Qualitative Evaluation of Phytochemical Composition, Antioxidant and Antimicrobial Activities of Extracts of Coral Tree - Erythrina Senegalensis DC

International Journal of Scientific Research in Chemical Engineering, 1(2), pp. 17-23, 2014

Available online at http://www.ijsrpub.com/ijsrce

ISSN: 2345-6787; 2014 IJSRPUB

http://dx.doi.org/10.12983/ijsrce-2014-p0017-0023

17

Full Length Research Paper

Qualitative Evaluation of Phytochemical Composition, Antioxidant and

Antimicrobial Activities of Extracts of Coral Tree - Erythrina Senegalensis DC

Oluremi Isola Adeniran*1, Sunday Felix Abimbade

2

1Department of Chemistry, Faculty of Science, University of Abuja, Nigeria

2Department of Industrial Chemistry, Federal University, Oye Ekiti, Nigeria

*Corresponding Author: [email protected]; Tel: 08027263867

Received 26 March 2014; Accepted 19 May 2014

Abstract. The inability of a majority of world population to afford the cost of modern healthcare is a serious problem that calls for careful research into health promoting components of plants and urgent need to tap from the potentials of their molecular

diversities. This study aimed at investigating some properties of Erythrina senegalensis, a plant with several uses in traditional

medicine. The n-hexane, ethyl acetate and ethanol extracts of each of the leaves, stem bark and root bark of the plant were

investigated for their phytochemical composition, antioxidant properties and antimicrobial potentials on some pathogens. The

phytochemical analysis revealed the presence of some pharmacologically important molecules such as, alkaloids, cardiac

glycosides, flavonoids and steroids in one or more parts of the plant that justify some of its ethno-medicinal applications. All

the extracts of each plant part show considerable antioxidant activity, but, the root bark extracts showed highest activity having

values ranging from 82.8 to 91.5% and 78.9 to 94.6% at the lowest (0.05 mg/ml) and optimum (0.5 mg/ml) concentrations

respectively. The antimicrobial susceptibility test revealed zones of inhibition 9 mm for extracts with activity while the stem bark extracts in its entirety showed no activity. Altogether, the plant has very narrow spectrum of activity.

Keywords: Erythrina senegalensis, qualitative evaluation, antioxidant, antimicrobial, phytochemical

1. INTRODUCTION

The use of plant in Nigeria traditionally for curative

purposes should be a sustained practice due to the fact

that a large majority of her population cannot afford

the cost of modern healthcare. Coupled with this is the

fact that the likelihoods of making new findings

become obvious considering that a single plant may

contain up to thousands of constituents; investigation

of plants thus become necessary for better

understanding of their properties, efficacy and safety

(Banso and Adeyemo, 2007; Nascimento et al., 2000;

Hostettmann et al., 1995). On these notes Erythrina

senegalensis, a plant used in traditional medicine to

cure many diseases but with several of these uses yet

to be scientifically explored, has been chosen for

investigation.

Erythrina senegalensis DC belonging to the family

Fabaceae is a prickly shrub with bright red flowers

(Doughari, 2010; Trease and Evans, 2002). Some of

its common names among some ethnic groups in

Nigeria include coral flower and parrot tree (English),

murjiya (Hausa), echichi (Igbo), and ologun sheshe

(Yoruba) (Blench, 2007; Udem et al., 2009). Erythrina

is a genus of flowering plants containing about 130

species, which are widespread in tropical and

subtropical regions universally (Trease and Evans,

2002). This generic designation probably stems from

the Greek word erythros, meaning "red" and denoting

the flower colour many species have (Saidu et al.,

2000). E. senegalensis is a tree 7-15 m tall. The

flowers, bright red and 4-5 cm in length occur in large

groups at the end of the twigs. The leaves are

composed of three leaflets, each having a surface area

between 20 and 150 cm2 and borne on a thorny stalk.

The fruit comprises a slightly hairy warped pod, 7-15

cm long (Doughari, 2010; Trease and Evans, 2002;

Sofowora, 1993). Coral tree is native to Senegal,

Nigeria, Mali, Liberia, Cameroon and Benin

(Akinpelu and Onakoya, 2006; Sofowora, 1993). It is

a plant that has a large number of traditional medicinal

uses in West Africa including treatment of

amenorrhea, liver disorders, kidney problems, dropsy,

epilepsy, venereal diseases and prevention of abortion

(Burkill, 1985).

Despite its numerous uses, there is, however,

dearth of information on the scientific evidence for

most of the usages of coral tree in traditional

Adeniran and Abimbade

Qualitative Evaluation of Phytochemical Composition, Antioxidant and Antimicrobial Activities of Extracts of Coral

Tree - Erythrina Senegalensis DC

18

medicine. This study therefore aims at investigating

the plants composition, antioxidant and anti-microbial activities with a view to tapping from its

health-promoting abilities for enhancement of human

wellbeing.

2. MATERIALS AND METHODS

2.1. Collection and preparation of samples

Fresh samples of Erythrina senegalensis (Leaves,

stem bark, and root bark) were collected from Sheda,

Kwali Area Council, Federal Capital Territory (FCT),

Abuja, Nigeria. Sample identification and

authentication were carried out at Botany Unit,

Department of Biological Science, University of

Abuja. The samples were washed, air-dried and

ground into powder.

2.2. Extraction of samples

About 500 g of each of the powdered samples was

subjected to gradient extraction with hexane, ethyl

acetate and ethanol successively, in a Soxhlet

extractor. Each extract so obtained was concentrated

using rotatory evaporator followed by evaporation to

dryness on water bath. The dry extracts were stored

for further analysis.

2.3. Phytochemical screening

The extracts were subjected to a blend of

phytochemical tests described by Debela (2002) and

Trease and Evans, (2002). Presence of alkaloids was

confirmed by a reddish-brown precipitate when 0.5 g

of extract is stirred with 5 ml of 1% aqueous HCl on

water bath and then filtered followed by addition of 1

ml of Wagners reagent to 1 ml of the filtrate. Appearance of a pink, red or violet colour in the

ammoniacal phase confirms the presence of free

anthraquinones on addition of 0.5 ml ammonia

solution to the filtrate obtained after shaking 0.2 g of

extract with 10 ml of benzene and filtering. On

dissolution of 0.5 g of extract in 2 ml glacial acetic

acid containing 1 drop of ferric chloride solution

under-laid with 2 ml of concentrated sulphuric acid, a

brown ring formation at the interphase indicates the

presence deoxy-sugar characteristic of cardiac

glycosides. Presence of flavonoids is detected by

decolourization of a yellow solution on addition of

concentrated HCl to a solution of the extract in dilute

NaOH. When 0.5g of the extract was added to 1%

ferric chloride in 50% aqueous methanol, a dirty green

precipitate indicates the presence of phenols. A

reddish precipitate formed when a few drops of 1%

HCl were added to 1ml of extract and boiled indicates

the presence of phlobatannins. Subjection of the

extract to frothing test as a preliminary test and to

haemolysis test for confirmation was carried out for

detection of saponin. When a well shaken mixture of

extract, chloroform and few drops of conc. H2SO4 is

allowed to stand for some time, appearance of red

colour at the lower layer indicates the presence of

steroids. To test for tannins, about 0.5 g of extract was

stirred with 10 ml of distilled water, filtered, and few

drops of 1% ferric chloride solution subsequently

added to 2 ml of the filtrate. The presence of tannins is

indicated by a blue-black, green or blue-green

precipitate. The formation of a turbid brown colour

shows the presence of terpenoids when 2 ml of

benzene was added to 1 ml of extract.

2.4. Determination of antioxidant activity

The free radical scavenging activities of the plant

extracts against 2, 2-diphenyl-1-picryl-hydrazyl

radical (DPPH) were determined according to

methods of Brand-Williams et al. (1995) and Mensor

et al. (2001) with a little modification. Different

concentrations (0.05, 0.1, 0.5, 1.0, 2.0 and 5.0 mg/ml)

of each of the nine extracts were prepared in

methanol. To various concentrations of each of the

test extracts was added 0.5 ml of 1 mM of DPPH. The

resultant mixture was allowed to stand for about 30

minutes in the dark at room temperature after which

the reading of absorbance was taken using UV-Visible

spectrophotometer at 517 nm. Vitamin C was used as

the antioxidant standard (positive control) at

concentrations of 0.05, 0.1, 0.5, 1.0, 2.0 and 5.0

mg/ml while a blank solution was prepared containing

the same amount of methanol and DPPH (negative

control).

Percentage antioxidant activity or percentage

inhibition of the extracts was calculated using the

formula:

Where: Ab = Absorbance of blank (without extract); Aa = Absorbance of test extract

2.5. Test for antimicrobial activity

The isolates (test bacteria) were seeded onto the

nutrient agar plates by swabbing using a sterile cotton

swab for each organism. Disc diffusion method was

used to determine the antibacterial activity of the plant

extracts. The papers were cut into small sizes and

introduced into each sample bottle containing the


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diluted extracts. They were dried at 50oC and used in

determining zone of inhibition. The sterilized discs

incorporated with the extracts were placed on the

nutrient agar plates that were seeded with the test

bacteria and incubated. The set-up was then incubated

for 24 hours at 37oC. The zones of inhibition were

measured.

3. RESULTS

Phytochemical constituents of extracts of E.

senegalensis Percentage Antioxidant Activity of

extracts of coral tree and standard have been shown in

tables 1 and 2. The effect of the hexane, ethyl acetate

and ethanol extracts of E. senegalensis (Leaves, Stem

bark and root bark) on some test bacteria revealed the

following results as shown in Table 3.

Table 1: Phytochemical constituents of extracts of E. senegalensis

Key: + = present; - = absent; Hex = hexane; EtAc = ethyl acetate; EtOH = ethanol

Table 2: Percentage Antioxidant Activity of extracts of coral tree and standard

Key: Hex = Hexane; EtAc = Ethyl acetate; EtOH = Ethanol; Vit. C = Vitamin C Standard.

Table 3: Antimicrobial activity of the Leaves, stem bark and root bark extracts E. senegalensis (Zones of inhibition are shown

in mm)

Key: NI = No inhibition, + = 9 mm, Hex = Hexane, EtAc = Ethyl acetate, EtOH = Ethanol




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4. DISCUSSION

Qualitative phytochemical investigation of the plant

extracts revealed that alkaloids and saponins were

present in all the plant parts leaves, stem bark and root bark- (Table 1). The coexistence of both alkaloid

and saponin in a plant has been reported to be

responsible for the antihypertensive property of such a

plant (Fahey, 2005; Krishnaiah et al., 2009). This

activity is attributed to ability of saponin to prevent

excessive intestinal absorption of cholesterol (Olaleye,

2007; Akinpelu and Onakoya, 2006; Raffauf, 1996).

The presence of anthraquinones and cardiac

glycosides in stem bark and root bark respectively

may be the reason for the use of the plant as a laxative

(Burkill, 1985) and treatment of some heart related

problems (Togola et al., 2005 ). Occurrence of

flavonoids especially in the leaves and root bark of the

plant may be a justification for its use in treatment of

diarrhoea. Schuier et al. (2005), credited the ability of

a plant to treat diarrhoea to the capability of

flavonoids to inhibit the development of fluids that

cause diarrhoea. On the other hand, it has been shown

that cardiac glycosides prevent cardiovascular

diseases by inhibiting the sodium ions-potassium ions

pump thereby increasing the level of sodium ions in

the myocytes, which then leads to a rise in the level of

calcium ions available for contraction of the heart

muscle, consequently improving cardiac output and

reducing heart distension. The antioxidant effect of

the extracts was evaluated on DPPH free radicals with

vitamin C as reference. All the extracts except root

bark hexane (RHex) extract showed dose-dependent

antioxidant activity at lower concentrations (from 0.05

mg/ml to 0.5 mg/ml) and a steady decline in activity at

higher concentrations (from 0.5 mg/ml to 5 mg/ml).

The exact opposite trend was observed for the root

bark hexane extract (Table 2 and Fig. 1).

Fig. 1: Antioxidant Activity of the Extracts of E. senegalensis

Key: LHex = Leaves hexane extract; LEtAc = Leaves ethyl acetate extract; LEtOH = Leaves ethanol extract;

SHex = Stem bark hexane extract; SEtAc = Stem bark ethyl acetate extract; SEtOH = Stem bark ethanol extract; RHex = Root bark hexane extract; REtAc = Root bark ethyl acetate extract; REtOH = Root bark ethanol extract.

Previous reports on the antioxidant activity of this

plant (Atsamo et al., 2013; Njayou et al., 2010;

Donfack et al., 2008) are mostly on the stem bark

extracts; the present study is about the first to report

the antioxidant activity of the root bark of the plant.

Although each of the extracts showed appreciable

antioxidant activity, the root bark extracts in general

compare favourably with the reference and the root

bark ethyl acetate (REtAc) extract in particular

exhibited activity (ranging from 91.0 to 94.6%) in

high proximity with the standard used (in the range

96.9 to 98.4%). It is obvious from the foregoing

evidence that these extracts have potentials of serving

as substitute for known standard antioxidants such as

ascorbic acid (Vitamin C).

The entire stem bark extracts as well as the leaf

hexane extract and root bark ethyl acetate extracts

showed no antimicrobial activity against the test

organisms and where there is activity the zone of

inhibition is less than 9 mm (Table 3). The ethyl

acetate extract of the leaf showed a weak activity

against only Proteus species while the ethanol extract

of the same was active against Proteus spp and S.

aureus. Similarly ethyl acetate extract of the root bark

showed activity against S. aureus and B. subtilis while

its ethanol extract inhibits S. aureus, B. subtilis and

Proteus spp. It could be inferred from the assessment


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of the antibacterial activity using the parameters

proposed by Alves et al. (2000) where zones of

inhibition are rated as: < 9 mm (inactive); 9 - 12 mm

(less active); 13 - 18 mm (active) and > 18 mm (very

active) that the extracts that even showed a weak

activity are inactive. In comparison with report by

Doughari (2010) this result showed that the plant does

not have a broad spectrum of activity. This narrow

spectrum of activity may be suggestive of the fact that

there is a synergistc effect of the phytoconstituents of

the extract obtained by extracting the plant material

with a polar solvent instead of successive extraction

with solvents of varying polarity.

5. CONCLUSION

The result of this study clearly revealed that the

antioxidant activity of the root bark of coral tree

compares favourably with that of the reference

(Vitamin C) used and it holds promise for future

application as a natural substitute to the hitherto

available standard but expensive antioxidants. This

finding is one too significant to be ignored and

evidence previously unobtainable being the first report

on the antioxidant activity of the root bark of the

plant. However, toxicological investigations for

ascertaining the clinical safety and therapeutic dose of

the plant extracts should be carried out.

ACKNOWLEDGEMENTS

The authors acknowledge Messrs Elkanah Daniel and

Salihu E. Yunusa for their assistance in the study.

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Adeniran Oluremi Isola Lectures at the Department of Chemistry, Faculty of Science, University of

Abuja, Nigeria. Adeniran holds an M. Sc. Degree in Organic Chemistry from the University of

Ibadan. He has a burgeoning research prospect in Natural Products/Medicinal Plants and has

published some scientific articles in the field. He has also served in the capacity of Course

Writer/Developer in the course team for Natural Products Chemistry of a certain institution.

ABIMBADE, Sunday Felix obtained his B.Tech degree in Pure and Applied Chemistry from Ladoke

Akintola University of Technology (LAUTECH), Nigeria in 2006. He also holds an M.Sc. degree in

Organic Chemistry from the University of Ibadan. Currently, he is running his PhD programme in the

University of Ibadan and he is a Lecturer in Federal University, Oye Ekiti. He has to his credit some

published scientific articles in reputable local and international journals. His research focus has been

on Natural Products Chemistry but recently, he added synthesis of medicinal natural products to his

research career.

Documents

Qualitative Evaluation of Phytochemical Composition, Antioxidant and Antimicrobial Activities of Extracts of Coral Tree - Erythrina Senegalensis DC