Efficacy Assessments of Medicinal Plants (Focused on Unstudied Species)

Discovering the Value of Native Plant Resources in Unexplored Countries

  Native plant species are known to contain various phytochemicals and have biological activities such as antioxidant, antibacterial, and anti-inflammatory activities. In particular, some plants that grow in unique geographic or severe climatic environments, such as wetlands, arid climates, and mountainous regions, are known for their health benefits and have long been used as traditional medicines. 

  To discover the value of new plant resources, we are researching to identify the antioxidant, antimicrobial, and bioactive components of plants native to various countries, including Nicaragua, Mongolia, Malaysia, Kazakhstan, and Indonesia. We have signed a Memorandum of Understanding (MOU) with the International Biological Material Research Center at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) to secure plant resources from various countries (2023.09.08.). 

Assessment Methodologies for Biological Activity

  We explore the value of plant resources from various countries by first screening the antioxidant and antimicrobial activities of the samples. Several methods can be used to assess antioxidant activity: ABTS assay, DPPH assay, and FRAP assay. Briefly, these assays identify the color change of reagents (free radicals, etc.) that react with bioactive substances in the extract. This allows the determination of the half-maximal inhibitory concentration (IC50) of the plant extract.

  Antibacterial activity can be confirmed by two methods (disk diffusion method and broth dilution method). First, the disc diffusion method is used to determine if a growth inhibition zone is created around the disc containing the plant extract. Then, the broth dilution method is used to determine the minimum inhibitory concentration (MIC) of the plant extracts.

Quantitative and Qualitative Analysis of Bioactive Ingredients

  The biological activities of plant extracts, such as antioxidant and antimicrobial activity, are primarily attributed to phytochemicals. It is possible to simply estimate the types of compounds abundant in a plant resource by analysis of the total phenolic, flavonoid, anthocyanin, and tannin content of the extract. In addition, specific compounds present in high amounts in plant extracts can be identified by quantitative and qualitative analysis using HPLC, LC-MS, and GC-MS.

  In the persimmon calyx extraction process, phenolics and flavonoids were recovered. We investigated the effects of major extraction parameters (ethanol concentration, extraction temperature, and extraction time) on the recovery of phenolics and flavonoids to determine the optimal extraction. Under the optimal condition, 21.7 g phenolics and 11.7 g flavonoids were predicted to be recovered per 1,000 g dry biomass.