Plants of the Kaliningrad region turned out to be rich in antioxidants and antimicrobials

Scientists from the Immanuel Kant Baltic Federal University stated that the biological activity of extracts of four plants that growing in the Kaliningrad region is provided by phenolic compounds — aromatic alcohols. These substances provide antioxidant and antimicrobic properties to Aesculus hippocastanum, Melilotus officinalis, Eryngium maritimum, and Hedysarum neglectum. The extracts of these plants can potentially be used as anti-inflammatory drugs in medicine for the treatment of heart diseases and pulmonology. The results of the research, supported by the Grant of the President program of the Russian Science Fundation (RSF), are published in the journal Food and Raw Materials.

During inflammatory processes, cells accumulate dangerous radicals and oxygen derivatives that can destroy membranes and DNA. Antioxidants can prevent these destructions. Such compounds are naturally found in medicinal plants. In addition, plants can produce substances with antimicrobial activity. Unlike antibiotics synthesized by humans, they don’t require expensive research. Official medicine recognizes the potential and gives preference to medicinal plants when it concerns the treatment of many diseases. However, despite the existence of obvious biological activity that is potentially attractive for medicine, some of the medicinal species remains underexplored.   

Scientists from the Immanuel Kant Baltic Federal University (Kaliningrad), Kaliningrad State Technical University (Kaliningrad) and Kemerovo State University (Kemerovo) studied the antioxidant and antimicrobial properties of medicinal plants growing in the Kaliningrad region. The researchers chose sea holly (Eryngium maritimum L.), sweet yellow clover (Melilotus officinalis Pall.), sweetvetch (Hedysarum neglectum Ledeb.), and horse-chestnut (Aesculus hippocastanum L.), the biologically active substances of which haven’t been determined yet. Scientists isolated extracts from stems, leaves and flowers and then tested the antioxidant activity of the samples. To do this, the biologists mixed the extracts with a solution of the radical DPPH, which was dark purple but lost its color when a solution of antioxidants was added. Thanks to this color reaction, the scientists were able to estimate whether the extracts contained molecules that prevented the accumulation of radicals.

Scientists also identified a chemical composition of compounds that characterize the antioxidant activity of the extracts. They did this using infrared (IR) spectroscopy, a method based on passing IR radiation through a sample and observing how a substance interacts with the light.

It turned out that the extracts contained a large number of phenols, which are substances containing alcohol with 6 carbon atoms in the form of a ring. The highest number of phenols was found in the leaves, which also showed the highest antioxidant activity against the DPPH radical.

The scientists also tested the antimicrobial activity of the extracts. To do this, they grew cultures of bacteria and microfungi such as E. coli and Candida albicans, which are normally harmless to humans but can cause infections in people with weakened immune systems. They placed extracts on a Petri dish with microorganisms. When plant extracts had antimicrobial substances, bacteria and fungi stopped growing around the place where the extracts were applied. The antimicrobial activity of the extracts was estimated according to the space free of microorganisms. It turned out that sea holly had the strongest antibacterial properties. It effectively suppresses the growth of the hay bacillus (Bacillus subtilis) found in soil, water, air, and human intestines. However, the antimicrobial activity of sea holly was twice lower than that of the industrially produced antibiotic kanamycin. However, although the antimicrobial activity of the plants studied was lower than that of industrial antibiotics, they can potentially be used in the treatment of inflammatory diseases.

“IR spectroscopy can be of great practical importance as a method of express analysis of infusions of medicinal plants. This method can be used in medicine and cosmetology to create safe and effective plant-based products. Thus, based on the results of IR spectroscopy, the studied plants from the Kaliningrad region can potentially be used in medicine for the treatment of heart diseases and pulmonology”, — says the head of the project supported by the grant of RSF, Olga Babich, Doctor of Engineering, Director of the Research and Education Center “Applied Biotechnologies”, leading research fellow of the Immanuel Kant Baltic Federal University.