This study was to compare the total phenolic (TP) content in extracts from eleven plant materials collected at different geographical locations in Kenya, Nigeria, and USA. These plants have been selected because the majority of them are highly pigmented, from yellow to purple, and would therefore have economic value in industries for producing antioxidants and surfactants. Two of them were collected from the industrial and domestic waste outlets. Each analysis was achieved using the Folin-Ciocalteau technique. The order of decreasing phenolic acid content as gallic acid concentration (mg/g dry weight) was Prunus africana (55.14) > Acacia tortilis (42.11) > Khaya grandifoliola (17.54) > Curcuma longa (17.23) > Vernonia amygdalina (14.9)> Russelia equisetiformis (14.03) > Calendula officinalis (7.96) >Phragmites australis (control) (7.09) > Rauwolfia vomitoria (6.69) > Phragmites australis (industrial) (6.21) > Cnidoscolus aconitifolius (5.6). The TP contents of Spartina alterniflora species were below the detection limit.

The Jamaican bitter yam (Dioscorea polygonoides) contains various bioactive components that may increase oxidative stress in various tissues at relatively high concentrations. The present study therefore investigated the effects of bitter yam supplementation (5%) on the integrity of the liver and kidneys. Two mice strains (inbred C57BL/6 and transgenic C57BL/6-Tg(APOA1)1Rub/J) were used in the study. Each strain was divided into two groups. One group was fed a basal diet without supplementation, and the second group was fed a basal diet supplemented with the Jamaican bitter yam. The results revealed that the transgenic mice fed diets with and without bitter yam supplementation experienced significant increases in weight, when compared with inbred mice fed similar diets. Hepatoprotective effects were observed in transgenic mice known to possess high serum high-density lipoprotein (HDL). Oxidative stress was induced in mice fed diets supplemented with bitter yam at a concentration of 5%. PRACTICAL APPLICATIONThe Jamaican bitter yam possesses potent anti-diabetic and hypocholesterolemic properties due to its high levels of sapogenin. Currently, the tuber is consumed in rural areas mostly during times of drought. No toxicology data, however, exist for consumption of this yam species. This study provides information on the possible toxicity from overconsumption and paves the way for future studies to establish an effective consumption dosage. With its potent cholesterol-lowering capabilities, the Jamaican bitter yam can be exploited in the nutraceutical industry and for the development of other value-added products for everyday consumption such as baked goods and granola bars, giving them a hypocholesterolemic twist.

The bitter yam tuber is consumed as a staple in various regions of the world and is known to possess medicinal properties due to the presence of bioactive compounds such as saponins. These compounds may induce health complications resulting in tissue damage in cases of overconsumption. This study was geared towards determining the effects of Jamaican bitter yam (5%) on tissue damage parameters in mice hearts and brains. Mice were fed diets with or without bitter yam supplementation for a period of four weeks after which they were sacrificed. Lipid peroxidation and antioxidant parameters were determined in the heart and brain. Significant increases in lipid peroxidation were observed in the hearts of mice fed bitter yam supplemented diets and in the brains of hypercholesterolemic mice only. Bitter yam supplementation significantly reduced glutathione peroxidase activities in the hearts of hypercholesterolemic mice and the hearts and brains of normocholesterolemic mice. Significant increase in catalase activity was only seen in the hearts of hypercholesterolemic mice fed a supplemented diet when compared to mice fed an unsupplemented diet. The results indicate that dietary supplementation with the Jamaican bitter yam at a high concentration may induce oxidative stress in mice hearts and brains.