Comparative Phytochemical Analysis of Five South African Bulbine Species Using Chromatography-Based Methods

Bulbine Wolf (Asphodelaceae) comprises over 80 species, with five holding significant medicinal value in South Africa for treating skin and gastrointestinal ailments. While roots are traditionally prioritised, the chemical profiles of leaves and rhizomes remain underexplored although they are also medicinally important. This study used chromatographic and mass spectrometry-based analytical techniques (HPTLC, LC-QToF-MS, and UPLC-MS) combined with chemometric analysis to chemically profile the metabolites of five Bulbine species from the Eastern Cape. Chemical profiling tentatively identified 73 compounds, including flavonoids, phenolic acids, and anthraquinones. Phenylanthraquinones, specifically knipholone and knipholone 6'-methyl ether, were ubiquitous across all taxa. Species-specific markers were identified, such as bulbine-knipholone in B. abyssinica, gaboroquinones in B. frutescens, and bulbnatalonosides in B. latifolia. Chemometric modelling revealed that while rhizome chemistry is relatively conserved, root profiles provide the most robust inter-species differentiation. Bulbine frutescens and B. latifolia displayed the highest chemical diversity, whereas B. asphodeloides was notably rich in anthocyanins. The significant overlap in bioactive constituents between leaves, roots and rhizomes suggests that aerial parts could serve as viable substitutes in traditional remedies. These findings establish a chemical basis for species authentication and support sustainable harvesting practices by reducing the destructive exploitation of rhizomes and roots.