Arthur (Articles)

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    Multifactorial optimization enables the identification of a greener method to produce (+)-nootkatone
    (Elsevier, 2024-09) Makhubela, Ida M.; Zawaira, Alexander; Brady, Dean; Pienaar, Daniel P.; daniel.pienaar@up.ac.za
    The natural aroma compound (+)-nootkatone was obtained in selective conversions of up to 74 mol% from inexpensive (+)-valencene substrate by using a comparatively greener biocatalytic process developed based on modifications of the previously published Firmenich method. Buffer identity and concentration, pH, temperature and downstream work-up procedures were optimized to produce a crude product in which >90 % of (+)-valencene had been converted, with high chemoselectivity observed for (+)-nootkatone production. Interestingly, the biotransformation was carried out efficiently at temperatures as low as 21 ºC. Surprisingly, the best results were obtained when an acidic pH in the range of 3–6 was applied, as compared to the previously published procedure in which it appeared to be necessary to buffer the pH optimally and fixed throughout at 8.5. Furthermore, there was no need to maintain a pure oxygen atmosphere to achieve good (+)-nootkatone yields. Instead, air bubbled continuously at a low rate through the reaction mixture via a submerged glass capillary was sufficient to enable the desired lipoxygenase-catalyzed oxidation reactions to occur efficiently. No valencene epoxide side-products were detected in the organic product extract by a standard GCMS protocol. Only traces of the anticipated corresponding α- and β-nootkatol intermediates were routinely observed.
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    First report of the thick-tailed bushbaby (Otolemur crassicaudatus) being preyed upon by an endemic carnivore (Caracal caracal) in South Africa
    (NISC (Pty) Ltd and Informa UK Limited (trading as Taylor & Francis Group), 2021) Cuozzo, F.P.; Halajian, A.; Sauther, M.L.; Rampedi, K.M.; Millette, J.B.
    To date, there have been few published reports of Caracal spp. (or other non-domestic carnivores) preying upon nocturnal strepsirrhine primates anywhere in continental Africa. However, in South Africa, most studies of caracal diet have been conducted outside of the known geographic range of South Africa’s nocturnal primates. Here we report Otolemur crassicaudatus (the greater or thick-tailed bushbaby/galago) remains recovered from the stomach of a caracal, collected in Limpopo province, South Africa, in 2018, which included portions of the limbs, tail, skull and dentition, allowing confident taxonomic assignment. Sixty-seven carnivores (equal in size or larger than O. crassicaudatus), including one other caracal, also had stomach contents examined between 2012 and 2019 in northern South Africa. None included O. crassicaudatus remains, making this the first documented example of this non-human primate species being preyed upon by an endemic carnivore; kills of O. crassicaudatus by domestic dogs, though not being consumed, have previously been documented. These data expand the knowledge of the diet of caracal in southern Africa and may signal an expanding caracal dietary regime and possible behavioural changes in O. crassicaudatus, such as increased terrestrial movement, with increasing human actions and reduction of endemic forests and habitats.