The fact that the sun’s ultraviolet (UVA and UVB) radiation reaches the earth’s surface associates sun exposure with many skin problems such as sunburn, photoaging, hyperpigmentation, and skin cancers. Because sunlight is unavoidable, sunscreen/sunblock application is essential to protect the skin from the mentioned problems. Zinc, in the form of zinc oxide, is an active ingredient in sunblocks as it deflects away UVA and UVB. Zinc is an immunologically important mineral that helps in wound healing, anti-inflammation, and cell protection. One natural and rich source of zinc is squash seeds, which many consider as trash.
This study features the formulation of a sunblock lotion using squash seeds as the active ingredient. Squash seeds extract and powder were first subjected to Atomic Absorption Spectrophotometry (AAS) to quantitate zinc content, and enough were used to formulate a sunblock lotion to a final zinc concentration of 5%. Various physical tests on the finished product showed that it is stable and gentle, having high melting point of 440C, and being easily spreadable, water insoluble, and weakly basic at pH 7.5. Patch tests gave negative results in all subjects, indicating the product’s hypoallergenicity. UV spectrophotometry revealed substantially low UV absorbance (<0.03 from 290nm – 320nm wavelengths), which is consistent with the action of zinc oxide as UV deflector, not absorber.
The Sun Protection Factor (SPF) was determined using a modified formula set by the US Food and Drug Administration (US FDA) Code of Federal Regulations Title 21 based on the ratio of minimal erythema (skin redness due to dilated dermal capillaries) on protected skin to that on unprotected skin, and was calculated to be SPF20. Further, costing and pricing analysis showed the production cost to be P0.80/mL, and recommended selling price (at 100% markup) of P1.60/mL, which is up to 13 times cheaper than popular commercial brands of similar effectiveness. Thus, the study successfully formulated a gentle, effective, and affordable sunblock lotion using squash seeds as organic active ingredient.