Microscopic Characteristics, Chromatographic Profiles and Inhibition of Peroxidase Activity of the Leaves of <i>Manihot esculenta</i>and <i>Manihot glaziovii</i>, Consumed as Traditional Vegetables

Methanolic extracts from the leaves of Manihot esculenta (Two cultivars) and Manihot glaziovii, consumed as traditional vegetables in DR. Congo was chemically characterized by Thin layer Chromatography and High Performance Liquid Chromatography. In vitro biochemical activities of extracts against Radical Oxidative Species (ROS) production were assessed in cellular models, on enzymes, Myeloperoxidase (MPO) and Horseradish Peroxidase (HRP) involved in inflammation. The microscopic analysis of the powder of leaves showed that each species displays specific and discriminating botanical microscopic features. Varieties of M. esculenta had a chemical fingerprint different from M. glaziovii. The majority of compounds were polyphenols, represented mainly by rutin, kaempferol-3-O-rutinoside, amentoflavone, phenolic acids such as gallic acid. All extracts exhibited high cellular antioxidant activity in the range of 0.1 to 10 μg·mL-1 using lucigenin with neutrophils, but a moderate cellular antioxidant activity ranging between 10 and 100 μg·mL-1 with DCFDA on HL60 monocytes. Extracts from Manihot leaves showed a pronounced inhibitory effect on the production of extracellular ROS, on HRP and myeloperoxidase activity. Cellular antioxidant activities, the inhibitory effect on HRP of extracts from M. glaziovii, M. esculenta cultivar Mwambu were significantly higher, but their inhibitory effect on the activity of MPO was lower than those of M. esculenta cultivar TEM 419. The biological activities of Manihot esculenta and Manihot glaziovii were well correlated to their phytochemicals that could justify their traditional use as vegetables, potential functional foods or nutraceutical resources and medicines.

Effect of honey on oxidation, chlorination and nitration by purified equine myeloperoxidase

Objective: To evaluate the antioxidant effect of honey using two classical methods generally used, and for the first time to test the effect of honey on the oxidation, chlorination and nitration by purified equine myeloperoxidase (MPO). Methods: The antioxidant activity of three Algerian honey samples (nectar honey, mixed honey and honeydew honey) was evaluated by two classical methods, the ferric- reducing/antioxidant power (FRAP) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity. Results: Honeydew honey had the highest reducing power and DPPH radical-scavenging activity, whereas nectar honey showed the lowest reducing power and DPPH radical-scavenging activity. All honey samples showed a significant inhibitory effect on the chlorination activity of equine MPO, but honeydew honey was the weakest inhibitor. The three samples were poorly inhibitor on the MPO oxidation and nitration activities, except for nectar honey that exerted an inhibitory effect at the highest tested concentration of 10%. These later results seem to contradict those obtained with DPPH and FRAP. Conclusions: The antioxidant capacity of honey is mainly due to the phenolic compounds and flavonoids it contained. It has been suggested that MPO might be involved in the antioxidant, not pro-oxidant, activity of phenolic compounds.