Banaba Leaf Extract (Corosolic Acid)

Banaba leaf extract is made from the dried leaves of Lagerstroemia speciosa (L.) Pers., a Lythraceae tree of tropical South and Southeast Asia known in India as Jarul or Tamhan and in English as Pride of India or queen's crape myrtle. Banaba is the Tagalog name, and the leaf has a long record of use as a tea in the Philippines, Taiwan and Japan. Indian material comes chiefly from the Western Ghats, Assam and West Bengal. The commercial marker is corosolic acid (CAS 4547-24-4, C30H48O4, MW 472.71), a pentacyclic triterpene acid whose IUPAC name is 2-alpha,3-beta-dihydroxyurs-12-en-28-oic acid. It is ursolic acid carrying one additional 2-alpha-hydroxyl group, and the two are close enough that an HPLC method has to be shown to resolve them before a corosolic figure means anything at all — co-elution with ursolic acid quietly inflates the assay, and it is the single most common reason a supplier's number and a buyer's incoming result disagree. Published measurements put corosolic acid in banaba leaf at roughly 0.31–0.38% of leaf weight, and an alcohol-concentrated banaba leaf extract at about 1%. That arithmetic sets the honest ceiling on a true leaf extract, and it is why Thovek's core grades are 1% and 2% corosolic acid by HPLC — both reachable by straightforward concentration of the leaf itself. Grades at 10%, 20% and above circulate widely and Thovek can supply them, but they are enrichment and isolation products rather than simple extracts, and buyers should know that the high-purity corosolic acid trade runs substantially on loquat leaf, Eriobotrya japonica, which carries a comparable natural level (about 0.36% in leaf) and is the feedstock named in the granted process patents for high-purity corosolic acid and ursolic acid. Thovek states the botanical origin of the corosolic acid on the specification for every enriched grade. A 98% corosolic acid isolate should never be sold as, or blended into, a product described simply as banaba leaf extract without that disclosure, and a brand that finds it has done so unknowingly has a labelling problem, not a sourcing preference. Corosolic acid is not the only thing in the leaf. Banaba also carries the ellagitannins lagerstroemin, flosin B and reginin A, along with maslinic acid, ellagic acid, kaempferol, quercetin, isoquercitrin, lagertannin and sitosterol. A native-ratio 10:1 or 20:1 leaf extract retains that fuller profile where a corosolic-enriched grade does not, so brands that want the composition of the traditional leaf tea should specify the ratio extract rather than the marker grade, and should say so on the purchase order because the two are quoted differently. The extract is vegan and vegetarian, with no milk, egg, soy, fish, crustacean, gluten or nut inputs and no bovine or porcine material or processing aids, and it is non-GMO. Tannin-bearing extracts are hygroscopic and darken on exposure to air and light, so drums ship double-lined with desiccant and should be resealed promptly; colour drift on an opened drum is almost always a handling issue rather than a specification failure. Every consignment carries a full certificate of analysis, botanical identity confirmation, heavy-metal, pesticide-residue and microbiological reports, an allergen and GMO statement and an MSDS. Organic (NPOP / NOP / EU), Kosher and Halal certified lots are available to order.