Lambertianin C

Lambertianin C at a Glance

Lambertianin C is an ellagitannin — a hydrolysable tannin built from gallic-acid units esterified onto glucose — and specifically the trimer of the Rubus series. Three glucose cores, each dressed in galloyl and hexahydroxydiphenoyl groups, are strung together by sanguisorbic acid ester bridges ^{1Reference 1Tanaka T et al. · 1993Tannins and related compoundsView study →}. The result is a molecule of formula C₁₂₃H₈₀O₇₈ and a molecular weight of about 2,806 daltons ^{2Reference 2Mullen W et al. · 2002Ellagitannins, flavonoids, and other phenolics in red raspberries and their contribution to antioxidant capacity and vasorelaxation propertiesView study →} — roughly fifteen times the size of aspirin, and one of the largest single molecules anyone will meet in a normal diet.

That size is the whole story, and it is why this is short. A molecule that big does not cross the gut wall. It is not absorbed intact in any meaningful quantity, so its pharmacology — real or claimed — belongs either to the gut lumen, where it stays and acts on food proteins, microbes and the epithelial surface, or to the smaller molecules it decomposes into: ellagic acid, lower-molecular-weight ellagitannins, and eventually the gut-bacterial urolithins.

Its practical importance is as a marker and a mass rather than as a drug. With sanguiin H-6 it is the compound that makes raspberry, blackberry and cloudberry ellagitannin-rich foods in the first place, and it is a large share of what makes raspberry leaf astringent. The isolated-compound literature is thin: mostly identification, quantitation and a handful of in-vitro assays, with no human trial of any kind.

The Size Problem

At ~2,806 Da lambertianin C sits far outside the range of molecules that get absorbed from the gut. This is not a footnote to its pharmacology — it is its pharmacology, and it shows up as a consistent, measurable pattern across the literature.

It behaves like a large polymer in food. When red raspberries are processed to juice, ellagitannin transfer into the juice falls sharply with molecular weight: going from 1,568 Da to 2,805 Da produced a more than ten-fold drop in transfer, and 68% of total ellagitannins stayed behind in the press cake ^{4Reference 4Sójka M et al. · 2016Transfer and mass balance of ellagitannins, anthocyanins, flavan-3-ols, and flavonols during the processing of red raspberries (Rubus idaeus L.) to juiceView study →}. The trimer is the fraction that gets left in the pomace.

It is the least stable of the series. Ellagitannin stability in aqueous solution is temperature- and pH-dependent, and the larger oligomers degrade first ^{25Reference 25Sójka M et al. · 2019Stability and transformations of raspberry (Rubus idaeus L.) ellagitannins in aqueous solutionsView study →}. In stored processed blackberry products, total ellagitannin content barely moved but the composition shifted in a way indicative of depolymerisation ^{19Reference 19Hager TJ et al. · 2010Processing and storage effects on the ellagitannin composition of processed blackberry productsView study →}. Under strong acid hydrolysis lambertianin C first sheds ellagic acid, then depolymerises; its characteristic breakdown product is a dimer-sized ellagitannin of 1,736 Da — one galloyl group heavier and one ellagic-acid unit lighter than the parent ^{12Reference 12Macierzyński J et al. · 2020Transformation of oligomeric ellagitannins, typical for Rubus and Fragaria genus, during strong acid hydrolysisView study →}.

Its size gates its own microbial conversion. This is the most interesting consequence. When rats were fed raspberry seeds (rich in the dimer and the trimer) versus strawberry seeds (rich in monomers and the dimer agrimoniin), the less polymerised strawberry ellagitannins produced higher caecal concentrations of urolithin A and nasutin — despite the raspberry seeds carrying more polyphenol overall ^{13Reference 13Kosmala M et al. · 2015AnimalChemical composition of defatted strawberry and raspberry seeds and the effect of these dietary ingredients on polyphenol metabolites, intestinal function, and selected serum parameters in ratsView study →}. Degree of polymerisation slows the microbial route to the metabolites that actually circulate.

Put those together and the honest position is this: an in-vitro result obtained by dosing cells with micromolar lambertianin C describes something that can happen in a dish, or in the gut lumen — never in plasma. Human plasma never sees this molecule. What it may eventually see is ellagic acid at sub-micromolar levels, and urolithins, and only in people whose gut microbiota produce them — the urolithin metabotype lottery that governs the entire ellagitannin class ^{16,17Reference 16Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →Reference 17Cortés-Martín A et al. · 2018The gut microbiota urolithin metabotypes revisited — the human metabolism of ellagic acid is mainly determined by agingView study →}.

Trimer & Dimer

Lambertianin C is almost never discussed alone, because it travels with its dimer. The two are oligomers of the same repeating unit, differing in how many times that unit repeats:

	Sanguiin H-6	Lambertianin C
Oligomer	dimer	trimer
Molecular weight	~1,870 Da	~2,806 Da
Usual rank in Rubus fruit	higher	lower
Behaviour on processing	more stable, transfers better	degrades and depolymerises first

Tanaka’s original 1993 paper described the whole ladder at once — lambertianins A and B (dimers), C (trimer) and D (tetramer) — all linked by sanguisorbic acid ester groups between glucopyranose units ^{1Reference 1Tanaka T et al. · 1993Tannins and related compoundsView study →}. Sanguiin H-6 is the same dimeric architecture under an older name, and the series continues upward into tetramers that turn up as minor components in blackberry and raspberry seed ^{23,13Reference 23Hager TJ et al. · 2008Ellagitannin composition of blackberry as determined by HPLC-ESI-MS and MALDI-TOF-MSView study →Reference 13Kosmala M et al. · 2015AnimalChemical composition of defatted strawberry and raspberry seeds and the effect of these dietary ingredients on polyphenol metabolites, intestinal function, and selected serum parameters in ratsView study →}.

Because the trimer sits one rung above the dimer on that ladder, its degradation products are dimer-sized ^{12Reference 12Macierzyński J et al. · 2020Transformation of oligomeric ellagitannins, typical for Rubus and Fragaria genus, during strong acid hydrolysisView study →} — which is why the two compounds’ measured ratios shift during processing and storage rather than staying fixed ^{19Reference 19Hager TJ et al. · 2010Processing and storage effects on the ellagitannin composition of processed blackberry productsView study →}. Together they account for the great majority of the ellagitannin fraction in Rubus fruit, which is why analytical papers on raspberry and blackberry almost always report them as a pair ^{3,26Reference 3Gasperotti M et al. · 2010Profiling and accurate quantification of Rubus ellagitannins and ellagic acid conjugates using direct UPLC-Q-TOF HDMS and HPLC-DAD analysisView study →Reference 26Mertz C et al. · 2007Analysis of phenolic compounds in two blackberry species (Rubus glaucus and Rubus adenotrichus) by high-performance liquid chromatography with diode array detection and electrospray ion trap mass spectrometryView study →}.

One caveat about “co-dominance”: which of the two leads depends on species, tissue and cultivar. In red raspberry fruit sanguiin H-6 usually runs higher — a freeze-dried commercial raspberry powder measured 0.4% sanguiin H-6 against 0.05% lambertianin C ^{14Reference 14Marino M et al. · 2024Nutritional and phytochemical characterization of freeze-dried raspberry (Rubus idaeus) — a comprehensive analysisView study →}, and the original Glen Ample analysis found the trimer at “lower levels” than the dimer ^{2Reference 2Mullen W et al. · 2002Ellagitannins, flavonoids, and other phenolics in red raspberries and their contribution to antioxidant capacity and vasorelaxation propertiesView study →}. In the leaves of the Siberian raspberry Rubus matsumuranus, by contrast, lambertianin C was the single most abundant compound of any kind at 57.1 mg/g dry weight ^{8Reference 8Kashchenko NI et al. · 2021Metabolites of Siberian raspberries — LC-MS profile, seasonal variation, antioxidant activity and thermal stability of Rubus matsumuranus phenolomeView study →}.

What It's Used For

The isolated-compound evidence base is small: a handful of in-vitro assays, one rodent study using an extract, and no human data. Everything below should be read against the size problem above.

Evidence by IndicationStrength of support · Beta

Support is an experimental score — weighted by study type (human > animal > in vitro) and volume, and capped hard where the finding belongs to a mixed extract rather than the pure molecule. A beta, not a validated metric. Every score here is low, and that is the finding: this molecule has been characterised far more than it has been tested.

01AntioxidantShaky30%Cell-free assays on isolated ellagitannins (DPPH, Fe²⁺ chelation, LDL/emulsion oxidation) ^{8,11Reference 8Kashchenko NI et al. · 2021Metabolites of Siberian raspberries — LC-MS profile, seasonal variation, antioxidant activity and thermal stability of Rubus matsumuranus phenolomeView study →Reference 11Kähkönen M et al. · 2012Antioxidant activity of isolated ellagitannins from red raspberries and cloudberriesView study →}

02GastroprotectionShaky26%Rat ethanol-ulcer model + gastric-cell NF-κB/IL-8, using Rubus ET extracts with partial attribution ^{9Reference 9Sangiovanni E et al. · 2013In vitroEllagitannins from Rubus berries for the control of gastric inflammation — in vitro and in vivo studiesView study →}

03AntimicrobialShaky18%Very high MIC vs. a yeast; in-vitro anti-biofilm but a negative in-vivo MRSA result ^{5,7Reference 5Klewicka E et al. · 2016Ellagitannins from raspberry (Rubus idaeus L.) fruit as natural inhibitors of Geotrichum candidumView study →Reference 7Aguilera-Correa JJ et al. · 2021Sanguiin H-6 fractionated from cloudberry (Rubus chamaemorus) seeds can prevent the methicillin-resistant Staphylococcus aureus biofilm development during wound infectionView study →}

04VasorelaxationShaky12%One 2002 study, activity localised to fractions containing the dimer and trimer, not the pure compound ^{2Reference 2Mullen W et al. · 2002Ellagitannins, flavonoids, and other phenolics in red raspberries and their contribution to antioxidant capacity and vasorelaxation propertiesView study →}

Mechanisms

The load-bearing row is the last-but-one. Nothing lambertianin C does to a cell in a dish is reachable in human tissue; what reaches human tissue is its microbial breakdown products, and less of them than a smaller ellagitannin would supply.

Pharmacokinetics

There is no pharmacokinetic study of lambertianin C, because there is essentially nothing to measure. At ~2,806 Da it is far beyond the size range for passive intestinal absorption, and no study has reported the intact trimer in plasma. An exploratory human study that fed volunteers red raspberries and profiled plasma, urine and breast milk identified 62 (poly)phenolic compounds — and what appeared were conjugated and microbial metabolites, chiefly sulfates and glucuronides, not the parent ellagitannins ^{15Reference 15Zhang X et al. · 2018An exploratory study of red raspberry (Rubus idaeus L.) (poly)phenols/metabolites in human biological samplesView study →}.

The real route is indirect and runs entirely through the colon. Ellagitannins are hydrolysed in the gut to free ellagic acid, which colonic bacteria then convert to urolithins (A, B, C, D) ^{16Reference 16Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →}. This step is the bottleneck, and it is personal: humans sort into urolithin metabotypes A, B and 0, so the same food yields quite different metabolite profiles in different people, with the pattern shifting with age ^{16,17Reference 16Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →Reference 17Cortés-Martín A et al. · 2018The gut microbiota urolithin metabotypes revisited — the human metabolism of ellagic acid is mainly determined by agingView study →}. On top of that, polymerisation degree slows the conversion — rats fed the more polymerised raspberry ellagitannins produced less caecal urolithin A than rats fed the less polymerised strawberry ellagitannins, despite a higher polyphenol intake ^{13Reference 13Kosmala M et al. · 2015AnimalChemical composition of defatted strawberry and raspberry seeds and the effect of these dietary ingredients on polyphenol metabolites, intestinal function, and selected serum parameters in ratsView study →}.

The practical reading: lambertianin C is a delivery vehicle for ellagic acid equivalents with a size penalty attached, and a luminal agent in its own right, but never a circulating one.

Clinical Trials

None. There is no completed, ongoing, planned or terminated clinical trial of isolated lambertianin C, and no human study in which it was administered as a purified compound. The human raspberry literature is whole-food and reports metabolites, not the parent ^{15Reference 15Zhang X et al. · 2018An exploratory study of red raspberry (Rubus idaeus L.) (poly)phenols/metabolites in human biological samplesView study →}.

Last checked: August 2026.

Isolate vs. Plant Studies

The split here is unusually clean, and unusually unflattering to the molecule. Where lambertianin C has been isolated, it has mostly been isolated in order to be measured, not tested. Gasperotti and colleagues purified sanguiin H-6 and lambertianin C specifically so that they could serve as external standards with known molar extinction coefficients — the point of the work was accurate quantification across Rubus cultivars, not pharmacology ^{3Reference 3Gasperotti M et al. · 2010Profiling and accurate quantification of Rubus ellagitannins and ellagic acid conjugates using direct UPLC-Q-TOF HDMS and HPLC-DAD analysisView study →}.

The genuine isolate studies number about four: the Geotrichum MIC work ^{5Reference 5Klewicka E et al. · 2016Ellagitannins from raspberry (Rubus idaeus L.) fruit as natural inhibitors of Geotrichum candidumView study →}, the Caco-2 genotoxicity study ^{6Reference 6Nowak A et al. · 2017Ellagitannins from Rubus idaeus L. exert geno- and cytotoxic effects against human colon adenocarcinoma cell line Caco-2View study →}, the MRSA fractionation study ^{7Reference 7Aguilera-Correa JJ et al. · 2021Sanguiin H-6 fractionated from cloudberry (Rubus chamaemorus) seeds can prevent the methicillin-resistant Staphylococcus aureus biofilm development during wound infectionView study →}, and the blackberry-seed lymphocyte study ^{18Reference 18Gođevac D et al. · 2011Blackberry seed extracts and isolated polyphenolic compounds showing protective effect on human lymphocytes DNAView study →}. Two of those four returned results that undercut the compound rather than supporting it — a very high MIC and a negative in-vivo MRSA result.

Everything else is a whole-extract or whole-fraction study in which lambertianin C was one named component: the gastric anti-inflammatory work ^{9Reference 9Sangiovanni E et al. · 2013In vitroEllagitannins from Rubus berries for the control of gastric inflammation — in vitro and in vivo studiesView study →}, the antioxidant fraction work ^{11Reference 11Kähkönen M et al. · 2012Antioxidant activity of isolated ellagitannins from red raspberries and cloudberriesView study →}, the raspberry-seed rodent feeding studies ^{13Reference 13Kosmala M et al. · 2015AnimalChemical composition of defatted strawberry and raspberry seeds and the effect of these dietary ingredients on polyphenol metabolites, intestinal function, and selected serum parameters in ratsView study →}, and the various Rubus extract assays. Attribution in those studies runs from “explicitly tested alongside the mixture” ^{9Reference 9Sangiovanni E et al. · 2013In vitroEllagitannins from Rubus berries for the control of gastric inflammation — in vitro and in vivo studiesView study →} down to “named because it is abundant”. A raspberry-leaf infusion delivers a mixed ellagitannin fraction whose composition varies severalfold with cultivar, harvest time and preparation — so extract-level findings should not be read as molecule-level findings, in either direction.

Its Role in Plants

Lambertianin C is a defensive tannin, and its size is the point there too. Hydrolysable tannins of this magnitude bind and precipitate proteins indiscriminately, which makes leaf and seed tissue astringent, hard to digest and unattractive to herbivores and pathogens. It is concentrated exactly where a plant would want that protection: in leaves ^{1,8,21Reference 1Tanaka T et al. · 1993Tannins and related compoundsView study →Reference 8Kashchenko NI et al. · 2021Metabolites of Siberian raspberries — LC-MS profile, seasonal variation, antioxidant activity and thermal stability of Rubus matsumuranus phenolomeView study →Reference 21Oszmiański J et al. · 2015Determination of phenolic compounds and antioxidant activity in leaves from wild Rubus L. speciesView study →} and in seeds rather than flesh — in blackberry, most ellagitannins were detectable only in seed tissue ^{23Reference 23Hager TJ et al. · 2008Ellagitannin composition of blackberry as determined by HPLC-ESI-MS and MALDI-TOF-MSView study →}.

Its level tracks growing conditions. In Glen Ample raspberry grown under controlled post-flowering temperatures, lambertianin C and sanguiin H-6 were by far the most prevalent ellagitannins and both increased significantly with increasing temperature ^{20Reference 20Remberg SF et al. · 2010Influence of postflowering temperature on fruit size and chemical composition of Glen Ample raspberry (Rubus idaeus L.)View study →}. Across ten red raspberry genotypes grown over three harvest seasons, every quality parameter varied significantly between seasons except ascorbic acid and lambertianin C ^{29Reference 29Mazur SP et al. · 2014Quality and chemical composition of ten red raspberry (Rubus idaeus L.) genotypes during three harvest seasonsView study →}. Genotype, by contrast, matters a great deal: cultivar-to-cultivar differences in ellagitannin pattern within both raspberry and blackberry are substantial ^{3,29Reference 3Gasperotti M et al. · 2010Profiling and accurate quantification of Rubus ellagitannins and ellagic acid conjugates using direct UPLC-Q-TOF HDMS and HPLC-DAD analysisView study →Reference 29Mazur SP et al. · 2014Quality and chemical composition of ten red raspberry (Rubus idaeus L.) genotypes during three harvest seasonsView study →}.

Prevalence in Nature

Lambertianin C is a Rosaceae molecule, and within Rosaceae mainly a Rubus one. Tanaka’s original survey found the trimer and the tetramer, together with sanguiin H-6, occurring widely across fifteen Rubus species collected in Japan and Taiwan ^{1Reference 1Tanaka T et al. · 1993Tannins and related compoundsView study →}. Since then it has been reported in red raspberry ^{2,3Reference 2Mullen W et al. · 2002Ellagitannins, flavonoids, and other phenolics in red raspberries and their contribution to antioxidant capacity and vasorelaxation propertiesView study →Reference 3Gasperotti M et al. · 2010Profiling and accurate quantification of Rubus ellagitannins and ellagic acid conjugates using direct UPLC-Q-TOF HDMS and HPLC-DAD analysisView study →}, blackberry ^{23,26Reference 23Hager TJ et al. · 2008Ellagitannin composition of blackberry as determined by HPLC-ESI-MS and MALDI-TOF-MSView study →Reference 26Mertz C et al. · 2007Analysis of phenolic compounds in two blackberry species (Rubus glaucus and Rubus adenotrichus) by high-performance liquid chromatography with diode array detection and electrospray ion trap mass spectrometryView study →}, cloudberry ^{11,7Reference 11Kähkönen M et al. · 2012Antioxidant activity of isolated ellagitannins from red raspberries and cloudberriesView study →Reference 7Aguilera-Correa JJ et al. · 2021Sanguiin H-6 fractionated from cloudberry (Rubus chamaemorus) seeds can prevent the methicillin-resistant Staphylococcus aureus biofilm development during wound infectionView study →}, boysenberry, the Siberian raspberry Rubus matsumuranus ^{8Reference 8Kashchenko NI et al. · 2021Metabolites of Siberian raspberries — LC-MS profile, seasonal variation, antioxidant activity and thermal stability of Rubus matsumuranus phenolomeView study →}, the wild blackberry Rubus ulmifolius (flowers) and the South American blackberries R. glaucus and R. adenotrichus ^{26Reference 26Mertz C et al. · 2007Analysis of phenolic compounds in two blackberry species (Rubus glaucus and Rubus adenotrichus) by high-performance liquid chromatography with diode array detection and electrospray ion trap mass spectrometryView study →}. Outside Rubus it turns up as a minor ellagitannin in strawberries — where agrimoniin, not lambertianin C, is the dominant one ^{27Reference 27Vrhovsek U et al. · 2012Clarifying the identity of the main ellagitannin in the fruit of the strawberry, Fragaria vesca and Fragaria ananassa DuchView study →} — and, unusually, as a major constituent of Sanguisorba minor root, where a half-rate-fertilised crop yielded 84 mg/g of dry root extract ^{24Reference 24Finimundy TC et al. · 2020Bioactive properties of Sanguisorba minor L. cultivated in central Greece under different fertilization regimesView study →}.

Concentrations, honestly. In fresh red raspberry fruit, lambertianin C runs 280-630 mg/kg depending on cultivar, against 360-750 mg/kg for sanguiin H-6 ^{5Reference 5Klewicka E et al. · 2016Ellagitannins from raspberry (Rubus idaeus L.) fruit as natural inhibitors of Geotrichum candidumView study →}; a commercial freeze-dried raspberry powder measured 0.05% ^{14Reference 14Marino M et al. · 2024Nutritional and phytochemical characterization of freeze-dried raspberry (Rubus idaeus) — a comprehensive analysisView study →}. In Fragaria viridis fruit it reaches 1.20-1.86 mg/g fresh weight, second only to agrimoniin ^{10Reference 10Olennikov DN et al. · 2020Fragaria viridis fruit metabolites — variation of LC-MS profile and antioxidant potential during ripening and storageView study →}. The richest documented tissue of all is a leaf: 57.1 mg/g of dry weight (~5.7%) in Rubus matsumuranus leaves, where it was the most abundant compound of any class ^{8Reference 8Kashchenko NI et al. · 2021Metabolites of Siberian raspberries — LC-MS profile, seasonal variation, antioxidant activity and thermal stability of Rubus matsumuranus phenolomeView study →}.

The gap that matters for this site. Our source herb is raspberry leaf, and there is no published lambertianin C figure for Rubus idaeus leaf. The two most detailed raspberry-leaf phytochemical studies both stop short of it: a 2025 LC-MS/MS survey of six raspberry-leaf samples quantified ellagitannins as ellagic acid after hydrolysis (155-394 mg/100 g) without targeting individual oligomers ^{22Reference 22Alkhudaydi HMS et al. · 2025Determination of the polyphenol composition of raspberry leaf using LC-MS/MSView study →}, and a 2022 quantitative analysis of a raspberry-leaf extract reported casuarinin as the dominant ellagitannin with no lambertianin C entry at all ^{28Reference 28Cyboran-Mikołajczyk S et al. · 2022Protection of erythrocytes and microvascular endothelial cells against oxidative damage by Fragaria vesca L. and Rubus idaeus L. leaves extracts — the mechanism of actionView study →}. Wild Rubus leaf surveys do better than that — across 26 wild Rubus (blackberry) leaf samples all three were quantified, with lambertianin C at 5.69–123.41 mg/g dry matter ^{21Reference 21Oszmiański J et al. · 2015Determination of phenolic compounds and antioxidant activity in leaves from wild Rubus L. speciesView study →}. But that is blackberry leaf, not R. idaeus. So the leaf figures cited above belong to a different Rubus species, and the raspberry figures belong to fruit. Neither should be quietly transplanted onto raspberry leaf. Cloudberry is in the same position — repeatedly named as a lambertianin C source ^{7,11Reference 7Aguilera-Correa JJ et al. · 2021Sanguiin H-6 fractionated from cloudberry (Rubus chamaemorus) seeds can prevent the methicillin-resistant Staphylococcus aureus biofilm development during wound infectionView study →Reference 11Kähkönen M et al. · 2012Antioxidant activity of isolated ellagitannins from red raspberries and cloudberriesView study →} with no clean concentration figure published.

Major Natural Sources

Source	Part	Reported level	Basis
Siberian raspberry (Rubus matsumuranus)	leaf	57.1 mg/g 8Reference 8Kashchenko NI et al. · 2021Metabolites of Siberian raspberries — LC-MS profile, seasonal variation, antioxidant activity and thermal stability of Rubus matsumuranus phenolomeView study →	dry weight; most abundant compound in the leaf
Salad burnet (Sanguisorba minor)	root extract	84 mg/g 24Reference 24Finimundy TC et al. · 2020Bioactive properties of Sanguisorba minor L. cultivated in central Greece under different fertilization regimesView study →	dry extract, not dry plant
Creamy strawberry (Fragaria viridis)	fruit	1.20-1.86 mg/g 10Reference 10Olennikov DN et al. · 2020Fragaria viridis fruit metabolites — variation of LC-MS profile and antioxidant potential during ripening and storageView study →	fresh weight
Red raspberry (Rubus idaeus)	fruit	280-630 mg/kg 5Reference 5Klewicka E et al. · 2016Ellagitannins from raspberry (Rubus idaeus L.) fruit as natural inhibitors of Geotrichum candidumView study →	fresh weight
Red raspberry (Rubus idaeus)	freeze-dried fruit powder	0.05% 14Reference 14Marino M et al. · 2024Nutritional and phytochemical characterization of freeze-dried raspberry (Rubus idaeus) — a comprehensive analysisView study →	dry weight
Raspberry / blackberry press cake & seed	seed, pomace	qualitative 4,23Reference 4Sójka M et al. · 2016Transfer and mass balance of ellagitannins, anthocyanins, flavan-3-ols, and flavonols during the processing of red raspberries (Rubus idaeus L.) to juiceView study →Reference 23Hager TJ et al. · 2008Ellagitannin composition of blackberry as determined by HPLC-ESI-MS and MALDI-TOF-MSView study →	ellagitannins concentrate here
Blackberry, cloudberry, boysenberry, R. ulmifolius	fruit, seed, flower	qualitative 7,11,23,26Reference 7Aguilera-Correa JJ et al. · 2021Sanguiin H-6 fractionated from cloudberry (Rubus chamaemorus) seeds can prevent the methicillin-resistant Staphylococcus aureus biofilm development during wound infectionView study →Reference 11Kähkönen M et al. · 2012Antioxidant activity of isolated ellagitannins from red raspberries and cloudberriesView study →Reference 23Hager TJ et al. · 2008Ellagitannin composition of blackberry as determined by HPLC-ESI-MS and MALDI-TOF-MSView study →Reference 26Mertz C et al. · 2007Analysis of phenolic compounds in two blackberry species (Rubus glaucus and Rubus adenotrichus) by high-performance liquid chromatography with diode array detection and electrospray ion trap mass spectrometryView study →	identified, not quantified
Raspberry leaf (Rubus idaeus)	leaf	no published figure	see gaps note

Discovery & Synthesis

Lambertianin C was first isolated in 1993 by Takashi Tanaka and colleagues at Kyushu University, working on the leaves of Rubus lambertianus Seringe — a Chinese/Japanese bramble — as part of the long-running Tannins and Related Compounds series. The paper (number CXXII in that series) reported four new ellagitannins at once: the dimers lambertianin A and B, the trimer lambertianin C, and the tetramer lambertianin D, all sharing sanguisorbic acid ester groups as the linking unit between glucopyranose cores ^{1Reference 1Tanaka T et al. · 1993Tannins and related compoundsView study →}. The name is purely botanical — it commemorates the species it was pulled out of, not a person or a property. In the same paper the authors screened fifteen Rubus species from Japan and Taiwan by HPLC and found the trimer and tetramer to be widespread in the genus ^{1Reference 1Tanaka T et al. · 1993Tannins and related compoundsView study →}, which is how a compound named after an obscure bramble became the standard name for raspberry’s second ellagitannin.

There is no total synthesis. Nothing of this size and stereochemical complexity has been assembled from scratch, and there is no commercial or synthetic route. Every gram of lambertianin C that has ever been studied was isolated from plant material — typically by extracting raspberry or blackberry press cake or cloudberry seed, cleaning the extract on Amberlite XAD resin, and finishing by preparative HPLC ^{5,7Reference 5Klewicka E et al. · 2016Ellagitannins from raspberry (Rubus idaeus L.) fruit as natural inhibitors of Geotrichum candidumView study →Reference 7Aguilera-Correa JJ et al. · 2021Sanguiin H-6 fractionated from cloudberry (Rubus chamaemorus) seeds can prevent the methicillin-resistant Staphylococcus aureus biofilm development during wound infectionView study →}. The 2010 Gasperotti work that produced purified sanguiin H-6 and lambertianin C standards, complete with molar extinction coefficients, was a notable step simply because the field had been quantifying these compounds without authentic standards ^{3Reference 3Gasperotti M et al. · 2010Profiling and accurate quantification of Rubus ellagitannins and ellagic acid conjugates using direct UPLC-Q-TOF HDMS and HPLC-DAD analysisView study →}. Pure lambertianin C remains an expensive research reagent, not an article of commerce.

Patents: not yet researched.

Toxicity & Safety

Lambertianin C carries a low flag. It is a normal constituent of berries and berry-leaf teas with a long dietary history, it is not absorbed intact, and no case of harm has ever been attributed to it. The one adverse signal in the literature is an in-vitro genotoxicity result that has a contradictory counterpart, and the practical cautions are the generic hydrolysable-tannin ones.

Safety at a Glance

✅ Low / no toxicity

• Long dietary history, essentially unabsorbed. A normal component of raspberries, blackberries, cloudberries and raspberry-leaf tea; at ~2,806 Da it does not enter the circulation intact, which caps systemic risk.
• In-vitro genotoxicity to colon cells. Isolated lambertianin C damaged DNA in Caco-2 cells at concentrations said to correspond to those in raspberry-containing foods — the one adverse finding for the pure compound.
• Tannin-class effects at the gut surface. Like all hydrolysable tannins it binds proteins non-specifically, which is what astringency is; large amounts of concentrated tannin can cause gastric irritation and reduce non-heme iron absorption.
• Nothing is known about isolated exposure. No human study, no toxicology package, no interaction data for the pure molecule; safety inference comes from the food matrix, not from the compound.

Full Safety & Interactions Detail

The genotoxicity finding, and its counterweight. Nowak and colleagues tested a red raspberry ellagitannin preparation (2.5-160 µg/mL) and the two main individual ellagitannins — sanguiin H-6 (12.8-256 µM) and lambertianin C (9.3-378 µM) — against human colon adenocarcinoma Caco-2 cells, at concentrations they described as corresponding to those found in raspberry-containing foods. All three showed strong concentration-dependent genotoxicity, inducing DNA damage from 7.3% to 56.8%, with double-strand breaks and oxidation of DNA bases; at the preparation’s IC₅₀ of 124 µg/mL, nuclear morphology changed and apoptosis followed ^{6Reference 6Nowak A et al. · 2017Ellagitannins from Rubus idaeus L. exert geno- and cytotoxic effects against human colon adenocarcinoma cell line Caco-2View study →}. The authors themselves framed this as chemopreventive rather than harmful — DNA damage and apoptosis in a colon cancer line is what a chemopreventive agent is supposed to do — but it is a genuine in-vitro genotoxicity signal and should be recorded as one.

Against that: isolated lambertianin C from blackberry seed was tested in a cytochalasin-B-blocked micronucleus assay on normal human peripheral lymphocytes and, together with sanguiin H-6, was protective — reducing micronucleus frequency rather than raising it ^{18Reference 18Gođevac D et al. · 2011Blackberry seed extracts and isolated polyphenolic compounds showing protective effect on human lymphocytes DNAView study →}.

The two results are not necessarily in conflict (different cell types, different concentrations, transformed versus normal cells), but they mean no confident verdict can be drawn from either. There is no in-vivo genotoxicity study.

Tannin-class cautions. Hydrolysable tannins bind and precipitate proteins, and binding avidity increases with molecular size, so a 2,806-Da trimer is at the strong end of that behaviour. In practice this means astringency, potential gastric irritation from concentrated tannin preparations, reduced non-heme iron absorption when taken with meals, and non-specific inhibition of digestive enzymes. These are class effects and none has been measured for lambertianin C specifically.

Interactions. No drug-interaction data exist for this molecule. Because it is not absorbed, a systemic CYP- or transporter-mediated interaction is implausible; a luminal interaction — binding a co-ingested drug or nutrient in the gut, as tannins do — is the mechanistically plausible one and is entirely untested.

Reproductive note. No reproductive or developmental toxicity study has been performed on isolated lambertianin C. Raspberry-leaf preparations have their own pregnancy literature, but that belongs on the herb page where intake is decided, not to this molecule.

Dosage

No dose exists. Isolated lambertianin C has never been administered to a human, there is no established or studied dose, and — because the molecule is not absorbed intact — a systemic dose is not a coherent concept for it. Human exposure is dietary and herbal, as one component of a mixed ellagitannin fraction:

The one place a concentration figure has any pharmacological meaning is the gut lumen, and even there the published in-vitro numbers (an MIC of 10 mg/mL, a Caco-2 IC₅₀ of 124 µg/mL for the whole preparation) come from dishes, not from measured intestinal contents. These are research figures and observations, not a personal recommendation.

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