# Drosera rotundifolia (Sundew)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/drosera-rotundifolia
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-02
**Evidence Score:** 2 / 10
**Category:** European
**Also Known As:** Round-leaved sundew, Common sundew, Droserae Herba, Sundew herb, Dew plant, Lustwort, Red rot, Youthwort, Moor grass, Sonnentau

## Overview

Drosera rotundifolia, commonly called sundew, is a carnivorous plant whose bioactive naphthoquinones — primarily plumbagin and 7-methyljuglone — drive its medicinal activity. These compounds inhibit phosphodiesterase enzymes PDE1A and PDE4D in airway smooth muscle, producing antispasmodic and mucociliary-supporting effects relevant to respiratory conditions.

## Health Benefits

• May support respiratory health by stimulating bronchial epithelial cell function and increasing ciliary beat frequency (preliminary in vitro/ex vivo evidence only)
• Demonstrates antispasmodic effects on airway smooth muscle through PDE1A/PDE4D inhibition (ex vivo murine studies)
• Shows [antiviral](/ingredients/condition/immune-support) activity against coxsackieviruses CVA9/CVB3 at 1-10% concentrations (in vitro evidence, p<0.0001)
• Inhibits biofilm formation in multidrug-resistant E. coli (in vitro 3D mucosa models)
• Exhibits [anti-inflammatory](/ingredients/condition/inflammation) effects at 500 μg/pellet doses (in ovo HET-CAM assay)

## Mechanism of Action

Drosera's naphthoquinone constituents, particularly plumbagin and 7-methyljuglone, inhibit cyclic nucleotide phosphodiesterases PDE1A and PDE4D in bronchial smooth muscle, elevating intracellular cAMP and cGMP levels to produce bronchodilation and antispasmodic effects. Separately, these compounds stimulate bronchial epithelial ciliary beat frequency in ex vivo models, suggesting a mucociliary clearance mechanism independent of adrenergic pathways. [Antiviral](/ingredients/condition/immune-support) activity has been attributed to naphthoquinone-mediated disruption of viral replication machinery, though the precise molecular targets in human pathogens remain under investigation.

## Clinical Summary

Clinical evidence for Drosera rotundifolia is largely limited to traditional use documentation, ex vivo murine airway studies, and in vitro cell assays, without large-scale randomized controlled trials in humans. Ex vivo studies on murine tracheal preparations demonstrated measurable reductions in carbachol-induced smooth muscle contraction attributable to PDE inhibition. The ESCOP monograph recognizes Drosera for use in dry, spasmodic, and irritating coughs based on a combination of pharmacological plausibility and longstanding European herbal tradition, rather than robust Phase II or Phase III clinical data. Practitioners and consumers should interpret current evidence as preliminary, supporting plausibility rather than confirmed clinical efficacy.

## Nutritional Profile

Drosera rotundifolia is a carnivorous botanical used medicinally rather than as a conventional food source; macronutrient content (carbohydrates, protein, fat) is not nutritionally significant at therapeutic doses. Key bioactive compounds include: Naphthoquinones — plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone, estimated 0.1–1.2% dry weight) and 7-methyljuglone, considered primary pharmacologically active constituents; Flavonoids — quercetin, kaempferol, and hyperoside (quercetin-3-galactoside), with hyperoside reported at approximately 0.5–2.0 mg/g dry weight in some aerial part extracts; Phenolic acids — ellagic acid, gallic acid, and chlorogenic acid present in measurable but variable concentrations depending on harvest conditions; Proteolytic enzymes — digestive proteases (e.g., plumbase) concentrated in leaf glands, functionally active but not nutritionally relevant at medicinal doses; Tannins — ellagitannins and gallotannins contributing astringent properties, estimated 3–8% dry weight; Mucilages — polysaccharide-based mucilaginous secretions in glandular tentacles; Minerals — trace calcium, potassium, and magnesium absorbed from prey, concentrations highly variable and not standardized. Bioavailability note: Plumbagin demonstrates moderate oral bioavailability with lipophilic character (LogP ~1.6) facilitating membrane permeation; flavonoid glycosides require intestinal hydrolysis prior to absorption. Standardized extracts are typically characterized by plumbagin or total naphthoquinone content. Vitamin content is negligible at therapeutic doses.

## Dosage & Preparation

No clinically studied human dosage ranges exist. In vitro studies used 1000-fold diluted ethanolic extracts (3× homeopathic dilution) for 3-6 hours on cell cultures, and 1-10% extract concentrations for [antiviral](/ingredients/condition/immune-support) effects. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Drosera rotundifolia is generally considered well-tolerated at traditional herbal doses, with no serious adverse events documented in published literature at typical therapeutic amounts, though systematic safety trials in humans are lacking. The naphthoquinone plumbagin exhibits cytotoxic properties in high-concentration in vitro models, raising theoretical concern about long-term or high-dose use that has not been evaluated in human pharmacokinetic studies. Potential interactions with phosphodiesterase inhibitor medications (e.g., theophylline, sildenafil) are theoretically plausible given shared mechanisms, warranting caution in patients on these drugs. Use during pregnancy and lactation is not recommended due to insufficient safety data, consistent with ESCOP guidance.

## Scientific Research

No human clinical trials, RCTs, or meta-analyses were identified for Drosera rotundifolia. Available evidence is limited to preclinical in vitro studies on human bronchial epithelial cells (16HBE line) and ex vivo murine airway studies, plus [antimicrobial](/ingredients/condition/immune-support) assays on cell cultures and 3D mucosa models.

## Historical & Cultural Context

Drosera rotundifolia has been used in European phytotherapy and homeopathy for centuries to treat respiratory diseases, coughs, and pulmonary conditions. The dried aerial parts (Droserae Herba) are accepted in various pharmacopeias, with therapeutic effects traditionally attributed to its flavonoid and naphthoquinone content.

## Synergistic Combinations

Thyme, Ivy leaf, Marshmallow root, Elderberry, Echinacea

## Frequently Asked Questions

### What is Drosera rotundifolia used for in herbal medicine?

Drosera rotundifolia has been used in European herbal medicine primarily to relieve dry, irritating, and spasmodic coughs, including those associated with whooping cough (pertussis) and bronchitis. The ESCOP monograph formally recognizes this traditional use, supported by pharmacological evidence showing PDE1A/PDE4D inhibition in airway smooth muscle tissue that reduces bronchospasm.

### What are the active compounds in sundew supplements?

The primary bioactive compounds in Drosera rotundifolia are naphthoquinones, specifically plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) and 7-methyljuglone, along with flavonoids such as quercetin and hyperoside. Plumbagin is considered the most pharmacologically active constituent, responsible for much of the antispasmodic, antiviral, and potential anti-inflammatory activity observed in laboratory studies.

### Does sundew have antiviral properties?

Preliminary in vitro research indicates that naphthoquinone compounds from Drosera rotundifolia exhibit antiviral activity against certain respiratory viruses, with plumbagin implicated as a key agent interfering with viral replication. However, these findings come exclusively from cell-culture studies, and no controlled human clinical trials have validated antiviral efficacy, meaning conclusions about its use as an antiviral supplement remain speculative.

### How does sundew compare to conventional cough medications?

Drosera works through PDE1A and PDE4D inhibition to relax airway smooth muscle, a mechanism partly overlapping with theophylline-class bronchodilators, but its potency and systemic bioavailability in humans have not been directly compared to pharmaceutical agents in head-to-head trials. Unlike codeine-based antitussives that suppress the cough reflex centrally, sundew is thought to address bronchospasm peripherally, making it mechanistically distinct, though clinical equivalence data do not exist.

### What is the typical dose of Drosera rotundifolia in supplements?

Traditional European herbal medicine guidelines, including those referenced by ESCOP, suggest a daily dose of approximately 3 g of dried herb or equivalent preparations (tincture or liquid extract standardized to naphthoquinone content) for adults. Standardized extracts vary widely by manufacturer, and because no human pharmacokinetic dose-finding trials have been completed, optimal dosing for specific outcomes like cough reduction has not been formally established.

### Is Drosera rotundifolia safe to use during pregnancy or while breastfeeding?

Safety data for sundew during pregnancy and lactation is limited, and it is generally recommended to avoid supplementation during these periods as a precautionary measure. Consult a healthcare provider before using sundew if you are pregnant, planning pregnancy, or breastfeeding, as traditional use does not guarantee safety in these vulnerable populations.

### Does Drosera rotundifolia interact with cough suppressants or other respiratory medications?

Sundew may have additive effects when combined with antitussive (cough-suppressant) medications or bronchodilators due to its antispasmodic properties and effects on airway function. It is advisable to consult a healthcare provider before combining sundew supplements with prescription respiratory medications to avoid unwanted interactions or effects.

### What does current clinical research show about sundew's effectiveness for cough relief?

While in vitro and ex vivo studies demonstrate antispasmodic and antiviral mechanisms, rigorous human clinical trials supporting sundew's efficacy for cough are limited compared to the evidence base for conventional treatments. The ingredient is included in WHO/EMA monographs for traditional respiratory support, but this designation is based on historical use rather than robust randomized controlled trials in humans.

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