Frangula purshiana · PhytoNexus

01 Identity and provenance

Accepted binomial: Frangula purshiana
Common names: Cascara Sagrada
Family (APG IV): Rhamnaceae
Part used: Bark
Verification tier: Tier 1 · chemistry only Taxonomy, plant part and marker chemistry are populated and stable. The clinical columns are deliberately empty because no primary source has been retrieved for them yet. Interactions shown below are rule predictions from the constituent chemistry, not clinical findings.
Reviewer note (2026 audit): TIER 1 populated (name, family, part, constituent class, marker) - stable taxonomic/phytochemical facts. TIER 2 columns (analogue, application, brand, interactions, side effects) left blank BY DESIGN - populate only from retrieved primary literature. Do not use clinically until Tier 2 is filled and a reference is recorded.

02 Constituent chemistry

Chemical class	Marker compound	Synthetic analogue in use
Anthraquinone glycosides	Cascarosides A-D Bark	none listed

The analogue column is what makes the interaction reasoning tractable: where a constituent has a marketed structural counterpart, the counterpart's interaction profile is the starting hypothesis for the plant.

Looking up structures and physicochemical properties from PubChem…

03 Stated application

Left empty by design — this is a Tier 1 entry, and the clinical columns are only populated once a primary source has been retrieved for them.

04 Interaction matrix

Predicted from constituent chemistry

These edges are not clinical findings. Each one is a rule inference: a constituent class in this plant is known to act on a target that the drug class also acts on. They are shown because a blank cell reads as “safe”, and for a Tier 1 entry a blank cell only means “not yet looked at”. Treat them as a literature-search agenda, not as a warning.

Drug class	Severity	Mechanism type	Provenance	Expected effect
Cardiac glycosides (digoxin, digitoxin) Cardiovascular	4Contraindicated	PD-additive + PK-transporter + assay interference	predicted D	Nausea, xanthopsia, bradyarrhythmia, AV block, ventricular tachycardia an…	why ▾
Chemistry of this pair. Hydroxyanthracene derivatives are colonic prokinetics activated by gut flora; chronic use produces potassium loss through the colon. Class mechanism. Cardenolide- and bufadienolide-bearing plants are themselves Na+/K+-ATPase inhibitors, so co-administration is pharmacological overdose. Several also inhibit intestinal P-glycoprotein, raising digoxin exposure, and cross-react with digoxin immunoassays so that serum levels become uninterpretable. Expected Nausea, xanthopsia, bradyarrhythmia, AV block, ventricular tachycardia and death; falsely reassuring or falsely high assay results. Management Treat as an absolute contraindication. If exposure has occurred, manage on ECG and clinical grounds, not on assay values, and consult toxicology about digoxin-specific Fab. Onset rapid Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism
Corticosteroids Endocrine	3Major	PD-additive + PK-CYP3A4	predicted D	Pseudohyperaldosteronism: hypertension, hypokalaemia, oedema, myopathy; C…	why ▾
Chemistry of this pair. Hydroxyanthracene derivatives are colonic prokinetics activated by gut flora; chronic use produces potassium loss through the colon. Class mechanism. Glycyrrhizin inhibits 11-beta-hydroxysteroid dehydrogenase type 2 and prolongs cortisol half-life, potentiating mineralocorticoid effect. Anthraquinone laxatives compound steroid-driven potassium loss, and CYP3A4 inhibition raises systemic corticosteroid exposure. Expected Pseudohyperaldosteronism: hypertension, hypokalaemia, oedema, myopathy; Cushingoid features at unchanged steroid dose. Management Restrict licorice-containing products. Check potassium and blood pressure. Reduce steroid dose if features of excess appear. Onset rapid Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism
Diuretics Renal	3Major	PD-additive + electrolyte-mediated	predicted D	Hypokalaemia, hyponatraemia, dehydration, muscle weakness, cramps, arrhyt…	why ▾
Chemistry of this pair. Hydroxyanthracene derivatives are colonic prokinetics activated by gut flora; chronic use produces potassium loss through the colon. Class mechanism. Aquaretic and saluretic botanicals add to renal potassium and sodium loss. Anthraquinone laxatives compound this through colonic potassium loss, and glycyrrhizin causes mineralocorticoid-like retention of sodium with kaliuresis. Expected Hypokalaemia, hyponatraemia, dehydration, muscle weakness, cramps, arrhythmia; potentiation of digoxin toxicity through low potassium. Management Check potassium, sodium and creatinine 1-2 weeks after starting. Avoid the combination entirely in patients also on digoxin. Onset rapid Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism
Laxatives and antidiarrhoeals Gastrointestinal	3Major	PD-additive	predicted D	Cramping, diarrhoea, electrolyte loss, melanosis coli with chronic anthra…	why ▾
Chemistry of this pair. Hydroxyanthracene derivatives are colonic prokinetics activated by gut flora; chronic use produces potassium loss through the colon. Class mechanism. Anthraquinone and mucilage botanicals add to stimulant and bulk laxative action; tannin-rich astringents oppose it. Expected Cramping, diarrhoea, electrolyte loss, melanosis coli with chronic anthraquinone use; or constipation and obstruction risk with astringents plus inadequate fluid. Management Limit stimulant laxative botanicals to under 2 weeks. Ensure adequate fluid intake with any bulk-forming product. Onset rapid Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism

05 Hazard register

The audit recorded no hazard beyond the interaction profile. The controlled-vocabulary field reads not assessed, which means the assessment has not been done rather than that it came back clear.

06 Confusable material

No same-genus or shared-common-name entry in the corpus.

07 Mechanism map

Chemistry sorts to the left, pharmacology to the right. Dashed edges are predicted. Drag nodes, scroll to zoom, export at 3× for a figure.

species

chemical class

marker compound

drug class

expected effect

hazard

08 Open literature

Abstract-scoped query built from this binomial, its common names and its marker compounds, run live against Europe PMC, PubMed and OpenAlex, then ranked locally against an evidence hierarchy.

Checking openFDA spontaneous reports…

09 Isomechanistic neighbours

Species whose interaction profile overlaps this one, ranked by shared severity weight rather than by count — a shared contraindication counts for more than a shared minor signal. Practical use: these are the plants you should not stack with this one, because the mechanisms summate.

Species	Family	Shared classes	Jaccard
Aloe barbadensis Mill Aloe Vera	Asphodelaceae	4	0.44
Rubia cordifolia Manjistha	Rubiaceae	4	0.36
Cassia fistula Amaltas	Fabaceae	4	1.00
Rheum emodi Rhubarb	Polygonaceae	4	1.00
Aloe ferox Cape Aloe	Asphodelaceae	4	1.00
Reynoutria japonica Japanese Knotweed	Polygonaceae	4	1.00

10 References and notes

No citation is on record for this entry. That is itself the finding: the audit flagged it, and it is why the entry does not carry an A evidence grade.

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