Anti-Multiple Myeloma Potential of Secondary Metabolites from Hibiscus sabdariffa-Part 2.

Multiple Myeloma (MM) is an aggressive tumor causing millions of deaths every year and currently available therapies are often unsuccessful or correlated with severe side effects. In our previous work we demonstrated that the Hibiscus sabdariffa hydroalcoholic extract inhibits the growth of the MM cell line and we isolated two metabolites responsible for the activity: Hib-ester and Hib-carbaldehyde. Herein we report their interaction with proteasome, one of the main targets in the fight against MM. The molecular modelling study outlined a good interaction of both compounds with the target and these results prompted us to investigate their potential to inhibit proteasome. Metabolites were then isolated from the calyces and an extract with a high content of Hib-ester and Hib-carbaldehyde was prepared. An anticancer profile was drawn, evaluating apoptosis, autophagy and proteasome inhibition, with the anticancer properties being mainly attributed to the Hib-ester and Hib-carbaldehyde, while the proteasome inhibition of the extract could also be ascribed to the presence of anthocyanins, a class of secondary metabolites already known for their proteasome inhibitory activity.

Anti-Multiple Myeloma Potential of Secondary Metabolites from Hibiscus sabdariffa.

Multiple myeloma (MM) belongs to hematological cancers and its incidence is increasing worldwide. Despite recent advances in its therapy, MM still causes many deaths every year. In fact, current therapies sometimes fail and are associated with severe adverse effects, including neurotoxicity. As a part of our ongoing efforts to discover new potential therapies against MM, we prepared Hibiscus sabdariffa extracts obtained by a microwave-assisted solvent extraction and investigate their activity by in vitro assays on the RPMI-8226 cell line. The bioguided fractionation of the crude ethanolic extract allowed the identification of HsFC as the most effective extract. We assessed cell viability (MTT and Tripan blue test), cell migration (Boyden chamber assay), and neurotoxicity (DRG neurotoxicity assay). The promising results prompted us to further fractionate HsFC and we obtained two molecules effective against RPMI-8226 cells without neurotoxic effects at their active concentrations. Moreover, both compounds are able to significantly reduce cell migration.

Multimodal analysis in acute and chronic experimental autoimmune encephalomyelitis.

Different experimental autoimmune encephalomyelitis models (EAE) have been developed. However, due to the different experimental conditions applied, observations simultaneously considering different pathological targets are still scarce. Using EAE induced in Dark Agouti rats with syngenic whole spinal cord homogenate suspended in incomplete Freund's adjuvant, we here analyze neurosteroidogenic machinery, cytokine levels, microglial cells, infiltration of inflammatory cells, myelin proteins and Na(+), K(+)-ATPase pump activity in the spinal cord. Data obtained in the acute phase of the disease confirmed that neurological signs were accompanied by the presence of perivascular infiltrating T cells (CD3(+) cells) and activated monocytic/microglial cells (ED1(+) and MHC-II(+)) in the spinal cord. In particular, the number of MHC-II(+) cells was significantly increased in association with increased expression of pro- (i.e., TNF-α, IL-1ß) and anti-inflammatory (i.e., TGF-ß) cytokines as well as with decreased expression of proteolipid protein and myelin basic protein. During the chronic phase of the disease, the number of MHC-II(+) cells was still increased, although less than in the acute phase. Changes in the number of MHC-II(+) cells were associated with decreased Na(+),K(+)-ATPase enzymatic activity. A general decrease in the levels of neuroactive steroids, with the exception of an increase in tetrahydroprogesterone and 17ß-estradiol, was detected in the acute phase. These changes were maintained or reverted in the chronic phase of EAE. In conclusion, we report that modifications in the neuroimmune response in the acute and chronic phases of EAE are associated with specific changes in myelin proteins, Na(+),K(+)-ATPase pump and in the levels of neuroactive steroids.