The antioxidant, anti-microbial activity and potential application of oil palm (Elaeis guineensis) leaf extract (OPLE) as a skin lightening and sunscreen agent in topical application were evaluated. Currently, there are no evidence of skin lightening effect and protection against ultraviolet (UV) irradiation of OPLE. OPLE contains 9.84±0.06 mg gallic acid equivalent per gram of dry extract and shows antioxidant activity through 2,2-diphenyl-1-picrylhydrazyl assay with IC 50 of 247±0.58 µg ml -1 . OPLE was effective only against gram-positive bacteria and the minimum inhibitory concentration was 12.5 mg ml -1 . OPLE also inhibited mushroom tyrosinase enzyme with IC 50 254.88 µg ml -1 . Determination of UV spectrophotometric and in vitro sun protection factor (SPF) indicated that OPLE provides a protection against ultraviolet B (UVB) and ultraviolet A (UVA) irradiation. OPLE were mixed with glycerine at 1%, 5% and 10% concentrations and showed slightly increase in SPF values from 0.96, 1.48 and 1.87, respectively. The UVA/UVB ratios were significantly increase from 0.076 for glycerine to 0.645, 0.906 and 0.910 for OPLE at 1%, 5% and 10% in glycerine, respectively. OPLE showed potentially good UV absorbance at UVB and UVA range wavelength and can be used as natural sunscreen and skin lightening agent for topical application.

Many types of phytochemicals have been found to be present in oil palm leaf and could potentially be used as functional ingredients for skincare product. However, as of today, there is no published report on hazard identification and safety assessment of oil palm ( Elaeis guineensis) leaf extract (OPLE), particularly on skin and eye irritation. In this study, potential hazard of OPLE on skin and eye irritation was evaluated as an initial step to the safety assessment of OPLE. In vitro cell viability study of OPLE on normal human dermal fibroblasts showed that OPLE was nontoxic to the cells with percentage viability more than 90% after 24 and 48 hours of incubation. Skin irritation potential of OPLE was evaluated using in vitro SkinEthic reconstructed human epidermis (RHE) model (Organization for Economic Cooperation and Development [OECD] Test Guideline 439, 2015), while eye irritation potential was evaluated using in vitro SkinEthic Human corneal epithelium (HCE) model (OECD test guideline 492, 2017). Hazard identification results showed that OPLE at 1%, 5%, and 10% (wt/wt) was classified as nonirritant to the skin and eye where mean tissue viabilities of SkinEthic RHE and SkinEthic HCE were more than 50% and 60%, respectively. Therefore, we recommend a further safety assessment, such as human patch testing, to confirm the nonirritant of OPLE.

Therefore, future studies to clarify the eye irritation potential of the palm-based MES will be needed, and could include; methods to improve the test substance solubility, use of test protocol for solids, and/or inclusion of a benchmark anionic surfactant, such as sodium dodecyl sulphate within the study design.

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