lupanine
compound / compound-lupanine
ルパニン
Lupanine is a major quinolizidine alkaloid of Lupinus seeds. In Lupinus mutabilis seeds, it is reported to account for 47–58% of total QA.
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Reading the bitterness
Lupanine is a major quinolizidine alkaloid (QA) found in Lupinus (lupin) seeds. According to the composition table of the 2019 risk assessment by the European Food Safety Authority (EFSA), in Lupinus mutabilis (an Andean species) seeds, lupanine accounts for 47–58% of total QA, followed by sparteine (7.4–16%) and 13α-hydroxylupanine (7–15%). However, the source data cultivar is recorded as "Not stated" (in translation: "Not stated").
In three species—Lupinus angustifolius, L. luteus, and L. albus—cultivated in Europe and Australia, low-alkaloid lines directly edible without water processing for bitterness removal are genetically fixed by multiple independent recessive loci segregating independently. These loci (iucundus, etc., in L. angustifolius; amoenus, etc., in L. luteus; pauper, etc., in L. albus) show 1:3 Mendelian segregation and according to a 2017 review, were first identified in wild populations in Germany from the late 1920s to the early 1930s. This represents a domestication pathway contrasting with Andean L. mutabilis, which traditionally requires water processing for bitterness removal.
The major sweet locus pauper in L. albus is caused by the acetyltransferase gene AT (Lalb_Chr18g0051511) on chromosome 18, as shown by population analysis and functional validation of 227 samples from 26 countries. The causative SNP resulting in amino acid substitution (Asp35Glu) reduces enzyme activity to 0.6% of wild-type level, and the seed alkaloid content of this 「甘味」 (in translation: "sweet") line is reported to remain at 0.02–0.05% dry weight. In the same paper, a functional null mutation of the AT ortholog in a different species, L. angustifolius, also showed seed alkaloid content reduced from 3.07% of wild-type to 0.028%, approximately 1/110.
Sources for this overview
Checked for this overview: The EFSA 2019 QA composition table is used as evidence for this paragraph.
Quinolizidine Alkaloid Biosynthesis in Lupins and Prospects for Grain Quality Improvement
Checked for this overview: The 2017 review's compilation of loci is used as evidence for this paragraph.
The causal mutation leading to sweetness in modern white lupin cultivars
Checked for this overview: Population analysis and functional validation results for the AT gene are used as evidence for this paragraph. / Alkaloid reduction results in ATKO mutants are used as evidence for this paragraph.
Follow the connections
lupanine →is the major quinolizidine …→ Andean lupin
lupanine →contributes to→ bitterness →can be measured separately …→ astringency
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (1)
Scope: EFSA 2019's table of QA composition by species
Show data
compound-lupanine —is_the_major_quinolizidine_alkaloid_of→ organism-lupinus-mutabilisMechanism and receptors (3)
Scope: Lupinus angustifolius / L. luteus / L. albus
Note: Contrasts with the existing organism-lupinus-mutabilis (Andean origin, traditionally requiring water processing for bitterness removal). The 3 species cultivated in Europe and Australia are distinctive in having genetically fixed low-alkaloid lines directly edible without water processing.
Show data
compound-lupanine —has_biosynthesis_controlled_by→ "Multiple recessive loci in Lupinus angustifolius (iucundus, esculentus, depressus, tantalus), L. luteus (amoenus, dulcis, liber), and L. albus (pauper, mitis, reductus, exiguus, nutricius), among others, segregating independently (1:3 Mendelian segregation). First identified in wild populations in Germany from the late 1920s to the early 1930s."Scope: Lupinus albus (227 accessions of wild types, landraces, breeding lines, and cultivars from 26 countries)
Note: The same paper also reports that in an AT-ortholog loss-of-function mutant (ATKO) of narrow-leafed lupin (L. angustifolius), seed alkaloid content fell from 3.07% to 0.028% of the wild type, to roughly 1/110, showing that the same enzymatic mechanism holds in another species too.
Show data
compound-lupanine —has_biosynthesis_controlled_by→ "The causal gene of pauper, the major sweet-seed locus of Lupinus albus, is the acetyltransferase gene AT (Lalb_Chr18g0051511) on chromosome 18. The Asp35Glu substitution caused by SNP_2 lowers enzyme activity to 0.6% of the wild type. Seed alkaloid content in 'sweet' lines is 0.02-0.05% of dry weight."Scope: Layer: Literature (review citing previously reported GC-MS analysis results in a speculative statement).
Note: Original review phrasing is 'might be contributing' (hedged). Do not alter to a definitive claim.
Show data
compound-lupanine —contributes_to→ sensation-bitter