Cistus incanus Prevents Viruses from Entering Cells – An In Vitro Clinical Study Summary

   Categories: Herbs, Supplements
17 Mar 2020

Cistus incanus (commonly known as rock rose) is a crucial ingredient in our V-Defence Formula™. In this post, we take a look at it’s observed ability to prevent viruses to docking onto a host cell’s membrane [1].

This feature was evidenced by Dr  Stephanie Rebensburg & team in 2016 with the results published in the prestigious Scientific Reports journal [1]. The paper can be accessed here and we discuss it’s key excerpts below.

Cistus incanus (Rock rose) flower

Cistus incanus (Rock rose) flower. Beautiful to humans, lethal to viruses.

A Quick Introduction of Cistus incanus

Also known as rock rose, Cistus incanus is a plant native to southern Europe and Northern Africa [1]. It boasts an elegant flower with purple petals.

The plant is sometimes enjoyed as an infusion tea or taken in concentrated, extract form. The leaves and stalk are the parts of the plant which are richest in antioxidants (flavonoids) and other bioactive alkaloids [2].

C. incanus has historically been used extensively in folk medicine as an anti-spasmodic, anti-mycotic and anti-viral agent and a remedy for diarrhoea.


General Observed Antiviral Activity

The antiviral properties of C. incanus have been documented by Rebensburg et al. (2016) in vitro against different strains of HIV and filoviruses [1]. Furthermore, Kalus et al. (2009) observed anti-viral activity in humans, in particular against influenza A [3]. We will discuss the results of Rebensburg et al. in greater detail below.

On a side note, C. incanus has also been found to exhibit antibacterial properties and has recently been observed to be effective against a strain of lyme-causing bacteria [4]. Please see our post on the subject for more information.


Antiviral Docking Mechanism of Cistus incanus

We look at the results presented by Rebensburg et al. (2016) [1]. The team were investigating the potential antiviral activity of different aqueous extracts of Cistus incanus against different strains of HIV and Filoviruses (such as Ebola and Marburg viruses).


In particular, 5 different extracts of C. incanus were used: an extract from a proprietary C. incanus product (CYSTUS052®), an extract from dried C. incanus herbs, a hot water extract from fresh plants and a polyphenol-enriched extract [1].

These were tested on 5 strains of HIV-isolate, including one resistant to conventional antiretroviral treatment (HIV-1V13-03413B), and synthetic Ebola & Marburg strains. Cultivated human cells were used as targets for the different viruses and fluorescent color was applied to visually assess the degree of infection [1].


When testing the outright effect of the various C. incanus extracts upon the various HIV strains, the research team noted that the various C. incanus extracts inhibited type 1 & type 2 HIV infections. In particular, they were also effective against the drug-resistant strain HIV-1V13-03413B . It was noted that the polyphenol-enriched C. incanus extract performed even better [1].

Crucially, the team observed that C. incanus-treated cells hardly showed any HIV-1 RNA genomes within them (figure B below). Through spinning disc confocal microscopy, it was also observed that C. incanus prevented the attachment of viruses onto host cells (figures C & D below – c.f. Ci & CiPP “attachment control”) [1].

This is believed to be triggered by an early inhibition of the replication cycle of HIV [1].


Cistus incanus - Rebensburg et al (2016) - Figure 3

Above: Cistus incanus blocks the invasion of cells by HIV. A) Inhibition of  replication mechanisms (using Time-of-addition Assay) B) Estimates of HIV genomic RNA – C. incanus extracts prevents the delivery of HIV RNA to cells.  C) Estimates of GFP-spots (number of HIV attachments onto cells) – C. incanus blocked the entry of HIV into cells. D) Representative images of each experiment’s sample. Note: CiPP = polyphenol-enriched Cistus incanus extractSource: Rebensburg et al. (2016) [1].

Furthermore, it was noted that C. incanus extracts were able to target the envelope proteins of the various tested HIV strains. Assessing infection using cells pre-incubated with C. incanus, resulted in lower infection levels lower than through simultaenous exposure, thus evidencing the antiviral activity of C. incanus on its own.

In addition, the research team did not observe that the various HIV strains developed any resistance to the C. incanus extracts during an observation period of 24 weeks [1].

The researchers observed similar protein envelope-targeting behavior on the Ebola & Marburg strains too [1].


The study by Rebensburg et al. showed that extracts from C. incanus not only inhibit many strains of HIV, Ebola & Marburg but crucially also prevent them from attaching onto host cells [1].

Ultimately, the study conlcludes that “These results demonstrate that Ci [Cistus incanus] extracts show potent and broad in vitro antiviral activity against viruses that cause life-threatening diseases in humans and are promising sources of agents that target virus particles” [1].

The authors credited in the paper are Stephanie Rebensburg, Markus Helfer, Martha Schneider, Herwig Koppensteiner, Josef Eberle, Michael Schindler, Lutz Gürtler & Ruth Brack-Werner.


Link to paper: [Full-text Article in Scientific Reports (Open Access)]


Scientific References

[1] Rebensburg S, Helfer M, Schneider M, et al. Potent in vitro antiviral activity of Cistus incanus extract against HIV and Filoviruses targets viral envelope proteins. Sci Rep. 2016;6:20394 [Scientific Reports (Open Access)].

[2] Dimcheva V, Karsheva M. Cistus incanus from Strandja Mountain as a Source of Bioactive Antioxidants. Plants(Basel). 2018;7(1) [PubMed:29373566]

[3] Kalus U, Grigorov A, Kadecki O, Jansen JP, Kiesewetter H, Radtke H. Cistus incanus (CYSTUS052) for treating patients with infection of the upper respiratory tract. A prospective, randomised, placebo-controlled clinical study. Antiviral Res. 2009;84(3):267-71. [PubMed:19828122]

[4] Feng J, Leone J, Schweig S, Zhang Y. Evaluation of Natural and Botanical Medicines for Activity Against Growing and Non-growing Forms of B. burgdorferi. Front Med. 2020;7. [Frontiers in Medicine (Open Access)]


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