New Natural and Sustainable Cosmetic Preservative Based on Sugarcane Straw Extract

Preservative ingredients in cosmetic formulations undertake a necessary role in the prevention of microbial contamination. In this field, there is an unmet need for natural, sustainable, and effective preservatives. Thus, the main goal of this work was to evaluate a sugarcane straw extract-based ingredient and investigate its potential as a preservative for cosmetic applications. Different ingredients were developed using several cosmetic solvents to improve the solubility of the extracted compounds. The antimicrobial activity was assessed against <i>Staphylococcus aureus</i>, <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, and <i>Candida albicans</i>. The 1,2-hexanediol was the solvent that allowed us to achieve the ingredient (20% dry extract dispersed in 25% 1,2-hexanediol in water) with the best antimicrobial performance, showing a minimum inhibitory concentration of between 5% and 3% (<i>I</i>). The 5% (<i>w</i>/<i>v</i>) concentration of this ingredient complied with the USP51 standards for cosmetic preservatives. Real-time (25 °C, 65% RH) and accelerated stability (40 °C, 75% RH) tests were conducted to determine the ingredient stability, and it was found that one month of storage time at room temperature would be ideal for better ingredient stability and performance in terms of composition, pH, color, and antioxidant activity.