Over the past decade the science has studied synthetic
photosensitizers used in
photodynamic therapy (
PDT) or
photochemotherapy as anticancer candidates. In this context, compounds extracted from vegetable species present interesting potential in the
cancer field. In our laboratory, we studied Heterophyllaea pustulata a phototoxic shrub that habit the northwest of Argentina. From this vegetal, by in vitro germination, we obtained
Rubiadin and
Soranjidiol, two
anthraquinones that exhibited significant photocytotoxicity on human
cancer cells. In addition, the fraction obtained from callus cultures allowed us to get a satisfactory content of these compounds compared to those found from the original plant. Under
PDT regimen, we found that cell destruction resulted in a dose-dependent manner and occasioned apoptosis on photosensitized cells. Biochemical analysis revealed the involvement of
caspase-3, PARP cleavage and DNA fragmentation in
Rubiadin induced apoptosis. Moreover,
Soranjidiol-
PDT led to μ-
calpain-induced apoptosis involving caspases-3-independent DNA fragmentation. We also showed that both
anthraquinones are cytoplasmatically distributed and out of nucleus. In addition, we demonstrated a synergic cytotoxic effect when we combined them. Our data demonstrated that
Rubiadin and
Soranjidiol could be further considered as natural photocytotoxic compounds against
cancer cells and callus cultures are a plausible source of these anthraquinonic compounds.