Dendrogenin A synergizes with Cytarabine to Kill Acute Myeloid Leukemia Cells In Vitro and In Vivo.

Dendrogenin A (DDA) is a mammalian cholesterol metabolite that displays potent antitumor properties on acute myeloid leukemia (AML). DDA triggers lethal autophagy in cancer cells through a biased activation of the oxysterol receptor LXRß, and the inhibition of a sterol isomerase. We hypothesize that DDA could potentiate the activity of an anticancer drug acting through a different molecular mechanism, and conducted in vitro and in vivo combination tests on AML cell lines and patient primary tumors. We report here results from tests combining DDA with antimetabolite cytarabine (Ara-C), one of the main drugs used for AML treatment worldwide. We demonstrated that DDA potentiated and sensitized AML cells, including primary patient samples, to Ara-C in vitro and in vivo. Mechanistic studies revealed that this sensitization was LXRß-dependent and was due to the activation of lethal autophagy. This study demonstrates a positive in vitro and in vivo interaction between DDA and Ara-C, and supports the clinical evaluation of DDA in combination with Ara-C for the treatment of AML.

Natural and semisynthetic oxyprenylated aromatic compounds as stimulators or inhibitors of melanogenesis.

It has been very recently shown how naturally occurring oxyprenylated coumarins are effective modulators of melanogenesis. In this short communication we wish to generalize the potentialities as skin tanning or whitening agents of a wider panel of natural and semisynthetic aromatic compounds, including coumarins, cinnamic and benzoic acids, cinnamaldehydes, benzaldehyde, and anthraquinone derivatives. A total number of 43 compounds have been tested assaying their capacity to inhibit or stimulate melanin biosynthesis in cultured murine Melan A cells. The wider number of chemicals herein under investigation allowed to depict a detailed structure-activity relationship, as the following: (a) benzoic acid derivatives are slightly pigmenting agent, for which the effect is more pronounced in compounds with longer O-side chains; (b) independently from the type of substitution, cinnamic acids are able to increase melanin biosynthesis, while benzaldehydes are able to decrease it; (c) coumarins with a 3,3-dimethylallyl or shorter skeletons as substituents in position 7 are tanning agents, while coumarins with farnesyloxy groups are whitening ones; (d) double oxyprenylation in position 6 and 7 and 3,3-dimethylallyl or geranyl skeletons have slight depigmenting capacities, while farnesyl skeletons tend to marginally increase the tanning effect; (e) the presence of electron withdrawing groups (acetyl, COOH, and -Cl) and geranyl or farnesyl oxyprenylated chains respectively in positions 3 and 7 of the coumarin nucleus lead to a whitening effect, and finally (f) oxyprenylated anthraquinones have only a weak depigmenting capacity.

Quantification of biologically active O-prenylated and unprenylated phenylpropanoids in dill (Anethum graveolens), anise (Pimpinella anisum), and wild celery (Angelica archangelica).

An analytical strategy based on different extraction methodologies and HPLC with spectrophotometric (UV-vis) detection has been developed to investigate the presence of and to quantitate biologically active selected unprenylated and O-prenylated phenylpropanoids, namely umbelliferone, 4'-geranyloxyferulic acid, 7-isopentenyloxycoumarin, auraptene, and umbelliprenin in dill (Anethum graveolens L.), anise (Pimpinella anisum L.), and wild celery (Angelica archangelica L.). Absolute ethanol or 7:3 water/ethanol mixtures were seen to be the most powerful extraction solvents to perform "classic" maceration or ultrasound-assisted one in terms of yields in secondary metabolites. For anethum and anise, umbelliprenine was found to be the most abundant prenyloxy secondary metabolite, while in wild celery 4'-geranyloxyferulic acid recorded the highest concentration. Our experimental approach demonstrated to be efficient for the simultaneous identification and quantitation of the above mentioned prenyloxyphenylpropanoids in the title plant species, that is reported herein for the first time in the literature.