In Ethiopia, differentparts of Croton macrostachyus (C. macrostachyus) are used as a common traditional medicine forinfectious diseases such as typhoid and measles, but there is no documentedreport on the antimicrobial activity of stem bark of this plant. C. macrostachyus stem bark was extractedusing chloroform, absolute methanol and water and tested for theirantimicrobial activities against Escherichiacoli (E. coli), clinical isolates and standard, and Staphylococcusaureus (S.
aureus), clinical isolates and standard, using agar well diffusion and broth dilution methods. Chloramphenicol was used as positivecontrols, while dimethyl sulfoxide (DMSO) was served as negative control. The present study showedthe potent antibacterial activity of the C.
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macrostachyus stem bark extract againstthe all tested bacterial pathogens.Methanol extract of C. macrostachyusstem 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). In this study theminimum inhibitory concentration (MIC) and minimumbactericidal concentration (MBC) values of 500 & 500 mg/ml, 62.5 & 125mg/ml and 250 & 500mg/ml were obtained for water; methanol and chloroform extractsof C. macrostachyus stem bark againstclinically isolated E.
coli respectively. On the other hand, MIC & MBC values of250 & 250, 125 & 250 and 125 & 250 mg/ml were recorded for water; methanoland chloroform extracts of C.macrostachyus stem bark against S. aureus (standard) respectively. C.
macrostachyus stem bark extracts havedemonstrated antibacterial effects particularly on E. coli and S. aureus. Thus, C. macrostachyus stem bark could be effective for prevention ofbacterial infections and may be considered as an alternative to antibioticregimens. But further studies should be conducted with different extractionsolvents and toxicity and phytochemical analysis must be performed on theseplants to use as sources and templates for the synthesis of drugs.
Keywords: Antibacterialactivity; Crotonmacrostachyus extracts; MBC and MIC INTRODUCTION Microbial diseases continued to be major threats to the world regardless ofefforts and progress in developing modern medicine. This is due to bacterialspecies present the genetic ability to acquire and transmit resistance againstcurrently available antibacterial since there are frequent reports on theisolation of bacteria that are known to be sensitive to routinely used drugsand became multi-resistant to other medications available on the market (Nascimentoet al., 2000). The impact of microbial diseases is especially important indeveloping countries such as Ethiopia where there is limited access to moderndrugs and prices are mostly unaffordable when the latter are available.
Extensive use of antibiotics often resulted in the development of resistantstrains and these create a problem in management of infectious diseases.Furthermore side effects associated with antibiotics are often fewer when usingmedicinal plants (Nega and Tigist,2015) Medicinalplants have some reward over antibiotics such that there is better patienttolerance, relatively less costly, approval due to long history of use andbeing renewable in nature (Vermani and Garg, 2002). Currently, theever-increasing risk from drug-resistant bacteria calls for a universal effortto search for novel solutions that can also be based on the natural products fromplants that are selected on the basis of documented ethnomedicinal use (Lulekalet al., 2014).
Medicine from herbs isreadily obtained in our widely varied vegetation, inexpensive and all plantparts carry the potential for introducing new templates into modern medicine (Jackie, et al., 2016). Natural plantsources are usually the raw material for most pharmaceutical company (Amin etal., 2016).
Crotonmacrostachyus is a deciduous tree belonging to the familyEuphorbiaceae. The leaves are largeand green, turning to orange before falling. It is also characterized by creamyto yellow-white colored flowers with green (whenyoung) to grey (at maturity)fruits. C. macrostachyus is commonly named as ‘Bisana’ in Amharic, Ethiopiaand it is an important medicinal plant in EastAfrica 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 etal., 2007), Tineaversi color, diarrhea, hepatitis, jaundice, andscabies (Teklehaymanot and Giday, 2007). In case of medicinal value C. macrostachyus has many uses. Leaf extract is applied against itchy scalp. A decoction of theleafy twigs mixed with Justiciaschimperiana is taken to treat jaundice and smallpox.
The preparation is taken with pepper, butter and milk. Aninfusion of the leafy branches and roots is used as a mouthwash to treattoothache. The leaves or young shoots of C. macrostachyus are eaten to treat fever and oedemaand mashed leaves are used for haemorrhoids.
C. macrostachyus stem bark maceration is drunk as anabortifacient and uterotonic, to expel a retained placenta. In addition to thisstem bark is chewed to treat toothache (PROTA4U,2014; Tesemma, 2007)Severalhydroalcoholic C.
macrostachyus stembark 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 positivereports on the antibacterial activity of methanol extracts from C. macrostachyus leaves (wagate et al., 2010; Matu and Van, 2003; Jackieet al., 2016). Contrastingresultscould be attributed to the locality of plant species, parts used, time ofcollection, storage conditions, and methods of analysis (Jackie et al.
, 2016; Suffredini et al., 2006). Even though majority ofthe Ethiopian population uses traditional medicine, only limited studies wereconducted on the traditional medicinal plants compared to the diversity inculture and vegetation of the country. The antibacterial effect of C. macrostachyus leaf was studied butthere is no study conducted on the other parts of this plant. Therefore, the objective of this studywas to evaluate the antimicrobial activity of chloroform, methanol and waterextracts from C. macrostachyus stembark against both clinical and standard strains of E.
coli and S. aureus.