia.

In the Mediterranean region, humans have always lived in harmony with nature.

This scene from the island of Čiovo, Croatia, shows dry walls that were once quintessential of farming in Dalmatia.

Herbs that naturally grow in the wild come with properties that help them survive the long and dry summer months and to defend themselves against disease and pests.

These properties are usually the healing agents in herbs, recognised by traditional herbal medicine.

Please, keep in mind that I am not a doctor. I am not giving any medical advice or prescribing a therapy. If you are ill, please talk to a medical professional before resorting to any alternative therapy, including using herbs.

Rockrose (bušin in Croatian, or Cistus spp.)

Rockrose, or Cistus incanus, with seed pods

The rockrose (Cistus) is an ancient and potent medicinal plant from the Mediterranean. The first mention of the use of the rockrose for medicinal purposes dates back to the 4th century BC. It was commonly used in religious rituals, so that the rock rose was a frequently buried with the deceased.

The healing properties of the rock rose are impressive: diarrhoea, skin problems, canker sores, candida and flu-like infections. The plant can therefore be used in prevention or as a therapy for a wide variety of complaints .

The rock rose is a small bush that is native to the Mediterranean. In hot summers, the rock rose simply folds its leaves and waits for the next rain. It can remain in this inconspicuous form for months.

The leaves of the rock rose are used to make teas and oils. Due to their high resin content, they are sticky. Tea made of its leaves has a pleasant and slightly resinous flavor, too.

After the first autumn rain, it opens its leaves and forms thick flower buds over the winter. In spring, the delicate petals appear.

Rockrose Works Against Bacteria And Fungal Infections

In 1999, a study by the University of Marrakesh / Morocco was published in a specialised journal. It showed powerful in vitro antibacterial and anti-fungal effects of the leaf extracts from Cistus incanus and Cistus monspeliensis.

Rockrose For Colds And Flu

In 2009 the first clinical studies with the rock rose were carried out. Researchers at the Charité in Berlin initiated a randomized and placebo-controlled study with 160 patients with a cold (upper respiratory tract infections). They received a rockrose extract (CYSTUS052), which contains a high percentage of polyphenols and has already proven itself in the past as a strong antiviral agent against flu.

Most cold symptoms and also the inflammation marker CRP decreased significantly in the rockrose group, while there was a barely noticeable improvement in the placebo group.

Another study reached similarly exciting conclusions:

CYSTUS052, a plant extract from a variety of Cistus incanus , rich in polymeric polyphenols, exhibits antiviral activity against a highly pathogenic avian influenza A virus (H7N7) in cell culture and in a mouse infection model.

In vitro and in vivo treatment was performed with an aerosol formulation, because the bioavailability of high molecular weight polyphenols is poor. In MDCK cells, a 90% reduction of plaque numbers on cells pre-incubated with the plant extract was achieved.

Mice treated with CYSTUS052 did not develop disease, showed neither differences in their body temperature nor differences in their gross motor-activity and exhibited no histological alterations of the bronchiolus epithelial cells.

Droebner K, Ehrhardt C, Poetter A, Ludwig S, Planz O. CYSTUS052, a polyphenol-rich plant extract, exerts anti-influenza virus activity in mice. Antiviral Res. 2007;76(1):1-10. doi:10.1016/j.antiviral.2007.04.001

Olive Leaf (list masline in Croatian, or Olea Europea leaf)

Knowledge of the healing properties of the olive, its fruit oil and leaves, is not a recent discovery. It is known that even the ancient Egyptians valued the unusual properties of olive leaves, considering them a symbol of divine power and using them in the process of mummifying their kings.

Medical reports from the 1850s testify to the use of olive leaves in the treatment of malaria, and recent research, intensified in the second half of the 20th century, confirms the strong antiviral, antifungal, antibacterial, and antiparasitic effects of olive leaf extract. It is believed that the compounds present in olive leaves strengthen the immune system, increase the body’s energy, have anti-inflammatory effects, lower blood pressure and cholesterol levels and reduce blood sugar levels.

Special attention was drawn to the report of a group of researchers on the exceptional antioxidant capacity of the liquid extract prepared directly from fresh olive leaves, which proved to be many times higher than the capacity of green tea and vitamin C.

There are a number of diseases and conditions in which olive leaf-based preparations have been shown to be effective: urinary tract infections, botulism, chicken pox, chlamydia, colds, flu, human papillomavirus (HPV) diseases, fungal infections, hepatitis A, B and C , herpes, tuberculosis, diabetes, encephalitis, mumps, arthritis, heart disease …

What is the secret of the healing properties of olive leaves? The medicinal properties of the leaves are due to the bioactive components contained in them. Oleuropein, a bitter phenolic glycoside, is the main ingredient of olive leaves and has a number of pharmacological properties – it has antimicrobial, antiviral and anti-inflammatory effects, protects the skin and prevents aging, and its positive effects in preventing atherosclerosis and antitumor activity have been observed.

Oleuropein is also found in olive fruit and oil, but it is mostly found in the leaves. Hydroxytyrosol is a product of the breakdown of oleuropein and one of the strongest antioxidants known today, which has antibacterial properties and the ability to stimulate the immune system.

Although the strong antiviral and antimicrobial activity of oleuropein – the main ingredient in olive leaf extract – has been confirmed, the exact mechanism of this action has not been fully elucidated.

Its ability to cause changes or damage to bacterial membranes and to slow down or disable the action of bacterial enzymes, thus preventing the harmful action of bacteria, has been observed.

Oleuropein has also been shown to be effective in cases of viral infections because it has the ability to enter a virus-infected cell where it prevents the virus from multiplying.

There is a possibility of a side effect, the so-called Herxheimer’s reaction, which may occur when taking higher doses of olive leaf tea. This reaction is due to the exceptional effectiveness of the preparation and manifests itself as a mild and transient form of the symptoms of the virus. It occurs in response to the increased presence of destroyed microorganisms that the body is unable to remove immediately.

After the elimination of destroyed microorganisms and toxins, the symptoms disappear, so it is recommended to drink plenty of fluids to speed up the process. Olive leaf extract is not recommended, however, to be taken at the same time as antibiotics, as it can lead to their inactivation.

How to make olive leaf tea

Put about 10 g of dried and shredded olive leaves (alone or in combination with other types of herbs) in 2-2.5 dl of boiled water. Stir and reduce the heat and let it simmer for 3-4 minutes. Then cover the bowl and let it rest for an additional 10-15 minutes, and then strain the tea. Drink it fresh, hot or cold.

A commercial plant extract derived from olive tree leaf (Olea europaea) (LExt) and its major compound, oleuropein (Ole), inhibited the in vitro infectivity of the viral haemorrhagic septicaemia virus (VHSV), a salmonid rhabdovirus. Incubation of virus with LExt or Ole before infection reduced the viral infectivity to 10 and 30%, respectively.

Furthermore, LExt drastically decreased VHSV titers and viral protein accumulation (virucidal effect) in a dose dependent manner when added to cell monolayers 36 h post-infection. On the other hand, both the LExt and Ole were able to inhibit cell-to-cell membrane fusion induced by VHSV in uninfected cells, suggesting interactions with viral envelope.

Therefore, we propose that O. europaea could be used as a potential source of promising natural antivirals, which have demonstrated to lack impact on health and environment. In addition, Ole could be used to design other related antiviral agents.

Micol V, Caturla N, Pérez-Fons L, Más V, Pérez L, Estepa A. The olive leaf extract exhibits antiviral activity against viral haemorrhagic septicaemia rhabdovirus (VHSV). Antiviral Res. 2005;66(2-3):129-136. doi:10.1016/j.antiviral.2005.02.005

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