Abstract:

Microemulsions (MEs) have gained increasing interest as carriers of hydrophobic bioactives in the last decades. However, it is still difficult to control the uptake and the release of bioactives directly extd. from plants. In this study, modified ME nanodroplets (nano-sized self-assembled liqs., NSSLs) were employed as extn. medium of gossypol, a toxic component of cottonseed. Loading was performed using both pure gossypol, and gossypol obtained by extn. from cottonseed. We achieved two goals: (i) remove gossypol from cottonseed to obtain cotton-oil free of gossypol; and (ii) ext. gossypol directly into a nano-delivery vehicle for biomedical purposes. Structural and dynamical information on the unloaded and gossypol-loaded NSSL systems were obtained by self-diffusion NMR, SD-NMR, and spin-probe ESR (EPR) studies. The results showed that NSSL formed fluid water-in-oil (W/O) nano domains at the lowest water contents; a more viscous bicontinuous structure at comparable oil and water contents, and, finally, oil-in-water (O/W, micellar-like) at the higher concn. of water. These micellar-like structures were more fluid at the external hydrated surface, as demonstrated by SD-NMR, while the lipidic region tested by EPR revealed an increasing packing. In all these structures, gossypol mainly localized in the lipophilic region close to the water interface. Overall, SD-NMR and EPR provided complementary information, helping to clarify the structural properties of NSSLs formed at different water contents and their ability to incorporate gossypol also directly from cottonseed-NSSL mixts. [on SciFinder(R)]