Salvia plebeia R. Brown is a medicinal plant containing various bioactive compounds, including flavonoids, and has been reported to exhibit diverse pharmacological effects such as anti-inflammatory, antioxidant, and hepatoprotective activities. However, previous studies on S. plebeia have mainly focused on phytochemical identification and pharmacological evaluation, while biotechnological approaches aimed at enhancing the productivity of major bioactive compounds—particularly metabolic regulation and content improvement through elicitor treatment in in vitro culture systems—remain largely unexplored. In this study, we investigated the effects of elicitor treatments on the accumulation of homoplantaginin, a major bioactive compound in the leaves of in vitro–cultured S. plebeia, as well as the associated changes in anti-inflammatory activity. In vitro–grown plantlets were treated with yeast extract at concentrations of 1, 2, and 5 mg/L and polyethylene glycol (PEG) at concentrations of 1, 2, and 5% (w/v), respectively. Homoplantaginin content was quantitatively analyzed using high-performance liquid chromatography (HPLC), and anti-inflammatory activity was evaluated by measuring nitric oxide (NO) production inhibition in RAW 264.7 macrophage cells. As a result, the homoplantaginin content was significantly increased in the treatment with 2 mg/L yeast extract compared to the control, while the highest NO inhibition activity was observed in the 5% PEG treatment. These findings suggest that elicitor treatment can effectively enhance the production of bioactive compounds and anti-inflammatory activity in in vitro–cultured S. plebeian. Furthermore, this study provides fundamental data supporting the potential industrial application of S. plebeia through further elucidation of metabolic pathways and optimization of culture conditions.

Abstract
Introduction
Material and Methods
    1. Plant materials and in vitro culture
    2. Elicitor treatment
    3. Preparation of plant extracts
    4. HPLC analysis
    5. Cell culture and cell viability assay
    6. Evaluation of anti-inflammatory activity via inhibitionof LPS-induced NO production
    7. Statistical analysis
Results and Discussion
    1. Effects of elicitor treatments on homoplantaginincontent
    2. Cytotoxicity of S. plebeia leaf extracts in RAW264.7 cells
    3. Inhibitory effects on LPS-induced NO productionin RAW 264.7 cells
    4. Elicitor-induced modulation of homoplantagininaccumulation
    5. Yeast extract- and PEG-mediated regulation ofhomoplnataginin biosynthesis in S. plebeia
    6. Relationship between homoplantaginin accumulationand NO inhibitory activity
Acknowledgements
References

• Kwan Been Park(Graduate Student, Department of Forest Resources, Gyeongsang National University, Jinju, 52828, Korea)
• Seon A Kim(Graduate Student, Department of Forest Resources, Gyeongsang National University, Jinju, 52828, Korea)
• Do Hyun Kim(Graduate Student, Department of Forest Resources, Gyeongsang National University, Jinju, 52828, Korea)
• Seung A Cha(Graduate Student, Department of Forest Resources, Gyeongsang National University, Jinju, 52828, Korea)
• Ji Hyun Lee(Graduate Student, Department of Forest Resources, Gyeongsang National University, Jinju, 52828, Korea)
• Jenna Jung(Graduate Student, Department of Forest Resources, Gyeongsang National University, Jinju, 52828, Korea)
• Ju Yeong Kang(Graduate Student, Department of Forest Convergence Science, Gyeongsang National University, Jinju, 52828, Korea)
• Young Min Kang(Professor, Korean Convergence Medical Science Major, University of Science and Technology (UST), Daejeon, 34113, Korea, Principal Researcher, Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine (KIOM), Naju, 58245, Korea)
• Yeong Jun Ban(Adjunct Professor, Korean Convergence Medical Science Major, University of Science and Technology (UST), Daejeon, 34113, Korea, Senior Researcher, Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine (KIOM), Naju, 58245, Korea)
• Bong Gyu Kim(Professor, Division of Environmental Forest Science & Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 52828, Korea)
• Myung Suk Choi(Professor, Division of Environmental Forest Science & Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 52828, Korea) Corresponding author