Southern Africa as a ‘cradle of incense’ in wider African aromatherapy

Abstract

The modern paradigm of aromatherapy is based on in vitro assays of pure volatile organic compounds (as an essential oil), with activity at non-clinically significant concentrations. Yet traditional use of aromatic species did not involve pure essential oils because hydrodistillation was only invented in relatively recent times (estimated 1200 AD). Instead, more complex ‘full-bodied’ extracts and blends were made by following unsophisticated extraction processes resulting in mixtures of volatile organic compounds and non-volatile (fixed) metabolites. The first humans on earth were the first to experiment with aromatic medicinal plants. The close interaction between humans and aromatic plants during evolution encourages us to consider how it has informed natural selection. Modern biology has revealed a kind of specialised metabolism of natural products that recycles conjugated xenobiotics in infectious/inflammatory tissues via the secretion of β-glucuronidase. Informed by in vitro and chemical evidence, the current review narrates the philosophical argument that traditional methods of aromatic medicinal plant use in prehistoric cultures achieves tangible positive effects. What we learn from the ‘cradle of incense’ is that full-bodied extraction of aromatic medicinal plants (or aromatic exudates) can sometimes be better than hydrodistilled essential oils from the same species. This is because volatile organic compounds are more powerful when combined with other products where they act as gene expression modulators, potentiators or synergistic ingredients in deriving therapeutic outcomes.