Development of a reproducible and scalable process to produce a saponin-enriched extract from Quillaja brasiliensis leaves

Fraction B (FB) is a purified immunoadjuvant saponin fraction obtained from the aqueous leaf extract of Quillaja brasiliensis (Qb) through solid-phase extraction (SPE-C18). These triterpenoid saponins are structurally similar to those of Quillaja saponaria (Qs), a Chilean tree that serves as the main industrial saponin source [ 1 ] [ 2 ]. Saponins from Qb leaves offer a sustainable alternative to those from Qs bark. Two commercially relevant Qs-derived adjuvants are Quil A ®​ , a complex saponin mixture, and QS-21, a mixture of two isomeric saponins. This study aims to develop and characterize a high-value, reproducible, and scalable biotechnological product as an alternative to FB, using Qb leaf saponins purified through diafiltration. Diafiltration was performed with Pellicon ®​ XL CassetteUltracel ®​ (10 kDa) using aqueous leaf extract (25 g/L). Two parallel processes were carried out: one in water (P1) and another in 0.1% formic acid (P2). Each solution was filtered and concentrated three times, yielding three permeates and one retentate. The process was monitored by determining total saponins using HPLC-DAD and UHPLC-MS (Full MS), while QS-21 isomers were analyzed by UHPLC-MS (SIM, m/z 1987). Preliminary LC-MS data suggest the presence of four QS-21-like compounds in Qb leaves [ 1 ] [ 2 ] [ 3 ]. Additionally, total phenolic compounds were determined using Folin-Ciocalteu method. Two high-value extracts were obtained: one enriched in saponins and another in phenolics. In both cases, P2 was more efficient than P1. Although this process produces saponins of intermediate purity, the resulting product could have direct applications or serve as a starting material for more efficient purification of pure compounds. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany