Although South Africa is known as one of the most biodiverse countries in the world, based on its unique plants and animals, microorganisms have received much less attention. Microorganisms in general and actinobacteria in particular are an underexplored source of new medicines. Recent studies have demonstrated the presence of diverse cultivable actinobacteria from various biomes. However, investigations of the natural product diversity associated with these microorganisms are lacking. We hereby present a review of natural products isolated from South African actinobacteria together with their biological activities. Many of these natural products are structurally novel and include compounds belonging to the following classes: anthraquinones, isoflavonoids, ketolides, macrolides, macrolactams, tripeptides and depsipeptides. They show a wide range of biological activities including antibacterial, antifungal, cytotoxic and antitumour activities. SIGNIFICANCE: • This review highlights the importance of actinobacteria in the discovery of new medicines and summarises the state-of-the-art on their research in South Africa. • We reveal a gap in the exploitation of this resource and emphasise the opportunities for multidisciplinary research.

In December 2019, the World Health Organization officially announced the discovery and fast spread of the new coronavirus disease (COVID-19), which is caused by the SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), discovered in Wuhan, China. Since the beginning of the pandemic, there has been a global search for the discovery of antiviral candidates capable of treating the infection caused by SARS-CoV-2. However, none of them has shown proved efficacy and low toxicity for an effective dose. In view of this, research with plants based in natural products has been highlighted by the low toxicity of its metabolites and reduced side effects, since plants have been used for millennia in the treatment of various diseases. In this review, we highlight some plant species and plant metabolites belonging to the structural class of phenolic, alkaloids and terpenes with promising antiviral potential against coronavirus that could be explored as potential candidates for drug prototypes in the treatment of COVID-19.