Dereplication of Bioactive Markers from the Leaves of Anthocleista nobilis: Searching for new Bioactive Metabolites

Anthocleista nobilis is a small to medium-sized tree up to 18 – 30 m tall which occurs in several African countries including Nigeria. Various parts of the plant are used for the treatment of several ailments including venereal diseases, constipation, hernia, haemorrhoids, leprosy, malaria and menstrual problems [1]. The plant belongs to the genus Anthocleista which are known to be rich source of bioactive secondary metabolites such as alkaloids, xanthones, phthalides, secoiridoids and terpenes, many of which have been isolated and reported [2]. Nevertheless, there are still yet-to-be isolated metabolites which could be implicated by dereplication approaches. Dereplication strategy was applied to discriminate between previously known and potential novel compounds. Ultra-high performance liquid chromatography/electro-spray ionization-quadrupole time-of-flight mass spectrometry (UHPLC/ESI-qTOF MS) technique was adopted for dereplication of secondary metabolites of the leaves of A. nobilis. Based on ultra-violet (UV) profiles, chromatographic retention times (tR) and positive mode-ESI mass spectra data, five previously reported compounds (1 – 5) (Figure 1) were successfully dereplicated from a pool of sixty-eight queried molecular ion masses and common adducts. The compounds were known to be a secoiridoid (1), a dibenzo-α-pyrone (2), a a triterpene (3), a xanthone (4), and a phytosterol (5). Interestingly, the remaining sixty-three masses could be potential novel bioactive compounds from the genus Anthocleista and could provide template for guided isolation and identification.

Fig. 1: Compounds dereplicated from UHPLC/ESI-qTOF MS of A. nobilis leaf

Acknowledgement: The authors are grateful for the opportunity to use the LC/MS facility of the Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Germany.

[1] Burkill HM. The useful plants of West Tropical Africa. Vol. 3. Families J-L. Kew; Royal Botanic Gardens; 2000: 32 – 50

[2] Anyanwu GO, Rehman N, Onyeneke CE, Rauf K. J Ethnopharmacol, 2015; 175: 648 – 667.