Novel nanocarriers for the bioactive natural products alkannins for topical use

Nanocarriers, such as liposomes, niosomes and nanoemulsions are extensively investigated drug delivery systems (DDS) for lipophilic and hydrophilic drugs [1]. Alkannins and shikonins (A/S) are naturally occurring hydroxynaphthoquinones with a well-established spectrum of wound healing, regenerative, antimicrobial, anti-inflammatory, antioxidant and antitumor activities [2]. Our group has successfully developed and characterized liposomal DDS of A/S using several phospholipids [3]. The aim of the present study was to prepare and characterize novel nanocarriers containing a mixture of alkannin and its derivatives (API) isolated as in [4] from the hexane extract of Alkanna tinctoria roots, using PHOSAL^® 40IP (kindly donated by Lipoid GmbH, Ludwigshafen, Germany), by the reverse phase evaporation technique [5]. PHOSAL^® contain soybean phosphatidylcholine in sunflower oil and can be used as carriers for lipophilic and amphiphilic APIs. In order to optimize the formulation, different ratios of PHOSAL:cholesterol (10:1, 6.5:1 and 3:1 w/w) and PHOSAL:drug (40:1, 22.5:1 and 5:1 w/w) were examined, monitoring the particle size distribution, ζ-potential values, entrapment efficiency and drug release. The prepared formulations exhibited mean particle size from 120–200 nm, PDI values ranging between 0.117–0.269 and ζ-potential ones ranging from − 11 to − 18 mV. Furthermore, the API loading ranged between 3.12–5.98%, while entrapment efficiency reached 70%. The in vitro release was measured at phosphate buffer saline (pH 5.5 with 1% SDS) using UV spectrophotometry at 519 nm, as shown in [Fig. 1]. These findings are considered promising and could be used for further design of dermal nanocarriers using PHOSAL^® 40 IP.

Fig. 1 Release profile of APIs from different samples (519 nm).

Acknowledgements

The authors acknowledge support of this work by the project “Upgrading the plant capital” (MIS5002803) implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).

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