Study on the Phytochemical and Antimicrobial Screening of Ethylacetate Extract of Plumeria
Rubra Leaves and Stems Bark
Bawa Emmanuel, Kagoro Mary L and Wapwera Jidimma A*
1Department of Chemistry, University of Jos, Nigeria
Submission:April 19, 2019; Published: May 21, 2019
*Corresponding author: Wapwera Jidimma A, Department of Chemistry, University of Jos, Jos, Nigeria
How to cite this article: Bawa Emmanuel, Kagoro Mary L, Wapwera Jidimma A. Study on the Phytochemical and Antimicrobial Screening of Ethylacetate
Extract of Plumeria Rubra Leaves and Stems Bark. Agri Res& Tech: Open Access J. 2019; 21(4): 556170. DOI: 10.19080/ARTOAJ.2019.21.556170
Plumeria rubra leaves and stems bark was extracted using ethyl acetate by maceration process of solvent extraction. The leaves and bark were screened for phytochemicals, antifungal and antibacterial activity. The leaves and bark extract showed the presence of tannins, alkaloids, balsam, cardiac glycosides, phenols, terpenes and steroids. The extract indicates the absence of flavonoids, saponins and resins. The bark extract showed the presence of alkaloids, cardiac glycosides, resins, terpenes and steroids; absence of flavonoids, tannins, saponins and balsam. The zones of inhibition ranges from 10-28mm and the plant extracts showed a broad spectrum of antimicrobial activity against gram positive and gram-negative bacteria. It was more pronounced on gram negative bacteria especially Proteus mirabilis. Furthermore, the ethyl acetate crude extract was effective against Pseudomonas aeruginosa which is usually resistant to most antimicrobial agents. The extracts were also effective against the fungi Candida albicans
Medicinal plants have been used for centuries as remedies for human diseases; they contain components of therapeutic value . Researches into biologically active compounds from natural sources have always been of great interest for scientist looking for new sources of drugs against infectious diseases. It is an undisputable fact that the western pharmaceuticals have their origin in plants .
The use of herbs in the treatment of man and animal diseases has been practiced before the advent of antibiotics. In England, Digatalis purpurea L. has been used for centuries as an effective treatment for dropsy a condition in which the in efficient working of the heart leads to retention of fluids and general swelling of the body.
In South America, the decoction of the leaves of Mango tree is used as oral contraceptive abortifacient . In Taiwan Waltheria indica has recently been reported to be effective in the treatment of inflammatory diseases. Recently, a list of plants that people of Kenya and Tanzania use as remedies to treat infections and wounds that have not been studied extensively were compiled for an ethno botanical research project . The root and bark of Zambia’s Africana hiern is popular remedy for various skin diseases in Tanzania . The few examples described above
point towards the need for continual research into plants used in traditional medicine worldwide especially in countries where folk knowledge is still available.
An antimicrobial is a substance that kills or inhibits the growth of microbes such as bacteria, fungi, protozoa, virus etc. Antimicrobial drugs have different mode of actions. Antimicrobial drugs which kill the microbes is said to be microbiocidal and that which prevents the growth of microbes is said to be microbiostatic. The main classes of antimicrobial include antibiotic drugs, antiviral drug, antifungal drugs, antiparasitics and non-pharmaceutical antimicrobials.
Phytochemicals are chemical compounds that occur naturally in plants. The term is generally used to refer to those chemicals that may affect health but are not established as essential nutrients. Phytochemicals have been used for drug for millennia e.g. Hippocrates may have prescribed willow tree leaves to abate fever. They are bioactive agent found in plants. Phytochemicals include flavonoids, resins, phenols, steroids, alkaloids, cardiac glycosides, tannins etc.
Aim: The aim of this research is to determine the phytochemical
and antimicrobial activity of Plumeria rubra leaves and stem bark.
Objectives of the study: The objectives of the research
a. Extracting the leaves and stem bark of Plumeria rubra
leaves and stem bark using ethyl acetate as the solvent.
b. Determining the phytochemicals present in the leaves
and stem bark.
c. Determining the antimicrobial activity of the plant
against gram positive and gram-negative microorganism.
The leaves and stems bark of Plumeria rubra were collected
and dried at room temperature (25˚C). The dried leaves and
stems bark were pulverized using a mortar and pestle and sieved
using a mesh. The leaves (80.5g) and stems bark (96.30g) were
respectively extracted in 250mL of ethyl acetate in a conical flask
for 50 hours and filtered using a whatsman filter paper. The crude
extract of leaves and stems bark were concentrated in a rotary
evaporator after which they are evaporated to dryness on a hot
The general standard methods for detecting and determining
an invitro antibiotic activity include:
a. Plate diffusion test.
b. Serial diffusion test.
c. Streak test.
The analysis carried out include the preliminary sensitivity
testing, determination of minimum inhibitory concentration
(MIC), determination of the minimum bactericidal concentration
(MBC) and the determination of the minimum lethal concentration
The phytochemical screening was done using organic solvent
and carried out using standard operating procedures adopted
from Trease & Evans . The tests carried out are the Wagner test
for alkaloids, Ferric chloride test for flavonoids, Solkowski test for
cardiac glycosides, Liebermann-Burchard test for terpenes and
steroids, general tests for saponins, phenols, resins and balsam.
Bulk extraction: The bulk extraction of the leaves and stems
bark using ethyl acetate obtains a yield of 2.34g for the leaves and
2.08g for the stems bark. The percentage yield was 2.90% for the
leaves and 2.10% for the stems bark respectively.
Antibacterial activitySensitivity test: Table 1 & 2.
Anti-fungal activity: (Table 3 & 4)
Result of minimum inhibitory concentration (MIC): Table
Results of minimum bactericidal concentration (MBC):
Table 9 & 10.
Key: - = Complete inhibition; + = Growth.
Results of minimum lethal concentration (MLC):Table 11
Solubility of each constituent in a plant is very specific to
different solvents in the extraction process. Hence, chemical
nature as well as the pharmacological activity of herbal extracts
obtained using same herb with different solvents will differ .
The result of the phytochemical screening showed the presence
of alkaloids, tannins, balsam, cardiac glycosides, terpenes and
steroids, phenols and absence of flavonoids, saponins and phenols
in the leaves extract. The bark extract showed the presence of alkaloids, cardiac glycosides, terpenes and steroids, resins and
absence of flavonoids, tannins, saponins, balsam and phenols. This
reveals the presence of tannins which could be responsible for
the antibacterial activity of the plant . The terpenoids reveals
the reason the plant is widely used in herbal medicine . Since
the plant extract contains other constituents, such as alkaloids as
revealed by the phytochemical screening in Table 13, the actual
content of tannins which possess the antibacterial activity in the
concentration used might not be much. If the tannins constituents
of this plant are isolated and tested, there may be a resultant
increase in antibacterial activity of the plant extract . The plant
extract containing chemical such as tannins with the antibacterial
properties have been useful in treating bacterial and fungal
The results of the antibacterial activity showed that the
leaves and bark of the plant Plumeria rubra extracted with the
solvent ethyl acetate posses’ antibacterial activity as indicated
in the zones of inhibition (Table 1-4). Staphylococcus aureus
had the zone of inhibition of 27mm and ranged from 10.0mm -
27.0mm at concentrations of 25mg/mL - 100mg/mL for the leaves
extract. From Table 1, the zones of inhibition of Staphylococcus
aureus and Proteus mirabilis were equal to that of the positive
control, gentamicin. From Table 2, the bark of the plant had more
antibacterial activity on Proteus mirabilis with the highest zone
of inhibition of 28.0mm and ranged from 24mm - 28mm with the
concentration range of 25mg/mL - 100mg/mL. Interestingly, the
zone of inhibition for Proteus mirabilis at 100mg/mL of the extract
was greater than that of gentamicin. Pseudomonas aeruginosa had
the least zone of inhibition at 100mg/mL for both leaves and bark
which were 23.0mm and 18.0mm respectively.
Furthermore, from the dermatophytes, only Candida albicans
showed appreciable activity against the plant extract, it had a
significant zone of inhibition of 25.0mm and 14.0mm at 100mg/
mL for the leaves and stems bark respectively. A point of note from
Table 3 & 4 was that the plant extract was not effective against
Aspergillus flavus. The growth of Protus mirabilis was inhibited at
25mg/mL, 50mg/mL and 100mg/mL. Staphylococcus aureus and
Pseudomonas aeruginosa were inhibited in the broth at 50mg/mL
and 100mg/mL for the leaves and stems bark extracts as seen in
Table 5 & 6 respectively. In addition, from Table 7 & 8, growth was
inhibited at 50mg/mL and 100mg/mL for the leaves extract while
it was inhibited at 100mg/mL only for the stems bark.
The result of the minimum bactericidal concentration showed
that the leaves and bark were bactericidal at concentration of
50mg/mL and 100mg/mL for Proteus mirabilis, Staphylococcus
aureus and Pseudomonas aeruginosa at only 100mg/mL as shown
in Table 9 & 10 respectively. The minimum lethal concentration
for the leaves extract was 50mg/mL for Candida albicans, also the
minimum lethal concentration for the bark extract was 100mg/
mL which killed Candida albicans as shown in Table 11 & 12.
It is reasonable from the result obtained to suggest that the
plant extracts possess broad spectrum antimicrobial activity. The
antimicrobial activity was more pronounced in the gram-negative
Staphylococcus aureus, a gram-negative bacterium. The plant
extract was also effective against the fungi Candida albicans.
We would like to suggest that further work should be
carried out on each of these plants extract since it was basically
investigated for activity against bacteria and fungi. This research
could be extended to other classes of organisms.