Isolation of Polyphenols from Soursop Annona muricata L Leaves Using Green Chemistry Techniques and their Anticancer Effect

HIGHLIGHTS Isolate, fractionate and characterize extracts obtained from soursop leaves. Use of emerging green technologies such as microwave-ultrasound hybridization. The extracts contain kaempferol, procyanidins, catechin, and quercetin. The total ethanolic extract demonstrates cytotoxic effect on HeLa cells.

Abstract Cervical cancer is classified as the fourth most common malignancy in women. Natural compounds are a therapeutic alternative in cancer therapy. The aim of the study is to isolate, fractionate, and characterize extracts obtained from soursop leaves (Annona muricata L.) and determine their cytotoxic effect against HeLa cervical cancer cells and non-carcinogenic fibroblast 3T3 cells. The phytochemicals of soursop leaves were extracted through emerging green technologies such as the novel use of microwave-ultrasound hybridization and the use of environmentally friendly solvents (water and ethanol), in addition to the purification of extracts enriched in polyphenols by liquid chromatography with Amberlite XAD-16. Total aqueous and ethanolic extract were purified, as well as the fraction one of each extract. The extracts recovered from soursop leaves contained kaempferol and its isomers, procyanidins, catechin, and quercetin. The viability of the cells was determined with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. HeLa and 3T3 cells were exposed to concentrations of 25, 50, 75, 100, 150, 200, and 250 ppm of a solution of soursop leaf extract powder. The MTT assay showed that soursop leaf extracts were toxic to both cell lines in general, however, the ethanolic extract at 25 and 50 ppm demonstrated inhibition in cell viability against the HeLa cancer line and low cytotoxicity for 3T3 fibroblast cells. In conclusion, the novel microwave-ultrasound hybridization technology allows the extraction of polyphenols that may have a potential cytotoxic effect on cancer cells.

Tea polyphenols induce S phase arrest and apoptosis in gallbladder cancer cells

Gallbladder cancer (GBC) is the most common malignancy in the biliary tract. Without effective treatment, its prognosis is notoriously poor. Tea polyphenols (TPs) have many pharmacological and health benefits, including antioxidant, anti-inflammatory, anti-tumor, anti-thrombotic, antibacterial, and vasodilatory properties. However, the anti-cancer effect of TPs in human gallbladder cancer has not yet been determined. Cell viability and colony formation assay were used to investigate the cell growth. Cell cycle and apoptosis were evaluated by flow cytometry analysis. Western blot assay was used to detect the expression of proteins related to cell cycle and apoptosis. Human tumor xenografts were used to examine the effect of TPs on gallbladder cancer cells in vivo. TPs significantly inhibited cell growth of gallbladder cancer cell lines in a dose- and time-dependent manner. Cell cycle progression in GBC cells was blocked at the S phase by TPs. TPs also induced mitochondrial-related apoptosis in GBC cells by upregulating Bax, cleaved caspase-3, and cleaved PARP expressions and downregulating Bcl-2, cyclin A, and Cdk2 expressions. The effects of TPs on GBC were further proven in vivo in a mouse xenograft model. Our study is the first to report that TPs inhibit GBC cell growth and these compounds may have potential as novel therapeutic agents for treating gallbladder cancer.

Neutralising antibodies for Mayaro virus in Pantanal, Brazil

The Pantanal hosts diverse wildlife species and therefore is a hotspot for arbovirus studies in South America. A serosurvey for Mayaro virus (MAYV), eastern (EEEV), western (WEEV) and Venezuelan (VEEV) equine encephalitis viruses was conducted with 237 sheep, 87 free-ranging caimans and 748 equids, including 37 collected from a ranch where a neurologic disorder outbreak had been recently reported. Sera were tested for specific viral antibodies using plaque-reduction neutralisation test. From a total of 748 equids, of which 264 were immunised with vaccine composed of EEEV and WEEV and 484 had no history of immunisation, 10 (1.3%) were seropositive for MAYV and two (0.3%) for VEEV using criteria of a ≥ 4-fold antibody titre difference. Among the 484 equids without history of immunisation, 48 (9.9%) were seropositive for EEEV and four (0.8%) for WEEV using the same criteria. Among the sheep, five were sero- positive for equine encephalitis alphaviruses, with one (0.4%) for EEEV, one (0.4%) for WEEV and three (1.3%) for VEEV. Regarding free-ranging caimans, one (1.1%) and three (3.4%), respectively, had low titres for neutralising antibodies to VEEV and undetermined alphaviruses. The neurological disorder outbreak could not be linked to the alphaviruses tested. Our findings represent strong evidence that MAYV and all equine encephalitis alphaviruses circulated in the Pantanal.