Quillaia

Quillaia extracts (synonyms, soapbark extracts, Quillay bark extracts, bois de Panama, Panama bark extracts, quillai extracts) are obtained by aqueous extraction of the milled inner bark or of the wood of pruned stems and branches of Quillaja saponaria Molina (family Rosaceae). The term ‘quillaia’ refers to the dried inner bark of the tree, which is a large evergreen with shiny, leathery leaves and a thick bark, native to China and several South American countries, principally Bolivia, Chile, and Peru. Unpurified extracts contain over 60 triterpenoid saponins, consisting predomi-nantly of glycosides of quillaic acid. Polyphenols and tannins are major components. Some simple sugars and calcium oxalate are also present. The saponin concentration of freshly prepared, unpurified extracts is 190–200 g/kg of solids (about 20%). The extracts are treated with ‘stabilizing agents’ such as egg albumin and polyvinyl-pyrrolidone and then filtered through diatomaceous earth. The stabilizing agents remove substances that would probably precipitate during storage, such as protein–polyphenol complexes. After filtration, the liquid is concentrated, and the concentrate may be sold as such (solids constituting about 550 g/L) or be spray-dried and sold as a powder containing carriers such as lactose and maltodextrin. The unpurified extracts are used in food applications, primarily for their foaming properties. Semi-purified powdered extracts are produced by subjecting unpurified extracts to ultra-filtration or affinity chromatography to remove most non-saponin solids, such as polyphenols. These semi-purified extracts have higher saponin concentrations (750–800 g/kg of solids; about 80%) and better emulsifying properties than unpurified extracts. Highly purified extracts are produced for use as adjuvants in the production of animal and human vaccines and not for food use. These products generally contain more than 90% saponins. In previous evaluations, the Committee considered data that related to unpurified quillaia extracts. Quillaia extract was reviewed toxicologically by the Committee at its twenty-sixth meeting (Annex 1, reference 59). The available toxicological data included adequate lifetime studies in mice and rats, from which a NOEL was identified. However, in the absence of data, no specifications were prepared, and, hence, no ADI could be allocated. At its twenty-ninth meeting (Annex 1, reference 70), the Committee prepared new tentative specifications and established an ADI of 0–5 mg/kg bw. The Codex Committee on Food Additives and Contaminants (CCFAC) (2000) at its thirty-second session requested the Expert Committee to re-evaluate all relevant information on the toxicity and, in particular, the intake of quillaia extracts. No new data were submitted to the Committee. Published reports on quillaia extracts or specific saponins that provided information relevant to a toxicological assessment of quillaia extracts were evaluated at the present meeting. Quillaia extracts are mixtures of biologically active compounds, including saponins, tannins, polyphenols, and calcium oxalate. The saponins present in quillaia extract have a variety of biological activities: haemolytic, cytotoxic, immune-enhancing (adjuvant), mucosal irritation and inflammation, and anti-hypercholesterolaemic. The biological activities and the potency of individual saponins vary widely and depend in vivo primarily on the route of administration. Saponins extracted with ethanol from soapbark trees and administered orally to rabbits with experimental atherosclerosis resulted in an increased ratio of plasma lecithin to cholesterol, normalized blood cholesterol levels, and decreased elevated blood pressure. Subcutaneous injection of the saponin extract did not affect the atherosclerotic symptoms (Efimova et al., 1966). Groups of 12 Swiss mice (strain and sex unstated) were injected into the footpad with aliquots of seven different 5% extracts of Q. saponica bark. Ani