Pharmacognosy intro
Achillea millefolium L. (Asteraceae), commonly known as yarrow, milfoil, or soldier's woundwort, is a circumboreal perennial herb distributed across temperate regions of Europe, Asia, and North America. The species is named for the Greek hero Achilles, who reputedly used the plant to treat wounded soldiers at Troy. The aerial parts, particularly the flowering tops, are the primary medicinal material, harvested at peak bloom. The species epithet millefolium (thousand-leaf) describes the extremely fine dissection of the feathery foliage. The phytochemical profile is broad. The flavonoid fraction includes apigenin, luteolin, rutin, quercetin, and artemetin. Caffeic acid derivatives, principally caffeoylquinic acids (chlorogenic acid, 1,5-di-O-caffeoylquinic acid), contribute antioxidant capacity. Sesquiterpene lactones (achillin, achillicin, leucodin) provide bitter and anti-inflammatory activity. The essential oil (0.2 to 0.8% yield) contains chamazulene, a blue azulene formed during steam distillation from proazulene precursors, which is the same anti-inflammatory compound class found in German chamomile. Additional oil components include 1,8-cineole, camphor, sabinene, beta-pinene, borneol, and trace thujone (significantly less than mugwort). The alkaloid achilleine is specific to the genus and provides hemostatic activity. Tannins contribute astringent effects, and salicylic acid derivatives may contribute to anti-inflammatory action. Yarrow's hemostatic mechanism involves achilleine promoting platelet aggregation and fibrin clot formation at the wound site, with tannins providing additional astringent and styptic effects through protein precipitation. This dual mechanism reduces bleeding time in topical wound applications. The anti-inflammatory profile is multi-pathway: chamazulene inhibits inflammation through the same mechanisms as in chamomile; flavonoids (apigenin, luteolin) inhibit both COX-2 and 5-LOX; sesquiterpene lactones contribute NF-kB suppression. Strzepek-Gomolka et al. (2021, Oxidative Medicine and Cellular Longevity) documented yarrow's inhibition of NO production in LPS-stimulated RAW264.7 macrophages and confirmed its antioxidant capacity through DPPH and ABTS radical scavenging assays. The flavonoid apigenin binds GABA-A receptors, producing mild anxiolytic and antispasmodic effects. As a diaphoretic, yarrow promotes sweating when taken as hot infusion, forming part of the traditional European flu tea (yarrow, elderflower, peppermint). Clinical evidence is largely observational and review-based rather than from large RCTs. Strzepek-Gomolka et al. (2021) provided a comprehensive review supporting yarrow's dermatological applications. The hemostatic use for wound treatment represents one of the longest continuous applications of any medicinal plant in documented history. Clinical applications include topical wound care, nosebleed management (fresh leaf insertion, leveraging achilleine), digestive bitter therapy for dyspepsia, antispasmodic relief for dysmenorrhea, and astringent application for hemorrhoids. Yarrow is contraindicated in pregnancy due to its emmenagogue and uterine stimulant properties. Its interaction with anticoagulant therapy is complex, as the plant contains both hemostatic compounds (achilleine) and anticoagulant compounds (coumarin derivatives), making the net effect unpredictable.