Anticholinesterase and antioxidant activities of foliar extract from a tropical species: Psidium guajava L. (Myrtaceae) grown in Algeria

Guava (Psidium guajava L.) is a fruit tree largely used in folk medicine in tropical and subtropical areas. This exotic species was introduced in a botanical garden in the northeast of Algeria in the 1950’s. The aim of this study is to estimate, for the first time, the antioxidant and anticholinesterase activities of chloroform, ethyl acetate and n-butanol extracts of P. guajava growing in Algeria. Six antioxidant assays were tested, results showed very important efficiency in free radical scavenging, reducing power and β-carotene bleaching of tested extracts. Values of IC₅₀ or A0.5 of some samples were lower than those of standards. With regard to anticholinesterase activity, the inhibitory of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) was investigated. The extracts exhibited interesting capacity to inhibit these enzymes with low values of IC₅₀ and even less than that of galanthamine. These activities were correlated with total phenolic content which was more important compared to the one found in extracts from trees growing in tropical and subtropical region. This could be due to resistance and adaptation of P. guajava grown in Algeria. The data obtained suggest the use of bioactive compounds from P. guajava leaves as antioxidant and drugs for symptomatic treatment of Alzheimer disease.