ISOLATION, CHARACTERIZATION AND ANTI-INFECTIVE STUDY OF COMPOUNDS FROM THE LEAF OF ALOE BARBADENSIS MILLER

Abstract

Extracts from the leaves of Aloe barbadensis Miller were prepared and two compounds, namely, 1,8-dihydroxy-3- hydroxymethyl-9- antracenone (Aloin A) and 5, 22-Cholestadien-24-ethyl-3β-ol, (Stigmasterol) were isolated, formulated as ointments and tested for antimicrobial activities against E. coli, K. pneumoniae, P. aeruginosa, S. aurous, C. albicans and T. fluvus. The structure of the two compounds were characterized on the basis of extensive spectral data (1H-NMR, 13C-NMR, IR and GC-MS). Although not novel compounds, their formulation with polyethylene glycol (PEG) as an ointment against wound pathogenic microorganisms may have been accomplished in this work for the first time. The activity of Aloin A- PEG-ointment against the test microorganisms was stronger and more effective than the pure Aloin A alone. This was observed from the low MIC values recorded; 2.5, 0.63, 0.63, 0.32, 0.32 and 1.25 mg/g for P. aeruginosa, E. coli, K. pneumoniae, S. aureus, C. albicans and T. fluvus respectively. Similarly, the activity of Stigmasterol-PEG ointment on the test microorganisms resulted in very low MIC values as compared to that of pure stigmasterol only and was statistically significant (P ˂ 0.05). The MIC values obtained were as follows: 0.08, 0.63, 1.25, 0.63, 1.25, and 0.16 mg/g for P. aeruginosa, E. coli, K. pneumoniae, S aureus, C. albicans and T. fluvus respectively. The data of this current research confirms the antibacterial and antifungal actions of Aloe barbadensis Miller and presented the biologically active bioactive compounds which include Aloin A and a phytosterol known as stigmasterol. The plant isolate-PEG ointments should be explored further in vivo to determine the effectiveness of these ointments for possible potential use for treating infectious diseases.