Geographic Influence on Secondary Metabolite Profiles in Leaves of the Endemic Agathosma betulina (P.J. Bergius) Pillans. in the Western Cape Province, South Africa.

The role of medicinal plants in primary healthcare and livelihoods around the world is both ancient and well-documented. Agathosma betulina (P.J. Bergius) Pillans, commonly known as 'buchu', has long been utilised in traditional medicine as a household remedy for various ailments and is also valued for its essential oils in the cosmetics and pharmaceutical industries. This study aimed to profile and quantify the secondary metabolites in buchu using ultra-performance liquid chromatography quadrupole time-of-flight combined with mass spectrometry (UPLC-QTOF-MS) techniques, whereby plant material from three distinct locations in the Western Cape Province, Groot Winterhoek, Citrusdal, and Cederberg, was collected. A total of 32 maker compounds were identified from buchu leaves. The results revealed a significant location-dependent variation in the accumulation of multiple classes of phytochemicals, including phenolic acids, flavonoids, saponins, terpenoids, oligosaccharides, vitamins, and steroids. Citrusdal samples had the most bioactive compounds compared to the Cederberg and Groot Winterhoek. Citrusdal had the highest flavonoid levels, while Cederberg samples were the richest in phenolic acids and Groot Winterhoek was dominant in iridoid glycoside levels. Principal component analysis (PCA) revealed distinct clusters corresponding to the three different regions, confirming chemical differences. Elucidating the distribution of secondary metabolites in this species may provide new information for possible medicinal and pharmacological uses, such as the creation of novel and enhanced organic medications and food products. These results will aid in selecting a buchu chemotype with optimal attributes for the intended therapeutic application, helping to protect wild populations from over-exploitation through cultivation.