## 1 Introduction  
Medicial plants have been used to prevent and treat various health problems for many ages [1; 2; 3], and despite the great advancement in modern medicine, phytotherapy is still commonly used [3]. Various phytochemicals produced by plants may vary both qualitatively and quantitatively according to many factors such as weather, ecology, time and age of collection [4]. Their active components, including phytosterols, essential oils and phenolics, have been investigated as potential therapeutic agents and towards isolation of novel compounds that can be later structurally modified for therapeutic purposes [5]. Both monophenolic and polyphenic components from a large number of plants have been proven to delay or lessen the initiation, progression and spread of cancers in both in vitro and in vivo studies [6]. This anti carcinogenic activity is primarily due to the ability of phenolic compounds to induce cell cycle arrest, inhibit oncogenic signalling cascades controlling cell proliferation, angiogenesis and apoptosis, modulate ROS levels, promote tumour suppressor proteins such as p53 and enhance the ability to differentiate and transform into normal cells [7]. Additionally, the body's immune system ability to recognize and destroy cancer cells is enhanced by phenolics, and they appear to increase the efficacy of standard chemo- and radiotherapeutic regimens and avert resistance to these agents [8; 9]. One of such promising plant is _Vernonia amygdala_, especially its aerial parts (the leaves). This bushy shrub or small tree, with green and bitter elliptic petiolate leaves about 6 mm in diameter, grows to 2-5 m in height. The stems have light grey or brown bark, which is rather rough and longitudinally flaking, as well as brittle branches. It bears small thistle-like, creamy-white flower heads that are sometimes slightly touched with mauve. The fruit is a small nutlet, with miniature glands and coarse hairs on the body and a long tuft of bristly hairs at the top [10]. In other studies, _V. amygdala_ is documented to demonstrate diverse therapeutic activities, including anti-cancer properties, that have been attributed to its presence of coumarins, flavonoids, sesquiterpene lactones and edotides [11]. Colorimetric MTT assay measuring cell metabolic activity found that _V. amygdala_ leaf extract inhibits the proliferation and induces apoptosis of MCF-7 and MDA-MB-231 human breast cancer cell lines in a time- and dose-dependent manner through both extrinsic and intrinsic pathways [12]. The same study pointed that _V. amygdala_ inhibits the expression of ER-\(\alpha\) and its downstream products, and given that ER-\(\alpha\) is expressed in around 70% of diagnosed breast cancers, that has been a crucial finding. The same plant also exhibited compatibility with doxorubicin, indicating that it can complement current chemotherapy [12].  
Although previous phytochemical analyses of _V. amygdala_ leaf extract have examined its flavonoids, lipids, mucilage and polyphenol content [13], no detailed qualitative or quantitative analyses of its polyphenols have been performed. Moreover, as part of efforts in our laboratory to understand the effect of combining this plant methanolic extract with other plant extracts and compounds on breast cancer [14] and its possible medicinal use in the management of this disease, detailed knowledge of its active constituents is needed. Therefore, the present study performed qualitative and quantitative analysis of the phenolic compounds in _V. amygdala_ methanolic leaf extract of Ugandan origin.