## 1 Introduction  
Despite the progress of modern therapeutic and diagnostic methods, cancer remains the most challenging disease for medical science. Breast cancer is the most frequently diagnosed cancer and the leading cause of mortality in women worldwide [1]. In addition, recent investigations on the incidence and mortality of liver cancer showed an estimated annual mortality rate of over 650,000 patients globally in 2017, particularly in Asian countries [2, 3]. Currently, surgical interventions followed by chemotherapy and adjuvant radiation therapy are frequently used to improve the survival rate of cancer patients. On the other hand, natural products, including medicinal plants, are also routinely utilized in primary health care, mainly in developed countries. Since the emergence of ancient medicine, natural products and chemical compounds derived from plants have been used to treat human diseases for centuries and have received increasing consideration for their potential as novel cancer therapeutic agents over the past several years [4]. An alternative approach to the use of traditional therapeutic methods involves the application of anticancer compounds derived from plants. Additionally, growing evidence suggests the possible use of plant-derived compounds to combat carcinogenesis and associated progression, underlining the significance of these products in cancer treatment. Interestingly, approximately 55% of anticancer drugs are currently formulated from natural products [5]. This expanding area of research continues to explore novel natural products from different plant sources, including the sea, which has a nearly endless supply of resources [6; 7], facilitating the analysis of more selective, potent, and less toxic compounds to provide better therapeutic approaches for designing a wide range of new anticancer drugs. Here, we examined the effects of eight whole-plant extracts (methanol extraction) from different plant species on two human cancer cell lines: Breast carcinoma and hepatocellular carcinoma cell cultures. Among them, _Pyracantha angustifolia_ (fruits) and _Paullinia cupana_ (seeds) were then selected for additional detailed apoptosis research focusing on cell death markers elevated by these crude plant extracts. _Pyracantha_ plants, which are found in South Korea, southern Europe, and southwest China, can reach up to 4.5 m. As an evergreen coniferous plant, _Pyracantha_ has many branches and leaves, flowers, and fruits. [PERSON] et al. showed that one _Pyracantha_ species, _P. coccinea_, can be used in traditional medicine for diuretic, cardiac, and tonic purposes due to its phenolic and antioxidant activities [8]. In another study, _Pyracantha fortuneana ([PERSON])_ exhibited satisfactory antitumor activity in breast and ovarian cancer cells due to the anti-mutation and anti-oxidation activities of its selenium-enriched polysaccharides [9]. _Paullinia cupana_, commonly known as guarana, is a Brazilian plant that is frequently touted for its pharmacological activities in neurodegenerative disorders, such as Parkinson's disease, due to the high content of methylxanthines and tannins in its seeds [10]. [PERSON] et al. suggested that the administration of _P. cupana Mart. var. Sorbilis_ defends neuroblastoma cells from rotenone-induced cytotoxicity [11]. In this study, we hypothesized that different plant extracts might contain diverse molecules with antitumor activities and are very effective in selective cancer cell death. After screening eight medicinal plant extracts, we investigated the anticancer effects of _P. angustifolia_ and _P. cupana_ extracts in more detail as they showed maximum inhibitory activity on breast carcinoma and hepatocellular carcinoma cells without affecting their normal counterparts. We observed that _Pyracantha_ and _Paullinia_ exerted a protective effect in both cancer cell line models, as observed by cell proliferation assays.