curcumin catabolic process

GO:0036040

The complete two-step reductive curcumin pathway converts curcumin through dihydrocurcumin to tetrahydrocurcumin using the NADPH-dependent CurA homodimer. The graph follows MetaCyc PWY0-1527 and the two native reactions in PathBank SMP0001910. The primary study first found activity in a fecal Escherichia coli isolate, then used K-12 DH10B for purification and gene identification and a recombinant BL21 host for detailed enzyme characterization. Reviewed K-12 CurA and the native MG1655 annotation support the selected K-12 scope; this is not a direct MG1655 flux measurement. Both C=C reductions and their shared intermediate are retained. The redundant net Rhea reaction is excluded. Tetrahydrocurcumin is the demonstrated CurA endpoint, without an assertion of complete mineralization, downstream fate, or a curcumin transporter. NADPH is a diffusible cosubstrate; the reported enzyme is metal-independent. Cytosol localization is retained only as an explicitly computational native annotation.

Pathway type

curcumin degradation

Organism scope

Escherichia coli K-12 NCBITaxon:83333

Read the source YAML

Pathway network

12 nodes · 17 asserted directed edges

Arrows show recorded subject → object relationships, not necessarily metabolic flow. Select a node for details or an arrow for evidence. Scroll, zoom or find a node to explore.

Reaction / activity
Chemical / cofactor
Protein / complex
Cell / process context
Pathway
Solid arrow: mechanistic relation
Dashed arrow: membership, location or cofactor relation

Show at full size (scroll to explore)

Components and activities

Declared biological components and source reaction directions
Node	Kind or role	Source direction
Escherichia coli K-12 `NCBITaxon:83333`	taxon
curcumin `CHEBI:3962`	small molecule
dihydrocurcumin `CHEBI:67262`	small molecule
tetrahydrocurcumin `CHEBI:67263`	small molecule
NADPH(4-) `CHEBI:57783`	cofactor
NADP(3-) `CHEBI:58349`	small molecule
hydron `CHEBI:15378`	small molecule
NADPH-dependent curcumin reductase `UniProtKB:P76113`	protein
NADPH-dependent curcumin/dihydrocurcumin reductase `MetaCyc:CPLX0-7927`	complex
cytosol `GO:0005829`	cellular component
curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	molecular activity	right to left
dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	molecular activity	right to left

Mechanistic edges

Mechanistic edges and their cited evidence
Subject	Predicate and description	Object	Evidence
curcumin `CHEBI:3962`	consumes	curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	RHEA:34821 Source assertion: Rhea RHEA:34821 assigns CHEBI:3962 to its substrates, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34821']/rh:substrates; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34819_R']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34819_compound_7627']; rh:compound/rh:chebi`
NADPH(4-) `CHEBI:57783`	consumes	curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	RHEA:34821 Source assertion: Rhea RHEA:34821 assigns CHEBI:57783 to its substrates, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34821']/rh:substrates; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34819_R']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34819_compound_3438']; rh:compound/rh:chebi`
hydron `CHEBI:15378`	consumes	curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	RHEA:34821 Source assertion: Rhea RHEA:34821 assigns CHEBI:15378 to its substrates, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34821']/rh:substrates; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34819_R']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34819_compound_3249']; rh:compound/rh:chebi`
curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	produces	dihydrocurcumin `CHEBI:67262`	RHEA:34821 Source assertion: Rhea RHEA:34821 assigns CHEBI:67262 to its products, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34821']/rh:products; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34819_L']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34819_compound_7626']; rh:compound/rh:chebi`
curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	produces	NADP(3-) `CHEBI:58349`	RHEA:34821 Source assertion: Rhea RHEA:34821 assigns CHEBI:58349 to its products, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34821']/rh:products; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34819_L']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34819_compound_5188']; rh:compound/rh:chebi`
dihydrocurcumin `CHEBI:67262`	consumes	dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	RHEA:34813 Source assertion: Rhea RHEA:34813 assigns CHEBI:67262 to its substrates, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34813']/rh:substrates; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34811_R']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34811_compound_7626']; rh:compound/rh:chebi`
NADPH(4-) `CHEBI:57783`	consumes	dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	RHEA:34813 Source assertion: Rhea RHEA:34813 assigns CHEBI:57783 to its substrates, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34813']/rh:substrates; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34811_R']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34811_compound_3438']; rh:compound/rh:chebi`
hydron `CHEBI:15378`	consumes	dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	RHEA:34813 Source assertion: Rhea RHEA:34813 assigns CHEBI:15378 to its substrates, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34813']/rh:substrates; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34811_R']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34811_compound_3249']; rh:compound/rh:chebi`
dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	produces	tetrahydrocurcumin `CHEBI:67263`	RHEA:34813 Source assertion: Rhea RHEA:34813 assigns CHEBI:67263 to its products, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34813']/rh:products; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34811_L']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34811_compound_7625']; rh:compound/rh:chebi`
dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	produces	NADP(3-) `CHEBI:58349`	RHEA:34813 Source assertion: Rhea RHEA:34813 assigns CHEBI:58349 to its products, with coefficient 1 in rh:contains1. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34813']/rh:products; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34811_L']/rh:contains1[@rdf:resource='http://rdf.rhea-db.org/Participant_34811_compound_5188']; rh:compound/rh:chebi`
NADPH-dependent curcumin/dihydrocurcumin reductase `MetaCyc:CPLX0-7927`	catalyzes The same supported homodimer catalyzes both reductions. These are experimentally supported enzyme reactions, not a claim that curcumin is the only possible CurA substrate.	curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	MetaCyc:RXN0-6676 Source assertion: RXN0-6676 assigns CPLX0-7927 as the enzyme through ENZRXN0-7454, with the native reduction in its left-to-right orientation. Source location `Reaction[@frameid="RXN0-6676"]/enzymatic-reaction/Enzymatic-Reaction[@frameid="ENZRXN0-7454"]/enzyme; left; right; reaction-direction` UniProtKB:P76113 Source assertion: Reviewed K-12 CurA assigns curcumin to dihydrocurcumin to physiological RHEA:34821, citing ECO:0000269 PMID:21467222. Its homodimer annotation cites the same experiment. Source location `/comments/3/reaction; /comments/3/physiologicalReactions; /comments/6` PMID:21467222 Source assertion: Purified CurA produces DHC and THC; the time course places DHC between curcumin and THC. The inspected experiments identify both products by mass spectrometry and UV-visible spectra. Source location `PMC3080977: Results, Identification of the Reaction Products; Discussion; Figures 2, 3 and 4` PMID:21467222 Source assertion: The study detected activity in K-12 DH10B and used it for purification and gene identification; later enzyme analyses used recombinant CurA in a BL21 expression host. Source location `PMC3080977: Results, Discovery of Curcumin-Converting Microorganisms; Cloning of the Gene Encoding the Curcumin-Converting Enzyme; Overexpression and Purification` UniProtKB:P76113 Source assertion: Reviewed CurA is assigned to taxon 83333, Escherichia coli K-12, with experimental functional and homodimer evidence from PMID:21467222. Source location `/organism/taxonId; /comments/0; /comments/6`
NADPH-dependent curcumin/dihydrocurcumin reductase `MetaCyc:CPLX0-7927`	catalyzes The same supported homodimer catalyzes both reductions. These are experimentally supported enzyme reactions, not a claim that curcumin is the only possible CurA substrate.	dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	MetaCyc:RXN0-6677 Source assertion: RXN0-6677 assigns CPLX0-7927 as the enzyme through ENZRXN0-7455, with the native reduction in its left-to-right orientation. Source location `Reaction[@frameid="RXN0-6677"]/enzymatic-reaction/Enzymatic-Reaction[@frameid="ENZRXN0-7455"]/enzyme; left; right; reaction-direction` UniProtKB:P76113 Source assertion: Reviewed K-12 CurA assigns dihydrocurcumin to tetrahydrocurcumin to physiological RHEA:34813, citing ECO:0000269 PMID:21467222. Its homodimer annotation cites the same experiment. Source location `/comments/2/reaction; /comments/2/physiologicalReactions; /comments/6` PMID:21467222 Source assertion: Purified CurA produces DHC and THC; the time course places DHC between curcumin and THC. The inspected experiments identify both products by mass spectrometry and UV-visible spectra. Source location `PMC3080977: Results, Identification of the Reaction Products; Discussion; Figures 2, 3 and 4`
NADPH-dependent curcumin reductase `UniProtKB:P76113`	part_of Native complex membership agrees with the gel-filtration/SDS-PAGE homodimer assignment; the protein node is not asserted to be a sufficient monomeric catalyst.	NADPH-dependent curcumin/dihydrocurcumin reductase `MetaCyc:CPLX0-7927`	MetaCyc:CPLX0-7927 Source assertion: CPLX0-7927 contains two G6760-MONOMER subunits; its experimental mass is 82 kDa. Source location `Protein[@frameid="CPLX0-7927"]/component/Protein; component/coefficient; molecular-weight-exp` MetaCyc:G6760-MONOMER Source assertion: G6760-MONOMER has an explicit UNIPROT P76113 unification cross-reference. Source location `Protein[@frameid="G6760-MONOMER"]/dblink[dblink-db="UNIPROT"]/dblink-oid; dblink-relationship` PMID:21467222 the enzyme consists of two identical subunits. Source location `PMC3080977: Results, Molecular mass, UV-Absorption of the Curcumin-Converting Enzyme`
curcumin + NADPH + H(+) => dihydrocurcumin + NADP(+) `RHEA:34821`	part_of	`GO:0036040`	GO:0036040 Source assertion: GO:0036040 denotes curcumin catabolic process, includes the exact synonym curcumin degradation, and cites PMID:21467222 for its definition. Source location `/results/0/name; /results/0/definition; /results/0/synonyms` MetaCyc:PWY0-1527 Source assertion: PWY0-1527 contains RXN0-6676; its ordered route is RXN0-6676 followed by RXN0-6677, from curcumin through dihydrocurcumin to tetrahydrocurcumin. Source location `Pathway[@frameid="PWY0-1527"]/reaction-list; reaction-ordering; reaction-layout` RHEA:34821 Source assertion: RHEA:34821 explicitly cross-references MetaCyc RXN0-6676; master RHEA:34819 links this directed variant. The selected substrates and products follow the native reduction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34821']/rdfs:seeAlso; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34819']/rh:directionalReaction; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34821']/rh:substrates; rh:products`
dihydrocurcumin + NADPH + H(+) => tetrahydrocurcumin + NADP(+) `RHEA:34813`	part_of	`GO:0036040`	MetaCyc:PWY0-1527 Source assertion: PWY0-1527 contains RXN0-6677; its ordered route is RXN0-6676 followed by RXN0-6677, from curcumin through dihydrocurcumin to tetrahydrocurcumin. Source location `Pathway[@frameid="PWY0-1527"]/reaction-list; reaction-ordering; reaction-layout` RHEA:34813 Source assertion: RHEA:34813 explicitly cross-references MetaCyc RXN0-6677; master RHEA:34811 links this directed variant. The selected substrates and products follow the native reduction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/34813']/rdfs:seeAlso; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34811']/rh:directionalReaction; rdf:Description[@rdf:about='http://rdf.rhea-db.org/34813']/rh:substrates; rh:products`
NADPH-dependent curcumin/dihydrocurcumin reductase `MetaCyc:CPLX0-7927`	has_cofactor NADPH is the freely supplied redox cosubstrate consumed by both reactions. This edge does not imply a permanently bound prosthetic group or a metal requirement.	NADPH(4-) `CHEBI:57783`	PMID:21467222 Source assertion: CurA activity lost on dialysis recovered after NADPH addition; NADH did not restore it. The paper identifies NADPH-dependent conversion in both steps. Source location `PMC3080977: Results, Addition of Various Cofactors to the Curcumin-Converting Enzyme; Discussion`
NADPH-dependent curcumin reductase `UniProtKB:P76113`	located_in This is a native computational localization annotation, not a direct localization experiment inspected here; it is not extended to an assertion about transporter identity.	cytosol `GO:0005829`	MetaCyc:G6760-MONOMER Source assertion: G6760-MONOMER is annotated to GO:0005829 with EV-COMP-AINF (computational inference without human oversight) and PMID:19054114; its native location is CCO-CYTOSOL. Source location `Protein[@frameid="G6760-MONOMER"]/has-go-term[GO-Term/@frameid="GO:0005829"]/evidence; location`

References

GO:0036040 Gene Ontology curcumin catabolic process (source version: QuickGO response retrieved 2026-10-11)
UniProtKB:P76113 UniProtKB P76113, NADPH-dependent curcumin/dihydrocurcumin reductase (source version: 2026_03)
PMID:21467222 Discovery of the curcumin metabolic pathway involving a unique enzyme in an intestinal microorganism. (source version: 2011; full PMC article HTML retrieved 2026-10-11)
MetaCyc:PWY0-1527 MetaCyc PWY0-1527, native curcumin pathway object (source version: MetaCyc 22.5 public mirror XML; retrieved 2026-10-11)
MetaCyc:CPLX0-7927 MetaCyc CPLX0-7927, native curcumin pathway object (source version: MetaCyc 22.5 public mirror XML; retrieved 2026-10-11)
MetaCyc:G6760-MONOMER MetaCyc G6760-MONOMER, native curcumin pathway object (source version: MetaCyc 22.5 public mirror XML; retrieved 2026-10-11)
MetaCyc:RXN0-6676 MetaCyc RXN0-6676, native curcumin pathway object (source version: MetaCyc 22.5 public mirror XML; retrieved 2026-10-11)
MetaCyc:RXN0-6677 MetaCyc RXN0-6677, native curcumin pathway object (source version: MetaCyc 22.5 public mirror XML; retrieved 2026-10-11)
RHEA:34821 Rhea 34821, directed curcumin pathway reduction (source version: 142 (2026-09-02); SHA256 of exact gzip response body)
RHEA:34813 Rhea 34813, directed curcumin pathway reduction (source version: 142 (2026-09-02); SHA256 of exact gzip response body)

Curation history

2026-10-11T00:42:35Z codex
- CREATE — Add the complete two-step CurA curcumin degradation pathway
  Created exact GO:0036040 with both native CurA reductions and the dihydrocurcumin intermediate, supported homodimer membership, NADPH cosubstrate role and explicitly computational localization. Preserved K-12 DH10B versus recombinant BL21 experimental scope and excluded redundant net reaction, downstream mineralization, invented transport and metal requirements. Reassessed the prior single-enzyme exclusion: this record denotes the complete source-defined two-reaction pathway. Author replay verified both reaction sides, balances, all identifiers, source hashes and local schemas. Evidence is in research/pathway_additions/2026-10-10-next-routes/curcumin-curation.md and curcumin-validation.json. Independent scientific review and final corpus gates follow before publication.
Read this curation session