Red-Blue LED lights promoting on biomass production and MRSA inhibition properties in callus cultures of the endemic Thai plant Platostoma hemratianum Suddee, Puudjaa & Kiewbang (Lamiaceae)
摘要
Platostoma hemratianum Suddee, Puudjaa & Kiewbang, an endemic plant found in Phu Langka National Park, Thailand, is recognized for its antibacterial properties. This study aimed to enhance callus growth and improve antioxidant and antibacterial activities in callus cultures using different LED light spectra: (1) control 100% white, (2) 1:1 white-blue, (3) 1:1 white-red, and (4) 1:1 red-blue. Callus induction was performed on MS medium with 0.5 mg/L BA and 0.5–2.0 mg/L IAA or NAA, initially cultured in the dark for 7 days, then exposed to white light for 28 days. The highest callus fresh weight (0.85 g) was obtained with 0.5 mg/L BA and 1.0 mg/L IAA. The 1:1 red-blue light yielded the best growth index (GI) for fresh (12.58) and dry weights (0.92). Antioxidant activity, measured by DPPH assay, showed the lowest IC50 (62–64 µg/mL) under 1:1 white-red and 100% white light. The 1:1 red-blue light demonstrated the strongest antibacterial activity, with inhibition zones of 12.67 ± 0.02 mm for Staphylococcus aureus and 11.19 ± 0.03 mm for Vibrio harveyi at 2,000 µg/disk. Further testing on methicillin-resistant Staphylococcus aureus (MRSA) (DMST 20651) showed MIC values of > 2,500 µg/mL for S. aureus, 2,500 µg/mL for MRSA, and 4,000 µg/mL for V. harveyi. These findings suggest that 1:1 red-blue LED light not only promotes growth but also enhances the bioactive properties of P. hemratianum callus cultures. The study emphasizes the potential of multispectral LED lighting as a tool for optimizing in vitro production of bioactive phytochemicals, offering promising applications for medicinal plant conservation and phytochemical enhancement.
Graphical Abstract