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Distribution and antioxidant activity of polyphenols in ripe and unripe tree pepper (capsicum pubescens)

Journal of food biochemistry 2007 v.31 no.4 pp. 456-473
Capsicum pubescens, antioxidant activity, brain, condiments, diet, disease prevention, food processing, free radical scavengers, free radicals, fruits, human diseases, lipid peroxidation, oxidative stress, pepper, peppers, phenol, plant-based foods, polyphenols, rats, sauces, seeds, trees, Africa
Capsicum pubescens, commonly known as tree pepper with its distinctive thick-fleshed pungent fruit (ripe and unripe), is used as a vegetable condiment or made into a sauce. The present study sought to determine the distribution of polyphenols and antioxidant activity in its thick flesh and seeds. Free, bound and total phenol content of each extract was subsequently determined, while reducing power, Fe (II)-chelating ability, OH radical-scavenging ability and ability of the extracts to inhibit lipid peroxidation in basal and Fe (II)-induced lipid peroxidation in brain was used for antioxidant capacity. Unripe pepper had higher total phenol content than ripe pepper; however, there was no significant difference ( P > 0.05) in the total phenol content of flesh for both peppers (unripe [110 mg/100g], ripe [95 mg/100 g]) and the seed (unripe [110.0 mg/100 g ], ripe [90 mg/100 g]). Nevertheless, the free polyphenols in flesh and seed of the peppers were significantly higher ( P < 0.05) than the bound polyphenols. All the extracts inhibited lipid peroxidation in a dose-dependent manner, although free polyphenols from the flesh of ripe pepper caused the highest inhibition in malondialdehyde production in rat's brain. Free and bound polyphenols from the flesh of unripe pepper had the highest Fe (II)-chelating and OH radical-scavenging ability. While the free polyphenols from the flesh of ripe pepper had the highest reducing power, this may have accounted for its ability to reduce Fe (II)-induced lipid peroxidation. Therefore, by removing the seed from pepper, a 50% loss in the total phenol content would result, which will substantially reduce antioxidant activity. Because many degenerative human diseases have been recognized as being a consequence of free radical damage, there have been many studies undertaken on how to delay or prevent the onset of these diseases. The most likely and practical way to fight against degenerative diseases is to improve body antioxidant status, which could be achieved by higher consumption of vegetables and fruits. Foods from plant origin usually contain natural antioxidants that can scavenge free radical. The inclusion of either ripe or unripe pepper in a diet is a common practice in Africa and some other parts of the world; our recent findings on the antioxidant properties of Capsicum pubescens clearly indicate that its inclusion in the diet will contribute greatly in the prevention of neuro-degenerative diseases associated with oxidative stress, by inhibiting lipid peroxidation. Moreover, removing the seeds of this pepper during food processing will reduce the total phenol content by 50%, and consequently reduce the antioxidant activity.