Aqueous ethanol ananas comosus peel extract as the bioactive ingredient in an oil-in-water nanocream for topical delivery

Abstract

The polyphenols-rich Ananas comosus peels extract (AcPE) can be developed as an alternative topical nanocream for the cosmeceutical industry. Also, active ingredients of nano formulated products are proven more effective in penetrating the stratum corneum of the human skin. However, there are yet no published works or known formulations of the AcPE for topical skin use. Therefore, the present study proposed the formulation of an AcPE nano cream (AcPENc) to explore further applications of the pineapple biomass to benefit humankind. This study optimized an integrated high-energy method using ultrasonic assisted extraction (UAE) for responses, high yield, and high total phenolic content (TPC) of AcPE. While the UAE gave an insignificant effect on the extraction yield (p > 0.05), the optimum conditions for the highest TPC extracted from AcPE were successfully identified, namely ultrasonication time (5 min), solvent ratio (50 %), amplitude (65 %), and liquid-solid ratio (35:1 mL/g). The characterization of AcPE revealed an adequate antioxidant capacity for the total flavonoid content (TFC), 1,1- diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) with corresponding values of 1146.86 mg QE/g, 11.83 mg/mL, and 1578.07 ± 25.96 µM Fe2+/100g DW. High-Performance Liquid Chromatography (HPLC) analysis showed the presence of polyphenols in AcPE, with catechin as the major flavonoid, followed by quercetin and gallic acid. Next, the study successfully formulated the oil-in-water (O/W) AcPENc using integrated low- and high-energy methods of phase inversion temperature (PIT) and ultrasonication. The D-Optimal Mixture design (MED)-assisted optimization of AcPENc yielded a stable formulation comprising olive oil (1 %), grapeseed oil (12 %), Tween 80 (12.63 %), and water (74.37 %). The particle size and polydispersity index (PDI) of the optimized nano-cream (OPT-AcPENc) were 187.37 ± 0.81 nm and 0.248 ± 0.017, respectively. Most importantly, the OPT-AcPENc formulation exhibited characteristics that supported its long-term stability for storage, with a zeta potential value of -35.40 ± 2.71 mV, with a pH value of 4.56 ± 0.01. These attributes agree well with the recommended range for effective topical delivery of the active ingredients through human skin. The high conductivity (1346.67 ± 5.77 µS/cm) of the OPT-AcPENc verified its O/W characteristics, while the rheological data proved the cream’s shear-thinning (pseudoplastic) behavior. The OPT-AcPENc transmission electron microscopy micrograph revealed spherically shaped nano-sized particles of < 350 nm. The OPT-AcPENc was stable against high centrifugal force, mechanical shock, light test, and heating-cooling cycles in the stability study. Results of the accelerated stability test under three different incubation temperatures (4 ± 2, 25 ± 2, 50 ± 2 °C) for 6 weeks revealed 25 ± 2 °C to be the best storage temperature for the OPT-AcPENc. The suitability was evident from OPT-AcPENc’s stability in pH, particle size, and PDI, without phase separation. Relevantly, the OPT-AcPENc was safe from microorganisms and heavy metal contamination and fulfilled the prerequisite of the National Pharmaceutical Regulatory Agency (NPRA) Malaysia for cosmetic products. Sensory evaluation by 47 consumer panelists through the scoring method revealed that the OPT-AcPENc was well accepted. The cream was favored for its color, fragrance, spreadability, adsorption, film/coating, and non-irritancy, as proven in the radar plot. Thus, the present study conclusively demonstrated the potential of AcPE as a nano cream for topical human skin use in the cosmeceutical industry.