The Ananascomosus stem extract is a complex mixture containing various cysteine ​​proteases of the C1A subfamily, such as bromelain and ananain. This mixture used for centuries in Chinese medicine, has several potential therapeutic applications as anti-cancer, anti-inflammatory and ecchymosis degradation agent. In the present work we determined the structures of bromelain and ananain, both in their free forms and in complex with the inhibitors E64 and TLCK. These structures combined with protease-substrate complexes modeling clearly identified the Glu68 as responsible for the high discrimination of bromelain in favor of substrates with positively charged residues at P2, and unveil the reasons for its weak inhibition by cystatins and E64. Our results with purified and fully active bromelain, ananain and papain show a strong reduction of cell proliferation with MDA-MB231 and A2058 cancer cell lines at a concentration of about 1 μM, control experiments clearly emphasizing the need for proteolytic activity. In contrast, while bromelain and ananain had a strong effect on the proliferation of the OCI-LY19 and HL-60 non-adherent cell lines, papain, the archetypal member of the C1A subfamily, had none. This indicates that, in this case, sequence/structure identity beyond the active site of bromelain and ananain is more important than substrate specificity.

Background: Antiplatelet, anticoagulant and fibrinolytic activities of stem bromelain (EC 3.4.22.4) are well described, but more studies are still required to clearly define its usefulness as an antithrombotic agent. Besides, although some effects of bromelain are linked to its proteolytic activity, few studies were performed taking into account this relationship. Objective: We aimed at comparing the effects of stem bromelain total extract (ET) and of its major proteolytic compounds on fibrinogen, fibrin, and blood coagulation considering the proteolytic activity. Methods: Proteolytic fractions chromatographically separated from ET (acidic bromelains, basic bromelains, and ananains) and their irreversibly inhibited counterparts were assayed. Effects on fibrinogen were electrophoretically and spectrophotometrically evaluated. Fibrinolytic activity was measured by the fibrin plate assay. The effect on blood coagulation was evaluated by the prothrombin time (PT) and activated partial thromboplastin time (APTT) tests. Effects were compared with those of thrombin and plasmin. Results: Acidic bromelains and ananains showed thrombin-type activity and low fibrinolytic activity, with acidic bromelains being the least effective as anticoagulants and fibrinolytics; while basic bromelains, without thrombin-like activity, were the best anticoagulant and fibrinolytic proteases present in ET. Procoagulant action was detected for ET and its proteolytic compounds by the APTT test at low concentrations. The measured effects were dependent on proteolytic activity. Conclusion: Two sub-populations of cysteine proteases exhibiting different effects on fibrin (ogen) and blood coagulation are present in ET. Using well characterized stem bromelain regarding its proteolytic system is a prerequisite for a better understanding of the mechanisms underlying the bromelain action.

The objective of this study was to carry out a systematic review of the substances isolated from the African medicinal plant Erythrina senegalensis, focusing on compounds harboring activities against cancer models detailed in depth herein at both in vitro and in vivo preclinical levels. The review was conducted through Pubmed and Google Scholar. Nineteen out of the forty-two secondary metabolites isolated to date from E. senegalensis displayed interesting in vitro and/or in vivo antitumor activities. They belonged to alkaloid (Erysodine), triterpenes (Erythrodiol, maniladiol, oleanolic acid), prenylated isoflavonoids (senegalensin, erysenegalensein E, erysenegalensein M, alpinumisoflavone, derrone, warangalone), flavonoids (erythrisenegalone, senegalensein, lupinifolin, carpachromene) and pterocarpans (erybraedine A, erybraedine C, phaseollin). Among the isoflavonoids called “erysenegalensein”, only erysenealenseins E and M have been tested for their anticancerous properties and turned out to be cytotoxic. Although the stem bark is the most frequently used part of the plant, all pterocarpans were isolated from roots and all alkaloids from seeds. The mechanisms of action of its metabolites include apoptosis, pyroptosis, autophagy and mitophagy via the modulation of cytoplasmic proteins, miRNA and enzymes involved in critical pathways deregulated in cancer. Alpinumisoflavone and oleanolic acid were studied in a broad spectrum of cancer models both in vitro and in preclinical models in vivo with promising results. Other metabolites, including carpachromen, phaseollin, erybraedin A, erysenegalensein M and maniladiol need to be further investigated, as they display potent in vitro effects.

Although Erythrina senegalensis is a plant widely used in traditional medicine in sub-Saharan Africa, its biological properties have been poorly investigated to date. We first characterized by conventional reactions the composition of several stem bark extracts and evaluated in acellular and cellular assays their pro- or antioxidant properties supported by their high phenolic and flavonoid content, particularly with the methanolic extract. The pro- or antioxidant effects observed did not correlate with their IC50 concentrations against five cancer cell lines determined by MTT assay. Indeed, the CH2Cl2 extract and its ethyl acetate (EtOAc) subfraction appeared more potent although they harbored lower pro- or antioxidant effects. Nevertheless, at equipotent concentration, both extracts induced ER- and mitochondria-derived vacuoles observed by fluorescent microscopy that further led to non-apoptotic cell death. LC coupled to high resolution MS investigations have been performed to identify chemical compounds of the extracts. These investigations highlighted the presence of compounds formerly isolated from E. senegalensis including senegalensein that could be retrieved only in the EtOAc subfraction but also thirteen other compounds, such as 16:3-Glc-stigmasterol and hexadecanoic acid, whose anticancer properties have been previously reported. Nineteen other compounds remain to be identified. In conclusion, E. senegalensis appeared rich in compounds with antioxidant and anticancer properties, supporting its use in traditional practice and its status as a species of interest for further investigations in anticancer drug research.

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