DISTRIBUTION OF POL YPHENOLS AND ANTIOXIDANT ACTIVITIES IN SOME NIGERIAN PEPPER FRUITS (Capsicum spp)

Abstract

The seed and flesh of four varieties of pepper Capsicum annuum var. grossum, Capsicum annuum var. abbreviatum, Capsicum annuum var. accuminatum and Capsicum frutescence var. baccatum were each extracted with methanol and 1M Hel (1:1, w/v) mixture and investigated for polyphenol contents and (free radical scavenging activity, reducing power and Fe (II) chelating ability). Furthermore, the prophylactic ability of pepper seeds and flesh against oxidative stress in rat brain tissue and liver was determined by feeding rats with 2% and 4% pepper diets for 14 days. Oxidative stress was induced by intraperitoneal injection of cyclophosphamide (75mg/kg BW) 24 hours before the termination of the experiment. The result revealed that the flesh [CO annuum var. grossum (3.3%)-C. frutescence var. baccatum (3.5%)] had a significantly higher (p<0.05) total phenol content than the seed [Co annuum var. accuminatum (1.9%)-C. annuum var. abbreviatum (2.7%)] and this consequently resulted in a significantly higher antioxidant capacity of the flesh as typified by higher free radical scavenging activity (c. annuum var. accuminatum: 38.7%-C. frutescence var. baccatum: 70.1%) and Fe (IT) chelating ability (C. annuum var. grossum: 43.6%-C. frutescence var. baccatum: 78.7%) when compared with the seed [free radicai scavenging activity (C. annuum var. abbreviatum: 7.7%-C. frutescence var. baccatum: 47.3%); Fe (II) chelating ability (C. annuum var. grossum: 33.7%-C. frutescence var. baccatum: 61.8%)]. However, there was no significant difference in the reducing power of the flesh and seed of the pepper analyzed (except in C. frutescence var. baccatum) where the flesh showed a significantly higher antioxidant capacity. Furthermore, intraperitoneal injection of cyclophosphamide resulted in significant increase (p<0.05) in rat brain Malondialdehyde (MDA) content (147.2%) and serum activities of aspartate aminotransferase (AST)- 32.3UI1L), alanine aminotranferase (ALn - 22.2UIIL, Alkaline phosphatase -40.1UIIL, and Total bilirubin - 1.4mgdL-1 levels. However, pepper diets were able to reduce the brain MDA content in rat brain tissue as well as serum activity of AST, ALT, ALP and total bilirubin content in a dose-dependent manner; with the flesh showing a higher inhibitory effect. The flesh of pepper was therefore observed to be a better protectant of rat brain tissue and hepatocyte from oxidative stress which could have been as a result of its high total phenol content that conferred greater antioxidant capacity. Moreover, C. frutescence var. baccatum showed the greatest antioxidant capacity.