Gramine — Donaxine (Indole Mannich Base Alkaloid · Antifeedant · Vasoconstriction · Synthesis Intermediate)
| Compound | Gramine (Donaxine; 3-(Dimethylaminomethyl)indole) |
| Chemical class | Alkaloid — Indole (Simple dimethylaminomethyl indole; Mannich base-type alkaloid) |
| CAS | 87-52-5 |
| Primary source | Arundo donax (giant reed / donax, leaves), Hordeum vulgare (barley, seedlings), Lupinus spp. |
| Key applications | Vasoconstriction; smooth muscle contraction; antifeedant; serotonin receptor modulation; availability on request |
| Claim strength | Moderate (pharmacological); Emerging (supplement applications) |
| Typical form | Arundo donax leaf extract or barley seedling extract; gramine isolate (research grade) |
| Buy from Herbuno | Request availability and bulk pricing → |
Name origin: From Gramineae (the former family name for grasses; now Poaceae). Gramine (also donaxine, from Arundo donax) is a structurally simple indole alkaloid — an indole ring with a dimethylaminomethyl group at the 3-position. It is one of the simplest indole alkaloids and was among the first to be identified in cereal grasses. Distribution: Gramine occurs in barley seedlings (Hordeum vulgare) where it functions as an antifeedant — deterring aphids and other insects from feeding on young plants. It also occurs abundantly in giant reed (Arundo donax) and various lupins. In barley, gramine content in seedlings correlates inversely with aphid susceptibility, making it an agronomically interesting plant defence compound. Pharmacological interest: Gramine has attracted research for: (1) vasoconstriction via alpha-adrenergic and serotonin receptor modulation; (2) antifeedant (insect deterrence) properties relevant to botanical crop protection; (3) indole alkaloid scaffold for chemical synthesis (gramine is a key intermediate in the synthesis of tryptophan and other indoles via the Madelung synthesis and related chemistry). Commercial source: Not currently in the Herbuno catalogue. Contact Herbuno for availability assessment from Arundo donax or barley seedling extracts.
Evidence for Gramine Applications
Vasoconstriction and cardiovascular effects: Gramine produces vasoconstriction in isolated vessel preparations via alpha-adrenergic receptor agonism and 5-HT2 receptor modulation. Animal studies show blood pressure elevation. The cardiovascular mechanism has attracted interest for circulatory applications but the profile is not well-differentiated from safer vasoactive agents. Claim strength: Moderate (pharmacological mechanism; animal data).
Antifeedant and plant defence: Gramine at concentrations found in barley seedlings significantly reduces aphid settling and feeding behaviour. This antifeedant activity is the primary ecological function of gramine in grasses. Research into gramine as a botanical insect deterrent for crop protection applications is ongoing. Claim strength: Moderate (well-characterised in plant ecology; agronomic rather than supplement application).
Synthetic chemistry intermediate: Gramine’s most commercially significant role is as a synthetic intermediate — its dimethylaminomethyl group participates readily in substitution reactions, enabling introduction of diverse functional groups at the 3-position of indole. This Mannich base chemistry makes gramine a key building block for indole natural product synthesis (tryptophan derivatives, indole alkaloids). Commercial chemistry reference.
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Dosage & Formulator Specification
No established human supplement dose for gramine. Pharmacological active concentrations in vascular smooth muscle: 10–100 μM. Sub-toxic oral bioavailability data in humans are absent. Gramine is not commercially formulated as a supplement ingredient. For any formulation interest, note that barley seedling extract concentrations of gramine are relatively low — dedicated extraction from Arundo donax or concentrated barley seedling extract would be required for meaningful gramine content. Contact Herbuno for botanical extract availability and gramine quantification.
Frequently Asked Questions — Gramine
Why does barley contain gramine?
Gramine in barley seedlings functions as an antifeedant — the compound deters aphids (particularly the grain aphid Rhopalosiphum padi and bird cherry-oat aphid) from colonising young plants. Plant breeders have studied the correlation between gramine content and aphid resistance as a potential trait for breeding aphid-resistant barley varieties without pesticide use. Gramine content peaks in young barley seedlings and decreases as the plant matures — consistent with the high predation pressure on seedlings.
Is gramine related to tryptamine or serotonin?
Structurally yes — all share the indole scaffold. Gramine (3-dimethylaminomethylindole) is the simplest 3-substituted indole alkaloid. Tryptamine (3-[2-aminoethyl]indole) has an ethylamine side chain instead of gramine’s methylamine. Serotonin (5-hydroxytryptamine) adds a 5-hydroxyl to the tryptamine scaffold. Gramine’s serotonin receptor activity (particularly 5-HT2) reflects its structural kinship with the tryptamine class, though it is substantially less potent than tryptamine or serotonin at these receptors.
Can Arundo donax be used as a commercial source of gramine?
Arundo donax (giant reed) is one of the highest-yielding biomass crops globally — fast-growing, drought-tolerant, and producing 30–40 tonnes of dry biomass per hectare annually. Its leaves and stems contain gramine as a secondary metabolite. While gramine can be extracted from Arundo leaves, the commercial demand for isolated gramine is primarily for synthetic chemistry (as an indole building block) rather than supplement applications. Arundo is also under investigation as a bioenergy feedstock, and gramine extraction could be a value-added co-product of Arundo biorefineries.
What is the Mannich base chemistry associated with gramine?
Gramine is a Mannich base — a compound formed by Mannich condensation (reaction of an active hydrogen compound + formaldehyde + dimethylamine). Its dimethylaminomethyl group can be displaced by nucleophiles (malonate, cyanide, azide) in a classic substitution reaction, introducing diverse functional groups at the indole 3-position. This makes gramine the starting material for indole-3-acetic acid (auxin plant hormone), L-tryptophan industrial synthesis, and numerous other indole natural product preparations. The Mannich base reactivity of gramine is exploited in multi-step syntheses of complex indole alkaloids.
Related compounds: Tryptamine, Harmine, Voacangine, Lycorine
Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.
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