Study of ethnobotany and phytochemistry of Pavetta crassipes leaves and Calotropis procera bark from Malawi.

This study aims to analyse the phytochemistry of two medicinal plants locally
used by herbalists Pavetta crassipes leaves and Calotropis procera bark from
Malawi. The specific objectives of the study are: To extract Pavetta crassipes
leaves and Calotropis procera bark using 80% methanol and 100% methanol
respectively. To isolate compounds using open column and medium pressure
liquid chromatography. To elucidate the structures of isolated pure compounds
using nuclear magnetic resonance spectral techniques.
The research design was an experimental method. The dried Pavetta crassipes
leaves (2900g) and Calotropis procera bark (4500g) was extracted with 3L 80%
methanol and 100% MeOH respectively, at room temperature after 72 hours.
Using various column chromatographical techniques each of the extracts was
isolated to get the pure compounds. The isolated pure compounds were
elucidated and characterized using Proton Nuclear magnetic Resonance
Spectrum (1H NMR), Carbon Nuclear Magnetic Resonance (13C NMR),
Heteronuclear Multiple Bond Coherence (HMBC), Heteronuclear Single
Quantum Coherence (HSQC), Distortionless Enhancement via Polarization
Transfer (DEPT), Nuclear Overhauser Effect Spectroscopy (NOESY) and
Correlation Spectroscopy (COSY). The elucidation of pure compounds from
Pavetta classipes yielded flavonoid Quercetin-3-O-rutinoside (1), Chlorogenic
acid (2) and Methyl chlorogenate (3) and Calotropis procera yielded
taraxasteryl acetate (4) and calactin (5).