Guava (Psidium guajava Linn.) stem bark extracts: Toxicity and Free radical scavenging activity
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Date
2014
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Publisher
Academia Arena
Abstract
Free radicals and reactive oxygen species (ROS) are associated with various physiological and pathological situations. They are capable of damaging DNA, proteins, carbohydrates and lipids which are generally in aerobic organisms. Therefore, this study was aimed at determining the lethal dose (LC50) and investigating the effect of solvents of different polarity on free radical scavenging activity of Nigerian specie of Psidium guajava stem bark using UV-Visible Spectrophotometer. The crude methanol extract of P. guajava (CMEPG) stem bark was partitioned using hexane (HEFPG), ethyl acetate (EAFPG), butanol (BUFPG) and water (AQFPG). Free radical scavenging activities of CMEPG and the partitioned extracts were tested on 1, 1-Diphenyl-2-Picrylhydrazyl radical (DPPH) and hydroxyl radical generated from Hydrogen Peroxide (H O ). Their activities were compared with 22 known antioxidant standards; ascorbic acid (ASCAD), butylatedhydroxyanisole (BHA) and alpha-tocopherol (α-TOCO). The highest percentage inhibition was observed in HEFPG (97.39%) and BUFPG (96.50%) at 1.0 mg/ml in the DPPH test. BUFPG also scavenged hydroxyl radical generated from H2O2 better than CMEPG and other extracts. CMEPG had a percentage inhibition of 98.91% which is comparable to α−TOCO having 99.86% inhibition at 0.1 mg/ml. Brine shrimp lethality test was carried out to investigate the toxicity of P. guajava to lower animals and the result revealed that HEFPG was the most toxic with LC50 value of 41.7170 µg/ml while AQFPG with LC50 greater than 1,000 was non-toxic. Thus, Psidium guajava grown in Nigeria is a promising antioxidant agent.
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Keywords
Psidium guajava, polarity, 1, 1-Diphenyl-2-Picrylhydrazyl radical, hydrogen peroxide, Free radicals, toxicity