Abstract:
The search for new bioactive compounds from the wild often leads to conservation issues.
Plant tissue culture, a less destructive source of plant materials is a priority technique.
There is paucity of studies on potentials of plant tissue culture for the accumulation of
secondary metabolites in wild and cultivated Musa species, with wide medicinal
applications. This study was, therefore, designed to improve the phytoconstituents and
profile the biological activities of selected Musa species.
Fifteen taxonomic reference Musa species accessions (A-O) were micropropagated.
Genomic DNA obtained from each accession was used to generate Single Nucleotide
Polymorphic (SNP) markers using Diversity Array Sequencing (DArTseq) approach to
analyse genetic fidelity. Antioxidant and anticholinesterase activities of field and
micropropagated accessions were evaluated using spectrophotometric methods and High
Performance Thin Layer Chromatography (HPTLC) hyphenated with High Resolution
Mass Spectrometry (HRMS) for compounds identification. The Effect-Directed Analysis
(EDA) of the Musa species was done on HPTLC plates with antioxidant,
anticholinesterase, antidiabetic, and genotoxicity assays for bioprofiling. Gallic acid,
eserine, acarbose, 4-nitroquinoline-1-oxide, were used as standards. Compounds were
characterised with HRMS. Six of the accessions were subjected to elicitation experiments
using different doses of sugar (30-50 g/L), temperature (15, 20 and 25 °C) and Jasmonic
Acid (JA, 0–200 µM) as elicitors. The Total Phenolic Content (TPC), antioxidant profile
and biological activities of the resulting elicited samples (71) were analysed with HPTLC.
Data were analysed using one-way ANOVA followed by Dunnett’s multiple comparison
at α0.05.
The micropropagated accessions were shown to be true-to-type with the field samples.
Micropropagated plants gave significantly higher TPC (2.43±0.30 to 124.52±12.72
mgGAE/g), DPPH antioxidant (10.68±0.27 to 154.42±6.44 µg/mL), ferric reducing
antioxidant power (10.58±0.52 to 152.16±2.80 mgTE/g) and acetylcholinesterase
(11.53±0.12 to 1181.00±91.25 µg/mL) activities than the field plants.
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Acetylcholinesterase (AChE) activity of micropropagated accession F (11.53±6.52
µg/mL) was significantly higher than that of eserine (31.23±7.33 µg/mL). Results of the
HPTLC-EDA were similar to those of the spectrophotometric assays; accession F also had
the highest AChE inhibition. Three multipotent compounds characterised by their base
peaks (m/z) and molecular formula were identified as asparagine (1), aniracetam (2) and
linolenic acid (3). All the compounds had AChE and butylrylcholinesterase (BuChE)
inhibitory activities. Compounds 1 and 2 had antioxidant activity, while compound 1
exhibited α and β-glucosidase inhibition. None of the samples were genotoxic at the
concentrations tested. The elicitation experiments increased the TPC and antioxidant
activity of Musa species. In accession B, the TPC increased from 39.43 to 138.64
ngGAE/g (4.89 folds) when 30 and 50 g/L of sugar were used, respectively. Plants grown
at 20 °C gave a higher TPC than other treatments. Addition of JA (200 µM) increased the
TPC of accessions L and N by 2.24 and 1.68 folds, respectively.
The plant tissue culture technique was validated as a suitable method for the production of
genetically uniform Musa species and for sustainable supply of more bioactive
metabolites. The identified compounds had antioxidant, anticholinesterase and antidiabetic
activities. The diversity and titre of the phytoconstituents were also improved in the
elicited accessions
