Article Number: DRJBB26459844

DOI: https://doi.org/10.26765/DRJBB26459844

ISSN: 2734-2158

Vol. 7 (1), pp. 1-7, January 2021

Copyright © 2021

Author(s) retain the copyright of this article


Original Research Article

Phytochemical, Antimicrobial and GC-MS Analysis of the Bark Extracts and Fresh Leaves Hydro-distillate of Piliostigma Thonningii (Caesalpiniaceae)

*Okwute, S. K.

Hammed, A.

Echoga, E. O.


Abstract

The plant Piliostigma thonningii (Caesalpiniaceae) is used in ethnomedicine for the treatment of a number of infections. In this work, the root and stem barks and the fresh leaves were investigated for antimicrobial activity and chemical constituents to confirm the traditional medicinal uses of the plant. The root and stem barks were separately subjected to extraction to obtain the crude methanol extracts, while the fresh leaves were hydro-distilled to obtain the volatile oils. The crude methanolic extract each was fractionated to obtain fractions; the hexane, chloroform, and 50% methanol-chloroform. Phytochemical screening of the two crude methanolic extracts showed that the stem bark extract contained most of the common phytochemicals such as saponins, terpenoids, glycosides, flavonoids, tannins, steroids, alkaloids, and carbohydrates, but the root-bark extract lacked terpenoids, flavonoids, steroids, and carbohydrates. The two crude extracts and their fractions were subjected to antimicrobial screening against some pathogens. The root-bark extracts generally did not exhibit reasonable activity (MICs=6.25mg/ml-50mg/ml) compared to the stem-bark extracts (MIC=500µg/ml-2000µg/ml). Also, for each of the extracts, the 50% chloroform/methanol fraction was the most active against the test organisms. The most active fraction, 50% chloroform/methanol of each extract, was subjected to GC-MS analysis which showed that the stem-bark extract had more volatile components (29) than the root-bark (17) at 0.5% and above. Also, for both extracts, the volatiles were mostly long-chain hydrocarbons, fatty acids, and derivatives (amides, esters, ketones, alcohols, and aldehydes) and phthalates. Of significance structurally, though in small quantity was 4-phenylbut-3-ene-1-yne in the root-bark extract. The fresh leaves of Piliostigma thonningii were subjected to hydro-distillation to obtain the volatile yellowish oil which was subjected to GC-MS to identify the chemical constituents. The gas-chromatogram showed 9 major components, including, 6-methyl-5-heptene-2-one, myrcene, linalool, carveol, trans-citral, cis-citral, cyclopropane methanol,2-methyl-2-(4-methyl-3-pentyl),6,10-dodecadien-1-yn-3-oland3,7,11-trimethyl-1,6,10-dodecatriene,7,11 dimethyl-3-methylene. Of great significance was the presence of citrals which constituted about 83% of the volatiles of the fresh leaves. Some of the above phytochemicals may be responsible for the traditional medicinal uses of the plant and therefore validate the ethnomedicinal uses of the plant in the management of microbial infections. Also, the high percentage of the citrals has shown that Piliostigma fresh leaves provide a new source of citrals which are important in the perfumery industry.


Keywords: Piliostigma thonningii, root bark, antimicrobial activity, chemical constituents, leaves, hydro-distillate, GC-MS, volatile components


 Received: December 16, 2020  Accepted: January 12, 2021  Published: January 30, 2021

Okwute Et Al


Copyright © 2021 Direct Research Journal of Biology and Biotechnology