Volume 8 No. 2March 2013
pp 27-34 (Vol 8 No. 2 2013)
West Kristian Paraiso 1 2 * and Glenn Alea 1
1Chemistry Department, De La Salle University, Manila, Philippines, 1004
2Department of Pharmaceutical Chemistry, University of the Philippines-Manila, Philippines, 1000
Phthalimide derivatives were synthesized using the concept of molecular hybridization or combination of two pharmacophores in one drug. In this paper, the concept was utilized to synthesize new antimycobacterial compounds to combat emerging resistant Mycobacterium tuberculosis strains. Four new phthalimides were successfully prepared using a single-step condensation reaction between phthalic anhydride and four different sulfonamides: sulfadimethoxine, sulfathiazole, sulfamethizole, and sulfamethoxypyridazine. IR and 1H NMR spectroscopic and mass spectrometric data verified the identity and structure of the synthesized compounds. The antimycobacterial activity of the synthesized phthalimides and their starting materials was evaluated according to CLSI standard procedures using the agar proportion method. The calculated LogP of both starting materials and phthalimides were also compared. Sulfathiazole, sulfadimethoxine, and sulfamethizole showed significant activity against Mycobacterium tuberculosis H37Rv strain at 0.01 mg/ml, the lowest concentration at which they were tested. One of the four new compounds, 4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-N-(1,3-thiazol-2-yl)benzenesulfonamide, which was synthesized from sulfathiazole also exhibited the same activity. The derivatives from sulfadimethoxine and sulfamethizole, however, showed a decrease in activity. The phthalimides overall gave higher LogP values. The active new compound demonstrates that molecular hybridization may be used to design antimycobacterial compounds with improved activity and pharmacokinetic properties.
Inventory of Locally Traded Stony Corals (Phylum Cnidaria, Order Scleractinia) in the Cartimar Shopping Center, Pasay City
pp 21-26 (Vol 8 No. 2 2013)
Benjamin O. Uy and Wilfredo Y. Licuanan*
Biology Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines.
* E-mail: firstname.lastname@example.org
The Philippines is known for its high marine BIODIVERSITY and for the high risk to that diversity. Of the human activities implicated in the degradation of coral reefs, collection of organisms for the aquarium trade is probably the most controversial. As a first step in determining the local impact of this trade and how, if possible, it can be managed, this paper presents an inventory of the corals being sold in Cartimar Shopping Center, the center of the pet trade in Metro Manila. A total of 29 species in nine families were found, with pocilloporids and Acropora being the best-selling. Euphyliids and gonioporids were also common in the shops, probably because these corals survive well in tanks. Ten of the species identified were categorized as near threatened, and another six were categorized as vulnerable in the IUCN Red List of Threatened Species. Therefore, corals in both categories should not be in the trade. Suggestions on how the aquarium trade could be made self-regulating are presented in this work.
pp 9-20 (Vol 8 No. 2 2013)
Elmer R. Magsino*, Christian Michael Dollosa, Samuel Gavinio, Gerard Hermoso, Nico Laco, and Louise Angelo Roberto
Electronics and Communications Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
Most quadrotor flight controllers make use of an attitude control loop, which is responsible for stabilizing the flight of the vehicle by directly driving the four motors via the electronic speed controllers (ESCs). Such a control loop loses its effectiveness when the motors and ESCs are not well matched resulting in variation of the control performance. This study presents an alternative control structure that incorporates an inner speed and torque control loop within the attitude and altitude loop in order to achieve better flight stability and maneuverability. The control structure is designed to make use of PID control in order to correct for errors in the process and drive the motors correspondingly. The control system is simulated and tuned using Simulink and later implemented on a dsPIC33 microcontroller where various feedback and instrumentation sensors are interfaced. The attitude feedback is implemented using a complementary filter to fuse the accelerometer and gyrometer data in order to arrive at usable attitude estimates. The result of the flight testing reveals that the experimental and simulation results vary only by an attitude standard deviation of less than 5° and an altitude standard deviation of 50 cm. The control structure not only compensates for motor and ESC mismatches but also allows the attitude control loop, the one whose effects on the stability is most visible, to operate at the range of operation.
First Report of Perkinsus sp. in Cultured Oysters Along the Coastal Waters of Manila Bay, Philippines
pp 1-8 (Vol 8 No. 2 2013)
Anthony Joseph M. Contreras, Lindel A. Sacmar, Daryne Claire F. Molina, Pablo C. Evangelista Jr., James Kason P. Lalas, Jyle Chito E. Villones, Mary Jane Cruz-Flores*
Biology Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
Oysters cultured in the Manila Bay, specifically in Cavite City; Naic, Cavite; and Obando, Bulacan, were surveyed for the occurrence of Perkinsus sp. for three months from June to August 2012. Ray’s fluid thioglycollate medium (RFTM) revealed the presence of Perkinsus sp. hypnospores in oyster tissues. Based from the hypnospores present, the infection rate was recorded highest in Obando, Bulacan, with 79.4%, followed by Naic, Cavite, with 66.1% and Cavite City with 62.8% as the lowest. Light infection intensity was likewise recorded highest in Obando, Bulacan, with 18.93, followed by Naic, Cavite, with 12.86 and Cavite City with 12.56 as the lowest in which no significant differences occurred across sites. However, a decreasing pattern in the intensity of infection was observed from June to July 2012, and an increase was observed in the month of August 2012, which revealed significant differences across the collection period, specifically during July 2012 and the first collection in August 2012. Furthermore, histological sections were made to confirm the RFTM for the occurrence of the parasite and its potential damage to the host tissue. Oyster hemocytes were likewise observed along with Perkinsus sp. Circular damage in the mantle was evident. In comparison with the usual size of Perkinsus sp. which is ~1 µm, the observed smaller size of the trophozoite stage is indicative of a species only endemic in the country.