Potential of Psidium guajava Leaf as Natural UV Filter in Topical Sunscreen Emulsion

Abstract

This study aims to develop a sunscreen formulation using guava (Psidium guajava) leaf extract (GLE), obtained via ethanol-water (4:1 v/v) extraction. The crude extract was greenish-brown solid with a percentage yield of 19.88 ± 0.28. The extract possessed total phenolic and flavonoid content of 2, 879.86 ± 2.18 mg gallic acid equivalent (GAE)/g GLE and 699.37 ± 8.30 mg quercetin equivalent (QE)/g GLE, respectively. The DPPH radical scavenging activity was 348.85 ± 4.18 mg ascorbic acid equivalent (AAE)/g GLE. The extract absorbed UVB light with maximum wavelengths at 286 nm. Topical sunscreen product contained 6% titanium dioxide and 7 % methylene bis-benzotriazolyl tetramethylbutylphenol was prepared as oil-in-water emulsion and it exhibited SPF of 21.73 ± 1.34. Incorporating 5% GLE increased SPF from 21.73 ± 1.34 to 34.55 ± 3.27, reflecting a 59% enhancement. The emulsion formulated with 5% GLE alone achieved an SPF value of 2.23 ± 0.29, demonstrating a comparatively higher sun protection efficacy than existing natural UV filter extracts. The stability of sunscreen containing guava leaf extracts was studied under heating-cooling cycle and at ambient temperature (30-35 °C), and 45 °C. The product exhibited a slight darkening in color while maintaining relative stability in viscosity and pH . After four weeks of storage at ambient temperature and 45 °C, the sun protection efficacy declined from SPF 34.55 ± 3.27 to 30.76 ± 3.08 and 23.90 ± 2.57, respectively, indicating a moderate reduction in efficacy under elevated temperature conditions. The findings highlight the potential of guava leaf extract as a natural ingredient that can significantly enhance the sun protection efficacy of synthetic sunscreens in cosmetic formulations.

Keywords

• guava leaf
• sunscreen emulsion
• sun protection factor
• stability