Sennoside B

Sennoside B at a Glance

Sennoside B is one of the two dianthrone diglucosides that make senna a laxative. Chemically it is a rhein dianthrone diglucoside — two rhein-anthrone units joined at their central carbons and capped with glucose — and it is the meso stereoisomer of sennoside A, the molecule it co-occurs with, interconverts with, and is quantified alongside ^{1,5Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 5Yagi T et al. · 1990AnimalProstaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colonView study →}. Pharmacopoeias, in fact, express the total hydroxyanthracene-glycoside content of senna as sennoside B, which makes this molecule the reference yardstick for the whole herb’s strength ^{1,12Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}.

Like its twin, sennoside B is a prodrug that does nothing as swallowed. It is large, polar and poorly absorbed, so it survives the stomach and small intestine and reaches the colon intact; there, gut bacteria cleave the sugars and reduce the liberated dianthrone to rhein-anthrone, the reactive metabolite that actually stimulates colonic motility and reverses water absorption into secretion ^{1,4Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 4Kon R et al. · 2014Rheinanthrone, a metabolite of sennoside A, triggers macrophage activation to decrease aquaporin-3 expression in the colon, causing the laxative effect of rhubarb extractView study →}. Everything sennoside B “does” as a laxative, it does through that downstream anthrone.

Two honesties frame the page. First, almost no pharmacology is done on sennoside B alone — it is nearly always studied as the sennoside A + B pair or as standardised whole senna, and its mechanism is shared with sennoside A (see below) ^{1,3,5Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 3Hwang IY · 2015Gastroprotective activities of sennoside A and sennoside B via the up-regulation of prostaglandin E2 and the inhibition of H+/K+-ATPaseView study →Reference 5Yagi T et al. · 1990AnimalProstaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colonView study →}. Second, it carries the full stimulant-laxative / anthranoid caution set — electrolyte loss, dependence with chronic use, melanosis coli, and the EU/EFSA regulatory scrutiny of hydroxyanthracene derivatives ^{11,12Reference 11Zhang R et al. · 2023ReviewReview on melanosis coli and anthraquinone-containing traditional Chinese herbs that cause melanosis coliView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}.

Sennoside B vs. Sennoside A

This is the point of the page, so it is worth stating precisely. Sennoside A and sennoside B are stereoisomers with the same atoms and the same laxative job — they differ only in the three-dimensional arrangement at the two central carbons that join the dianthrone.

• The stereochemistry. Each molecule is built from two rhein-anthrone halves linked at C-10 and C-10′, and each of those carbons is a chiral centre. In sennoside A the two centres share the same handedness, so the molecule is chiral and optically active (dextrorotatory). In sennoside B one centre is left-handed and the other right-handed, so the molecule is meso — internally symmetric and therefore optically inactive ^{5Reference 5Yagi T et al. · 1990AnimalProstaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colonView study →}. B is, in effect, the “achiral twin” of the optically active A.
• They co-occur and interconvert. The two are not isolated products of different plants; they appear together in the same senna leaf and pod, and sennoside A can epimerise to sennoside B in aqueous alkaline conditions ^{1Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →}. Because they are so readily quantified together and interconvert, pharmacopoeias abandon any attempt to dose them separately and instead standardise the total as sennoside B ^{1,12Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}.
• The pharmacology is shared. Both are inert diglucoside prodrugs; both are converted by colonic flora to rhein-anthrone, and the literature repeatedly names rhein-anthrone “the active metabolite of sennosides A and B,” treating the pair as one functional unit ^{4,5,6Reference 4Kon R et al. · 2014Rheinanthrone, a metabolite of sennoside A, triggers macrophage activation to decrease aquaporin-3 expression in the colon, causing the laxative effect of rhubarb extractView study →Reference 5Yagi T et al. · 1990AnimalProstaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colonView study →Reference 6Yagi T et al. · 1991AnimalSuppression of the purgative action of rhein anthrone, the active metabolite of sennosides A and B, by indomethacin in ratsView study →}. In the one head-to-head preclinical setting where B was tested on its own — a rat gastroprotection model — sennoside B behaved comparably to (and on one endpoint better than) sennoside A ^{3Reference 3Hwang IY · 2015Gastroprotective activities of sennoside A and sennoside B via the up-regulation of prostaglandin E2 and the inhibition of H+/K+-ATPaseView study →}, but no clean human trial isolates B’s laxative potency from A’s.

The honest headline: there is very little pharmacology that belongs to sennoside B specifically rather than to the A + B pair or to whole senna. Where the text describes mechanism, it is describing the shared sennoside → rhein-anthrone route, told once.

What It's Used For

Sennoside B’s pharmacology is narrow and derivative: it is a delivery vehicle for rhein-anthrone, and its evidence sits one layer up in the trials and pharmacopoeial use of standardised senna. The isolated-molecule work is almost entirely the A + B pair or preclinical.

Evidence by IndicationStrength of support · Beta

Support is an experimental score — weighted by study type (human > animal > in vitro) and volume. A beta, not a validated metric. Sennoside B is nearly always studied as the sennoside A + B pair or as standardised whole senna, so these scores reflect shared/mechanistic strength, not standalone-B human data. Each application links to its write-up.

01Stimulant Laxative (Sennoside Prodrug)Promising50%Established senna effect + bacterial rhein-anthrone mechanism; standardisation expressed as sennoside B ^{1,4,12Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 4Kon R et al. · 2014Rheinanthrone, a metabolite of sennoside A, triggers macrophage activation to decrease aquaporin-3 expression in the colon, causing the laxative effect of rhubarb extractView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}

02Gastroprotection (Preclinical)Shaky22%Single rat model; PGE2 up, H⁺/K⁺-ATPase inhibited — B tested specifically ^{3Reference 3Hwang IY · 2015Gastroprotective activities of sennoside A and sennoside B via the up-regulation of prostaglandin E2 and the inhibition of H+/K+-ATPaseView study →}

Mechanisms

The load-bearing point: sennoside B is not itself the actor — its pharmacology is the pharmacology of the rhein-anthrone it releases, which is why it and its stereoisomer sennoside A are treated as one functional unit.

Pharmacokinetics

Sennoside B behaves like its twin: as a large, polar diglucoside it is minimally absorbed intact from the upper gastrointestinal tract, which is exactly what lets it reach the colon as a functioning prodrug ^{1,2Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 2Wang D et al. · 2021Pharmacokinetics of anthraquinones from medicinal plantsView study →}. There is no meaningful systemic bioavailability of sennoside B itself to quote — its site of action is the colonic lumen, where bacteria convert it to rhein-anthrone. What is subsequently absorbed and measured in plasma, urine and breast milk is not the glycoside or the reactive anthrone but the anthrone’s stable oxidation product rhein ^{1,2Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 2Wang D et al. · 2021Pharmacokinetics of anthraquinones from medicinal plantsView study →}. The practical consequence is that the controllable input is the administered glycoside dose (expressed as sennoside B), and the conversion to active anthrone is microbiota-dependent — germ-free animals do not convert the sennosides and do not purge ^{7Reference 7Van Hoestenberghe A et al. · 1992AnimalThe effect of rhein and rhein anthrone on intestinal fluid transport and on large intestine transit in germ-free ratsView study →}.

Clinical Trials

There are no clinical trials of isolated sennoside B. It is not developed or dosed as a standalone drug; the human clinical record belongs to standardised senna (and to the sennoside A + B pair), an established over-the-counter stimulant laxative whose strength is expressed as sennoside B ^{1,12Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}. The gastroprotection finding is preclinical (rat) ^{3Reference 3Hwang IY · 2015Gastroprotective activities of sennoside A and sennoside B via the up-regulation of prostaglandin E2 and the inhibition of H+/K+-ATPaseView study →}.

Last checked: July 2026.

Isolate vs. Plant Studies

Sennoside B is a textbook case of the isolate-vs-plant gap. The isolate is well characterised chemically — a defined meso dianthrone diglucoside, a reference standard for senna assays — yet it is almost never studied pharmacologically on its own ^{1,5Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 5Yagi T et al. · 1990AnimalProstaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colonView study →}. What evidence exists is either the sennoside A + B pair (the gastroprotection and mechanism work name both) ^{3,4Reference 3Hwang IY · 2015Gastroprotective activities of sennoside A and sennoside B via the up-regulation of prostaglandin E2 and the inhibition of H+/K+-ATPaseView study →Reference 4Kon R et al. · 2014Rheinanthrone, a metabolite of sennoside A, triggers macrophage activation to decrease aquaporin-3 expression in the colon, causing the laxative effect of rhubarb extractView study →} or standardised whole senna, whose laxative efficacy is a herb effect that routes through rhein-anthrone. Even the dose is a plant-level construct: pharmacopoeias quantify total hydroxyanthracene glycosides as sennoside B rather than measuring pure B ^{12Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}. So the honest framing is three-layered — the chemistry is sennoside B’s, the mechanism is shared with sennoside A and belongs to the rhein-anthrone metabolite, and the dose and trials attach to standardised senna, the only form anyone actually takes.

Prevalence in Nature

Sennoside B occurs wherever sennoside A does, and in comparable company:

• Senna (Senna alexandrina / Cassia angustifolia) — the principal source, in leaf and pod, as one of the two co-principal sennosides (A and B) alongside minor sennosides C and D (the rhein–aloe-emodin heterodianthrones) ^{1Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →}. Senna also carries trace aloe-emodin dianthrone diglucosides that are non-purgative alone but potentiate sennoside purgation (~1.3× in mice) — a reminder that the whole-herb effect is more than any single sennoside ^{13Reference 13Nakajima K et al. · 1985AnimalIsolation of a new aloe-emodin dianthrone diglucoside from senna and its potentiating effect on the purgative activity of sennoside A in miceView study →}. Pharmacopoeial material is standardised to total hydroxyanthracene glycosides expressed as sennoside B: leaf typically ~2–3%, pod ~3–4%, with a common minimum around 2.5% ^{1,12Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}. Leaf is more potent but more griping than pod.
• Rhubarb (Rheum spp.) — rhizome, where sennoside-type dianthrone glycosides accompany the free anthraquinones rhein, emodin, aloe-emodin and chrysophanol; sennoside content is a minor share of the anthranoid fraction and swings widely with species and processing (raw vs steamed vs charred) ^{2Reference 2Wang D et al. · 2021Pharmacokinetics of anthraquinones from medicinal plantsView study →}.

Because sennoside A and B interconvert and are quantified together, published “sennoside” figures usually report the A + B total, not a separate value for B — a real analytical limitation noted in the gaps tracker rather than a gap in the plant itself.

Discovery & Synthesis

The sennosides were isolated and structurally characterised in the mid-twentieth century by Stoll, Becker and co-workers, who resolved senna’s purgative principle into a pair of dianthrone diglucosides — sennoside A (optically active) and sennoside B (its meso diastereomer) — and established that each is built from two rhein-anthrone units linked at C-10/C-10′ and capped with glucose ^{1Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →}. From the outset sennoside B was defined relative to sennoside A: the achiral, internally-compensated twin of the dextrorotatory molecule. Chemically the two are interconvertible — sennoside A epimerises to sennoside B under aqueous alkaline conditions ^{1Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →} — which is one reason analytical and pharmacopoeial practice standardises the total as sennoside B rather than isolating a single stereoisomer. Manufacture today is by extraction from senna (leaf and pod) rather than total synthesis: sennoside B is obtained as a purified reference standard and as part of the standardised sennoside laxative fraction, and the article of commerce is the standardised senna extract, not the pure meso compound.

Patents: not yet researched.

Toxicity & Safety

Sennoside B carries a moderate flag, identical to its stereoisomer sennoside A and to the anthranoid siblings rhein, rhein-anthrone, emodin and aloe-emodin. The cautions are the stimulant-laxative / anthranoid class cautions, applied to a prodrug that generates the reactive anthrone in the colon.

Safety at a Glance

⚠️ Moderate toxicity

• Direct genotoxicity/carcinogenicity testing is reassuring. Senna, the sennosides and rhein were negative in standard genotoxicity batteries, and a 2-year oral carcinogenicity study of senna in rats found no carcinogenic effect at doses up to 300 mg/kg/day ^{8,10Reference 8Heidemann A et al. · 1993The genotoxicity status of sennaView study →Reference 10Mitchell JM et al. · 2006AnimalAn oral carcinogenicity and toxicity study of senna (Tinnevelly senna fruits) in the ratView study →}.
• Poorly absorbed as swallowed. The intact diglucoside acts locally in the colon; systemic exposure is largely to the downstream oxidation product rhein, not to sennoside B itself ^{1,2Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 2Wang D et al. · 2021Pharmacokinetics of anthraquinones from medicinal plantsView study →}.
• Stimulant-laxative class risks. Electrolyte loss (especially potassium) with overuse, cramping/griping, and — with habitual daily use — laxative dependence and reduced spontaneous bowel tone.
• Melanosis coli with chronic use. Long-term anthranoid-laxative use pigments the colonic mucosa (lipofuscin in macrophages) from laxative-induced epithelial apoptosis — benign and reversible on stopping, and not linked to increased colon-cancer risk, but a marker of sustained use ^{11Reference 11Zhang R et al. · 2023ReviewReview on melanosis coli and anthraquinone-containing traditional Chinese herbs that cause melanosis coliView study →}.
• Regulatory context for the class. EU/EFSA scrutiny of hydroxyanthracene derivatives rests on the reactive free anthrone as the structural basis for a genotoxicity concern, even though whole-senna and sennoside genotoxicity tests came back negative ^{9,12Reference 9Brusick D · 1997Assessment of the genotoxic risk from laxative senna productsView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}.

Full Safety & Interactions Detail

Genotoxicity — the class concern vs the negative herb data. Sennoside B is a prodrug of rhein-anthrone, the reactive anthrone at the heart of the anthraquinone genotoxicity question, and regulators treat the whole hydroxyanthracene-derivative class cautiously on that structural basis, unable to set a safe intake ^{12Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}. Against that, direct testing has been reassuring: senna, the sennosides and rhein did not increase mutation frequencies across bacterial and mammalian assays (aloe-emodin was the class member showing in-vitro mutagenicity, without an in-vivo effect) ^{8Reference 8Heidemann A et al. · 1993The genotoxicity status of sennaView study →}, and a formal assessment concluded the genotoxic risk to patients using senna laxatives under prescribed conditions is not established ^{9Reference 9Brusick D · 1997Assessment of the genotoxic risk from laxative senna productsView study →}.

Carcinogenicity — negative in the pivotal animal study. A 2-year oral carcinogenicity and toxicity study of Tinnevelly senna fruits in Sprague-Dawley rats found no treatment-related neoplastic changes at daily doses up to 300 mg/kg/day ^{10Reference 10Mitchell JM et al. · 2006AnimalAn oral carcinogenicity and toxicity study of senna (Tinnevelly senna fruits) in the ratView study →}. Chronic use produces melanosis coli — dark colonic pigmentation from laxative-induced epithelial apoptosis and lipofuscin-laden macrophages — which is benign, reversible on stopping, and not associated with increased colorectal-cancer risk ^{11Reference 11Zhang R et al. · 2023ReviewReview on melanosis coli and anthraquinone-containing traditional Chinese herbs that cause melanosis coliView study →}.

Class laxative cautions. As a sennoside, sennoside B underlies the familiar anthranoid concerns: potassium and fluid loss with excessive use (which can compound digoxin, diuretic and antiarrhythmic effects), abdominal cramping, and — with habitual daily use — laxative dependence and diminished spontaneous bowel function. These are dose- and duration-driven, and stimulant laxatives are intended for short-term use.

Reproductive note (prose only). Senna is generally regarded as one of the more acceptable stimulant laxatives for short-term use in pregnancy, reflecting its poor systemic absorption and local colonic action; even so, systemic anthranoid metabolites — chiefly rhein, the circulating oxidation product — are excreted into breast milk ^{1,2Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 2Wang D et al. · 2021Pharmacokinetics of anthraquinones from medicinal plantsView study →}, so the caution is real and not a green light. Consistent with house policy, the pregnancy/lactation decision belongs on the herb or product page where intake is chosen, not on this molecule page; it is stated here only as the cited finding. No dedicated reproductive-toxicity dataset exists for isolated sennoside B.

Dosage

There is no dose for isolated sennoside B — it is not taken as a standalone molecule but as part of the standardised sennoside pair. Human dosing is entirely at the senna / total-sennoside level, and pharmacopoeias express that total as sennoside B ^{1,12Reference 1Le J et al. · 2021Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compoundView study →Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}. For reference only, a common adult over-the-counter senna dose is on the order of 15–30 mg total sennosides per day, taken short-term; senna material is standardised to not less than roughly 2.5% hydroxyanthracene glycosides (as sennoside B) ^{12Reference 12EFSA ANS Panel · 2018Safety of hydroxyanthracene derivatives for use in foodView study →}. The amount of active rhein-anthrone actually generated depends on the individual’s colonic microbiota, not on a fixed conversion ^{7Reference 7Van Hoestenberghe A et al. · 1992AnimalThe effect of rhein and rhein anthrone on intestinal fluid transport and on large intestine transit in germ-free ratsView study →}. These are parent-preparation and pharmacopoeial figures for context and are not a personal recommendation — stimulant laxatives are intended for short-term use.

References

1. Le J, et al. (2021). Pharmacology, toxicology, and metabolism of sennoside A, a medicinal plant-derived natural compound. Frontiers in Pharmacology. https://pubmed.ncbi.nlm.nih.gov/34764866/
2. Wang D, et al. (2021). Pharmacokinetics of anthraquinones from medicinal plants. Frontiers in Pharmacology. https://pubmed.ncbi.nlm.nih.gov/33935728/
3. Hwang IY, Jeong CS (2015). Gastroprotective activities of sennoside A and sennoside B via the up-regulation of prostaglandin E2 and the inhibition of H+/K+-ATPase. Biomolecules & Therapeutics. https://pubmed.ncbi.nlm.nih.gov/26336586/
4. Kon R, et al. (2014). Rheinanthrone, a metabolite of sennoside A, triggers macrophage activation to decrease aquaporin-3 expression in the colon, causing the laxative effect of rhubarb extract. Journal of Ethnopharmacology. https://pubmed.ncbi.nlm.nih.gov/24412547/
5. Yagi T, et al. (1990). Prostaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colon. Journal of Pharmacy and Pharmacology. https://pubmed.ncbi.nlm.nih.gov/1981580/
6. Yagi T, et al. (1991). Suppression of the purgative action of rhein anthrone, the active metabolite of sennosides A and B, by indomethacin in rats. Journal of Pharmacy and Pharmacology. https://pubmed.ncbi.nlm.nih.gov/1680171/
7. Van Hoestenberghe A, et al. (1992). The effect of rhein and rhein anthrone on intestinal fluid transport and on large intestine transit in germ-free rats. European Journal of Pharmacology. https://pubmed.ncbi.nlm.nih.gov/1555634/
8. Heidemann A, Miltenburger HG, Mengs U (1993). The genotoxicity status of senna. Pharmacology. https://pubmed.ncbi.nlm.nih.gov/8234427/
9. Brusick D, Mengs U (1997). Assessment of the genotoxic risk from laxative senna products. Environmental and Molecular Mutagenesis. https://pubmed.ncbi.nlm.nih.gov/9020301/
10. Mitchell JM, et al. (2006). An oral carcinogenicity and toxicity study of senna (Tinnevelly senna fruits) in the rat. Archives of Toxicology. https://pubmed.ncbi.nlm.nih.gov/16205914/
11. Zhang R, et al. (2023). Review on melanosis coli and anthraquinone-containing traditional Chinese herbs that cause melanosis coli. Frontiers in Pharmacology. https://pubmed.ncbi.nlm.nih.gov/37214441/
12. EFSA ANS Panel (2018). Safety of hydroxyanthracene derivatives for use in food. EFSA Journal. https://pubmed.ncbi.nlm.nih.gov/32625659/
13. Nakajima K, Yamauchi K, Kuwano S (1985). Isolation of a new aloe-emodin dianthrone diglucoside from senna and its potentiating effect on the purgative activity of sennoside A in mice. Journal of Pharmacy and Pharmacology. https://pubmed.ncbi.nlm.nih.gov/2867138/

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