The aim of this work was to rationally design and characterize nanocapsules (NCs) composed of an oily core and a polyarginine (PARG) shell, intended for oral peptide delivery. The cationic polyaminoacid, PARG, and the oily core components were selected based on their penetration enhancing properties. Insulin was adopted as a model peptide to assess the performance of the NCs. After screening numerous formulation variables, including different oils and surfactants, we defined a composition consisting of oleic acid, sodium deoxycholate (SDC) and Span 80. This selected NCs composition, produced by the solvent displacement technique, exhibited the following key features: (i) an average size of 180nm and a low polydispersity (0.1), (ii) a high insulin association efficacy (80-90% AE), (iii) a good colloidal stability upon incubation in simulated intestinal fluids (SIF, FaSSIF-V2, FeSSIF-V2), and (iv) the capacity to control the release of the associated insulin for >4h. Furthermore, using the Caco-2 model cell line, PARG nanocapsules were able to interact with the enterocytes, and reversibly modify the TEER of the monolayer. Both cell adhesion and membrane permeabilization could account for the pronounced transport of the NCs-associated insulin (3.54%). This improved interaction was also visualized by confocal fluorescent microscopy following oral administration of PARG nanocapsulesto mice. Finally, in vivo efficacy studies performed in normoglycemic rats showed a significant decrease in their plasma glucose levels after treatment. In conclusion, here we disclose key formulation elements for making possible the oral administration of peptides.

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Hepatic-related diseases, in particular hyperlipidemia and hypercholesterolemia, are a thorn on the side of the national health institutes around the globe. Indeed, liver lipid and cholesterol dysregulation could lead to atherosclerotic plaque formation and cardiovascular diseases. Currently, statin administration and monacolin K consumption are the main therapies proposed to counter this alarming connection, but relevant side effects are known. To overcome this issue, safe nutraceutical formulations and/or vegetal extracts, endowed with anticholesterolemic activity, could be instrumental in hypercholesterolemia prevention and treatment. In the present work, the anticholesterolemic efficacy of three vegetal extracts used in traditional medicine (artichoke, caigua, and fenugreek), their unique blend (ACFB), and the monacolin K-containing red yeast extract (RYR), was investigated with an in vitro approach based on hepatic cell line HepG2. The impact on cholesterol of the three extracts, their blend, and RYR were investigated by determining hepatocyte total and free cholesterol and bile acids biosynthesis. According to our results, the anticholesterolemic activity of the vegetal extracts was confirmed, and a novel choleretic activity of caigua extract was evidenced. ACFB showed to be safer than RYR while showing a similar effect on total and free cholesterol and bile acids synthesis compared to it. The anticholesterolemic activity of the blend was obtained with lower vegetal extract concentrations compared with the single vegetal extract, potentially indicating an additive effect between the extracts. In conclusion, the vegetal extracts and their blend, ACFB, are safe and are endowed with anticholesterolemic activity, potentially providing complementary therapies to the statin-based ones for hyperlipidemia and hypercholesterolemia-related complications.

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