Phytochemical analysis of Amelanchier parviflora subsp. chelmea and identification of their anti-angiogenic secondary metabolites

The genus Amelanchier (Rosaceae) comprises species that are characterized by the presence of secondary metabolites belonging to anthocyanins, flavonoids and terpenoids [1]. Amelanchier parviflora subsp. chelmea is an endemic Greek plant for which there are currently no published phytochemical studies. EtOAc and MeOH extracts of the aerial part were evaluated for their angiogenic properties using endothelial cell-based functional assays [2]. The results showed that both extracts exhibited important inhibition of endothelial cell proliferation at 20 µg/ml (inhibition 65.4% and 54.4% for the EtOAc and the MeOH extract, respectively). Furthermore, in this study the phytochemical analysis of the extracts was achieved in two steps. Initially the extracts were fractionated by step-gradient Fast Centrifugal Partition Chromatoraphy (FCPC) and subsequently the chosen fractions were further purified. This procedure afforded 36 natural compounds including six flavonoids, five phenolic compounds, three biphenyls, two lignans, five hydroxycinnamic esters of triterpenes and six hydroxycinnamic esters of aliphatic alcohols. It is important to say that the compounds 4-hydroxy-2′,3,4′,5,5′-pentamethoxybiphenyl, 3-hydroxy-2′,4,4′,5,5′-pentamethoxybiphenyl and 2′′,4′′-dimethoxy-sorlanine are new natural products. The identity of isolated compounds was confirmed by NMR and MS spectroscopy. Moreover, the FCPC fractions were evaluated for their ability to inhibit or induce angiogenesis and the active fractions were further studied in order to identify their bioactive components. Subsequently, the evaluation of isolated compounds with the above mentioned assays demonstrated that betulinol, 3-β-O-trans-p-coumaroylbetulinol and 3-β-O-trans-caffeoylbetulinic acid possess significant anti-proliferative activity with 64.9%, 66.7% and 38.9% inhibition at 100µM, respectively. The bioactive compounds will be evaluated in advanced in vitro and in vivo models to establish their anti-angiogenic effects.

Keywords: Amelanchier, Rosaceae, angiogenesis, biphenyls, lignans, flavonoids, terpenoids

References:

[1] Jocelyn A. Characterization of Cyanidin- and Quercetin-Derived Flavonoids and Other Phenolics in Mature Saskatoon Fruits (Amelanchier alnifolia Nutt.). J. Agric. Food Chem. 2007; 55:10414 – 10424

[2] Mosmann T. Rapid colorimetric assay for cellular growth and survival: application to proliferation and cytotoxicity assays. J. Immunol. Methods. 1983; 65:55 – 63