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.

Application of deep eutectic solvents in Chinese materia medica / 中草药

Deep eutectic solvents (DESs), as a class of novel green solvents, show the promising applications in many fields due to their unique properties such as simple preparation, low cost, environmental friendliness, low volatility, high dissolution power, feasibility of structural design and biodegradability. Recently, DESs have been applied for the extraction, separation and chromatography of active components (flavonoids, saponins, polysaccharides, alkaloids, quinones, phenolic acids, volatile oil, etc) from Chinese materia medica. This article introduced the preparation and properties of DESs, reviewed the development of DESs applications in the field of traditional Chinese medicine, discussed the existing problems and outlined the general trends as well.

Coupled monolithic columns as an alternative for the use of viscous ethanol-water mobile phases on chromatographic fingerprinting complex samples

ABSTRACT Concepts of sustainability have received attention from people involved in investigation of nature-derived matrices. The effects of concomitant pollutant activities are cumulative and harmful to the environment from which these matrices are obtained. High performance liquid chromatography analyses generate millions of litters of chemical waste worldwide every year. Reduction of organic solvent consumption during the analyses and replacement of harmful solvents with greener options are the main approaches to mitigate this problem. This work explored the strategy of employing monolithic columns when the problematic acetonitrile is intended to be replaced with the greener but more viscous ethanol in fingerprinting a leaf extract of Lippia sidoides Cham., Verbenaceae, by high performance liquid chromatography. Two monolithic columns were coupled in series to test a more critical backpressure condition while doubling the number of theoretical plates, which can be useful to separate the hundreds of compounds present in plant extracts. All work was conducted by employing design of experiments. A mathematical model indicated an optimum point in which ethanol was the only organic solvent of the mobile phase. However, the use of a proper metric, which considered environmental parameters together with separation parameters, evidenced that an experimental condition of the original central composite design should be preferred over the former even if containing 20% acetonitrile in the organic modifier mixture. Flow rates of up to 3 ml/min were accommodated with two coupled monolithic columns without exceeding 250 bar. These findings reinforced that no state-of-the-art instruments are needed to shift from traditional harmful solvents to greener ones, but only require a shift in researchers' approach toward sustainability.