Effect of sun drying and shade drying on phytochemical constituents and elemental composition of methanolic extract of scent leaves Ocimum gratissimum

Abstract

Ocimum gratissimum is an aromatic plant used as spice in food and for medicinal purposes. There are various processes by which medicinal leaves are prepared for consumption which may affect the phytochemistry of the end product. This study is aimed at investigating the effect of different drying methods (shade-drying and sun-drying). The plant leaves were collected, washed, dried, mashed and sieved. Qualitative analysis using standard procedures and quantitative methods was carried out on the fresh, shade- dried and sun-dried samples for the presence of phytochemicals. Elemental analysis was also carried out on the fresh, shade-dried and sun-dried samples. The compositions of nutrients and the metals present in the medicinal plants were determined using an atomic absorption spectrophotometer (Model PinAAcle 900H, PerkinElmer). In all the samples, flavonoids, saponin, tannins, terpenoids, alkaloids and steroids were present, while anthraquinones were absent. Shade- dried leaves were found to contain significantly higher amounts of flavonoid (380 mg/g), saponin (220 mg/g) and tannins (24 mg/g), compared to the sun- dried sample which contained flavonoids (180 mg/g), saponin (80 mg/g) and tannins (22 mg/g). The elemental analysis showed the presence of Na, Ca, Mg, Fe, Cr, Ni, Mn, Pb, Zn, and Cd in the medicinal plants with some of the values, above the tolerant level, which could be dangerous to health. Drying techniques were found to have a significant impact on the values of the phytochemicals. Shade-drying was found to be the most appropriate method for the preparations of Ocimum gratissimum for high phytochemical constituents that are beneficial to humans on consumption, and the most effective method for preserving the phytochemicals present in medicinal plants.