STUDIES OF SOME PHYTOCHEMICAL AND CYTOTOXIC PRINCIPLES OF LEAVES AND SEEDS EXTRACTS O F Crotalaria retusa L.
STUDIES OF SOME PHYTOCHEMICAL AND CYTOTOXIC PRINCIPLES OF LEAVES AND SEEDS EXTRACTS O F Crotalaria retusa L.
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Date
1999-05
Authors
AMAKO, NGIZI FRANCESCA
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Abstract
The leases and seeds of Nigerian Crotalaria retusa L. were extracted using
different solvents 95% Ethanol was found to extract the largest amount of materials
Specific methods of isolation of pyrrolizidine alkaloids (past) showed that the seeds have
higher alkaloidal content than the leaves.
Qualitative chemical tests for various classes of natural products were carried out
on ethanolic as well as water extracts of leaves and seeds using standard phylochemical
methods These tests revealed the presence of alkaloids, tannins, cardiac glycosides,
flavonoids and saponins in ethanolic leaves and seeds extracts Water extracts of seeds
and leaves were devoid of alkaloids.
Specific chemical analytical test for past was carried out on fresh plant parts
(seeds, leaves, flowers, roots) The seeds, leaves and flowers of C. relusa contain past and
PA-N-oxides. Flowers are particularly rich in these alkaloids The roots are devoid of
past but have PA-N-oxide, which is apparently reported for the first time
The crude mixture of past extracted from leaves was purified by crystallization
and cleaning-up methods However the crystallization method produced a purer
component than cleaning-up method.
The active extracts were categorised into two broad groups for thin-layer
chromatography (TLC), based on the nature of the extracts and suitable solvent systems
employed. The TLC of ethanolic leaves extract, CAPL1 and ethanolic seeds extract,
CAPS1 when viewed under ultraviolet light (366nm) and visible light (254nm) each
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produced four spots CAPL1 Rf values (0.32, 0.53, 0.66 and 0.90) while CAPS1 RF values
(0.1 I. 0.25, 0.32 and 0.49). The trichloromethane leaves extract, CAPL2. produced five
spots whose RF. values arc 0.20, 0.71, 0.86, 0.93 and 0.96, when the same solvent system
was used.
The TLC of the crude mixture of past from leaves CAPL, and seeds CAPS, as
well as cleaned-up sample of past. CCAPL1, and crystals from crude mixture of past.
CCAPL3 were carried out using three different solvent systems The RF values of the
components of these samples varied slightly with the solvent systems uses and compared
with the RF values from literature. When chromatograms containing the aforementioned
samples were sprayed with visualizing reagents they revealed the present of past and
PA-N-oxides.
Preparative TLC was used to isolate components of CAPL1 and CAPL2, three
fractions and four fractions were obtained respectively The chromatograms containing
these fractions gave positive response for phenolic compounds, steroid glycosides and
flavonoids when sprayed with visualizing reagents The fractions obtained from CAPL1
and CAPL2 were available in very small quantities hence they were not used for
spectroscopic studies.
The leaves and seeds extracts obtained using different solvents were tested for
presence or absence of active principles using Brine Shrimp Lethality Bioassay. The LC50
values of the extracts, which are reported in this work for the first time, confirmed the
toxicity of C. retusa. It also revealed that the most active principle responsible for the
cytotoxicity of C. retusa are PAs.
The antimicrobial screening test of the extracts showed that crude mixtures past,
CAPL and CAPS as well as cleaned-up sample and crystals from CAPL. have significant
antifungal anf antibacterial activities against Candidas albicans and Pseudomonas
aeruginosa. However the trichloromethane leaves extract exhibited selective inhibitory
properties against some gram negative organisms such as Pseudomonas aeruginosa and
Escherichia coli.
The spectroscopic techniques such as Infrared and Ultraviolet-visible were used to
identify the functional groups present in the active extracts. These studies revealed the
presence of carbonyl and hydroxyl groups in CAPL.CAPS. CCAPL3. and CAPL2
samples. The ultraviolet-visible spectroscopy particularly showed the presence of
conjugated systems in CAPL2. The nuclear magnetic resonance spectroscopy confirmed
the presence of past in CAPL.
Description
A THESIS SUBMITTED TO THE POSTGRADUA'I E SCHOOL, AHMADU BEELO
UNIVERSITY, ZAR1A IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
AWARD OF MASTER OF SCIENCE ORGANIC CHIEMISTRY
DEPARTMENT OF CHEMISTRY
AHMADU BELLO UNIVERSITY
ZARIA
MAY. 1999
Keywords
STUDIES,, PHYTOCHEMICAL, CYTOTOXIC,, PRINCIPLES, LEAVES,, SEEDS,, EXTRACTS,, Crotalaria,, retusa L.