Study demonstrates antimicrobial action of polyalthic acid from copaiba oil
Findings reported in the journal Antibiotics by scientists working in Brazil and the United States pave the way for the development of drugs against resistant bacteria
Peer-Reviewed PublicationPolyalthic acid from copaiba oil is an effective antibacterial and should be used to develop alternative medications that can contribute to the effort to overcome antimicrobial resistance (“superbugs”), according to an article by researchers based in Brazil and the United States published in the journal Antibiotics.
More than 2.8 million antibiotic-resistant infections occur in the US and more than 35,000 people die as a result each year, says a report issued in 2019 by the Centers for Disease Control and Prevention (CDC).
Antimicrobial or antibiotic resistance is when germs (bacteria, fungi) develop the ability to defeat the antibiotics designed to kill them (it does not mean our bodies are resistant to antibiotics). It is expected to become the main global cause of death by 2050.
The crisis is due to improper prescribing of antibiotics, intense use of these drugs in agriculture, and overuse of a small number since the leading pharmaceutical companies decided to abandon the development of antibiotics owing to high cost and low return on investment.
In this context, resorting to plants as a source of novel drugs has proved a promising alternative. To stimulate knowledge production in this field, researchers in Brazil at the University of São Paulo’s Ribeirão Preto School of Pharmaceutical Sciences (FCFRP-USP) and São Carlos Institute of Physics (IFSC-USP), in collaboration with colleagues at the University of Franca (UNIFRAN), also in Brazil, and the College of Pharmacy and Health Sciences at Western New England University (WNE) in the US, investigated copaiba oil, derived from Copaifera trees and traditionally used in the Amazon region as a natural remedy for its wound-healing, anti-inflammatory and antimicrobial properties. Its main constituents are diterpenes (20%), including polyalthic acid, and sesquiterpenes (80%). Both groups of compounds are anti-inflammatory and antimicrobial.
The research was supported by FAPESP via six projects (13/07600-3, 11/23493-7, 11/13630-7, 22/07984-5 and 19/04788-8.
The researchers synthesized four polyalthic acid analogs with structural modifications to make them more active against pathogens, and investigated their efficacy against biofilms of Staphylococcus epidermidis, a bacterium that causes skin and digestive tract infections, and against several Gram-positive bacteria (Enterococcus faecalis, Enterococcus faecium, S. epidermidis and Staphylococcus aureus). They also determined the minimum dosage required to inhibit planktonic (free-floating) bacteria.
Activity tests and comparisons with the original polyalthic acid and the drug most prescribed by physicians showed that the analogs developed by the researchers eradicated S. epidermidis, and were active against all the Gram-positive bacteria tested. Although they were less active than the prescribed drug, the results reinforced the importance of additional in vitro and in vivo testing of the substance.
“The advantage of studying polyalthic acid is that previous research has shown that some terpenes don’t lose their activity, and their continuous use therefore doesn’t make bacteria develop resistance,” said Cássia Suemi Mizuno, a researcher at WNE and last author of the article.
The analogs were found to be safe in an analysis of hemolytic activity, i.e. their ability to destroy red blood cells.
Next steps
“Our research is an important contribution to efforts to beat antimicrobial resistance and serves as a foundation on which other groups can made further progress,” Mizuno said.
Next steps will include producing more derivatives with other parts of the polyalthic acid molecule, improving their activity and pursuing prospective partners in the pharmaceutical industry for more research, she added.
Investment in copaiba oil extraction in the Amazon will be needed, as will the recruitment of forest dwellers who are familiar with the native vegetation and can identify the species with the highest level of polyalthic acid content (Copaifera reticulata Ducke).
“It should be stressed that we don’t destroy any trees in our research. Extraction of copaiba oil is like rubber tapping. You just make a groove in the bark of the tree trunk,” Mizuno said.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.
ARTICLE TITLE
Synthesis and Antibacterial Activity of Polyalthic Acid Analogs
Cocoa pods — a source of chocolate, and potentially, flame retardants
IMAGE:
COCOA PODS, LIKE THIS ONE WITH PARTS OF THE HUSK REMOVED FOR ANALYSES, COULD BE A USEFUL STARTING MATERIAL FOR FLAME RETARDANTS.
view moreCREDIT: DIMITRIS CHARALAMPOPOULOS
As Halloween approaches, so too does the anticipation of a trick-or-treating stash filled with fun-sized chocolate candy bars. But to satisfy our collective craving for this indulgence, millions of cocoa pods are harvested annually. While the beans and pulp go to make chocolate, their husks are thrown away. Now, researchers reporting in ACS Sustainable Chemistry & Engineering show that cocoa pod husks could be a useful starting material for flame retardants.
It’s estimated that about 24 million tons of leftover cocoa pod husks are produced yearly. Waste husks have been explored as a source of carbohydrates and sugars, but they also contain lignin, a tough lipid polymer found in many woody plants. And lignin could be a renewable replacement for some substances typically derived from petroleum, such as flame retardants. While most methods to produce lignin have centered on hardwood trees, some scientists have processed other plant materials that would otherwise go to waste, such as rice husks and pomegranate peels. So, Nicholas J. Westwood and coworkers wanted to see if high-quality lignin could be extracted from cocoa pod husks and determine whether it has the potential to make valuable, practical materials.
The researchers obtained cocoa husks and milled them into a powder. After rinsing to remove fatty residues, they boiled the powdered husks in a mixture of butanol and acid, a standard lignin extraction method called the butanosolv process. They next confirmed the isolated lignin’s quality and high purity, finding no evidence of carbohydrates or other contaminants.
Then, over the course of three chemical steps, the team modified the pure lignin biopolymer to have flame-retardant properties. They attached 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which is a fire suppressant molecule called DOPO, into the backbone of the lignin polymer. In experiments, when the modified lignin was heated, it charred — but did not burn up — a sign that it could act as a flame retardant. The researchers recognize that human safety tests are important and plan to conduct them after the next phase of testing. In the future, the researchers say they will optimize the properties of their cocoa pod husk-based flame-retardant materials.
The authors acknowledge funding from the UK Biotechnology and Biological Sciences Research Council through the Global Challenges Research Fund and for in-kind contributions from Mars Wrigley Confectionery.
The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.
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JOURNAL
ACS Sustainable Chemistry & Engineering
ARTICLE TITLE
Organosolv Pretreatment of Cocoa Pod Husks: Isolation, Analysis, and Use of Lignin from an Abundant Waste Product
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