Volume 4 No. 1

January 2001
Antimicrobial Compounds from Spondias purpurea

Antimicrobial Compounds from Spondias purpurea

pp 24-28 (Vol 4 No. 1 2001)

Consolacion Y. Ragasa 1, Asteria T. Poblete 2 and Eugenio C. Navida 2

1 Chemistry Department, De La Salle University
2401 Taft Avenue, 1004 Manila, Philippines

2 Chemistry Department, Adamson University
San Marcelino Street, 1004 Manila, Philippines

ABSTRACT

The dichloromethane, ethyl acetate, ethanol and water extracts of the freeze-dried bark of Spondias purpurea were tested for antimicrobial activities against seven microorganisms. Results of the study indicated that all the extracts at 30 µg have low antimicrobial activities against E. Coli, P. aeruginosa and T. mentagrophytes. The water and ethanol extracts showed low activity against C. Albicans, while the ethyl acetate extract gave low activity against A. niger. All the extracts were inactive against S. Aureus and B. subti/is. The dichloromethane extract was fractionated by silica gel chromatography. It afforded 1, 2 and a mixture of hydrocarbons. Compounds 1 and 2 were identified by comparison of their 1H NMR spectral data with those of lutein and sistosterol, respectively. Sitosterol and the mixture of hydrocarbons were tested against the same microorganisms. Result of the study indicated that both compounds had low activity against E. Coli and P. aeruginosa at 30 µgand inactive against S. Aureus, B. subtilis, T. mentagrophytes and A. niger. Sitosterol gave low activity against C. albicans. 

 

Detection of Paralytic Shellfish Poisoning (PSP) Toxins in Philippine Mussel Samples by Electrospray Mass Spectrometry

Detection of Paralytic Shellfish Poisoning (PSP) Toxins in Philippine Mussel Samples by Electrospray Mass Spectrometry

pp 1-10 (Vol 4 No. 1 2001)

Ma. Christina Grace Z. Floresca, Barbra Michelle Abad, Tabitha Amora, Mary Angelica Lim, and John Paulo Marquez
Chemistry Department, De La Salle University
2401 Taft Avenue, 1004 Manila, Philippines

ABSTRACT

The occurrence of toxic red tide outbreaks is an environmental and public health hazard in the Philippines. Thus, it is necessary to develop monitoring programs to protect the shellfish industry and the general public. Previous methods for the detection of paralytic shellfish poisoning (PSP) toxins make use of mouse bioassays and/or fluorescence detection through High Performance Liquid Chromatography (HPLC). The mouse bioassay, while cheap and rapid, requires a large amount of sample, and is capable of detection of toxin concentrations that are already near the regulatory limit. Fluorescence HPLC analysis of derivatized PSP samples is des true t ive and is not sufficiently reproducible. We report a new procedure for the rapid detection of components of samples contaminated by Pyrodinium bahamense var compressum using a combination of reverse-phase HPLC and electrospray mass spectrometry. The procedure is fast and requires minimal amounts of sample, so that purified toxins need not be derivatizated as a prerequisite for its detection. In addition, results from this study complement earlier findings that the main toxic components of Philippine toxic red tide are neosaxitoxin, decarbamoy/saxitoxin, and gonyautoxin. 

The Bandwidth of the Cartesian Product of a Double Star and a Path

The Bandwidth of the Cartesian Product of a Double Star and a Path

pp 29-37 (Vol 4 No. 1 2001)

Yvette Fajardo-Lim·
Department of Mathematics
De La Salle University
2401 Taft Avenue, Manila

ABSTRACT

The cartesian product of two graphs G and H, written G X H, ,s the graph with vertex set V(G) X V(H) and with (u1, vi) adjacent to (u2, v2) if u1 is adjacent to U2 in G and V1 = V2 or u1 = u2 and V1 is adjacent to V2 in H. This paper establishes the bandwidth of the cartesian product of a double star and a path.

Lead Uptake and Growth Responses in Pistia Stratiotes Linn. (Quiapo)

Lead Uptake and Growth Responses in Pistia Stratiotes Linn. (Quiapo)

pp 16-23 (Vol 4 No. 1 2001) 

Rosario S. Espinosa
Ateneo de Zamboanga University
Zamboanga City, 7000 Philippines

ABSTRACT

Pistia stratiotes was cultured in hydroponics solutions amended with three different lead (Pb) levels – 2ppm, 4ppm and 8ppm [Pb in the form of Pb (No,)). AAS analysis revealed that Pb accumulation in the plant tissue (BCF) increased with increasing Pb levels in the culture solutions. Pb accumulation had caused the development of chlorotic leaves and decreases in the fresh biomas of the plants. However, there was no interference of the Pb accumulation on the growth responses of Pistia in terms of moisture, chlorophyll, and protein contents. These findings imply that P. stratiotes might be useful in heavy metal decontamination process in industrial and domestic wastewaters. These responses also indicate the potential of Pistia as a lead scavenger and bioremediation tool in the aquatic environment. 

On Maximal Biconnected Graphs

On Maximal Biconnected Graphs

pp 11-15 (Vol 4 No. 1 2001)

Alex C. Gonzaga
Department of Physical Sciences and Mathematics
University of the Philippines-Manila
Padre Faura Street, 1004 Manila, Philippines

ABSTRACT

A biconnected graph is a connected graph that contains no complete bipartite spanning subgraph. This paper deals mainly with maximal biconnected graphs. We provide a characterization and some properties of this class of graphs. We determine their
dominance and independence numbers. We also prove some properties in G and format.

Hydrothermal Synthesis and Characterization of an Akaganeite-type Iron Oxide Octahedral Molecular Sieves

Hydrothermal Synthesis and Characterization of an Akaganeite-type Iron Oxide Octahedral Molecular Sieves

pp 1-10 (Vol 4 No. 1 2001)

Elaine Nicolas-Tolentino and Pamela Alfornon
Chemistry Department, De La Salle University
2401 Taft Avenue, 1004 Manila, Philippines

ABSTRACT

Iron oxide octahedral molecular sieve with 2×2 tunnel, designated as FeOx-OMS (2×2) was successfully synthesized by hydrothermal method. FeOx-OMS (2×2) has high degree of purity and higher thermal stability than those of previously reported akaganeite­type materials. The X-ray powder diffraction (XRD) pattern shows peaks that are characteristic of pure akaganeite-system. Based on its TGA profile, its thermal stability is reported up to 255 •c, and beyond 402 °C, new phases are formed which is a mixture of hematite and magnetite based on its XRD pattern. The SEM result shows needle-like morphology that is typical of a tunnel structure. 1