Saponins Extracted from Tea (Camellia Sinensis) Flowers Induces Autophagy in Ovarian Cancer Cells.

Yi Charlie Chen,Youying Tu,Chen Xia,Yaomin Wang,Lianfu Chen

doi:10.3390/molecules25225254

Abstract

Tea flower saponins (TFS) possess effective anticancer properties. The diversity and complexity of TFS increases the difficulty of their extraction and purification from tea flowers. Here, multiple methods including solvent extraction, microporous resin separation and preparative HPLC separation were used to obtain TFS with a yield of 0.34%. Furthermore, we revealed that TFS induced autophagy—as evidenced by an increase in MDC-positive cell populations and mCherry-LC3B-labeled autolysosomes and an upregulation of LC3II protein levels. 3-MA reversed the decrease in cell viability induced by TFS, showing that TFS induced autophagic cell death. TFS-induced autophagy was not dependent on the Akt/mTOR/p70S6K signaling pathway. TFS-induced autophagy in OVCAR-3 cells was accompanied by ERK pathway activation and reactive oxygen species (ROS) generation. This paper is the first report of TFS-mediated autophagy of ovarian cancer cells. These results provide new insights for future studies of the anti-cancer effects of TFS.

Highlights

Epithelial ovarian cancer continues to be a deadly disease due to its high mortality rate and poor long-term prognosis [1,2,3,4]
As reactive oxygen species (ROS) generation is considered to be an essential aspect of apoptosis and autophagy [29], we previously reported that Tea flower saponins (TFS) induces apoptosis in A2780/CP70 and OVCAR-3 cells [17]
We showed for the first time that TFS induced autophagic cell death in ovarian cancer cells

Summary

Introduction

Epithelial ovarian cancer continues to be a deadly disease due to its high mortality rate and poor long-term prognosis [1,2,3,4]. Much attention has been focused on studying natural products and searching for compounds which possess anti-cancer effects [5,6,7]. The effectiveness of tea (Camellia sinensis) against different types of cancer has been extensively studied owing to the numerous bioactive constituents contained in the tea plant [8,9,10,11]. Tea flowers are the reproductive organs of tea, and recent studies have demonstrated the effective anti-cancer effects of tea flowers and compounds extracted from tea flowers [12]. Tea flowers contain a number of bioactive constituents including polyphenols, polysaccharides, amino acids and saponins [13,14,15,16]. The diversity and complexity of tea flower saponins increases the difficulty of their extraction and separation from tea flowers, which limits the research of tea flower saponins

Methods

Results

Discussion

Conclusion