Browsing by Author "Oloyede, Ganiyat Kehinde"
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Item CHEMICAL COMPOSITION, TOXICITY AND ANTIOXIDANT ACTIVITIES OF ESSENTIAL OILS OF STEM BARK OF NIGERIAN SPECIES OF GUAVA (PSIDIUM GUAJAVA LINN.)(EXCLI Journal, 2011-03-21) Fasola, Remi Taiye; Oloyede, Ganiyat Kehinde; Aponjolosun, Babalola SundayEssential oil from the stem bark of Nigerian species of Psidium guajava of the family Myrta- ceae was obtained by hydro-distillation using an all-glass Clavenger apparatus. GC and GC/MS analysis were carried out on the essential oil and was found to contain 62 compounds constituting 99.98 % of the total oil composition. The principal constituents are hydrocarbons, amines, amides and esters with 3,6-dioxa-2,4,5,7-tetraoctane,2,2,4,4,5,5,7,7-octamethyl (11.67 %) and cyclononane (10.66 %) dominating the total essential oil. Brine shrimp lethal- ity test was carried out to determine the toxicity of the oils to living organisms (shrimps). LC50 value (µg/ml) of 1.0009 obtained showed that the essential oil of P. guajava stem bark was toxic. The antioxidant property of essential oil was investigated by measuring the de- crease in absorption at 517 nm of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) in a UV/visible spectrophotometer. The oil showed better activity as a radical scavenger than α- tocopherol. The oil activity was 71.83 % at 0.2 mg/ml and the absorption is stoichiometric with respect to the number of electron taken up. Thus, the results of this study showed that the essential oil from P. guajava was not only toxic; it possessed antioxidant activity, which could exert beneficial actions against pathological alterations caused by the presence of highly reactive free radicals. The toxicity of the oil can be taken advantage of in the therapy of dis- eases involving cell or tumor growth.Item Guava (Psidium guajava Linn.) stem bark extracts: Toxicity and Free radical scavenging activity(Academia Arena, 2014) Fasola, Taiye Remi; Oloyede, Ganiyat Kehinde; Aponjolosun, Babalola SundayFree 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.