Changes in shoot proliferation and chemical components of in vitro cultured Dendrobium officinale due to organic additives

Tissue culture has become a promising technique to produce biomass and active secondary metabolites in some species of medicinal plant with in short period of time. However, most of the plant growth regulators utilized as vital agents in the culture process are harmful to human bodies. In this study, Dendrobium officinale Kimura et Migo PLBs was subcultured on Murashige and Skoog medium supplemented with 30 g L-1 sucrose, 8 g L-1 agar, and various concentrations of coconut water or banana extract to investigate the effect of these organic additives on Protocorm-like bodies (PLBs) proliferation and shoot regeneration. Subsequently, the chemical composition of the material was qualitatively analyzed by standard color reactions and the methanolic extract were also tested upon DPPH radical scavenging and inhibition assay for antioxidant and antimicrobial activity assessment, respectively. The nutrient screening showed that treating 0.3 g fresh PLBs of D. officinale in medium containing 20 % coconut water produced the highest PLB biomass (2.21 g) whereas the similar culturing using 20 % banana extract generated only 1.98 g PLB biomass. The qualitative chemical tests recognized the presence of various phytoconstituents such as glycosides, flavonoids, steroids, triterpenes, phenolic compounds and saponins. The DPPH assay revealed the antioxidant activity of the methanol extract in a dose dependent manner with the IC50 value of 0.84 mg mL-1. In addition, this methanol extract showed a stronger inhibitory activity against Gram negative bacteria than Gram positive bacteria. These finding suggested that coconut water could be a potential alternative nutrient to common unhealthy regulators in the production of the biomass of interest.