4-Hydroxyisoleucine
Compiled from published pharmacological and botanical literature. Not independently verified by Herbuno. Spotted an error or have a correction? Flag it below →
| Chemical Class | Non-protein branched-chain amino acid |
| Molecular Formula / CAS | C₆H₁₃NO₃ · CAS 55399-93-4 |
| Primary Botanical Source(s) | Fenugreek (Trigonella foenum-graecum) |
| Plant Part | Seed |
| Typical Content | An unusual amino acid found, to current knowledge, almost exclusively in fenugreek seed among common food and botanical sources |
| Solubility / Format | Water-soluble amino acid; available as standardised extract powders |
| Sourcing Status | Product-live — genuine match via Herbuno’s fenugreek-derived extract line |
| Buy from Herbuno | 4-Hydroxyisoleucine 40% Powder (Fenugreek Extract) · 4-Hydroxyisoleucine 20% Powder |
Name origin: 4-Hydroxyisoleucine takes its systematic name directly from its chemical structure — a hydroxylated derivative of the branched-chain amino acid isoleucine, hydroxylated specifically at the 4-position. Traditional use: Fenugreek has an extensive traditional-medicine history across Ayurvedic, Middle Eastern and Mediterranean herbal systems specifically for blood-sugar-related complaints, alongside its widespread culinary use as a spice — a traditional indication that modern pharmacology has since traced substantially to 4-hydroxyisoleucine’s direct insulinotropic activity. Research trajectory: 4-Hydroxyisoleucine was characterised and named as a distinct bioactive compound in 1998, when researchers isolated it from fenugreek seed specifically because it accounted for a glucose-dependent insulin-releasing effect they observed in isolated pancreatic islet studies; research since has expanded from basic insulin-secretion pharmacology into broader investigation of its effects on insulin resistance, lipid metabolism, and liver function in animal models of metabolic dysfunction. Commercial source: Fenugreek seed is, to current knowledge, essentially the sole practical commercial source of 4-hydroxyisoleucine, and Herbuno’s standardised extracts reflect this genuine, well-established botanical match.
Evidence for 4-Hydroxyisoleucine Applications
4-Hydroxyisoleucine was formally characterised in 1998 as a novel amino acid potentiator of insulin secretion, isolated and purified from fenugreek seed specifically because it increased glucose-induced insulin release through a direct effect on isolated pancreatic islets of Langerhans from both rats and humans, in a strictly glucose-dependent manner — the compound was ineffective at low or basal glucose concentrations but potentiated insulin release at supranormal (hyperglycaemic-range) glucose concentrations (Sauvaire et al. 1998). This glucose-dependence is mechanistically significant, since it distinguishes 4-hydroxyisoleucine from insulin secretagogues that risk inducing hypoglycaemia regardless of ambient blood glucose. Claim strength: Moderate.
A comprehensive review of 4-hydroxyisoleucine’s effects on obesity-associated insulin resistance summarised evidence that the compound regulates blood glucose, reduces plasma triglycerides, total cholesterol and free fatty acid levels, and improves liver function, acting mechanistically through increased Akt phosphorylation alongside reduced activation of JNK, ERK, p38 MAPK, and NF-κB signalling pathways implicated in insulin resistance (Avalos-Soriano et al. 2016). This mechanistic breadth positions 4-hydroxyisoleucine as relevant to the broader metabolic syndrome picture, not solely acute insulin secretion. Claim strength: Moderate.
A dedicated review of fenugreek’s three principal bioactive components — diosgenin, 4-hydroxyisoleucine, and dietary fiber — examined their combined and individual mechanisms of action relevant to metabolic syndrome, concluding that 4-hydroxyisoleucine’s insulin-secretion and insulin-sensitisation properties represent one of the more mechanistically well-characterised components of fenugreek’s traditional antidiabetic reputation (Fuller & Stephens 2015). Claim strength: Moderate.
Animal studies have extended 4-hydroxyisoleucine research into liver-specific outcomes, finding that in fructose-fed and streptozotocin-diabetic rat models, 4-hydroxyisoleucine treatment restored elevated liver damage markers (aspartate and alanine transaminase) toward control values alongside improving glucose measures, suggesting a hepatoprotective effect that complements its pancreatic insulin-secretion mechanism. This remains animal-model evidence and has not been confirmed in human liver-function trials specifically. Claim strength: Emerging.
Because 4-hydroxyisoleucine and fenugreek’s soluble fibre content both contribute to fenugreek’s traditional hypoglycaemic reputation through distinct mechanisms — direct insulinotropic action versus delayed carbohydrate absorption — formulators should specify whether their sourcing intent is the isolated amino acid or the broader fenugreek seed fibre complex, since a 4-hydroxyisoleucine-standardised extract will not necessarily deliver a proportional fibre-mediated glucose effect. Claim strength: Moderate.
Dosage & Formulator Specification
Animal research has used 4-hydroxyisoleucine doses in the range of 18–50 mg/kg body weight daily across various rodent models of insulin resistance and diabetes; no formally established human clinical dosing range exists for the isolated compound specifically, distinct from broader whole-fenugreek-seed dosing precedent (typically 2.5–15 g/day of crushed defatted seed in clinical fenugreek studies). Formulators building a product around isolated 4-hydroxyisoleucine rather than whole fenugreek seed should be transparent that human dose-response data for the isolated compound remains an evidence gap relative to the animal-model literature.
Analytical quantification of 4-hydroxyisoleucine content is performed by HPLC, the standard method used across the fenugreek research literature; formulators should request HPLC-verified 4-hydroxyisoleucine percentage rather than a generic fenugreek saponin or fibre specification, since these represent chemically and functionally distinct fenugreek constituents.
Because 4-hydroxyisoleucine has documented glucose-lowering and insulin-potentiating activity, formulators should note the same general caution applied to hypoglycaemic botanical ingredients: individuals taking insulin or other glucose-lowering medications may need blood glucose monitoring when combining these with a 4-hydroxyisoleucine-standardised product, though its glucose-dependent mechanism of action is mechanistically distinct from, and potentially lower-risk than, non-glucose-dependent insulin secretagogues.
Regulatory positioning for 4-hydroxyisoleucine follows established fenugreek food and botanical-ingredient precedent in most markets, given fenugreek’s long culinary and traditional-medicine use history; no 4-hydroxyisoleucine-specific regulatory limit exists beyond standard fenugreek-derived ingredient documentation.
Frequently Asked Questions — 4-Hydroxyisoleucine
Its insulin-releasing effect is strictly glucose-dependent — the original 1998 research found it was ineffective at normal or low blood glucose levels but potentiated insulin release specifically when glucose concentrations were elevated. This distinguishes it from secretagogues that could trigger insulin release regardless of blood sugar status.
To current scientific knowledge, fenugreek is essentially the sole practical commercial and research source of 4-hydroxyisoleucine among common botanical and food sources, making it one of the more source-specific compounds in the HerbIQ index.
No. They are distinct fenugreek constituents that both contribute to fenugreek’s traditional hypoglycaemic reputation through different mechanisms: 4-hydroxyisoleucine acts directly on pancreatic insulin secretion, while fenugreek’s soluble fibre works by slowing carbohydrate absorption in the gut.
Beyond insulin secretion, research has found it reduces plasma triglycerides, cholesterol and free fatty acid levels, and improves liver function markers in animal models, suggesting effects relevant to broader metabolic syndrome rather than blood sugar alone.
Related compounds: Diosgenin, Corosolic Acid