The phytochemical investigation of the whole plants of Coelogyne fuscescens Lindl. var. brunnea led to the discovery of three new phenolic glycosides, i.e., coelofusides
A–C (1–3) and 12 known compounds (4–15). For the first time, we reported the nuclear
magnetic resonance (NMR) data of 4-O-(6′-O-glucosyl-4″-hydroxybenzoyl)-4-hydroxybenzyl alcohol
(4) in this study. The identification of the structures
of newly discovered compounds was done through the analysis of their
spectroscopic data [NMR, mass spectrometry, ultraviolet, Fourier transform
infrared, optical rotation, and circular dichroism (CD)]. In comparison
to anticancer drugs (i.e., etoposide and carboplatin), we evaluated
anticancer potential of the isolated compounds on two different breast
cancer cell lines, namely, T47D and MDA-MB-231. Human fibroblast HaCaT
cells were used as the control cells. After a 48 h incubation, flavidin
(8), coelonin (10), 3,4-dihydroxybenzaldehyde
(11), and oxoflavidin (12) showed significant
cytotoxic effects against breast cancer cells. Among them, oxoflavidin
(12) exhibited the most potent cytotoxicity on MDA-MB-231
with an IC50 value of 26.26 ± 4.33 μM. In the
nuclear staining assay, oxoflavidin induced apoptosis after 48 h in
both T47D and MDA-MB-231 cells in a dose-dependent manner. Furthermore,
oxoflavidin upregulated the expression of apoptotic genes, such as
p53, Bax, poly(ADP-ribose) polymerase, caspase-3, and caspase-9 genes
while significantly decreasing antiapoptotic protein (Bcl-2) expression
levels.