Phytochemistry and comparative analysis of the Antitussive potential of Allium sativum and Garcinia kola against clinical isolates of respiratory tract infections

Aqueous and ethanol extracts of Allium sativum and Garcinia kola were comparatively assessed for phytochemical compositions and antitussive activity on bacterial isolates from respiratory tract and associated clinical samples (nasal and throat swabs). Using standard phytochemical and analytical microbiological techniques, the results revealed the presence of alkaloids, flavonoids, cardiac glycosides and tannins, indicating that ethanol was a better solvent than water and of significantly (p<0.05) higher yields in G. kola than A. sativum. The antibacterial activity of A. sativum and G. kola were assessed by agar-disc diffusion technique against the isolated respiratory tract infection pathogens: Staphylococcus aureus, Streptococcus pyogens, Streptococcus pneumoniae, Klebsiella pnuemoniae and Pseudomonas aeruginosa. The results revealed broad-spectrum of antibacterial activity by ethanol extracts of both plants. The antibacterial activity was significantly (p<0.05) higher for the ethanol extracts of G. kola than those of A. sativum; while the aqueous extracts of both plants were inactive, except slight activity by G. kola against S. aureus and the streptococci. The bioactive plants extracts basically exhibited static activity independent of the concentrations and incubation periods used in the study. INTRODUCTION Respiratory Tract Infection (RTI) is among the commonest infections, accounting for much consultation in general medical practices worldwide (Denyer et al., 2007). The RTI pathogens are regularly transmitted via oral and nasal discharges from infected eyes, ears or both (Fuerst, 1978). Oral and nasal secretions inevitably contaminate the atmosphere during talking, laughing, sneezing, coughing and similar actions that produce droplets and droplet-nuclei. This is in addition to the aerial dissemination of saliva and mucus, the spread of oral, nasal and conjunctival secretions by hands, eating utensils, drinking glasses and improperly maintained swimmingpools, which may be contaminated by feaces and urine as well as by respiratory secretions. Hence, the environment is constantly facing a formidable, unceasing and virtually ubiquitous onslaught of RTIs. Consequently, RTI and other associated airborne pathogens generally, are amongst the most difficult to control (Fuerst, 1978). Amongst the bacterial etiologic agents of RTI are Staphylococcus aureus, Streptococcus species, Klebsiella pneumoniae; Pseudomonas aeruginosa; Mycobacterium tuberculosis, Haemophilus influenzae; Mycoplasma pneumoniae, Legionella pneumophila, Chlamydia psittacosis, Bordettola pertussis, as well as anaerobes such as Bacteriodes species (Duerden et al., 1990; Laurence et al., 1997; and Denyer et al., 2007). The pathogenesis of these bacteria often result in the production of secretions, exudates, transudates or extraneous materials from the respiratory tract by the irritation of the airways and lungs mostly the bronchi, resulting in cough (Rang and Dale, 1994; Laurence et al., 1997). Cough is a protective reflex mechanism, the sole purpose of which is to remove foreign materials and secretions from the bronchi and bronchioles of the ISSN: 2141 – 3290