An oil in water (O/W) nanoemulsion formulation containing kojic monooleate (KMO) in thin film system was developed. Response surface methodology (RSM) was used to optimize and analyzed the effect of three variables, namely concentration of polyvinyl alcohol (PVA) (20–30% w/w), concentration of propylene glycol (PG) (1–10% w/w), and shear rate of high shear homogenizer (3000–9000 rpm) on droplet size as a response, while other compositions remained constant such as KMO (10.0% w/w), Tween 80 (3.19% w/w), castor oil (3.74% w/w), xanthan gum (0.70% w/w), and germall plus (0.7% w/w, PG (and) diazolidinyl urea (and) iodopropynyl butylcarbamate). The optimized KMO nanoemulsion formulation with desirable criteria was PVA (27.61% w/w) and PG (1.05% w/w), and shear rate (8656.17 rpm) with a predicted droplet size (110.21 nm) and actual droplet size (105.93 nm) with a residual standard error (RSE) of less than 2.0% was obtained. Analysis of variance (ANOVA) showed that the fitness of the quadratic polynomial fit the experimental data with a F-value of 65.30, p–value of p < 0.0001, and a non-significant lack-of-fit. The optimized KMO formulation shows the desired criteria of the thin film system and the physicochemical properties (Zeta potential −37.37 mV, PDI 0.13, pH 4.74) and stability at four different conditions indicate its suitability for cosmeceutical applications.

Background: Kojic monooleate (KMO) contains tyrosinase inhibitor and exhibits strong antioxidant activity makes it a good candidate to be incorporated into a formulation for topical application. A peel-off was chosen to ensure a better hydration effect and permeability of KMO into the skin. The objectives of this research were to analyze the kinetic release study of peel-off oil-in-water O/W nanoemulsion containing KMO and evaluate the moisturizing and hydration effect towards human volunteers. Methods: The peel-off formulation was developed by adding 27.61% w/w polyvinyl alcohol (PVA) and 1.05% w/w propylene glycol (PG). The study was performed by using Franz cell, tewameter and corneometer to analyze the release rate of KMO from peel-off O/W nanoemulsion, moisturizing, and hydration effect of formulation towards humans after 180 min of application, respectively. Results: The final formulation has a pH of 4.74, conductivity of 7.47 ± 4.05 x 10 -3 𝜇S/cm, viscosity 0.1058 Pa•s and spreadability of 61.86 ± 1.71 g•cm/s. It also disports 79.99 ± 2.53 % released of KMO after 180 min of study time. The results of the hydration effect of the formulation towards human volunteers' skin suggested that the peel-off O/W nanoemulsion containing KMO does increase the hydration of the skin by 12.33% due to the occlusive effect of KMO. Conclusion: In summary, this study presents new findings in the kinetic release study, hydration and moisturizing effect of peel-off O/W nanoemulsion containing KMO for topical application.

Running Head: Kojic monooleate (KMO) was incorporated into a formulation as the sole active ingredient, and the formulation was analysed for cytotoxicity using EpiDermTM tissue culture and melanin and tyrosinase inhibition using B16-F1 melanoma cells to confirm its capability to treat hyperpigmentation.Cell damage caused by exposure to UV radiation, as an external stress-inducing factor, may contribute to skin hyperpigmentation. Kojic monooleate (KMO) was used as an active in a nanoemulsion formulation for hyperpigmentation treatment. The objective of this study was to analyse the cytotoxicity and efficacy of a nanoemulsion formulation containing KMO. The formulation was prepared using high and low energy emulsification techniques and analysed for cytotoxicity and melanin and tyrosinase inhibition. Then, it was investigated for total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition, and elastase inhibition. The formulation inhibited tyrosinase and melanin by 74.14% and 36.80%, respectively, at 1 mg/mL concentration. It also contained a substantial amount of phenolic and flavonoid compounds with the values of 8.14 ± 0.03 mg/g eq. to gallic acid and 1.55 ± 0.03 mg/g eq. to rutin, respectively. The formulation also inhibited DPPH free radicals by 12.99% at 100 µg/mL. It also possessed the capability to prevent photodamage, as it inhibited elastase by 27.91% at 1000 µg/mL. The KMO nanoemulsion was also found to be non-irritant. In short, the KMO nanoemulsion formulation could provide good effects if applied to the skin frequently and safe for daily applications.