College of Science

Isolation, Structure Elucidation and Antimicrobial Assay of Secondary Metabolites from Six Philippine Medicinal Plants


(19 S U/C/S 1 06)

Dr. Consolacion Y. Ragasa
Chemistry Department

The air-dried leaves of Tectona philippinensis, an endemic and endangered Philippine medicinal tree, afforded four new chromomoric acid derivatives (1, 2, 3a and 3b). Their structures were elucidated by extensive 1D and 2D NMR spectroscopy. Antimicrobial testing was carried out on 1-3 against a panel of bacteria and fungi. The following known compounds were also obtained from the leaves of the plant: 5-hydroxy-3,7,4'-trimethoxyflavone (4), 5,4'-dihydroxy-3,7-dimethoxyflavone (5), squalene (6), a mixture of lupeol (7a) and β-amyrin (7b), chlorophyllide a (8), and hydrocarbons. Antimicrobial tests on 4 and 5 indicated low antifungal activity against the fungi, C. albicans and T. mentagrophytes. Compound 4 was also found to have low antibacterial activity against E. coli and P. aeruginosa.

SEE FIGURE 1

figure 1

The dichloromethane extract of the corm of Musa errans, an endemic form of wild banana afforded 31-norcyclolaudenone (1), squalene, and a mixture of stigmasterol and sitosterol. The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy. Antimicrobial tests on 1 indicated that it has low activity against C. albicans; E. coli, P. aeruginosa, and T. mentagrophytes; and inactive against B. subtilis, S. aureus, and A. niger.

SEE FIGURE 2

figure 2

The dichloromethane extract of the air-dried flowers of Tagetes erecta afforded 2,2':5',2'-terthiophene (1) and 5,7,4'-trihydroxyflavanone (2). Compound 2 showed moderate activity against C. albicans, low activity against E. coli, P. aeruginosa, S. aureus, and T. mentagrophytes, and inactive against A. niger. Compound 2 was tested for cytotoxicity against a human lung non-small cell adenocarcinoma (A549) cell line and a normal Chinese hamster ovarian cell line (AA8). It was found inactive against A549 and AA8.

SEE FIGURE 3

figure 3

The stem of Pouteria campechiana afforded 1 and a mixture of 2 and 3 in a 0.3:1 ratio by silica gel chromatography. Their structures were elucidated by extensive 1D and 2D NMR spectroscopy. Antimicrobial tests on 1 and a mixture of 2 and 3 indicated that they are slightly active against the bacteria, E. coli and P. areruginosa and the fungi, C. albicans and T. mentagrophytes. They are inactive against S. aureus, B. subtilis, and A. niger.

SEE FIGURE 4

figure 4

The dichloromethane extract of the air-dried flowers of Michelia champaca afforded 11,13-dehydrolanuginolide (1) by silica gel chromatography. The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy. Antimicrobial tests on 1 indicated that it is moderately active against the fungus, Candida albicans. It has low activity against the bacteria, P. aeruginosa and E. coli and the fungus, T. mentagrophytes. It is inactive against S. aureus, B. subtilis, and A. niger.

SEE FIGURE 5

figure 5

Air-dried leaves of Citrus microcarpa Bunge afforded 3',4',5,6,7,8-hexamethoxyflavone (1) and squalene. The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy. Antimicrobial tests on 1 indicated that it has moderate activity against the fungus, C. albicans and low activity against the bacteria, P. aeruginosa and B. subtilis and fungi, T. mentagrophytes, and A. niger.

SEE FIGURE 6

figure 6

Graphtex

(42 UERF 3 03)

Dr. Severino Gervacio
Mathematics Department

Preface

I first used plain TEXsometime in 1992. I needed to draw graphs (a collection of vertices and edges) and I had to look for drawing packages to create my drawings. There was no single package that will serve my purpose and I had to write additional macros on top of those that are available. This challenged me to create macros to draw graphs. The first version of GraphTEX (which contains about 55 macros) appeared in 1994. This version of GraphTEXcontains about 168 macros for drawing graphs plus a lot more. Macros for drawing special graphs such as paths, cycles, fans, wheels, complete graphs, complete bipartite graphs, and generalized Petersen graphs are included in GraphTEX Drawing Bézier curves with quadratic or cubic parametric equations are included. These are applied to make approximate drawings of circles, ellipses, hyperbolas, and sine and cosine curves. The approximation is shown to have a high degree of accuracy by showing that the maximum error in the drawing is very small and negligible. Parabolas are drawn correctly using second degree Bézier curves. GraphTEX is also capable of performing translation, reflection and rotation. Three-dimensional drawings and graphs can be created using GraphTEX. Miscellaneous macros about summation, multiplication, day, date, time, etc. are also included.

I hope that GraphTEXcould provide most if not all the things that one needs in making drawings in a TEXor LATEXdocument. What GraphTEXlacks could perhaps be added without much difficulty by building other macros from its existing macros.

This project which consisted of expanding and enhancing GraphTEX including the writing of this book was done during the period September 2004 to August 2005 under the Research Faculty Program of De La Salle University-Manila.

Quantum Percolation of Infinitely-Sized Disordered Clusters in Two Dimensions

(58 N 3 05)

Dr. Eduardo C. Cuansing Jr.
Physics Department

We study the hopping transport of a quantum particle through finite, randomly diluted percolation clusters in two dimensions. We investigate how the transmission coefficient T behaves as a function of the energy E of the particle, the occupation concentration p of the disordered cluster, the size of the underlying lattice, and the type of the connection chosen between the cluster and the input and output leads. We investigate both the point-to-point contacts and the busbar type of connection. For highly diluted clusters we find the behavior of the transmission to be independent of the type of connection. As the amount of dilution is decreased we find sharp variations in transmission. These variations are the remnants of the resonances at the ordered, zero-dilution, limit.

For particles with energies within 0.25 ≤ E ≤ 1.75 (relative to the hopping integral) and with underlying square lattices of size 20 x 20, the configurations begin transmitting near Pα = 0.60 with T against p curves following a common pattern as the amount of dilution is decreased.

Near Pβ = 0.90 this pattern is broken and the transmission begins to vary with the energy. In the asymptotic limit of very large clusters we find the systems to be totally reflecting in almost all cases. A few clear exceptions we find are when the amount of dilution is very low, when the particle has energy close to a resonance value at the ordered limit, and when the particle has energy at the middle of the band. These three cases, however, may not exhaust all possible exceptions.