Production of Bioactive Compounds in Grammatophyllum speciosum Blume Using Bioreactor Cultures Under Elicitation with Sodium Chloride

TL;DR

This study explores how salinity stress and bioreactor cultures can enhance the production of medicinal compounds in the endangered Grammatophyllum speciosum orchid.

Contribution

The novel use of a temporary immersion bioreactor system and sodium chloride elicitation to boost bioactive compound production in G. speciosum.

Findings

Shoot formation was optimized using ½ MS medium with NAA and BAP.

Sodium chloride at 100 µM maximized total phenolic content in G. speciosum.

Extracts showed antibacterial activity against acne pathogens.

Abstract

Grammatophyllum speciosum Blume is an endangered wild orchid with medicinal properties. In this research, we propagated G. speciosum from vegetative organs grown under aseptic conditions. Subsequently, salinity stress was applied at the plantlet stage to investigate its effect on the accumulation of bioactive compounds. Half-strength Murashige and Skoog (½ MS) medium supplemented with a combination of 1 mg of L−1 1-naphthaleneacetic acid (NAA) and 0.5 mg of L−1 6-benzylaminopurine (BAP) proved to be a more suitable medium for shoot formation (32.33 ± 2.52 shoots per explant). The protocorm-like bodies, derived from embryogenic callus, were transferred into a temporary immersion bioreactor (TIB) system; 10-min of immersion every 3 h enhanced the maximum number of shoots, shoot height, and the fresh growth index (127.00 ± 2.16, 5.00 ± 0.51 cm and 4.26 ± 0.52, respectively). The proliferated plantlets from the TIB system successfully rooted in Vacin and Went medium. Furthermore, the plantlets were maintained in ½ MS medium supplemented with sodium chloride (NaCl) (0, 50, 100 or 200 µM) under a white light-emitting diode for 72 h to determine the total phenolic content (TPC) in the in vitro cultures. The TPC was highest in the medium with 100 µM of NaCl (111.06 ± 2.24 mg gallic acid equivalent g−1 dry weight), the diphenyl picrylhydrazyl antioxidant activity was 24.50 ± 0.76% and ferric-reducing antioxidant power values were in the range 2441.79 ± 1.21 to 2491.96 ± 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.

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