Culture-Based No-Detectable-Growth Assessment And Antioxidant Profiling of Fresh Aloe vera Gel Extract

Aloe vera (Aloe barbadensis Miller) is widely used in topical and complementary medicine products. However, standardized laboratory workflows for simultaneous evaluation of total antioxidant capacity (TAC), pH behavior, culture-based no-detectable-growth status under defined conditions, and preliminary antimicrobial screening remain limited. Fresh inner-gel Aloe vera extract was prepared aseptically and formulated at 5%, 10%, 15%, and 20% (w/v). pH was measured potentiometrically, and TAC was determined by an automated ABTS radical cation-based colorimetric assay. Culture-based no-detectable-growth assessment was performed by inoculating the extract onto blood agar, eosin methylene blue agar, and Sabouraud dextrose agar, followed by aerobic incubation and visual inspection at 24 h, 48 h, and 72 h. Antimicrobial screening of a 70:30 (v/v) Aloe vera/N-acetyl-L-cysteine test mixture was performed against standard reference strains by disk diffusion and qualitative two-fold tube dilution assays. TAC differed significantly among groups (Kruskal-Wallis, p = 0.014), with the highest values observed in the 20% formulation. No visible bacterial or fungal growth was observed under the tested culture conditions during the 72 h observation period. The Aloe vera/N-acetyl-L-cysteine test mixture produced inhibition zones ranging from 11 mm to 17 mm, with the largest zone observed against Pseudomonas aeruginosa. This workflow provides a practical laboratory approach for preparing and preliminarily characterizing fresh Aloe vera.-based formulations for early-stage complementary medicine research.