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

Summary

This protocol describes the aseptic preparation of fresh Aloe vera inner-gel extract, potentiometric pH measurement, total antioxidant capacity assessment by an automated ABTS-based colorimetric assay, culture-based no-detectable-growth assessment under defined incubation conditions, and preliminary antimicrobial screening of a 70:30 (v/v) Aloe vera./N-acetyl-L-cysteine test mixture by disk diffusion and qualitative two-fold tube dilution.

Abstract

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.

Introduction

Aloe vera has continued to attract considerable scientific attention because of its long-standing use in traditional medicine and its expanding relevance in pharmaceutical, biomedical, cosmetic, and food research^1,2,3. This medicinal plant contains a diverse range of biologically active constituents, including polysaccharides, phenolic compounds, anthraquinones, vitamins, minerals, enzymes, and other low molecular weight metabolites that may contribute to its therapeutic and functional properties^1,2,

Protocol

1. Preparation of Aloe vera. extract and dilution series

1. Harvest the mature leaves of an aloe vera plant grown at room temperature and rinse them thoroughly under running water to remove any residue.
2. In a biosafety level 2 (BSL-2) cabinet, disinfect the leaf surface with 70% ethanol using sterile gloves. After applying 70% ethanol, allow the leaf surface to air-dry completely for at least 2 min before aseptic incision.
3. Using a sterile scalpel, remove the distal tip and margins of the leaf, allow the yellow latex exudate to drain completely for approximately 30 min, and then fillet the leaf long....

Results

pH values of Aloe Vera. extract at different concentrations

The pH profile showed a non-monotonic pattern across concentrations. Mean pH values were 6.47, 6.60, 6.26, and 6.28 for the 5%, 10%, 15%, and 20% formulations, respectively. Overall group differences were significant (p = 0.024). The 5% and 10% formulations showed relatively higher pH values, whereas the 15% and 20% formulations clustered at lower pH values (p < 0.05) (Table 1 and .......

Discussion

The present study provides an integrated laboratory workflow for the preliminary characterization of fresh inner-gel Aloe vera extract formulations by combining pH measurement, total antioxidant capacity (TAC) analysis, culture-based no-detectable-growth assessment, and descriptive antimicrobial screening. Increasing concentrations of fresh inner-gel Aloe vera. were associated with higher TAC values, while no visible bacterial or fungal growth was observed during short-term culture monitoring under the .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
(-)80 C Deep Freezer	Thermofisher/USA	Sample storage	TSX40086A
Vortex	Thermofisher/USA	Sample preperation	88882010
Blood Agar	RTA/Turkey	Culture inoculation	2001
Eosine Methilene Blue Agar	RTA/Turkey	Culture inoculation	2010
SDA Agar	RTA/Turkey	Culture inoculation	2036
Müller Hinton Agar	RTA/Turkey	Culture inoculation	2022
Müller Hinton Broth	RTA/Turkey	Culture dilution	1018
Pipettes	Thermofisher/USA	Sample preperation	4642090N
Hanna pH Meters	Hitachi/JAPAN	Sample analyses	HI2211-02
Rel Assay Plate Reader	Rel Assay(Turkey)	Sample TAC analyses	M201 (Smart Model)
TAC Kits	Rel Assay(Turkey)	Kit	RL0017