The escalating threat of solar Ultraviolet (UV) radiation to human health, primarily through the generation of Reactive Oxygen Species (ROS) and induction of oxidative stress, necessitates the development of effective photoprotective strategies. While conventional sunscreen formulations containing chemical UV filters have been the mainstay, concerns regarding their potential adverse effects, including allergies and endocrine disruption, have spurred the search for safer, plant-based alternatives. Bromelain, a natural enzyme derived from pineapple (Ananas comosus), has garnered significant interest due to its established antioxidant and anti-inflammatory properties, suggesting its potential as a dual-action skincare ingredient capable of mitigating UV-induced damage. This study investigates the in vitro and in vivo antioxidant and photoprotective efficacy of bromelain-based cream formulations, both as a standalone active ingredient and in combination with the chemical UV filter Octyl Methoxycinnamate (OMC).
The study involved the formulation of sunscreen creams containing 3% bromelain (F1), 5% OMC (F2), and a combination of 3% bromelain and 5% OMC (F3). The antioxidant activity of bromelain and the cream formulations was assessed using the DPPH radical scavenging assay. Photoprotective activity was evaluated by determining the Sun Protection Factor (SPF) in vitro using UV spectrophotometry and in vivo on rabbit skin exposed to UVB radiation. Additionally, the physicochemical properties and stability of the formulations were examined, and dermal and ocular irritation tests were conducted on rabbits.
Section-wise Key Points:
•Physicochemical Properties of the Sunscreen Cream Formulation: All sunscreen cream formulations (F1, F2, and F3) exhibited acceptable physical characteristics, including color, smell, consistency, pH (ranging from 5.15 to 5.48), viscosity (meeting the standard of 2000–50,000 cP), spreadability (within 5–7 cm), and adhesion (between 180 and 220 s)14 . Formulation F3, containing OMC, showed the highest viscosity.
•Formulation Cream Stability: Stability testing using a 6-cycle freeze-thaw method indicated that the organoleptic properties, spreadability, adhesion, and viscosity of all formulations remained consistent. However, one-way ANOVA analysis revealed a significant difference in pH across all formulas after the freeze-thaw cycles, suggesting potential instability in extreme temperatures based on pH values, possibly due to bromelain decomposition.
•Antioxidant Activity: The bromelain enzyme exhibited strong antioxidant activity with an IC50 value of 3.180 mg/mL, while the cream containing bromelain showed a slightly lower IC50 value of 4.004 mg/mL, indicating reduced potency in the cream formulation. Both demonstrated a dose-dependent increase in inhibition of DPPH radicals.
•Photoprotection Activity: Bromelain alone at 30 g/L showed an in vitro SPF of 7.34, considered insufficient for effective UV protection. However, formulations containing bromelain (F1, F2, and F3) demonstrated significantly higher SPF values compared to the base cream (in vitro SPF 1.125, in vivo SPF 6.34). Notably, F3, combining bromelain and OMC, exhibited the highest SPF values both in vitro (22.043 ± 0.277) and in vivo (21.3 ± 2.901), suggesting a synergistic effect.
•Dermal and Ocular Irritation Assessment: Irritation tests on rabbits revealed that the cream base, F1 (3% bromelain), and F3 (OMC + 3% bromelain) did not cause any erythema, eschar, edema, or ocular irritation. This indicates that bromelain, at the tested concentration, is safe and non-irritating for topical application.
This study provides compelling evidence for the potential of bromelain as a valuable ingredient in sunscreen formulations. The novelty of this research lies in its demonstration of the synergistic photoprotective effect achieved by combining bromelain, a natural antioxidant and potential photoprotective agent, with a chemical UV filter like OMC. The findings indicate that bromelain not only contributes to UV protection, likely through its antioxidant properties that combat ROS generated by UV exposure, but also enhances the efficacy of traditional UV filters, leading to higher SPF values. Furthermore, the study’s confirmation of the non-irritating nature of bromelain cream in animal models supports its potential for safe human use. Future research should focus on in vivo testing on human skin to validate these findings and further explore the long-term efficacy and benefits of bromelain-based sunscreen formulations in preventing UV-induced skin damage and photoaging. Understanding the precise mechanisms of bromelain’s synergistic action with UV filters could also pave the way for the development of more effective and safer broad-spectrum sunscreens.
Link to the study: https://www.mdpi.com/2079-9284/12/2/41
