Phytochemical and Antimicrobial Screening of Flavanones and Chalcones from Galenia africana and Dicerothamnus rhinocerotis.

This study focused on an 80% ethanol:water extract of Galenia africana and Dicerothamnus rhinocerotis in which a phytochemical study revealed the presence of flavonoids as the major secondary plant metabolites. Eleven pure flavonoids viz., (E)-2',4'-dihydroxychalcone 1, (S)-7-hydroxyflavanone 2, (E)-2',4'-dihydroxy-2,3-dihydrochalcone 3, (S)-5,7-dihydroxyflavanone 4, (S)-2',5,7,-trihydroxyflavanone 5, (S)-5,7-dihydroxy-2'-methoxyflavanone 6, 5,7-dihydroxy-4H-chromen-4-one 7, (S)-5-hydroxy-7-methoxyflavanone 8 and (E)-2-hydroxy-3',6'-dimethoxychalcone 9 were isolated from G. africana, while [sakuranetin] (S)-4',5-dihydroxy-7-methoxyflavanone 10 and [eriodictyol-3',7-dimethyl ether] (S)-4',5-dihydroxy-3',7-dimethoxyflavanone 11 were isolated from D. rhinocerotis. Compounds 6 and 9 are new while this is the first reported isolation of 1, 2, 3, 4, 5, 7, 8, 10 and 11 from these plants. All isolated compounds were tested for their antimycobacterial activity against the reference strain Mtb H37Rv. The most active compound, 9, demonstrated a MIC99 of 5 µM against Mtb H37Rv American Type Culture (ATCC) and (ATCC27294), which were also sensitive to Isoniazid (INH) and Rifampicin. The antibacterial activity of 9 might be ascribed to the presence of features such as the α,ß-unsaturated ketone and the substitution patterns on the A and B rings.

Relationship between firewood usage and urinary Cr, Cu and As in informal areas of Cape Town.

OBJECTIVES: The study investigated whether wood usage by informal food vendors and household residents in Cape Town results in the absorption of arsenic (As), chromium (Cr) and copper (Cu) owing to release of these metals in the burning of chromated copper arsenate (CCA)-treated wood. METHODS: The participants (N=78) selected included an equal number of food vendors and non-vendors from 2 informal settlements. All participants answered a questionnaire concerning exposure and were tested for urinary Cr, Cu and As, while the urine of 29 participants was also tested for toxic As (As(tox)). RESULTS: Multivariate analysis showed that the time spent in close proximity to the wood, as well as the quantity of wood used for cooking and for household use, was weakly positively associated with urinary levels of As, Cr and the sum of As, Cr and Cu. CONCLUSIONS: The study provides evidence that use of wood likely to contain CCA as a fuel for informal food outlets and household purposes may increase the absorption of inorganic As, Cu and Cr.