Chemical Constituents and Antimicrobial Evaluation of Selected Aloe vera Branded Commercial Products in Tanzania

Chemical compositions and antimicrobial activities of twenty-two Aloe vera branded commercial products in Tanzania, a case of marketed soaps, creams, lotions, petroleum jelly, toothpastes and hair conditioner products in Dar es Salaam, were investigated. Chemical compositions were analysed using gas chromatography-mass spectrometry (GC-MS) whereas antimicrobial activities were evaluated using agar dilution method against four bacteria species, namely Staphylococcus aureus, Escherichia coli, Klebsiella pneumoneae and Salmonella typhi) and two fungal species Candida albicans and Cryptococcus neoformans. The GC-MS analysis revealed the presence of seven non-polar constituents, namely methyl palmitate, 9-octadecenoic acid methyl ester, methyl stearate, tetratetracontane, hexacosane, and pentacosane and methyl tetradecanoate as the most common ingredients among the products. Eleven compounds were detected in both the commercial products and reference A. vera extracts. The commercial products AVC5 and AVL3 inhibited the growth of E. coli and S. typhi at minimum inhibitory concentrations (MICs) of 7.5 and 12.5% (v/v), respectively, whereas AVC2 and AVC5 inhibited the growth of C. albicans and C. neoformans at 5.0% (v/v). AVC6 had 7.5 and 15.0% (v/v) MICs for C. neoformans and C. albicans, respectively. Other commercial products and the reference A. vera extracts were inactive against the tested microbes at a screening concentration of 10.0 mg/mL.  Keywords: Aloe vera; Aloe vera branded commercial products; GC-MS; Antimicrobia

In vivo antimycobacterial studies of toussaintine A-chitosan nanocomposites

Chitosan (CS, molecular weight (MW) 20.2 kDA, stability of 210 °C and degree of deacetylation (DD) 73.31%) was obtained by deacetylation of chitin extracted from shrimp (Litopenaeus vannamei) shell wastes. The encapsulation of the studied bioactive natural product, toussaintine A (TA) isolated from the leaves of Toussaintia orientalis, on a chitosan-tripolyphosphate (CS/TPP) nanoformulation was attained through ionotropic gelation. Characterization of pure CS, CS/TPP and TA-CS/TPP nanocomposites was carried out by FTIR and SEM. The encapsulation efficiency and loading capacity of the TA were 69.33 and 0.46%, respectively. The in vitro release kinetics established an initial release of 27% of TA in the initial six hours followed by a slow and maintained release up to 72 h. The in vivo antimycobacterial acitivities of both TA and TA-CS/TPP nanocomposites against Mycobacterium indicus pranii (MIP) employing Galleria mellonella larvae as an infection model were evaluated. TA-CS/TPP nanocomposite formulations exhibited remarkable effectiveness against MIP than free TA.Keywords: Toussaintine A; chitosan; nanocomposites, antimycobacterial; Galleria mellonell