Background. Using plants as antimicrobials has long been a practice of traditional healers and validating these customs may lead to the discovery and development of useful herbal medicines. Objective. This study aimed to determine the antibacterial activity of guyabano, tsaang gubat, sambong, and ulasimang bato against common pathogens. Methods. Aqueous or alcoholic leaf extracts of the different medicinal plants were prepared. The solid agar dilution method was used to determine the MIC of guyabano, tsaang gubat, sambong, and ulasimang bato against common pathogens including Staphylococcus aureus, Echerichia coli, Streptococcus pneumoniae, Hemophilus influenzae, Pseudomonas aeruginosa, Salmonella typhi, and Shigella flexneri. Results. The alcoholic leaf extract of guyabano showed moderate activity against oxacillin-sensitive S. aureus with an MIC of 5-6.3 mg/mL. However, tsaang gubat did not exhibit any antibacterial activity for drug-resistant enteric organisms (S. typhi, S. flexneri, and E. coli) and S. aureus at a concentration of 25 mg/mL. Even at a concentration of 100mg/mL, ulasimang bato failed to show any antibacterial activity against drug-resistant S. aureus, S. pneumonia, H. influenzae, E. coli, and P. aeruginosa. Sambong alcoholic extract had some antibacterial activity against penicillin-resistant S. pneumoniae with an MIC of 12.5 mg/mL. Conclusions. Guyabano alcoholic leaf extract showed moderate antibacterial activity against oxacillin-sensitive S. aureus. Sambong alcoholic extract likewise exhibited inhibitory activity against S. pneumoniae. However, tsaang gubat and ulasimang bato aqueous extracts failed to show significant antibacterial activity for the pathogens tested.

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Infrared Spectroscopy is a powerful tool in investigating protein dynamics on an atomic level. Time-resolved Fourier-transform infrared spectroscopy (FTIR) was particularly helpful in elucidating individual proton transfer steps in bacteriorhodopsin (1). In an attempt to study the electron-driven proton translocation of oxidases we applied FTIR spectroscopy to cytochrome c oxidase from bovine heart and from R. spbaeroides. Preliminary experiments on fully-reduced and CO saturated enzymes exhibited very small but distinct spectral changes in the mid-infrared region after flashing-off the C O by a nanosecond laser pulse. Vibrational changes were recorded with the rapid-scan and the stepscan technique (present time-resolution: 100 cs).At 253K, CO photodissociation leads to a large negative band at 1963 cml. Transfer of C O from heme a3 to CUB resulted in a positive band at 2062 cm-l (for bovine heart oxidase). Accompanying those changes, highly resolved spectra in the region below 1800 cm-l indicated specific changes in the vinyl and formyl vibrations of the heme as well as vibrations of the binuclear center (2). Moreover, changes in frequencies of amino acid side chains could also be detected and resolved in time. Spectra were measured in H 2 0 and D 2 0 for the mammalian and compared to the bacterial enzyme.The Na,K-ATPase is an integral membrane enzyme which establishes and maintains the Na + and K+ electrochemical gradient across the plasma membrane. The Chemical modification of Lys-501 in the pig kidney Na,K-ATPase with FITC(fluorescein-5'-isothiocyanate) inhibits transphosphorylation of terminal phosphate of ATP to Asp-369 and reduced the apparent affinity for ATP. To investigate the role of this residue in Na,K-ATPase activity, Lys-508 in rat kidney Na,K-ATPase (correspond to Lys-501 in pig kidney Na,K-ATPase) was changed to Ala and Glu by site-specific mutagenesis, and the resultant enzymes were stably expressed in HeLa cells.Eikenella corrodens, a Gram-negative rod, was originally isolated fiom the human oral cavity and is an opportunist pathogen. It is a fastidious bacterium with sophisticated requirements for its culture in axenic medium; its growth in complex liquid medium is poor and not easily reproducible.Here we report our preliminary results concerning to some bioenergetic properties of E. cotrodens ATCC 23834 obtained fiom microaerophilic cultures (static) in the modified BMI liquid complex medium (Allaker et d., FEMS Microbiol. Lett. 123: 69-74, 1994). The aim of the work is to get insight into the composition and organization of the respiratory system of E. corrodens cultured under limited oxygen.We found that purifies cell membranes were able to oxidize NADH, succinate, ascorbate plus TMPD and formate. The spectroscopic analysis of membrane particles at room temperature and 77 K revealed the presence of c and &type cytochromes that were reducible by dithionite and physiological electron donors. CO-difference spectra suggested the presence of a cytochrome u-type oxidase however this could net be ...