Light to fight malaria!

To begin with

Scientists successfully use photochemical techniques to study herbal anti-malarial substances and suitably modify them to meet the needs of a new generation of low cost, more effective and long lasting drugs.

Keywords

Malaria, Polarized light, Fluorescence, Cyclodextrin, Circular Dichroism, Artemisinin, Chirality

About

Malaria is a terrible disease that kills more than a million of people every year and debilitates hundreds of millions worldwide. It is caused by parasites of the species Plasmodium that are transmitted via the bites of infected mosquitoes. People living in tropical and subtropical regions and especially those in the poorest countries are the most vulnerable to malaria infection. Inappropriate use of antimalarial drugs in the past century contributed to widespread resistance of malaria parasites.
Over the past decade though, a new group of medicinal therapies that make use of the therapeutic qualities of the Artemisia plant, has increased the efficacy of antimalarial drugs. These therapies are known as Artemisinin-based combinations. (watch Dr. Marconi presenting Artemisia Annua)
Scientists at the ISOF–CNR Institute in Bologna have successfully introduced an innovative method that uses laser light in order to study and enhance the properties of Artemisia based drugs. Their research results constitute an up-to-date weapon in the fight against malaria. 

Links with society

The fight against malaria, which kills millions of people every year, requires quite a lot of scientific effort as well as sophisticated techniques in order to obtain the most effective drug for chemotherapy in a relatively short time. Moreover, the suggested therapy should be economically affordable, so that the poorest populations that need it most to be able to make use of it. It is expected that the ideal drug shouldn’t show undesirable side effects and it will maintain its efficacy in the long run.
Inappropriate use of antimalarial drugs in the past century induced opposite effects reinforcing the potential threat of the disease. Nowadays, the scientists have turned to nature for help. They focus on a drug extracted from Artemisia annua (sweet wormwood), a plant of Chinese origin, and more specifically on a molecule called Artemisinin.  This molecule is able to directly affect the cycle of malaria parasites and clear them from the blood in three days.
Yet, Artemisinin cannot be obtained easily since it is produced in a very limited quantity, less than 0.05 % in weight. Secondly, in order for the plant to flower and produce Artemisinin in the sepals, a long photoperiod of at least 16 hours is needed. However, these weather conditions don’t exist especially in equatorial countries that are in need of an immediate solution. (watch Dr. Marconi talking about Artemisinin shortcomings)
The research results coming from the ISOF–CNR Institute in Bologna provide a satisfactory answer to this call. Based on nature’s medicines and laser light, the scientists succeeded in defining and enhancing the beneficial properties of Artemisinin molecule. Their work constitutes an up-to-date weapon to fight that terrible disease. (watch Dr. Manet talking about how they enhance the properties of antimalarial drugs)

Research innovation

A modern study on malaria aims to: i) create the most effective drug for chemotherapy in a very short time and ii) produce an economically affordable drug for the poorest populations. Moreover, this new drug shouldn’t show undesirable side effects. (watch Dr. Marconi talking about the innovative character of their research)
Scientists at the ISOF–CNR Institute in Bologna focused their efforts on producing such a drug from a natural molecule called Artemisinin, which is extracted from the plant Artemisia annua (sweet wormwood). They studied the curative properties of Artemisinin using sophisticated laser light techniques (spectroscopy and photophysics), which eventuated in better understanding the potentials of Artemisinin-based therapies.
Moreover, the scientists managed to overcome serious shortcomings emerging from the manipulation of the molecule. A major problem was its scarce solubility, which was treated with the inclusion of the molecules in artificial carriers soluble in water (cyclodextrins). Another disadvantage was the molecule’s short time of degradation in the human body, which required its coupling with another molecule that could prolong effective action. What is still under investigation is the activation mechanism at the cellular level concerning proteins and DNA. (watch Dr. Manet explaining how they tackled solubility problems)

Relevant scientific publications:

G. Marconi, E. Mezzina, I. Manet, F. Manoli, B. Zambelli and S. Monti: Stereoselective Interaction of Ketoprofen Enantiomers with β-Cyclodextrin: ground state binding  and Photochemistry, Photochem. Photobiol. Sci., 10, 48-59, 2010.

S. Monti, I. Manet, F. Manoli, S. Ottani, G. Marconi: Licochalcone-A bound to bovine serum albumin: a spectroscopic, photophysical and structural study, Photochem. Photobiol. Sci., 2009, 8, 805 – 813.

G. Marconi, S. Monti, F. Manoli, S.Ottani : Circular Dichroism and theoretical studies on the inclusion of the antimalarian drug Licochalcone-A in β-cyclodextrin, J. Incl. Phenom. Macrocycl. Chem., 57, 279-282, 2007.

R. Baraldi, B. Isacchi, S. Predieri, G. Marconi,  F. F. Vincieri, A. R. Bilia: Distribution of artemisinin and bioactive flavonoids from Artemisia annua L. during plant growth,  Biochemical Systematics and Ecology, 36, 340-348, 2008.

Description of the method

Following the researchers in their lab.

The study of malaria and its therapy are connected to various scientific disciplines. As far as it concerns the laboratory work, wide interdisciplinary research expertise is necessary, including knowledge on agriculture, botany, physiology of plants, extraction of natural substances etc. The photochemical research is mainly based on organic synthesis, spectroscopy, photophysics and molecular modeling. The scientists at the ISOF–CNR Institute in Bologna use laser light to reveal the secrets of the complicated structure of Artemisinin molecule and its interactions with biomolecules such as proteins. (watch Dr. Marconi describing the research methodology)

In more detail, the scientists employ Circular Dichroismcircularly polarized laser light and takes advantage of a property of matter called chirality. Chiral molecules are not superimposable on their mirror image (the same happens, for example, with our hands). The most frequent chiral molecules in organic chemistry contain a carbon atom connected to four different atoms or groups of atoms. Artemisinin is considered such a chiral molecule having 7 different centres of chirality, which is the reason why it is much easier to extract it by the plant instead of trying to synthesize it. (watch Dr. Marconi talking about chirality)

By hitting Artemisinin molecules with circularly polarized light beams, the scientists get signals of different absorption between left and right components that reveal important aspects of the molecules' structure. The detection of these signals is made with dichrograph, a scientific instrument widely used at the ISOF–CNR Institute for getting various types of information ranging from nanomaterials to biomolecules.

The scientists also use light as a probe. They are based on the fluorescence of the molecules in order to explore their surroundings. However, Artemisinin and other antimalarials extracted by plants are non-fluorescent (i.e. they do not emit detectable light when irradiated with laser). The next step is then to attach suitable dyes on the drug molecules that will fluoresce at specific wavelengths. Once these molecules are introduced into blood cells affected by the Plasmodium parasite, the scientists can follow their interactions with the help of a confocal fluorescence microscope. They can therefore gain knowledge on the drug main mechanism (membrane cell transport inhibition or radical formation or possibly both), which in turn brings improvements on the drug structure making it more effective in the fight against the parasite. (watch Dr. Manet talking about confocal microscopy in their research project)

Historical background

What was before?

The fight against malaria is one of the most fascinating in the history of medicine since it hasn’t been decisively won for more than 7000 years. The evolution of this adventurous search for remedies entailed many steps, going from the serendipitous discovery of quinine in the XVII century, to the serious attempts of great scientist to reveal the complex mechanism of the transmission and propagation of the infection (A. Laveran, R. Ross and G.B. Grassi, among others). Moreover, in the 1970s, during Chairman Mao's Cultural Revolution, young scientists uncovered the astonishing powers of the traditional herb qinghao or Artemisia annua (sweet wormwood) as a cure for malaria.  The story of this discovery is like a modern fairy tale. Finally, the chirality concept as well as the polarized light and its interaction with chiral compounds detected through the Circular Dichroism technique, have deep roots in the history of science and technology, going from the first Pythagoras’ observations to the Viking sunstones and the discoveries of Louis Pasteur concerning molecular dissymmetry.

The"face" of Science: Let's meet the scientists

The “face” of science: Dr. Giancarlo Marconi, senior scientist at the ISOF–CNR Institute in Bologna, Italy.

Brief introduction: Dr. G. Marconi holds a degree in Chemistry. He has been a postdoctoral researcher in USA (University of Utah) and Denmark (University of Aarhus) and senior visitor scientist in several labs in Japan. Since 1976 he has got a permanent position at CNR in Bologna.

Research interests: Theoretical aspects of Photochemistry, Optical activity of chiral molecules, Magnetic Circular Dichroism, Molecular modelling and Quantum mechanical calculations of CD spectra.

Sources of inspiration: His passion for the world of plants inspired him among others to devote this research project to antimalarial drugs.

Important moments in his “scientific life”: G. Marconi read about the possibility of curing malaria with the help of herbal drugs at the end of the nineties. He eventually joined his competence in botany and physical chemistry to fight the disease by trying to chemically improve these natural antimalarial substances and to better understand their action at a cellular and molecular level within the human body.

Research team behind the scenes: Apart from the researchers at the ISOF–CNR Institute (Dr. Manet, Dr. Monti, Dr. Ottani and Mr. Manoli), an important collaboration has been developed with synthetic chemistry (Dr. Greta Varchi, ISOF, Bologna) and microbiological groups (Prof. D. Taramelli, University of Milan).

Editing Team

Editing team of the Digital Exhibit “Light to fight malaria!”

Scientific editors: Dr. Giancarlo Marconi, senior scientist at the ISOF–CNR Institute

Content Coordination: Glykeria Anyfandi
Science Communication Editors: Evlalia Amygdalaki, Glykeria Anyfandi
Content Administration: Christina Troumpetari, John Stoitsis
Technical Development: John Stoitsis
Photographs, videos & web material: Evlalia Amygdalaki
e-Knownet Live experiments: Interactive Science & Technology Exhibition, Eugenides Foundation