A Okwori, C Dina, S Junaid, I Okeke, J Adetunji, A Olabode
antimicrobial, bacterial pathogens, extracts, nigeria
A Okwori, C Dina, S Junaid, I Okeke, J Adetunji, A Olabode. Antibacterial Activities Of Ageratum conyzoides Extracts On Selected Bacterial Pathogens. The Internet Journal of Microbiology. 2006 Volume 4 Number 1.
In-vitro antibacterial activities of
The African environment is probably the least explored in terms of available untapped resources. Herbal medicine is readily available in our diverse vegetation, cheap and above all carries the potentials of introducing new templates into modern medicine.
The use of medicinal plants all over the world predates the introduction of antibiotics and other modern drugs into African continent (Akinyemi
The use of various plant parts in the treatment of the sick developed into tradition which was handed down from one generation to another over the years verbally or written (Sofowora, 1982; Akinyanju, 1986). For thousand of years, medicine depended exclusively on leaves, flowers and barks of plants, only recently have synthetic drugs come into use and in many instances, these are carbon copies of chemicals identified in plants (Conway, 1973). In orthodox medicine, a plant may be subjected to several chemical processes before its active ingredients is extracted refined and made ready for consumption, while in traditional medicine, a plant is simply eaten raw, cooked or infused in water or native wine or even prepared as food (Conway, 1973).
Even before the discovery of modern antibiotics and other chemotherapeutic agents, traditional medicine has served as man's resort when attacked by infective agents such as bacteria and fungi (Crafton, 1983).
Traditional communities in India use this species as an antidysenteric and antilithic (Borthakur and Basuah, 1987) and in Asia, South America and Africa aqueous extract of this plant is used as an antibacterial agents (Almagboul, 1985; Ekundayo
This knowledge could enable more rational exploitation of the plant both in traditional medicine and in the empirical development of new antibacterials.
This work was based on scientific investigation of the widely acclaimed medicinal value of
Materials And Methods
Source of Ageratum conyzoides
Fresh plant materials were collected from a nearby farmland of the Root-crop Research Institute, near Vom. Their botanical identities were determined and authenticated at the Department of Botany, University of Jos and the Federal College of Forestry, Jos, Nigeria.
Processing of the plant
The fresh leaves, stems and roots were harvested, washed properly with tap water and rinsed with sterile distilled water. The various parts of the plants were dried separately using the hot air oven at 40 o C for three days.
The dried plants were pulverized using sterile laboratory mortar to obtain the powdered form. These were stored in air tight sterile containers protected from sunlight until required for analyses.
Cold/hot water and the methanolic/hexane soxhlet extraction as described by AOAC (1980) Akinyemi
Phytochemical screening methods
The presence of alkaloids, resins, saponins, glycosides, tannins, flavonoids, cardiac glycoside, steroidal ring, steroidal terpenes, anthraquinone and carbonhydrates were determined as described by Wall
Sources of Bacterial Isolates
The stock clinical isolates of
Preparation of the Test organisms
The isolates were subcultured onto selective and differential solid media and re-identified using API 20E strips (Biomerieux, Marcy I`Etoile, France).
Colonies of fresh cultures of the different bacterial isolates were selected and suspended in 10ml of nutrient broth (Biotec, Sufolk, UK). Using tenfold serial dilution, in sterile normal saline the population density for all the test organisms were determined (Miles and Misra, 1938). All cultures were incubated for 24hrs at 37 O C except for
Bacterial Susceptibility Testing
Agar diffusion test
A standardized inoculum of 1 – 2 X 10 7 cfu/ml was used for the inoculation of plates. The plates were allowed to dry in the incubator for 30minutes at 37 O C and with the aid of a sterile standard cork borer, 6 wells were bored at equidistant. The bottoms of the wells were sealed with sterile molten nutrient agar (Biotec, Sufolk, UK) to prevent seepage of the extract under the agar. The 5 th and 6 th wells served as positive and negative controls. The sterile distilled water served as negative control. Ciprofloxacin (10ug/ml) was used as the positive control. 0.2ml of each prepared concentration of the extracts was aseptically introduced into wells 1 – 4. The plates were allowed on the bench for 40 minutes for pre-diffusion followed by an overnight incubation at 37 O C. The resulting zones of inhibition were measured using a ruler calibrated in millimeters. The average of the three readings was taken to be zone of inhibition of the bacterial isolates in question at that particular concentration (Abayomi, 1982; Junaid
Determination of minimum inhibitory concentration (MIC) and minimum Bactericidal Concentration (MBC)
MIC of the extracts was determined by dilution to various concentration according to the macro broth dilution technique (Baron and Finegold, 1990; Akinyemi
The antibacterial activities of aqueous methanolic and hexane extract of
Aqueous methanol and hexane extracts of
The aqueous root extracts showed no inhibition on the bacterial isolates except for E. coli which was inhibited with a mean zone diameter of 7-12mm. The hexane root extracts inhibited the growth of the bacterial isolates giving a range of 7 – 12mm for S. aureus, 7 – 14mm for
The aqueous leaf extracts gave MIC results of (100, 25 and 50mg/ml for
The aqueous stem extracts gave MIC of (25,25,50 and 50) mg/ml for
The aqueous root extracts gave MIC of 100mg/ml for
The aqueous leaf extracts gave MBC of 50, 25 and 25mg/ml for
The aqueous stem extracts gave MBC(s) of 50, 25, 25 and 50 mg/ml for
The aqueous root extract gave MBC(s) of (12.5, 6.25, 25 and 6.25)mg/ml for
The percentage effectiveness of the leaf extract on the bacterial isolates used in this work was 75%, 50% and 100% respectively for the aqueous, methanolic and hexane leaf extracts. Also from this finding the root extract of
The phytochemical screening showed that
Medicinal plants constitute an effective source of both traditional and modern medicines. Herbal medicine has been shown to have genuine utility and about 80% rural population depends on its efficacy for their primary health care. Scientist from divergent fields in a similar efforts are investigating plants a new with an eye to their antimicrobial usefulness. A sense of urgency accompanies the search as the pace of species extinction continues. Over the years, the WHO advocated that countries should interact with traditional medicine with a view to identifying and exploiting aspects that provide safe and effective remedies for ailments of both microbial and non-microbial origins (WHO 1978). The results obtained in the study revealed antimicrobial efficacy of extract of
Although the inhibitory effects of aqueous and methanolic extracts of medicinal plants are usually reported (Tignokpa
In this study, the methanolic, stem or root extracts were non inhibitory to all the bacteria isolates used (
The minimum inhibitory concentrations observed for the aquoeus and methanolic (leaf, stem and root) extracts are quite high between a range of (25-100) mg/ml, while that of hexane (leaf, stem and root) extract are between a range of (6.25-50) mg/ml. This is further supported by claims that the active antimicrobial phytochemicals of the plant
The result obtained for the minimum bactericidal concentration (MBC) which gave a range of (25-50) mg/ml for aqueous and methanolic (leaf, stem and root) extract and a range of (3.13-25) mg/ml for hexane (leaf, stem and root), extracts varied considerably from the results obtained for the minimum inhibitory concentrations (MIC(s). These variations in results implies that the MBCs result obtained from plate cultures after plating on various dilutions of extracts is more reliable and accurate compared to MICs results obtained visually using turbidity as an index.
Interestingly, the observed antibacterial effects of
In central Africa, particularly Liberia,
The world has entered an era when health is increasingly managed with an eye to cost containment. Critical to developing a cost effective approach to the evaluation and management of clinical illness is the selective use of available diagnostic methods, therapies and preventive measure.
The emergence of bacterial strains that are resistant to many commonly used antibacterial agents means that treatment failures may become more common. Appropriate antimicrobial therapy can shorten illness and reduce morbidity in some bacterial and parastic infections and can be life saving in invasive infection.
This work shows that
The authors thank the Executive Director, National Veterinary Research Institute, Vom, Nigeria for permission to publish this paper.