PHYTOCHEMICAL INVESTIGATION AND ANTIMICROBIAL STUDY OF LEAF EXTRACT OF Plantago lanceolata

Abstract

Leaves of Plantago lanceolata were traditionally used to treat wounds, burns, inflammations, fevers, diabetes and cancer. The present study was carried out on the phytochemical investigation and antimicrobial activities of the leaves extract of Plantago lanceolata since the plant was used for wound healing in Ethiopia. The powdered leaves of Plantago lanceolata herb was sequentially extracted with organic solvents: petroleum ether, chloroform/methanol (1:1) and methanol, respectively. The crude extracts were subjected to phytochemical screening and revealed the presence of steroids, alkaloids, flavonoids, saponins, glycosides, phenols, tannins and terpenoids that might be responsible for the claimed activities by local people. The petroleum ether extract was subjected to silica gel preparative thin layer chromatography to yield compound PL-5. The structure of this compound was elucidated using different spectroscopic techniques such as FT-IR, 1 H-NMR, 13C-NMR and DEPT-135 and also by comparing the data with literature reports. The n-hexane extracted oil was investigated by GC-MS and showed the presence of 26 compounds. Among which, the major constituents of leaf oil were 9-Octadecenoic acid (24.20%) and hexadecanoic acid (23.65%). The crude extracts, isolated pure compound and n-hexane extracted oil were tested against four bacterial species (Gram negative bacteria: Escherichia coli and Salmonela thyphei; Gram positive bacteria: Staphylococcus aureus and Streptococcus agalactiae) and two fungal species (Aspergillus niger and Fusarium solani) using paper disc diffusion method. All crude extracts, isolated pure compounds and extracted oil were active against all the tested bacterial species. Additionally petroleum ether and chloroform/methanol (1:1) crude extracts and nhexane extracted oil were active against the two fungal species and hence the present work may support the medicinal use of plantago lanceolata.