PHYTOCHEMICAL INVESTIGATION OF THE FLAVONOIDS FROM PISTACIA LENTISCUS, JUNIPERUS PHOENICEA AND CUPRESSUS SEMPERVIRENS

Abstract

In the present study, three Libyan medicinal plants Juniperus phoenicea, Pistacia lentiscus and Cupressus sempervirens were investigated for their chemical constituents. Studies were conducted to determine the active chemical constituents of alcoholic extracts by way of phytochemistry and to evaluate its in vitro antimicrobial activity, using the disc diffusion technique as described by the National Committee of Clinical Laboratory Standard (1993). Using standard phytochemical analysis procedures, results revealed the presence of flavonoids and tannins in all the plants. Alkaloids, terpenoid and saponins were not detected in Pistacia lentiscus. Steriods and saponins were absent in Juniperus phoenicea. Only Cupressus sempervirens showed the presence of saponins. The alcoholic extracts of all plants produced a dose dependent zone of inhibition in all the organisms tested (Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae). However, the effects observed were less than those produced by the standard agent (Amoxcillin). Due to their medicinal value and relative abundance, it was decided to investigate the flavonoids from these plants. The present investigation has led to the isolation of five flavonoids (1-5) from an ethanol extract prepared from the leaves, barks and roots of Juniperus phoenicea, Pistacia lentiscus and Cupressus sempervirens by preparative thin-layer chromatography technique. Their structures were determined through a combination of spectrometric techniques including 1D and 2D NMR and high-resolution electrospray mass spectrometry to be 2’,4’,4-trihydroxy-6’-methoxy-3’-prenyl chalcone (1), 1-[2,4-dihydroxy-3-(2,3-dihydroxy-3-methylbutyl)-6-methoxyphenyl]-3-(4-hydroxyphenyl)-2-propen-1-one (2), 1-(3,4-dihydro-3,5,7-trihydroxy-2,2-dimethyl-2H-1-benzopyran- 6-yl)-3-(4-hydroxyphenyl)-2-propen-1-one (3), 1-[2,4-dihydroxy-3-(2-hydroxy-3-methyl-3-butenyl)-6-methoxyphenyl]-3-(4-hydroxyphenyl)-2-propen-1-one (4) and 6-prenylnaringenin (5).

However, the effects observed were less than those produced by the standard agent (Amoxcillin). Due to their medicinal value and relative abundance, it was decided to investigate the flavonoids from these plants.