Subclass of Phenolics

Anthraquinones

Colored phenolic compounds that stimulate bowel motility — the active laxative principle of several barks and roots.

Overview

About Anthraquinones

Anthraquinones are three fused six-membered rings with two ketone groups on the central ring. They are strongly coloured — yellow through red — and were among the earliest plant dyes, but in herbal medicine they are known for one thing above all: they are the stimulant laxative principle.

In the living plant they exist mostly as inactive O-glycosides. That is not incidental — it is the delivery mechanism, and it explains the whole class.

Where Anthraquinones Occur

A small number of laxative herbs account for nearly all medicinal use:

Senna

sennosides A–D

Cascara sagrada

cascarosides

Rhubarb root

emodin, rhein, aloe-emodin, physcion

Aloe latex (not the gel)

barbaloin/aloin

Yellow dock and buckthorn

mixed anthraquinone glycosides

Madder and morinda

the dye and marker anthraquinones

Note the aloe distinction: the bitter yellow latex just under the leaf skin is the laxative part; the clear inner gel is not, and confusing the two is a common error.

How the Prodrug Works

The glycoside form is the point. Sugar-bound anthraquinones pass through the small intestine unabsorbed, because the sugar prevents uptake. Only when they reach the colon do bacterial glycosidases cleave them, releasing the active anthrone at the site where it is wanted.

The free anthrone then stimulates colonic motility and inhibits water and electrolyte reabsorption. This is why the effect takes 6–12 hours and why it is reliably colonic rather than diffuse.

Pharmacological Importance

Anthraquinone laxatives are effective, cheap and long-established, and remain a legitimate short-term option for constipation where bulk and osmotic measures have failed.

The aglycones have a separate research literature — emodin and aloe-emodin have broad preclinical anti-inflammatory and antiproliferative activity — but that work is largely disconnected from how the herbs are actually used.

Toxicity & Safety

The central caution is duration, not dose. These are short-course medicines — typically no more than one to two weeks. Prolonged use causes electrolyte loss, particularly potassium, which paradoxically worsens bowel tone and creates dependence; it also produces melanosis coli, a reversible dark pigmentation of the colonic mucosa.

They are contraindicated in intestinal obstruction, inflammatory bowel disease, appendicitis and in children, and are generally avoided in pregnancy. Anthraquinone-driven potassium loss also potentiates cardiac glycoside toxicity — a real interaction where digoxin is involved.

Constituents

All Anthraquinones

37 total Filter anthraquinones

2-Hydroxymethyl-anthraquinone 1 herb

Aloe-emodin 6 herbs Aloins 1 herb Anthraquinone-2-carboxylic acid 1 herb

Barbaloin 2 herbs

Cascaroside A 1 herb Cascaroside B 1 herb Cascaroside C 1 herb Cascaroside D 1 herb Cascaroside E 1 herb Cascaroside F 1 herb Cascarosides 1 herb Chrysophanol 4 herbs Citreorosein 2 herbs Crispuside A 1 herb

Damnacanthal Danthron

Emodin 5 herbs Emodin-1-O-glucoside 1 herb Emodin-8-O-glucoside 2 herbs

Frangulin A Frangulin B

Glucofrangulin A Glucofrangulin B

Open in filterable index

Source Plants

Herbs Containing Anthraquinones

11 herbs

Plants in the materia medica documented to carry anthraquinones, with the compounds each one is listed for. The bar counts how many DISTINCT anthraquinones are on record for a plant, relative to the best-documented — it measures breadth of record, not potency, so a plant with one well-studied compound can outrank a richer source that has simply been analysed less. Where a measured concentration is on record it is quoted inline; most entries have none yet.