Wormlike micellar aggregates of saponins from Ilex paraguariensis A. St. Hil. (mate): A characterisation by cryo-TEM, rheology, light scattering and small-angle neutron scattering

Maria Paula G. G. Peixoto, Janine Treter, Pedro Ernesto de Resende, Nádya Pesce da Silveira, George G. Ortega, M. Jayne Lawrence, Cécile A. Dreiss

Research output: Contribution to journalArticlepeer-review

Abstract

This work reports the physico-chemical characterisation of the micellar structures formed by a saponin fraction obtained from an important South American species, Ilex paraguariensis (mate). The mate saponin-enriched fraction (MSF) mainly comprises triterpenic glycosides and was obtained from mate green fruits through solid-phase extraction. The physico-chemical studies focused on the determination of the critical micellar concentration (CMC), the size and shape of the micelles, using conventional transmission electronic microscopy (TEM), as well as Cryo-TEM, light scattering and small-angle neutron scattering. The rheological behaviour of the solutions up to 4 wt% was also determined using a controlled-strain rheometer. Finally, the MSF ability to solubilise poorly water-soluble drugs was assayed using carbamazepine and flurbiprofen as basic and weak acidic drug models. Small spherical micelles of around 20 Å radius were observed in the presence of elongated structures with lengths of more than 500 nm, possessing a well-defined CMC of 0.41 g/L. MSF solutions ranging from 0.25 to 4% (w/v) demonstrated a viscoelastic behaviour independent of the concentration. MSF could improve the solubility of carbamazepine in the range of 0.13 to 1.5% (w/v)
Original languageEnglish
Pages (from-to)536-546
Number of pages11
JournalJournal of Pharmaceutical Sciences
Volume100
Issue number2
DOIs
Publication statusPublished - Feb 2011

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