Abstract

ESSENTIAL OILS CONSTITUENTS, PHYTOCHEMICAL ANALYSES, AND ANTIMICROBIAL STUDIES ON LEAF AND STEM OF THUNBERGIA LAEVIS NEES

*Olaoluwa Omosalewa Olaoluwa, Dorcas Olufunke Moronkola Sichilongo Kwenga, Okwu Mgbeoji

ABSTRACT

Essential oils of leaf and stem of Thunbergia laevis were obtained by Clevenger-type apparatus, their chemical constituents were analyzed using gas chromatography [GC] and gas chromatography-mass spectrometry [GC-MS]. Hexane and ethanol extracts from leaf and stem of Thunbergia laevis were obtained by cold extraction and screened for phytochemical constituents. Antimicrobial activities of these oils, hexane and ethanol extracts were carried out against six bacteria and four fungi. Forty-six compounds identified in leaf oil account for 62.58% of it, dominated by phytol (4.10%) and i-Propyl hexadecanoate (3.19%); ten compounds in stem oil represent 62.40% of it, with most abundant methoxyl-phenyl-oxime (23.45%) and Z-11- hexadecenoic acid (12.28%). Leaf oil mostly contains hydrocarbons and esters, while stem oil have aromatic derivatives and acids. Antimicrobial studies of leaf oil caused strong inhibition in growth of Staphylococcus aureus and Candida albicans at concentration between 25 – 100% with the zone of inhibition ranging between 20 -28 mm and 14 – 18 mm respectively. Stem oil was most active on Candida albicans and Asprgillus niger at the same concentration with zone of inhibition of 14 - 18 mm and 12 – 18 mm respectively. Alkaloids, tannins, saponins, resins, phenols and terpenoids were observed in leaf and stem ethanol extracts. Leaf ethanol extract was most active on Staphylococcus aureus, Candida albicans and Rhizopus stolonifer. Stem ethanol extract moderately inhibited growth of these microorganisms. This study is on Thunbergia laevis leaf and stem essential oils constituents, phytochemical and antimicrobial analyses, which have not been earlier reported in literature

Keywords: Essential oil, Phytochemicals, Antimicrobial, Thunbergia Laevis, Acanthaceae.