Phytochemical Screening, Antioxidant and Antimicrobial Activities of Aloe rubroviolacea Schweinf.

Abstract

The purpose of this study was to investigate the phytochemical content, antioxidant capacity, and antibacterial efficacy of Aloe rubroviolacea leaf extracts. Methanol and aqueous leaf extracts (leaf skin and gel) were created using the rotary shaker method. Phytochemical analysis reveals the presence of Alkaloids, Saponins, Tannins, Phenol, Steroids, Reducing sugar, Flavonoids, and Carbonly in A. rubroviolacea methanol leaf (skin and gel) extracts, while; Alkaloids, Saponins, Tannins, Reducing sugar, Flavonoids, and Carbonyl compounds,  were recorded in aqueous leaves skin extract, whereas; Alkaloids, Saponins, Reducing sugar, Flavonoids, and Carbonyl compounds were found in aqueous gel extract. The FT-IR spectrum analysis exhibits the presence of Hydroxyl group (OH), C-H aliphatic, C=C aromatic, carbonyl group (C=O), and C-O group in the methanol leaf skin and gel extracts. Furthermore, the presence of accumulated double bonds / isocyanates and isothiocyanates was reported in the methanol gel extract. On the other hand, the FT-IR spectrum analysis displays the presence of the Hydroxyl group (OH), and methane group (C-H) in the aqueous leaf (skin and gel ) extracts, while N-H, CH₃, and C-N,  were only recorded in aqueous gel extract. The antioxidant activity of A. rubroviolacea methanol (leaf skin and gel) and aqueous (leaf skin and gel) extracts was investigated using the DPPH radical scavenging activity method. The methanol leaf skin and aqueous gel extracts exhibit a  high antiradical activity towards DPPH radical when compared to the aqueous leaf skin and methanol gel extracts.  The four extracts were tested for antimicrobial activity against four human pathogenic bacteria (Staphylococcus aureus, Streptococcus pneumonia, Escherichia coli, and Pseudomonas aeruginosa) and one fungal pathogen; Candida albicans, using the agar well diffusion technique. The methanol leaf skin extract was the most effective against all tested pathogens, followed by the methanol gel extract. The high antimicrobial activity of the methanol leaf skin extract could be suggested to the presence of high antioxidant components such as, phenolics, flavonoids & tannins compounds, and rhodoxanthin pigment in the extract.