COMPARATIVE PHYTOCHEMICAL ANALYSES OF METHANOLIC AND AQUEOUS LEAF EXTRACTS OF THREE MEDICINAL PLANTS USED IN PLANT DISEASE CONTROL, A RESEARCH PROJECT TOPIC ON PLANT SCIENCE
Investigations were conducted to determine the qualitative and quantitative phytohemical properties of methanolic and aqueous leaf extracts of Chromolaena odorata L., Carica papaya L., and Ocimum gratissimum L. using standard methods. The results revealed thatalkaloids, saponins, flavonoids, glycosides, reducing sugars, carbohydrates, steroids, tannins and terpenoids were present in all the test plants. However, methanolic leaf extract of C. odorata had the highest amounts of saponins, flavonoids and steroids and lowest tannins content. Carica papaya had highest content of alkaloids, carbohydrates and terpenoids and lowest content of glycosides, reducing sugars and steroids, while O. gratissimum had highest composition of glycosides, reducing sugars and tannins and lowest composition of alkaloids, saponins, flavonoids, carbohydrates and terpenoids. Comparisons on the aqueous leaf extracts of the test plants showed that C. odorata had the highest composition of glycosides and tannins and lowest composition of saponins, flavonoids and steroids. Carica papaya had the highest amounts of flavonoids and terpenoids and lowest composition of alkaloids, glycosides, carbohydrates and tannins, while O. gratissimum had the highest contents of alkaloids, saponins, reducing sugars, carbohydrates and steroids, and lowest composition of terpenoids. The compositions of the leaf extracts were significantly different at P ≤ 0.05. The significance of the test p lants and the importance of these phytochemicals were discussed with respect to the roles they play in plant disease control.
A large number of chemicals have been developed for the control of plant diseases, but due to the growing awareness of the hazardous side effects of these chemicals, more emphasis is given to the use of biocontrol agents. One of the major challenges in the field of Plant Pathology is the need for some ecofriendly and safe alternative control strategies for agriculture, which has led researchers to turn their attention to plant extracts as sources of biocontrol agents. Therefore, growing of most plants and tress now goes beyond afforestation purposes to making them available and accessible for exploitation for their natural chemical composition vis-à-vis their usefulness in the management and cure of both plant and animal diseases. These chemical compounds, known also as phytochemicals, provide defenses for the plants against diseases and other environmental factors. It is now evident that most of these plant chemicals could also be helpful in the treatment of both animal and human diseases.