Flavonoids, stilbenes and pentacyclic triterpenoids in antifungal bark and wood extracts of Terminalia brownii

Terminalia brownii is known for its various uses in African traditional medicine [1, 2]. Recently, ellagic acid derivatives [3]. and one chromone [4]. have been described from this plant, but no other classes of compounds have been reported in T. brownii earlier.
The purpose of this study was to screen stem bark and wood extracts of T. brownii for antifungal activity with emphasis on plant pathogenic fungi and to study the chemical composition of the extracts. Aqueous extracts of the bark and wood gave antifungal effects against Aspergillus niger and A. flavus (inhibition zones of 14 mm) as well as against Nattrassia mangifera and Gibberella moniliformis syn. Fusarium moniliforme (inhibition zones of 20 mm). Ethyl acetate extracts of the wood also gave promising antifungal effects. According to RP-HPLC-DAD data the stem bark and wood ethyl acetate extracts contain flavonoids and flavonoidal acids. Tandem mass spectrometry (MS/MS) led to the identification of ten compounds in wood ethyl acetate extract (Table 1); two of which were pentacyclic triterpenoidal acids. Resveratrol 3-O-- galloylglucoside was also identified in its cis and trans forms. In addition six flavonoids were identified in T. browni wood ethyl acetate extract.
These results support the eventual development and use of standardized extracts of T. brownii stem wood and bark as biopesticides against plant pathogenic fungi.