Major volatile and phenolic compounds in ‘kattekruid’ (Pseudodictamnus africanus), an important Cape herbal remedy

Pseudodictamnus africanus (L.) Salmaki & Siadati [previously called Ballota africana (L.) Benth.] is a well-known Cape traditional medicine in many parts of the Cape region of South Africa. Known as kattekruid, it is used to treat various ailments, including respiratory infections, pain and inflammation. To date, only a single chemical compound, hispanolone, has been identified in the species. This study reports for the first time the major volatile and non-volatile compounds of kattekruid. Using GC–MS, 52 compounds could be identified in 12 samples of essential oil, of which viridiflorol (14.22 %), β-caryophyllene (7.65 %), and caryophyllene oxide (7.41 %) were consistently present as major compounds. Using multivariate statistics, chemophenetic variation was observed amongst the 12 samples collected from four populations used in the study. For example, one population has β-bisabolene (13.09 %) as a major compound, whereas another exhibited germacrene-D (6.87 %) and sesquiabene hydrate (5.30 %). Non-volatile constituents separated using LC–MS, were tentatively identified as (3) forsythoside B, (4) verbascoside/acetoside, (5) isoverbascoside, (12) ballotenol, (13) ballotenic acid and (25) hispanolone. This exploratory study provides the foundation for further, in-depth studies on chemical variation in the species. The reported anti-inflammatory activity of some of the major volatile and non-volatile compounds provides a potential rationale for the traditional medicinal uses that have been recorded.