Bioactive Compound Production of <em>Grammatophyllum speciosum</em> Blume Using Bioreactor Cultures Under Elicitation with Sodium Chloride

Grammatophyllum speciosum is an endangered wild orchid with medicinal properties. This research propagated G. speciosum from vegetative organs grown under different NaCl-stressed conditions. Half-strength Murashige and Skoog (½ MS) medium supplemented with a combination of 1 mg L–1 1-naphthaleneacetic acid (NAA) and 0.5 mg L–1 6-benzylaminopurine (BAP) proved to be a suitable medium for shoot formation (32.33 ± 2.52 shoots per explant). The protocorm-like bodies were transferred into a temporary immersion bioreactor (TIB) system. A 10-min immersion time every 3 h enhanced the maximum number of shoots, the shoot height, and the fresh growth index (127.00 ± 2.16, 5.00 ± 0.51 cm and 4.26 ± 0.52, respectively). Rooting of proliferated plantlets from the TIB system was successfully achieved in Vacin and Went medium. The plantlets were maintained in ½ MS medium supplemented with Sodium chloride (NaCl) (0, 50, 100 or 200 µM) under white light-emitting diode light to induce the total phenolic content (TPC) from in vitro culture for 72 h. The TPC was highest in the medium with 100 µM NaCl (111.06 ± 2.24 mg gallic acid equivalents g-1 dry weight). The diphenyl picrylhydrazyl antioxidant activity was 24.50 ± 0.76% and ferric reducing antioxidant power values were in the range 2,441.79 ± 1.21 to 2,491.96 ± 3.23 µM ascorbic acid equivalent g-1 dry weight. The G. speciosum extracts showed antibacterial activity against acne pathogens, with minimum inhibitory concentration and minimum bactericidal concentration values in the ranges 6.4–12.8 mg mL–1 and 12.8–25.6 mg mL–1, respectively.