Available online at http://www.ajol.info/browse-journals ISSN 0794-5698 Nigerian Journal of Basic and Applied Science (2009), 17(2):235-239

Phytochemical and Antibacterial Properties of Leaf Extract of kunthianum ()

*1 M.S. Aliyu, 2 U.A. Hanwa, 1M.B.Tijjani, 3A.B. Aliyu, and 4B. Ya’u

1Department of Microbiology, 2Department of Pharmaceutical and Medicinal Chemistry, 3Department of Chemistry, Ahmadu Bello University, Zaria 4Department of Science Laboratory Technology, Nuhu Bamalli Polytechnic, Zaria [*Corresponding author’s e-mail: [email protected], Phone no. +2348022360774]

ABSTRACT: Phytochemical screening and studies on antibacterial activity of leave extract of Stereospermum kunthianum -a widely used by traditional medical practitioners in Northern Nigeria, were carried out on , , , spp, spp and using agar well diffusion technique. Preliminary phytochemical screening revealed the presence of sterols, coumarins, higher fatty acids and the absence of flavones aglycone and alkaloids in the leave extract. The activity of the extract was more potent at 30 mgml -1 with zone of growth inhibition against S. aureus (35 mm), Klebsiella spp (28 mm) and A. hydrophila (28 mm). The least activity was on P. aeruginosa (9 mm). The minimum inhibitory concentration (MIC) of the extract was 2.09 mgml -1 on Klebsiella spp and S. aureus while 4.17 mgml -1 on Salmonella spp and A. hydrophila . Similarly, the minimal bactericidal concentration (MBC) was 2.09 mgml -1 on S. aureus and 4.17 mgml -1 on Klebsiella spp. However, higher MIC and MBC of 16.67 mgml -1 were observed on P. aeruginosa . The spectra of activities displayed by the extract can be attributed to the presence of these phytochemicals which signifies the potential of S. Kunthianum as a source of therapeutic agents. This therefore, supports the traditional medicinal use of S. kunthianum in Zaria, Nigeria. KEYWORDS: Stereospermum kunthianum, phytochemical, antibacterial activity, Bignoniaceae

INTRODUCTION The use of for medicinal purposes is an age Stereospermum kunthianum is a deciduous shrub old tradition in Africa (Karou, et al., 2006). Today, or tree found in the dry areas of deciduous forest, more than 70% of the people in Africa refer to woodland, bush, rocky outcrops, termite mound traditional healers concerning health issues and margins of evergreen forests. The plant is (Kamanzy et al ., 2002). The World Health known locally as Sansami (Hausa) and is widely Organization (WHO) encourages the inclusion of used by traditional medical practitioners in herbal medicines of proven safety and efficacy in Northern Nigeria for the treatment of various the healthcare programs of developing countries human diseases. The pods are chewed with salt to because of the great potential they hold in treat coughs and are used in treatment of ulcers, combating various diseases (Amos et al., 2001). leprosy, skin eruptions and venereal diseases, Plant extracts represent a continuous effort to find while the stem bark decoction or infusion is used new compounds with the potential to act against to cure bronchitis, pneumonia, cough, rheumatic multi-resistant bacteria. Approximately 20% of the arthritis and dysentery (Gill, 1992). The twigs are plants found in the world have been submitted to chewed to clean teeth and to treat toothache. The pharmacological or biological test, and a roots and leaves have been found useful in treating substantial number of new antibiotics introduced venereal diseases, respiratory ailments, gastritis on the market are obtained from natural or semi- (Gill, 1992) and a disease called “ Rana ” with synthetic resources (Mothana and Lindequist, symptoms of haematuria (Dalziel, 1955). 2005). Thus, it is anticipated that phytochemicals Previous ly, the a ntiplasmodial activities of with adequate antibacterial efficacy will be used naphthaquinones and one anthraquinone from the for the treatment of bacterial infections. lipophilic root bark extract was reported (Onegi et al., 2002). Antidiarrhoeal (Ching et al., 2008),

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Aliyu el al. : Phytochemical and antibacterial properties of leaf extract of Stereospermum kunthianum…….. activities of stem bark (Ching et al., et al. (2006). Briefly, the test organisms from 2009), as well as the anthelmintic activity of growth on nutrient agar incubated at 37 oC for 18hr ethanol leave extract has been reported (Monglo et were suspended in saline solution (0.85% NaCl) al., 2006). The present study therefore, reports the and adjusted to match a turbidity of 0.5 (10 8 phytochemical screening and antibacterial activity cells/ml) McFarland standard. The standardized of the lipophilic leaves extract of Stereospermum suspension was used to inoculate the surfaces of kunthianum with a view to understanding the Mueller Hinton agar plates (90 mm in diameter) molecular basis of some of its therapeutic uses in using sterile cotton swab. Six millimetre (6mm) traditional medicine, which had not been diameter wells were punched using cork borer in investigated hitherto. agar and filled with the desired concentrations (30 mgml -1, 20 mgml -1 and 10 mg/ml -1) of the extracts. MATERIALS AND METHODS Commercial antibiotics (augmentin (30 µg) and Collection and identification of plant material gentamicin (10 µg) Abtek Code NO. GC 20/p) Whole fresh plant bearing fruits and leaves were used as reference standards to determine the growing wild was collected in Zaria in December, sensitivity of the isolates. Discs were directly 2005. The plant was authenticated at the herbarium placed onto the bacterial culture. The plates were unit of the Department of Biological Sciences, allowed to stand for 2 h at room temperature for Ahmadu Bello University, Zaria, where a voucher extract to diffuse into the agar and then incubated number 1381 was deposited. Leaves were air dried at 37 oC over night. Antibacterial activities were at room temperature for 21 days to a constant evaluated by measuring inhibition zone diameters. weight. The dried leaves were pulverized to coarse The entire test was conducted in duplicate. powder using mortar and pestle and sieved with 20 mesh (British standard). The powdered leaves were Determination of MIC and MBC stored for further studies. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of Extraction the plant extract were determined using agar One hundred and sixty five grams (165 g) of the dilution technique as described by Musa et al. powdered leaves were soxhlet extracted with (2000). The required extract concentrations were petroleum ether (60-80 oC) until the draining prepared in 20 ml sterile melted Mueller-Hinton solvent was clear (Chhabra, et al., 1982). The agar each and poured aseptically into sterile Petri solvent was removed under reduced pressure dishes (90 mm) in duplicates and allowed to below 50 oC to give a crude extract. The crude solidify. Sterile filter paper discs (6 mm diameter) extract was further dried in vacuum desiccator over were aseptically placed firmly on the agar in anhydrous copper sulphate to give a dry solid of triplicate per organism. Using a micropipette, 20 µl the extract (6.64 g). This was used for of the standardized inoculums was then placed on phytochemical screening and bioassay. the paper discs aseptically and incubated at 37 oC for 18 h. The lowest concentration that inhibited Phytochemical screening growth around the edges of the filter paper discs Phytochemical screening of the extract was carried was taken as the MIC. Filter paper discs in the out to identify the constituents, using standard determination of MIC that showed no visible phytochemical methods as described by Sofowora growth around their edges were sub cultured into (1993) and Trease and Evans (1996). Mueller-Hinton broth (supplemented with 3% Tween 80 and 0.5% egg lecithin) and incubated at Evaluation of antimicrobial activity 37 oC for 48 h. Concentrations at which there was Clinical isolates of Pseudomonas aeruginosa, no growth or turbidity were taken as the MBCs of Staphylococcus aureus, Escherichia coli, the plant extract. Salmonella spp , Aeromonas hydrophila and Klebsiella spp were obtained from the Department RESULTS AND DISCUSSION of Microbiology, Ahmadu Bello University, Zaria. Preliminary phytochemical screening of lipophilic The susceptibilities of the test organisms to the leaves extract of S. kunthiamun revealed the plant extract were assayed as described by Karou presence of sterols, coumarins, higher fatty acids

236 Nigerian Journal of Basic and Applied Science (2009), 17(2):235-239 and the absence of flavones, aglycone and alkaloids (Table 1). Antibacterial activity indicated Table 1: Phytochemical profile of the leaf extract by the zone of growth inhibition ranged from 6-35 of S. kunthianum mm. S. aureus had the largest zone of inhibition Constituent Occurrence (35 mm), Klebsiella spp (28 mm) and A. Sterols/ triterpenes + -1 hydrophila (28 mm) at concentration of 30 mgml , Flavone aglycone - while Pseudomonas aeruginosa had the smallest Coumarins + zone of inhibition (9 mm) (Table 2). The MIC and Alkaloids - MBC showed that Klebsiella spp and S. aureus had Higher fatty acids + -1 the lowest MIC (2.09 mgml ), while Salmonella Glycosides - spp and A. hydrophila had MIC value of 4.17 Carbohydrates + -1 mgml . Pseudomonas aeruginosa and E. coli had + = present, - = absent the highest MIC values of 16.67 and 8.34 mgml -1 respectively. Higher MBC of 16.67 mgml -1 was observed against P. aeruginosa , (Table 3). Table 2: Diameter of zones of inhibition (mm) by S. kunthianum leaf extract against the bacteria Test organism Zones of inhibition(mm)/concentration (mgml -1) 30 mgml -1 20 mgml -1 10 mg/ml -1 Escherichia coli 23 17 12 Staphylococcus aureus 35 28 22 Klebsiella spp 28 21 16 Salmonella spp 25 24 18 Aeromonas hydrophila 28 24 19 Pseudomonas aeruginosa 9 6 6 Values greater than 6mm indicate some activity

Table 3: MIC and MBC of S. kunthianum leaf extract against the test organisms (mgml -1) Test organism MIC (mgml -1) MBC (mgml -1)

Escherichia coli 8.3 0 10.41 Staphylococcus aureus 2.09 2.09 Klebsiella spp 2.09 4.17 Salmonella spp 4.17 8.34 Aeromonas hydrophila 4. 17 6.26 Pseudomonas aeruginosa 16.67 16.67

Antibacterial activity of the lipophilic leave especially on K. spp . and S. aureus is an extract of S. kunthianum has demonstrated indication that the lipophilic phytoconstituents significant antibacterial activity against most of have bactericidal potential. Similarly, the MIC the test organisms. The extract was more potent (4.17 mg/ml) and MBC (6.26 mg/ml) exhibited on gram-positive Staphylococcus aureus with against Aeromonas hydrophila -a gram negative maximum zone of growth inhibition of 35 mm, bacillus capable of causing septicemia in fish at 30 mg/ml. Although gram-negative bacteria and amphibians as well as gastroenteritis, tend to have higher intrinsic resistance to most cellulitis, meningitis, bacteraemia, soft tissue antimicrobial agents (Ndukwe et al ., 2005), In infections, peritonitis, broncho-pulmonary spite of this, impressive activity against gram- infections, in humans with compromised negative bacteria was observed ( E. coli 23 mm, immune systems (Janda 1991; Chang et al . S. typhi 25 mm, K. spp . 28 mm and A. 1997), is yet another indication of the hydrophila 28 mm). Low MIC and MBC values therapeutic potentials of the lipophilic extract (2.09 mg/ml) demonstrated by the extract against such diseases.

237 Aliyu el al. : Phytochemical and antibacterial properties of leaf extract of Stereospermum kunthianum……..

Owing to their popular use as remedies for many bacteria in pure culture. Appl. Environ. infectious diseases, plants with secondary Microb., 64:520-525. metabolites such as terpenoids, flavonoids, Amos, S., Kolawole, E., Akah, P., Wambebe, C. coumarins and steroids have been found in vitro and Gamaniel, K. (2001). Behavioral to have antimicrobial properties (Sibanda and effects of the aqueous extract of Guiera Okoh, 2007; Cowan, 2002). Terpenoids for senegalensis in mice and rats. Phytomed., instance, are synthesized from acetate units 8(5): 356-361. which share origins with fatty acids. Their Barre, J.T., Bowden, B.F., Coll, J.C., Jesus, J., tremendous activities against bacteria have been Fuente, V.E., Janairo, G.C. and Ragasa, reported (Ahmed et al ., 1993; Barre et al ., 1997; C.Y. (1997). A bioactive diterpene from Amaral et al ., 1998). It is perhaps not surprising Lantana camara . Phytochem., 45: 321- that higher fatty acids were found present in the 324. lipophilic extract (Table 1). Coumarins have Chang, C.Y. Thompson, H., Rodman, N., been found to exhibits great diversity with Bylander, J. and Thomas, J. (1997). respect to growth inhibition activity against both Pathogenic analysis of Aeromonas Gram positive and negative bacteria (Kayser and hydrophila septicemia. Ann. Clin. Lab. Kolodziej, 1999). Thus, the spectra of activity Sci., 27: 254-259. displayed by the crude lipophilic extract can be Chhabra, S. C., Shao, J. F. and Andmshiu, E. N. explained by the combined effects of terpenoids, (1982). Antifungal activity among coumarins and steroids or due to synergism. The traditionally used herbs in . Dar- purified components may have even more es-Salaam Med. J., 68: 68-73. potency with respect to inhibition of microbes. Ching, F.P., Omogbai, E.K.I., Ozolua, R. I. and Further work on the phytoconstituents isolation Okpo, S.O. (2008) . Antidiarrhoeal and purification of the bioactive components are activities of aqueous extract of recommended. Stereospermum kunthianum (Cham, In conclusion, the significant activity exhibited Sandrine Petit) stem bark in rodents. Afr. by the lipophilic extract against clinical isolates J. Biotech ., 7(9):1220-1225 of S . aureus (35 mm), E. coli (23 mm) Ching, F.P., Omogbai, E.K.I., Ozolua, R. I. and Klebsiella spp and A. hydrophila (28 mm) and Okpo, S.O. (2009) . Analgesic activity of Salmonella spp (25 mm) that are associated with aqueous extract of Stereospermum various infectious diseases, have provided kunthianum (Cham, Sandrine Petit) stems scientific justification in this research for the bark. Acta Poloniae Pharmaceutica -Drug ethno medicinal uses of the plant in Zaria, Research, 66(1):83-88. Kaduna State, Nigeria. Cowan, M.M. (2002). Plant Products as Antimicrobial Agents. Clin. Microbiol. ACKOWLEDGEMENT Rev ., 12: 564-582. We wish to acknowledge the contribution of Dalziel, J. M. (1955). The Useful Plants of West Ahmadu Bello University, Zaria, for providing Tropical Africa - An appendix to the Flora the facilities for conducting the research. of West Tropical Africa. Watmongh’s Ltd. Bradford. Pp. 442-446. REFERENCES Gill, L.S. (1992). Ethnomedicinal uses of plants Ahmed, A.A., Mahmoud, A.A., Williams, H.J., in Nigeria , University of Benin Press, Scott, A.I., Reibenspies, J.H. and Mabry, Benin city, Nigeria. p. 223. T.J. (1993). New Sesquiterpene α- Janda, J.M. (1991). Recent advances in the study methylene lactones from Egyptian plant of the taxonomy, pathogenicity and Jasonia candicans . J. Nat. Prod., 56:1276- infectious syndromes associated with 1280. genus Aeromonas . Clin. Microbiol. Rev ., Amaral, J.A., Ekins, A., Richards, S.R. and 4:397-410. Knowles, R. (1998). Effect of selected Kamanzy, A.K., M. Kone, C. Terraux, D. monoterpenes on methane oxidation, Traore, K. Hostettmann, and M. Dosso, denitirification and aerobic metabolism by (2002). Evaluation of the antimicrobial of

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