Antibacterial and antioxidant activity of different Raphanus sativus (black, red and Chinese) varieties

Interest in researching medicinal plants as natural sources of active chemicals has increased due to the growing resistance of bacteria to traditional antibiotics and the illnesses linked to oxidative stress. Because of their qualities, including their antibacterial and antioxidant capabilities, medicinal plants have become a major area of interest in both conventional and modern medicine. The vast range of biological chemicals they contain is what gives them these characteristics. Radish (Raphanus sativus L.) is regarded as a plant high in vitamins, minerals, and potent phytochemicals in many cultures. As a result, researchers have been paying more and more attention to it lately, especially because of the global movement to treat infectious and chronic diseases with natural and safe sources. Comprehensive comparisons across various species are still rare, despite a few limited research on the characteristics of various radish kinds. This is particularly true when it comes to how extraction techniques affect the potency of biological substances. The aim of this study is to examine the biological characteristics of three distinct varieties of radish (Raphanus sativus L.)—red, black, and Chinese radish—with a specific focus on their antibacterial and antioxidant properties. These properties were evaluated using two different extraction methods: ethanol and dichloromethane. The radish samples were collected from local markets in the Sakarya region of Turkey and were carefully selected based on their botanical features and suitability for laboratory analysis to ensure freshness and quality. For 72 hours, the plant components were freeze-dried, a process called lyophilization, which preserves the chemical structure of biologically active chemicals. In terms of preserving the integrity of plant chemicals, this approach is better than conventional drying methods. Following drying, an electric blender was used to grind the samples into an extremely fine powder. By increasing the dried plant material's surface area, this procedure makes it easier for it to interact with solvents and help extract chemicals. One essential step in making sure that every area of the plant received the same amount of solvent exposure was the grinding process. The effectiveness of removing physiologically active substances from plant tissues was boosted as a result. A Soxhlet device was utilised for efficient extraction once the plant components had been ground into a fine powder. Because it is so effective at producing the desired extracts, this approach is regarded as one of the best. The solvents were eliminated using a rotary evaporator in order to maintain the safety of the chemical compounds that were produced. In order to prevent heat effects that can harm the active compounds' chemical characteristics and maintain their structural integrity, this process was conducted at moderate temperatures and low pressure. Two primary techniques were used to assess the antioxidant activity of the extracted materials. The DPPH test is used in the first approach to scavenge free radicals. This test evaluates the extracts' ability to eliminate harmful free radicals and demonstrates the efficiency of the antioxidant components. The second approach makes use of the reduction test, which gauges antioxidant activity by determining the ability to convert ferric ions to ferrous ions. Furthermore, a popular method for figuring out how much phenolic chemical is present in plant samples—the Folin-Ciocalteu method—was applied. The extracts total phenolic content was ascertained using this technique. Milligrammes of gallic acid equivalent (mg GAE/g) per gramme of extract are used to display the results. The standard reference material used to ascertain the phenol content in the samples is gallic acid. According to the results of the DPPH test, Chinese radish can scavenge free radicals at a rate of 72% at a concentration of 1000 µg/mL. As a result, it is a superior antioxidant to the others. Red radish had the lowest performance at 39%, while black radish had the highest at 59%. These results show that antioxidant activity and phenol concentration are positively correlated. Chinese radish's high phenol concentration indicates that it has the capacity to eradicate dangerous free radicals. At all tested concentrations (250, 500, and 1000 µg/mL), Chinese radish showed iron reduction capacity, demonstrating its great efficiency in converting ferric (Fe³⁺) ions to ferrous (Fe²⁺) ions, hence highlighting its antioxidant capabilities. Black radish came in second place with a decent reduction capacity, while red radish had the lowest reduction capacity in this test. The Folin-Ciocalteu method was also used to determine the total phenolic content of the plant extracts. The results show that Chinese radish has the highest concentration of phenolic compounds, with the highest value being 18.1 milligrams of gallic acid equivalent (mg GAE/g). Red radish comes in second with 14.6 mg GAE/g, and black radish follows with 13.3 mg GAE/g. According to these results, Chinese radish has the highest phenolic content, which is consistent with its antioxidant capacity as shown by assays like the DPPH and iron reduction tests. According to these findings, Chinese radish is a great choice for a natural antioxidant component source because it has the highest antioxidant capacity of the three types. This characteristic is especially helpful in a variety of applications, including nutritional supplements and health goods. The efficacy of plant extracts against different bacterial strains was assessed by the use of the Disc Diffusion Method in the antibacterial activity test. The Microbiology Research Laboratory of Sakarya University's Department of Biology, Faculty of Science, provided the bacterial strains used in this investigation. These include Staphylococcus epidermidis (ATCC 12228), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 8739), Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (ATCC 29213), and Salmonella typhimurium (ATCC 14028). These strains were reactivated and kept in laboratory preservation conditions before to being employed in the tests. The majority of the tested strains were generally unaffected by the extracts made with ethanol and dichloromethane solvents. With inhibition zones of 11 mm and 14 mm, respectively, the black radish ethanol extract demonstrated antibacterial activity against Staphylococcus aureus and Enterococcus faecalis. With inhibition zones spanning from 17 to 22 mm, gentamicin, which served as a reference control, demonstrated broad-spectrum action against every strain that was tested. These results corroborate earlier studies showing that radish's high phenolic component content boosts its antioxidant effectiveness. It has been demonstrated that the ethanol-prepared extract has a significant impact on specific bacterial strains, including Enterococcus faecalis and Staphylococcus aureus. The bacterial strains employed in this investigation were unaffected by the other extracts. These findings pave the way for additional research targeted at pinpointing the substances causing this impact and providing a more thorough explanation of the mechanisms. According to the study's findings, it is advised that comprehensive chemical investigations be carried out in order to pinpoint the active ingredients that give radish extracts their biological activity, particularly in the extract that shown a definite impact on particular bacterial strains. In order to assess the efficacy of these extracts as possible natural substitute sources, it is also recommended that future studies employ bacterial strains that are resistant to antibiotics. To increase extraction efficiency and preserve the compounds' chemical structure, it's also necessary to try out different extraction techniques including ultrasonic extraction and extraction using supercritical solvents. To confirm if these extracts are safe for human usage, more research on toxicity and biosafety using cellular or animal models is advised. To support the possibility of creating therapeutic or preventative medicines based on radish components, in vivo tests are a crucial step in confirming the extracts' efficacy under actual biological settings.