A Conversation between Scientists and Philippine High School Students

The following is a series of messages taken from a discussion forum on Yahoo! (PhilScience: State of RP Science), an offshoot of email discussions initiated by Dr. Flor Lacanilao, a retired professor of marine science from the University of the Philippines. It illustrates the use of the internet in which students could ask questions to Philippine scientists. And the scientists are ready to answer.

Codium bartlettii
University of Michigan Herbarium Algae Type Collection
From: Katrina Arboleda
To: Dr. Lawrence Liao
Sent: Wednesday, July 4, 2012 1:22:48 PM
Subject: Rotavap

Good Day Dr. Liao,

We are senior students from Philippine Science High School- Western Visayas. We are currently conducting our research study which is entitled, "The Antibacterial Activity of hexane and methanol extracts of the seaweed Codium bartlettii against E. faecalis, E. coli, P. aeruginosa, and S. aureus".

Sir, firstly, we have powderized the seaweeds and we mixed them with the solvents separately. We are currently agitating the mixture by the use of shaker. We have observed that in our methanol extracts, the solvent has turned green but there are still powdered seaweeds that settles in the bottom of the flask. While in our hexane extracts, the powdered seaweeds settle at the bottom and no changes in the color of hexane was observed for five days. Sir, we are confused as to whether we have really extracted something from the seaweeds using hexane as our solvent. For this reason Sir, we would like to ask what are the indications that our solvents were able to extract something from the seaweeds. 
We are really hoping that you'll be able to help us whenever possible.

Katrina, Arboleda, Jamie Cuadra, and Paul Leo


On Wed, Jul 4, 2012 at 1:03 PM, Lawrence M. Liao wrote:

Hi Friends in Science

I am taking the liberty to forward this mail to you which was sent to me by students from the Philippine Science High School - Western Visayas campus.  I have corresponded with these students as well as with other students from Philippine schools and HEIs as a way of helping them out with some of their questions on science, etc.  I try my best to help them with answers, or with their requests for scientific article downloading, or simply to provide some inspirations and ideas to these students.  It is a small gesture that may have some impact on these young minds.

The questions in this forwarded mail are something some of you can answer easily and with more authority.  So may I request you to direct your answer and suggestions to these students straight into their inbox.  Please don't post them in our group since they are not members yet (although you can cc to our group).  I thank you for your kind attention and generosity of time.  Your help will go a long way towards inspiring these young students.


Lawrence M. Liao 
Graduate School of Biosphere Science
Faculty of Applied Biological Sciences
Hiroshima University
1-4-4, Kagamiyama, Higashi-Hiroshima
Japan 739-8528


Reply by: Ben O. de Lumen 
July 5, 2012, 5:03 AM 

to Katrina, ASBP 
Hi Katrina,

I think you are headed in the right direction.

1). You are using two different solvents: one hydrophilic or polar
(methanol) and the other non-polar or organic (hexane). Methanol would
extract polar cpds while hexane would extract non-polar cpds. I suggest
that you use ethanol instead of methanol because methanol is toxic while
ethanol is a more common solvent and less harmful and the two are very
similar in their solvation effects.

2. The methanol extract is green because the chlorophyll has been
extracted while the hexane being an organic solvent does not extract
cholorophyll but mostly non-polar cpds which are colorless.
3. Don't worry about the ground seaweed settling down - that would always happen and not a good indicator of the extent of extraction. Degree of extraction would be determined by extraction time, temperature and how much you stir.

4. Be careful with hexane - its highly flammable.

Best wishes,
Ben de Lumen

Ben O. de Lumen, PhD
Professor Emeritus
Nutritional Science & Toxicology
UC Berkeley, CA 94720-3104


Reply by: a_c_de_dios
July 5, 2012, 5:33 AM 

First, hexane and methanol differ in polarity. Methanol extracts will contain compounds that are polar while hexane extracts will be nonpolar. The green color generally comes from chlorophyll, whioh can be extracted by diethyl ether, acetone:water mixture, or methanol. To determine whether the extracts contain compounds from seaweed, spectroscopic methods (usually uv-vis spectroscopy) are employed since some of the compounds extracted are colorless, especially the macrolides, the substances responsible for antimicrobial activity.

I think the following articles say more of these in detail:

Angel C. de Dios
Department of Chemistry
Georgetown University
Washington, DC 20057

From: Flor Lacanilao
Date: Thu, Jul 5, 2012 at 6:43 PM
Subject: Re: Rotavap -- Students of Philippine Science High School
To: Katrina Arboleda

Science learning at the Philippine Science High School

Dear Katriina and others,

In senior high school, you are already doing experiment, as a way of learning science -- doing partly how scientists work. As you might have already learned, experiments are just one part of doing research. And from members of this science forum, you have so far got a few suggestions to improve your experiment (see above).

To complete a research work, you also have been told that your results should be communicated (published). If this is done properly, then it will allow other researchers in different parts of the world (your future peers) to verify or confirm your results, by repeating your experiments. This verification of results is an indication or measure of your contribution to scientific knowledge (science). You are fortunate that at the Philippine Science High School, you are already learning how to do research properly.

Another aspect of research you are being trained -- now in high school, later in college, and then in graduate school -- is how you will be able to help in solving problems facing your country. The most serious among them are the threats from global warming. With these climate-related problems, our government will have to turn to its scientists.

Let me give you a preliminary view of some of them, which, I hope will supplement what you have been hearing, reading, and taught at the Philippine Science High School. Below is a plenary lecture I gave 3 years ago.

 "Adapting to Climate Change through Research & Education" at any of these links,
See also attachment for a Power Point (Video) illustrating some of the things discussed in the paper.

I hope you find them useful in your present and future work. 

Best regards,
Flor Lacanilao

Retired professor of marine science
UP Diliman

Preparing for Climate Change
Dr. Flor Lacanilao