The use of Aloe barbadensis M. (Aloe vera) Extract as Potential Stains in Gram’s Staining Technique

Abstract

Aloe barbadensis miller (Aloe vera) aside being a potent antioxidant with effects attributed to the phytoconstituents (anthraquinone), can also serve as natural dyes. This study explored the staining potentials of A. barbadensis extract on microbial specimens in modified Gram’s staining technique. The plant was washed; shrubby edges of the leaves were scraped off and each leaf cut open to expel the gel content. The dried and grinded leaf material weighing 450g was treated with two different extraction methods (150g for heated alcoholic aloe extract (HAAE) and 150g each for the unheated alcoholic aloe extracts I & II (UAAE-1 & UAAE-II). Preliminary phytochemical screening of extracts using bontragers test was conducted. Solutions from the two extraction methods with and without a mordant were applied on bacterial smears. Anthraquinone-rich extract under optimal extraction conditions were 10.0, 4.84 and 18.8 respectively. Comparing the extraction methods, HAAE and UAAE1 & UAAEII are mutually convenient and easy to make; but the former was more cost-effective with regards to power and instrumentation while the latter was more cost-efficient with regards to solvent. The pH of various prepared solutions was acidic and the extracts contained a bioactive agent that imparts pigment on biological specimens. In comparing the mordanted and non-mordanted solutions, the former had no additional effects on the staining efficiency of the aloe dye extract. We concluded that A. barbadensis dye visibly stained bacterial Gram positive and Gram negative cells in modified Gram’s staining without structural differentiations. We recommend reductions in staining duration for microbial samples to ascertain the reasons for the variation in staining uptake.