Phytochemical and Biological Study on Schotia brachypetalae Family Leguminosae (Fabaceae)

Abstract

Polyphenols, a large class of chemicals which are found in plants, have attracted much attention in the last decades due to their properties and the hope that they will show beneficial health effects. So, in the present thesis particular emphasis has been focused on the constitutive phenolics of the extract of a phenolic rich plant, namely, Schotia brachypetala Sond. Family Leguminosae (Fabaceae).

The present study was divided into three parts:

Chapter I: Phytochemical investigation of the methanolic leaf extract

Schotia brachypetala Sond.

Chapter II: Biological investigation of the methanolic leaf extract of

Schotia brachypetala Sond.

Chapter III: Standardization of the methanolic leaf extract of Schotia brachypetala Sond.

Chapter I: Phytochemical investigation of the methanolic leaf extract of Schotia brachypetala Sond.

The phytochemical study of Schotia brachypetala Sond. included successive column chromatographic fractionation of the methanolic leaf extract, separation of individual phenolics, repeated purification of these individuals and establishment of their purity by paper chromatography.

For the structure elucidation of the isolated phenolics, the required structural information was obtained through chromatographic analysis, application of conventional spectroscopic techniques of analysis as well as nuclear magnetic resonance spectroscopic analytical techniques were applied in this thesis, either to unravel the chemical structure of the isolated natural phenolics, to clarify the full structure of some of the known phenolics or to report spectral data for some others.

As a result of this study, three phenolic constituents were individually isolated and identified for the first time from Genus Schotia namely:

Compound (1) Gallic acid

Compound (2) Myricetin-3-O-α-L-1C4-rhamnoside

Compound (3) Quercetin-3-O-L-1C4-rhamnoside

Also, the total phenolic content of the methanolic leaf extract of Schotia brachypetala Sond. was determined using the Folin-Ciocalteu method which was calculated as 376 mg of caffeic acid equivalents (CAE) per g of the extract while the total flavonoid content was determined using aluminum chloride colorimetric method and was calculated as 67.87 mg in one g extract quercetin equivalent (QE).

The methanolic leaf extract of Schotia brachypetala Sond., fraction (III), fraction (IV) and subfractions F1 and F2 were subjected to LC/ESI/MSn to identify (46) Compounds together with their isomers for the first time from the leaves of Schotia brachypetala Sond.

The following classes were identified:

Flavonoid glycosides, galloylated flavonoid glycosides, anthocyanins, hydroxybenzoic acid derivative, isoflavones, procyanidins, hydrolysable tannin, dihydrochalcone, gallotannin, methyl and acetyl flavonoid glycosides, methylflavone, flavanols and flavonols.

Chapter II: Biological investigation of the methanolic leaf extract of Schotia brachypetala Sond.

The biological study for the methanolic leaf extract of Schotia brachypetala Sond. had been divided into:

A) Anti-inflammatory activity against indomethacin. The extract showed significant amelioration of induced edema in different in-vivo models (carrageenan-induced rat paw edema model and croton oil induced rat ear edema model) at the tested concentrations showing promising anti-inflammatory capacity that was dose dependant and in a linear relationship. Its LD50 value was shown to be unclassified (safe). The histopathological examination confirmed the anti-inflammatory activity of the in-vivo models.

B) Anti-oxidant activity using both in-vitro and in-vivo models. Three in-vitro models (DPPH͘, TEAC persulfate decolorizing kinetic and FRAP assays) and four in-vivo models (survival assay under juglone-induced oxidative stress, intracellular ROS in Caenorhabditis elegans by DCF assay, quantification of hsp-16.2::GFP expression via flourescence microscopy and sub-cellular DAF-16 localization) were applied. The extract showed interesting anti-oxidant activity in both in-vitro and in-vivo models.

Chapter III: Standardization of the methanolic leaf extract of Schotia brachypetala Sond.

The crude methanolic leaf extract of Schotia brachypetala Sond. was standardized using gallic acid authentic. The method was accurate, precise and reproducible and the calibration curve was linear in the used concentration. Gallic acid content was calculated as 206mg per one gram of the extract.