Ginkgo Biloba (Ginkgo biloba)

Ginkgo biloba leaf extract is not a significant source of macronutrients (negligible protein <1%, fats <1%, carbohydrates minimal in standardized extracts). Its profile is defined by standardized bioactive compounds: Flavonoid glycosides (24% in EGb 761 standardized extract) — primarily quercetin glycosides (~9-10 mg/g), kaempferol glycosides (~8-9 mg/g), and isorhamnetin glycosides (~2-3 mg/g); these are hydrolyzed to aglycones post-absorption with moderate bioavailability (~70-80% for quercetin derivatives). Terpene lactones (6% in EGb 761) — ginkgolides A, B, C, J (total ~3.1-3.4 mg/g) and bilobalide (~2.6-2.9 mg/g); ginkgolide B is the most pharmacologically active PAF antagonist; oral bioavailability of ginkgolides ~80%, bilobalide ~72%. Ginkgolic acids — potentially toxic alkylphenols, regulated to <5 ppm (<5 µg/g) in quality extracts (USP/EMA standard). Proanthocyanidins — present at ~7% in crude leaf, reduced in standardized extracts; include catechin and epicatechin oligomers. Other polyphenols — biflavonoids (amentoflavone, bilobetin, ginkgetin) at ~0.2-0.5 mg/g; notable as CYP3A4 inhibitors but poorly bioavailable (~20-30%) due to low solubility. Minerals — trace amounts: potassium (~3.2 mg/g dry leaf), calcium (~8.1 mg/g dry leaf), magnesium (~2.1 mg/g dry leaf); negligible in concentrated extracts. Vitamins — minimal: trace vitamin C (~0.5-1.2 mg/g in fresh leaf, degraded in extract processing), trace beta-carotene. Fiber — crude leaf contains ~15-18% dietary fiber, essentially absent in standardized liquid/tablet extracts. Standard clinical dose of 120-240 mg EGb 761 extract delivers approximately 28.8-57.6 mg flavonoid glycosides and 7.2-14.4 mg terpene lactones. Bioavailability is enhanced by lipid co-administration for terpene lactones; Tmax for ginkgolide B ~2 hours, half-life ~4-4.5 hours; Tmax for flavonol aglycones ~1.5-2.5 hours post-hydrolysis.