Bulbine natalensis Baker. (Asphodelaceae) is indigenous to only southern Africa and is widely used as a skin remedy. B. natalensis contain secondary metabolites that have antibacterial properties. Phytosterols are a group of steroid alcohols and phytochemicals that occur naturally in plants. Aspergillus, Penicillium and Fusarium species are considered to be the most toxigenic fungi. They produce a large consortium of mycotoxins that include aflatoxins B1, B2, G1, G2, fumonisin B1 and ochratoxins. They are found in foodstuffs and are not destroyed by normal industrial processing or cooking since they are heat-stable. The purpose of the project was to extract and quantify phytosterols, such as ergosterol, stigmasterol and sitosterol from B. natalensis using phytochemical methods such as thin layer chromatography and high performance liquid chromatography. The extract was tested against Aspergillus flavus, Penicillium digitatum and Fusarium verticilloides for antifungal activities. 1 ml of saponified extract contained 0.07 µg of sitosterol, 0.16 µg of stigmasterol and 0.37 µg of ergosterol. Saponifiable, unsaponifiable and crude extracts showed minimal activity against F. verticilloides, whereas potent activity was exhibited against A. flavus. Key words: Bulbine natalensis, phytosterols, secondary metabolites, antifungal activity, mycotoxins.

A series of 1,2,3-trisubstituted indolizines (2a–2f, 3a–3d, and 4a–4c) were screened for in vitro whole-cell anti-tubercular activity against the susceptible H37Rv and multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB) strains. Compounds 2b–2d, 3a–3d, and 4a–4c were active against the H37Rv-MTB strain with minimum inhibitory concentration (MIC) ranging from 4 to 32 µg/mL, whereas the indolizines 4a–4c, with ethyl ester group at the 4-position of the benzoyl ring also exhibited anti-MDR-MTB activity (MIC = 16–64 µg/mL). In silico docking study revealed the enoyl-acyl carrier protein reductase (InhA) and anthranilate phosphoribosyltransferase as potential molecular targets for the indolizines. The X-ray diffraction analysis of the compound 4b was also carried out. Further, a safety study (in silico and in vitro) demonstrated no toxicity for these compounds. Thus, the indolizines warrant further development and may represent a novel promising class of InhA inhibitors and multi-targeting agents to combat drug-sensitive and drug-resistant MTB strains.

Hibiscus sabdariffa is an under-utilized plant that has reported to have great potential in the food industry. The vibrant red pigment from the calyces indicate a source of anthocyanins. Anthocyanins would make ideal natural food colourants with additional nutritional benefits however stability is a hindering factor. Stability studies were the main focus of this study. Crude anthocyanins were extracted using four different solvent systems. The crude extracts were analysed under the following parameters; heat (50 and 80 °C), light (darkness and 20 W light) and pH (pH 1-9) stability. Degradation kinetic studies were done on thermally treated samples. Radical scavenging ability was thereafter calculated. Anthocyanidins were identified and quantified by HPLC coupled with a Diode Array Detector (DAD). Total phenolic content was determined with Folin – Ciocalteu’s method. Approximately 87% of pigments were retained when heated at 50 °C while heating at 80 °C resulted in 61% pigment retention. The pH stability of samples incubated for 7 days indicated that crude anthocyanins degraded slower at acidic pH. Light stability showed slower degradation in dark incubated samples resulting in 84% pigment retention after a 10 day period. H. sabdariffa shows potential for the application of a food in products such as jelly and yoghurt.

The cyclooxygenase-2 (COX-2) enzyme is an important target for drug discovery and development of novel anti-inflammatory agents. Selective COX-2 inhibitors have the advantage of reduced side-effects, which result from COX-1 inhibition that is usually observed with nonselective COX inhibitors. In this study, the design and synthesis of a new series of 7-methoxy indolizines as bioisostere indomethacin analogues (5a–e) were carried out and evaluated for COX-2 enzyme inhibition. All the compounds showed activity in micromolar ranges, and the compound diethyl 3-(4-cyanobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5a) emerged as a promising COX-2 inhibitor with an IC₅₀ of 5.84 µM, as compared to indomethacin (IC₅₀ = 6.84 µM). The molecular modeling study of indolizines indicated that hydrophobic interactions were the major contribution to COX-2 inhibition. The title compound diethyl 3-(4-bromobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5c) was subjected for single-crystal X-ray studies, Hirshfeld surface analysis, and energy framework calculations. The X-ray diffraction analysis showed that the molecule (5c) crystallizes in the monoclinic crystal system with space group P 2₁/n with a = 12.0497(6)Å, b = 17.8324(10)Å, c = 19.6052(11)Å, α = 90.000°, β = 100.372(1)°, γ = 90.000°, and V = 4143.8(4)ų. In addition, with the help of Crystal Explorer software program using the B3LYP/6-31G(d, p) basis set, the theoretical calculation of the interaction and graphical representation of energy value was measured in the form of the energy framework in terms of coulombic, dispersion, and total energy.

Malaria, affecting all continents, remains one of the life-threatening diseases introduced by parasites that are transmitted to humans through the bites of infected Anopheles mosquitoes. Although insecticides are currently used to reduce malaria transmission, their safety concern for living systems, as well as the environment, is a growing problem. Therefore, the discovery of novel, less toxic, and environmentally safe molecules to effectively combat the control of these vectors is in high demand. In order to identify new potential larvicidal agents, a series of 2-aryl-1,2-dihydroquinazolin-4-one derivatives were synthesized and evaluated for their larvicidal activity against Anopheles arabiensis. The in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of the compounds were also investigated and most of the derivatives possessed a favorable ADMET profile. Computational modeling studies of the title compounds demonstrated a favorable binding interaction against the acetylcholinesterase enzyme molecular target. Thus, 2-aryl-1,2-dihydroquinazolin-4-ones were identified as a novel class of Anopheles arabiensis insecticides which can be used as lead molecules for the further development of more potent and safer larvicidal agents for treating malaria.