Metabolic Profiling Using Gas Chromatography–Mass Spectrometry and Optimization of Light‐Emitting Diodes for Callus Induction in Patchouli “Tapak Tuan” ( Pogostemon cablin Benth.)

INTRODUCTION: Patchouli is an aromatic medicinal plant. The essential oil from patchouli is widely used in the perfume and pharmaceutical industries. In vitro culture systems provide a sustainable platform for increasing biomass and secondary metabolite exploration; however, the role of light quality in regulating these responses in Tapak Tuan patchouli callus remains underexplored. OBJECTIVE: This study compared the effects of blue, red, and white light-emitting diodes (LEDs) with fluorescent light as the control on patchouli callus cultures. RESULTS: After 8 weeks, blue LEDs produced the highest callus fresh weight (7.34 ± 0.29) and promoted early organogenic responses, with shoot primordia observed in all explants, although complete plantlets were not obtained during the culture period. Red LED treatment showed the strongest qualitative flavonoid reaction based on phytochemical screening. Further GC-MS-based metabolite profiling, expressed as relative peak area (%), indicated that red LED-treated callus had the highest number of detected compounds, including several treatment-associated compounds, whereas blue LED-treated callus showed the presence of pogostone, a pharmacologically relevant metabolite. These results indicate that different light treatments, representing both spectral and PPFD differences, were associated with distinct callus growth responses and metabolite profiles in patchouli callus. CONCLUSION: The integration of qualitative phytochemical screening and descriptive GC-MS profiling provides preliminary insights into LED-associated variation in patchouli callus cultures and highlights the potential use of targeted lighting strategies for optimizing biomass production and metabolite profiling. Future studies using standardized PPFD, replicated GC-MS analysis, internal standards, and quantitative biochemical assays are needed to validate these findings and clarify the underlying mechanisms.