Anti-angiogenic activities of the leaves of Tapinanthus bangwensis (Engl. and K. Krause) Danser Loranthaceae growing on three host trees in south-western Nigeria

Abstract

The control of angiogenic process is of immense importance to the overall health of mankind to avert out-of-control complications such as tumours and cancers. Tapinanthus bangwensis (TBG) is a semi-parasitic plant with multipurpose uses in Nigerian ethno-medicine among which is its anti-infective properties as well as the anti-tumor and restoration of damaged tissues. Despite the wide and varied uses of TBG, the anti-angiogenic investigation of the plant on different host trees is lacking while the documentation and scientific validation of indigenous knowledge on plants' use is urgent. The present work focuses on the anti-angiogenic activities of the crude extracts and partitioned fractions of the leaves of Tapinanthus bangwensis (TBG) using the Chick chorio allantoic membrane (CAM) model. The plant was collected from three different host trees namely Albizia lebbeck (AL), Stereospermum kunthianum (SK) and Tabebuia rosea (TR). The methanolic crude extracts and solvent-partitioned fractions of TBG-SK samples were assessed for their anti-angiogenic activities using the chick chorio allantoic membrane (CAM) in ovo and in vitro assay methods respectively. Purification and isolation of major compound(s) in the chloroform fraction of TBG extract obtained from Stereospermum kunthianum host tree (TBG-SK) was carried out using chromatographic and spectroscopic methods (NMR, MS).The crude methanolic extract of TBG-SK was most potent (100% activity) in the CAM in ovo assay while the chloroform fraction produced a significantly (p<0.05) highest average reduction in blood vessels with resultant formation of large avascular zones on CAM following an in vitro CAM assay. The anti-angiogenic chloroform fraction revealed the presence of a UV-active triterpenoid moiety. Findings from this work, has provided some justification for the folkloric use of TBG and thus forms a potential basis for drug discovery for wide-ranging disease states.