Avocado-derived polyols for use as novel co-surfactants in low energy self-emulsifying microemulsions

Abstract

Avocado (Persea americana Mill.; Lauraceae) seed-derived polyhydroxylated fatty alcohols (PFAs) or polyols (i.e., avocadene and avocadyne) are metabolic modulators that selectively induce apoptosis of leukemia stem cells and reverse pathologies associated with diet-induced obesity. Delivery systems containing avocado polyols have not been described. Herein, natural surface active properties of these polyols are characterized and incorporated into self-emulsifying drug delivery systems (SEDDS) that rely on molecular self-assembly to form fine, transparent, oil-in-water (O/W) microemulsions as small as 20 nanometers in diameter. Mechanistically, a 1:1 molar ratio of avocadene and avocadyne (i.e., avocatin B or AVO was shown to be a eutectic mixture which can be employed as a novel, bioactive, cosurfactant that significantly reduces droplet size of medium-chain triglyceride O/W emulsions stabilized with polysorbate 80. In vitro cytotoxicity of avocado polyol-SEDDS in acute myeloid leukemia cell lines indicated significant increases in potency and bioactivity compared to conventional cell culture delivery systems. A pilot pharmacokinetic evaluation of AVO SEDDS in C57BL/6J mice revealed appreciable accumulation in whole blood and biodistribution in key target tissues. Lastly, incorporation of AVO in SEDDS significantly improved encapsulation of the poorly water-soluble drugs naproxen and curcumin. Avocados have been shown to be an exclusive source of unique long carbon chain (C 17 to C 21) polyhydroxylated fatty alcohols or polyols that possess anti-cancer, anti-inflammatory and anti-microbial properties 1-4. Previously, we demonstrated that avocatin B (AVO), a 1:1 mixture of two 17-carbon polyols (avocadyne and avocadene), target mitochondria and inhibit fatty acid oxidation (FAO) which selectively induces death in leukemia cells 5-8. More recently, avocadyne has been shown to exert potent immunomodulatory effects that impede dengue virus replication in vitro 9. Furthermore, our laboratory determined that AVO inhibited FAO in skeletal muscle and pancreatic β-cells reversing insulin resistance and restoring glucose tolerance in diet-induced obesity 10. The highly promising indications for avocado polyols in human disease and nutrition necessitate the complete characterization of their physicochemical properties and subsequent development of optimal formulations for future in vivo and clinical studies. To our knowledge, use of avocado polyols is prominent in topical cosmetic formulations described briefly in patent literature 11,12. This is the first report that avocadene and avocadyne possess unique physicochemical properties ideal for SEDDS applications. SEDDS comprise a mixture of oils, co-solvents, surfactants and co-surfactants that spontaneously self-assemble into oil-in-water (O/W) or water-in-oil (W/O) nano (~100-400 nm in diameter) or micro (<100 nm in diameter) emulsions 13. Surfactants delay droplet coalescence by reducing the surface free energy associated with the oil-water interface by creating a rigid, ...

Very long chain fatty acid metabolism is required in acute myeloid leukemia

“…While previous studies (Lee et al, 2015) (Ahmed et al, 2020) (Tabe et al, 2018) AML is a devastating blood cancer with limited therapeutic options that fail to eliminate the entire cancer cell population and are toxic to the normal hematopoietic population (Löwenberg et al, 2011)(Khwaja et al, 2016. Compared to the normal hematopoietic population, AML populations exhibit a distinct mitochondrial phenotype characterized by an increased reliance on higher rates of FAO (Samudio et al, 2010) (German et al, 2016) with a diminished capacity to oxidize other substrates upon inhibition of oxidative metabolism (Molina et al, 2018) (Lagadinou et al, 2013) (Sharon et al, 2019).…”

“…Jackson Laboratory) mice were used for xenotransplant and engraftment studies and conducted as previously described (Lee et al, 2015). A oil-in-water emulsion containing AYNE was used for treating mice (Ahmed et al, 2020). In brief, 50 µL of NeoBeeM5 (Stepan) and 50 µL of Tween Tumor volumes were measured as previously described (Lee et al, 2015) and tumor burden was calculated relative to each mouse's weight.…”

“…Analysis of complete blood counts, bilirubin, serological markers and mouse body weights showed no difference between control and AYNE treatment groups (Figure 5.2.25 A-M), further demonstrating an anti-AML therapeutic dose of AYNE that is well-tolerated by mice. (Ahmed et al, 2020) or an emulsion encapsulating AYNE (150 or 200 mg/kg) (N=3). (B) Schematic outlining thermal stabilization of a protein by ligand binding as assessed by cellular thermal shift assay (Ishii et al, 2017).…”

“…3.15.2 In Vivo Engraftment2.5*10^6 cells human AML cells solvated in 100 µL PBS were injected via tail vein and engrafted into the femurs over the course of one or four weeks. Mice received either a vehicle emulsion(Ahmed et al, 2020) or an emulsion(Ahmed et al, 2020) containing 200 mg/kg/week of (2R,4R)-AYNE for four weeks. Human leukemia cells in the femurs were recovered, incubated with anti-CD33 (Cat#303404; Biolegend) and anti-CD45 (Cat#103107; BioLegend) antibodies, and then quantified via flow cytometry on a Guava EasyCyte 8HT.…”

“…Human cells were given either a four or six week period to engraft into the femural bone marrow. Mice were then divided into two groups to receive either a vehicle emulsion(Ahmed et al, 2020) or an emulsion containing AYNE three times weekly for four or six weeks. Following sacrifice at the planned end of study, mice femurs were flushed, and human CD33+/CD45+ cells were quantified via flow cytometry.…”