Dihydromyricetin

Dihydromyricetin (DHM), also known as ampelopsin, is a flavanonol (dihydroflavonol) with the molecular formula C₁₅H₁₂O₈ and molecular weight 320.25 g/mol. It is not a food consumed for macronutrient content; rather, it is a bioactive polyphenolic compound typically consumed as a purified supplement or obtained from dietary sources. Key details: • Primary bioactive compound: Dihydromyricetin (ampelopsin) itself — a 3,5,7,3',4',5'-hexahydroxyflavanone. • Natural source concentration: Found abundantly in Ampelopsis grossedentata (vine tea/moyeam tea), where dried leaves contain approximately 20–40% DHM by weight, making it one of the richest natural sources of a single flavonoid. Also present in smaller quantities in Hovenia dulcis (Japanese raisin tree), Cedrus deodara, and certain Vitis species. • Supplement dosages typically range from 150–600 mg per dose, with clinical studies using 300–600 mg/day. • Macronutrients: Negligible — DHM is consumed in milligram quantities and contributes essentially zero calories, protein, fat, carbohydrate, or fiber. • Micronutrients (vitamins/minerals): None intrinsic to the purified compound. Vine tea extracts may contain trace minerals and other polyphenols (myricetin, gallic acid, quercetin derivatives) but these are incidental. • Key bioactive properties: DHM possesses six hydroxyl groups contributing to strong antioxidant capacity (ORAC and DPPH radical scavenging activity comparable to or exceeding that of many common flavonoids). It chelates metal ions (Fe²⁺, Cu²⁺) and modulates AMPK, SIRT1, Nrf2/ARE, and NF-κB signaling pathways. • Bioavailability notes: Oral bioavailability is relatively LOW, estimated at approximately 4–17% in animal models. DHM undergoes extensive first-pass metabolism including glucuronidation, sulfation, and methylation in the gut and liver. Absorption is primarily in the small intestine. Plasma half-life is short (~1.5–3 hours in animal studies). Bioavailability may be enhanced by co-administration with lipid-based carriers, phospholipid complexes (phytosomes), nanoformulations, or piperine. Gut microbiota metabolize unabsorbed DHM into smaller phenolic acids (e.g., phloroglucinol derivatives), which may contribute additional bioactivity. Peak plasma concentration (Tmax) occurs approximately 0.5–1.5 hours post-oral ingestion. Water solubility is limited (~20 mg/mL at room temperature), which partly explains the low bioavailability.