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Antimicrobial ellagitannin-rich extracts and ellagitannins in Terminalia kaiserana and Terminalia sambesiaca, two African medicinal plants
Terminalia sambesiaca and Terminalia kaiserana are native to East and South African woodlands. Roots, stem bark and leaves are made into hot water decoctions and teas or mixed with maize porridge for treatment of infectious diseases and their symptoms, diarrhea and cough (1). The leaves of T. sambesiaca are known to contain saponins (2), but this is the only report on chemistry of this species. T. kaiserana has not been studied in this context. Since ellagitannins are known from many species of Terminalia, we assumed to find high quantities of them also in T. kaiserana and T. sambesiaca. Therefore we have analyzed these plant species for their potential as sources of antimicrobial agents, with focus on ellagitannins.
Extracts and fractions of stem bark and roots of T. sambesiaca and T. kaiserana, obtained using solvent partition and Sephadex LH-20 as well as RP-18 and RP-8 column chromatography, were investigated for antibacterial activities against Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Pseudomonas aeruginosa and Mycobacterium smegmatis. Aqueous, butanol and methanol extracts of T. sambesiaca roots gave MIC values from 156 to 312 µg/ml against S. aureus. UHPLC-MS-TOF results show that the methanol extracts of the roots of T. sambesiaca contain moderate concentrations of corilagin, high concentrations of terchebulin and its isomer as well as ellagic acid glycosides. Aqueous and butanol extracts of the roots of T. kaiserana gave promising antimicrobial effects against S. aureus showing MIC values of 625 µg/ml. An ellagitannin-enriched Lobar RP-8 CC fraction of the roots of T. kaiserana effectively inhibited the growth of S. aureus with a MIC value of 250 µg/ml. The crude methanol extract of T. kaiserana roots is rich in punicalin, terchebulin, punicalagin and ellagic acid rhamnoside.
 Chhabra, S.C. et al., 1989. J. of Ethnopharmacol. 25, 339 – 359.
 Masoko, P. et al., 2005. Afr. J. of Biotechnol. 4 (12), 1425 – 1431.