A comparative study of screening and quantitative determination of phytochemical compounds in different parts of the antidiabetic medicinal plant Psidium guajava L. in Sri Lanka

Abstract

The prevalence of diabetes is increasing worldwide, especially in developing countries. Diabetes mellitus, a metabolic disorder and, if long-standing, too late complications leading to a reduced life expectancy. Psidi guajava L. (Myrtaceae) is commonly known as Guavas which are good snacks for diabetic patients due to low calorie and high soluble fibre content. Foods with low glycaemic load and high fibre content are good the control of blood glucose. Guava cultivars and variants abound in Sri Lanka. However, there is a scarcity scientific evidence on guava leaves, bark, fruits, and seeds. The goal of this study was to compare phytochemical properties of ethanolic, methanolic, and aqueous extracts of different parts of the Psi guajava used in the management of diabetes. The different parts as leaves, bark, fruits, and seeds of Psidium guajava were collected, and the identification was authenticated at the National Herbarium, Royal Botanic Gardens Peradeniya. dried each part were powdered and extracted with ethanol, methanol and water using the cold extracti technique separately. Standard methods were followed while screening for phytochemicals. The total content of phenols, flavonoids, tannins and alkaloids was evaluated by the colorimetric method using t spectrophotometer. The findings indicated that the presence of tannins, glycosides, phenols and flavon did not indicate the presence of anthocyanin and carboxylic acid in the ethanolic, methanolic, and aqueous extracts of leaves, bark, fruits, and seeds of this plant. Methanolic leaf extract showed the maximum total phenolic (131.33±0.577 μg/ml) and flavonoid contents (33.20±0.794 μg/ml); ethanolic bark extract w highest tannin content (1150.7±0.871 μg/ml) and the bark showed the highest alkaloid content (296.8 mg/g). Seeds of this plant has lowest phenolic, tannin, flavonoid and alkaloid contents. Based on these findings, leaves and bark of Psidium guajava have higher levels of phenolics, tannins, flavonoids and alkaloids than t fruits and seeds of this plant. Numerous studies reported that guava is the great supplementary for the control and management of diabetes. This study offered a complete assessment of the phytochemic properties of leaves, bark, seeds, and fruits of the Psidium guajava growing in Sri Lanka and this plant can used as a potential basis for the management of diabetes in the traditional system of medicine.