Phytochemical Investigation and Anti-Proliferative Effects of Rauvolfia vomitoria, Calliandra portoriscensis and Anthocleista djalonensis on Human Breast Cancer (MCF-7) Cell Line

Abstract

Breast cancer remains a global public health problem and natural products are increasingly being explored in search of new
therapeutic agents with scientific evidence. This study investigated phytochemical composition, antioxidant and anti-proliferative
activities of different solvent fractions of Rauvolfia vomitoria, Calliandra portoriscensis, and Anthocleista djalonensis in
estrogen receptor positive MCF-7 breast cancer cell line ex vivo. Liguid-liquid partitioning separation technique was used to
obtain the chloroform, ethyl acetate and aqueous fractions Rauvolfia vomitoria, Calliandra portoriscensis, and Anthocleista
djalonensis from their crude methanolic extracts. Qualitative and quantitative phytochemical analysis were performed to
determine the levels of total phenolics and flavonoids. Antioxidant activities of each extract fraction were determined using the
DPPH and NO scavenging assays. The MCF-7 cell line was cultured in DMEM medium overnight, exposed to different
concentrations (10-50 mg/mL) of each fraction for 48 h and growth inhibition was subsequently evaluated using the MTT assay.
Phytochemical analysis revealed the presence of alkaloids, flavonoids, tannins and phenols in the plants. The extract fractions of
C. portoriscensis, R. vomitoria and A. djalonensis at 10, 20, 30, 40 and 50 ug/mL were found to scavenge DPPH free radical
dose-dependently by 7.5 – 10.2%, 11.2 – 24.9%, 17.5 – 31.8 %, 27.8 – 47.1 % and 37.8 – 62.1%. The highest DPPH scavenging
activity of 62.1%, 55.4% and 54.2% was elicited by the chloroform fractions of A. djalonensis and C. portoriscensis and
ethylacetate fraction of R. vomitoria at 50 ug/mL Dose-dependent NO inhibition was also observed with the highest NO inhibition
elicited by R. vomitoria chloroform fraction (61.7%), followed by A. djalonensis ethyl acetate fraction (55.9%) and C.
portoriscensis chloroform fraction (49.6%) at 50 ug/mL the extract fractions also induced anti-proliferative effects on MCF-7
cell in a dose-dependent manner and significantly (P<0.05) with maximum elicitation observed at 96 h post treatment. On the
whole, only the chloroform extract fraction of A. djalonesis elicited moderate anti-proliferative potency against MCF-7 cell line
with an IC50 of 66.8 + 8.3 ug/mL, while other extract fractions have low to no potency with IC50 range of 237.4 – 605.7 ug/mL
Unlike cisplatin (IC50 of78.4 – 108.3 ug/mL,), the proliferation of the normal Vero cell lines was less affected by the extract
fractions (IC50 237.4 – 605.7 ug/mL). Findings in this study provide scientific evidence for chloroform fraction of Anthocleista
djalonensis as a potential source of novel therapeutic agents for future breast cancer pharmacotherapeutic explorations.