Use of LED light and plasma activated water (PAW) to stimulate pharmaceutical compound production in Catharanthus roseus plants

This study primarily aimed to enhance the foliar concentration of vindoline and catharanthine (referred to as monomeric precursors concentration – MPs) through stimulation with artificial light and plasma activated water (PAW). Additionally, it investigated the effects of light and PAW on vinblastine (VBL) content. Madagascar periwinkle plants were grown in an indoor farming system under four experimental treatments: red light (R) from LED lamps, white light (W) from fluorescent lamps (FL), W+PAW, and R+PAW. Plants were sampled at two time points (T1 – 45 days after pretreatment, and T2 – 70 days after pretreatment) to analyse variation in MPs and VBL concentration over time due to different treatments. The T2-R+PAW treatment resulted in significantly higher MPs concentration compared to all other treatments. At both T1 and T2, R+PAW-treated plants showed significantly higher MPs concentration compared to other treatments. Without PAW treatment, at T1, W-treated plants had significantly higher MPs concentration compared to R-treated plants, while at T2, the MPs concentration in W-and R-treated plants was statistically comparable. T2-W+PAW treatment produced a significantly higher VBL concentration than all treatments at T1 and compared to T2-R and T2-R+PAW treatments, but statistically comparable to the T2-W treatment. W+PAW treatment generally led to higher VBL concentration compared to other treatments at both T1 and T2. W-treated plants had significantly higher VBL concentration compared to R-treated plants. Generally, T2 treatments resulted in higher MPs and VBL concentration compared to T1 treatments. In conclusion, the results indicate that: 1) T2-R+PAW treatment maximizes MPs concentration, 2) R+PAW treatment is always advantageous, 3) R seems to contribute to MPs accumulation, but its impact becomes significant only when coupled with PAW, 4) W+PAW treatment is generally more effective in promoting VBL accumulation, but T2-W treatment still remains more advantageous for maximizing VBL concentration, 5) W strongly induces VBL synthesis, and 6) MPs and VBL levels increase with plant age.