Mauritian Endemic Medicinal Plant Extracts Induce G2/M Phase Cell Cycle Arrest and Growth Inhibition of Oesophageal Squamous Cell Carcinoma in Vitro.

Terrestrial plants have contributed massively to the development of modern oncologic drugs. Despite the wide acceptance of Mauritian endemic flowering plants in traditional medicine, scientific evidence of their chemotherapeutic potential is lacking. This study aimed to evaluate the in vitro tumor cytotoxicity of leaf extracts from five Mauritian endemic medicinal plants, namely Acalypha integrifolia Willd (Euphorbiaceae), Labourdonnaisia glauca Bojer (Sapotaceae), Dombeya acutangula Cav. subsp. rosea Friedmann (Malvaceae), Gaertnera psychotrioides (DC.) Baker (Rubiaceae), and Eugenia tinifolia Lam (Myrtaceae). The cytotoxicities of the extracts were determined against six human cancer cell lines, including cervical adenocarcinoma, colorectal carcinoma, oesophageal adenocarcinoma, and oesophageal squamous cell carcinoma. The potent extracts were further investigated using cell cycle analysis and reverse phase protein array (RPPA) analysis. The antioxidant properties and polyphenolic profile of the potent extracts were also evaluated. Gas chromatography mass spectrometry (GC-MS) analyses revealed the presence of (+)-catechin and gallocatechin in E. tinifolia and L. glauca, while gallic acid was detected in A. integrifolia. L. glauca, A. integrifolia, and E. tinifolia were highly selective towards human oesophageal squamous cell carcinoma (KYSE-30) cells. L. glauca and E. tinifolia arrested KYSE- 30 cells in the G2/M phase, in a concentration-dependent manner. RPPA analysis indicated that the extracts may partly exert their tumor growth-inhibitory activity by upregulating the intracellular level of 5'AMP-activated kinase (AMPK). The findings highlight the potent antiproliferative activity of three Mauritian endemic leaf extracts against oesophageal squamous cell carcinoma and calls for further investigation into their chemotherapeutic application.

Comparative suppressing effects of black and green teas on the formation of advanced glycation end products (AGEs) and AGE-induced oxidative stress.

This study aimed at investigating and comparing the anti-diabetic potential of black and green teas. Biochemical analyses indicate higher antioxidant potency, significantly correlated with the phytochemicals present, in green teas compared to black teas. Both extracts afforded a similar level of protection to erythrocytes against peroxyl radical-induced lysis. Non-cytotoxic concentration of green and black tea extracts significantly reduced the reactive oxygen species (ROS) production (P < 0.01), lowered the oxidation of proteins (P < 0.05) and decreased the IL-6 secretion (P < 0.01) induced by AGEs or H2O2 in 3T3-L1 preadipocytes. Both teas also inhibited the decline in the enzymatic activities of superoxide dismutase, catalase and glutathione peroxidase induced by the pro-oxidants. The teas further suppressed the glycation of BSA mediated by glucose, ribose and MGO by reducing fluorescent AGE, fructosamine, protein carbonyl and AOPP levels. Black and green teas also inhibited the activities of α-amylase (AA50: 589.86 ± 39.51 and 947.80 ± 18.20 µg mL-1, respectively) and α-glucosidase (AA50: 72.31 ± 4.23 and 100.23 ± 8.10 µg mL-1, respectively). The teas afforded a comparable level of protection at the cellular level and against glycation while black tea exerted the highest carbohydrate hydrolysing enzymes inhibitory activity. Our results clearly show that black and green teas represent an important source of antioxidants with anti-diabetic potential.

Morinda citrifolia L. fruit extracts modulates H2O2-induced oxidative stress in human liposarcoma SW872 cells.

Morinda citrifolia L. commonly known as noni is used by the pharmaceutical and cosmetic industries due to the plethora of pharmacological activities of its metabolites. In Mauritius, the fruits of M. citrifolia are used in folk medicine against a number of indications. The present study aimed at evaluating the antioxidant activity of ripe and unripe noni fruit at both biochemical and cellular levels. Using an array of established assay systems, the fruit antioxidant propensity was assessed in terms of its radical scavenging, iron reducing and metal chelating potentials. Ascorbic acid, total phenolic and total flavonoid contents of the fruits were also determined. The ascorbic acid content of ripe noni was 76.24 ± 1.13 mg/100 g while total phenolics of ripe and unripe fruit extracts were 748.40 ± 8.85 µg and 770.34 ± 2.27 µg GAE g(-1) FW respectively. Both the ripe and unripe extracts of M. citrifolia were potent scavengers of nitric oxide, superoxide and hydroxyl radicals. The ferric reducing capacity ranged from 11.26 ± 0.33 to 11.90 ± 0.20 mM Fe(2+) g(-1) FW while the IC50 values for the iron (II) chelating power were 0.50 ± 0.01 and 1.74 ± 0.01 g FW/mL for the ripe and unripe fruit extracts respectively. Cellular studies additionally demonstrated that noni were able to dose-dependently counteract accumulation of reactive oxygen species (ROS)-induced oxidative stress, a potential obesogenic factor within human liposarcoma SW872 cells as well as significantly restore cell death within the concentration range of 0.106-0.813 g/mL. Results reported herein suggest noni as an interesting source of prophylactic antioxidants modulated by its polyphenol composition.