Effect of different carbon sources on callus formation, pigment accumulation, and antiviral activity in cell cultures of Euphorbia milii

Background and aim Humans have long been relying on plants for food, shelter, and most importantly for medicines. In vitro culture techniques, which ensure rapid, consistent, and uniform mass production, are indispensable for manufacturing important plant-derived metabolites. However, insufficient information is available regarding the tissue culture of Euphorbia milii and its important bioactive compounds. This study mainly aims to explore the impact of different carbon sources on callus formation, pigment accumulation, and antiviral activity of E. milii. Materials and methods Using inflorescence tissues as explants, we investigated the effects of different types and concentrations of plant growth regulators (2,4-dichlorophenoxyacetic acid [2,4-D], alone or combined with benzyl aminopurine) on callus induction frequency. Moreover, we studied the effects of different concentrations of carbon sources (glucose, fructose, and mannose) on callus growth, pigment (chlorophylls, carotenoids, and anthocyanins) accumulation, and antiviral activities. Results and conclusion The results indicated that 2,4-D alone (1.0 mg/l or 1.5 mg/l) induced callus formation most effectively. Furthermore, glucose was detected to be the more effective carbon source for the accumulation of chlorophylls, carotenoids, and anthocyanins compared with fructose and mannose. The highest accumulation of pigments was induced by 20 or 40 mg/l glucose supplements, with no significant difference between the effects of different concentrations. Unlike glucose, fructose or mannose did not enhance pigment accumulation; moreover, high concentrations had negative effects on pigment accumulation. Similarly, glucose was more suitable for the antiviral activity of E. milii extracts than fructose and mannose. The results will support the effective production of secondary metabolites and offer insights into the antiviral potency of E. milii.