ABSTRACT as positive controls, while dimethyl sulfoxideABSTRACT as positive controls, while dimethyl sulfoxide

ABSTRACT

 

In Ethiopia, different
parts of Croton macrostachyus (C. macrostachyus) are used as a traditional medicine to treat
infectious diseases such as typhoid and measles, but there is no documented
report on the antbacterial activity of stem bark of this plan in Ethiopiat. C. macrostachyus stem bark was extracted
using chloroform, methanol, and water extraction solvents and tested for their
antibacterial activities against Escherichia
coli (E. coli), clinical isolates and standard, and Staphylococcus
aureus (S. aureus), clinical isolates and standard,  using agar well diffusion and broth dilution methods. Chloramphenicol was used as positive
controls, while dimethyl sulfoxide (DMSO) was served as negative control. The present study showed
the potent antibacterial activity of the C.
macrostachyus stem bark extract against all tested bacterial pathogens.
Methanol extract of C. macrostachyus
stem bark showed the highest zone of inhibition (17+1mm) against S. aureus
(standard) and the lowest zone of inhibition (12+1) against E. coli (clinical isolate). In this
study the minimum inhibitory concentration (MIC) and
minimum bactericidal concentration (MBC) values of 500 & 500 mg/ml, 62.5
& 125 mg/ml and 250 & 500mg/ml were obtained for water, methanol, and
chloroform extracts of C. macrostachyus
stem bark against clinically isolated E. coli
respectively.  On the other hand, MIC & MBC values of
250 & 250, 125 & 250 and 125 & 250 mg/ml were recorded for water, methanol,
and chloroform extracts of C.
macrostachyus stem bark against S. aureus (standard) respectively. C. macrostachyus stem bark extracts have
confirmed antibacterial effects, mainly on E.
coli and S. aureus. Thus, C.
macrostachyus stem bark could be effective for prevention of bacterial
infections and may be considered as an option to antibiotic regimens. But
further studies should be conducted with different extraction solvents and
toxicity and phytochemical analysis must be performed on these plants to use as
sources and templates for the synthesis of drugs.

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Keywords: Antibacterial
activity; Croton
macrostachyus extracts; MBC and MIC

 

 

INTRODUCTION

 

Microbial
diseases continued to be major threats to the world regardless of hard work and
advancement in developing modern medicine. This is due to bacteria possess the
genetic ability to acquire and transmit resistance against currently available
antibacterial since there are frequent reports on the isolation of bacteria
that are known to be sensitive to routinely used drugs and became multi-resistant
to other medications available on the market (Nascimento et al., 2000).

 

The
impact of bacterial diseases is especially important in developing countries
such as Ethiopia where there is inadequate access to modern drugs and prices
are mostly unaffordable when the latter are available. Extensive use of
antibiotics often resulted in the development of resistant strains and these
create a problem in the management of infectious diseases. Furthermore, side
effects associated with antibiotics are often fewer when using medicinal plants
(Nega and Tigist, 2015)

 

Medicinal
plants have some prize over antibiotics such that there is superior patient
tolerance, relatively less costly, agreement due to a long history of use and
are renewable in nature (Vermani and Garg, 2002). Currently, the
ever-increasing risk from drug-resistant bacteria calls for a universal effort
to search for novel solutions that can also be based on the natural products
from plants that are selected on the basis of documented ethnomedicinal use
(Lulekal et al., 2014). Medicine from
herbs is readily obtained in our widely varied vegetation, inexpensive and all
plant parts carry the potential for introducing new templates into modern
medicine (Jackie, et al., 2016). Natural
plant sources are usually the raw material for the most pharmaceutical company (Amin et
al., 2016).

 

Croton
macrostachyus is a deciduous tree belonging to the family
Euphorbiaceae. The leaves are large
and green, turning to orange before falling. It is also characterized by creamy
to yellow-white colored flowers with green (when young) to grey (at maturity)
fruits. C. macrostachyus is commonly named as ‘Bisana’ in Amharic, Ethiopia
and it is an important medicinal plant in East
Africa including Ethiopia (Abraham et al.,
2016). It is traditionally used for the treatment of wound (Giday et al., 2009; Teklehaymanot and Giday, 2007; Abraham et al., 2016)
malaria, rabies, and gonorrhea (Giday et
al., 2007), Tineaversi color, diarrhea, hepatitis, jaundice, and
scabies (Teklehaymanot and Giday, 2007). 

 

In case of medicinal value, C. macrostachyus has many uses. Leaf extract is applied
to the itchy scalp. A decoction of the leafy twigs mixed with Justicia schimperiana is taken
to treat jaundice and smallpox. The traditional preparation can be taken with
pepper, butter, and milk. The mixture of the leafy branches and roots is used
as a mouthwash to treat a toothache. The leaves or young shoots of C. macrostachyus are eaten to treat fever and oedema
and mashed leaves are used for hemorrhoids. C. macrostachyus stem bark maceration is drunk as an
abortifacient and uterotonic, to expel a retained placenta. In addition to this
stem bark is chewed to treat a toothache (PROTA4U,
2014; Tesemma, 
2007)

Several
hydroalcoholic C. macrostachyus stem
bark extracts have been tested against a clinical strain of Neisseria gonorrhoeae (Mesfin, 2007)
with the minimum inhibitory concentration (MIC) of 125–250 mg/ml. There are both negative and positive
reports on the antibacterial activity of methanol extracts from C. macrostachyus leaves (wagate et al., 2010; Matu and Van, 2003; Jackie
et al., 2016). Contrasting results
could be attributed to the locality of plant species, parts used, time of
collection, storage conditions, and methods of analysis (Jackie et al., 2016; Suffredini et al., 2006). Even though the majority
of the Ethiopian population uses C.
macrostachyus to treat different diseases traditionally, only a single
study was conducted on the antibacterial effect of C. macrostachyus leaf but there is no study conducted on the other
parts of this plant. Therefore, the
objective of this study was to evaluate the antibacterial activity of chloroform,
methanol and water extracts from C.
macrostachyus stem bark against both clinical and standard strains of E. coli and S. aureus.