Heteromannans are the predominant hemicelluloses in the gametophytic stem of the umbrella moss Hypnodendron menziesii and occur in the walls of all cell types.

MAIN CONCLUSION: Heteromannans are the predominant hemicelluloses in the gametophytic stem of the moss Hypnodendron menziesii and occur in the walls of all cell types Little is known about the cell-wall polysaccharides of mosses. Monosaccharide analysis of cell walls isolated from the stem of the umbrella moss Hypnodendron menziesii was consistent with heteromannans, probably galactoglucomannans, being the predominant hemicellulosic polysaccharides in the walls. Immunofluorescence and immunogold microscopy with the monoclonal antibody LM21, specific for heteromannans, showed that these polysaccharides were present in the walls of all stem cell types. These cell types, except the hydroids, have secondary walls. Experiments in which sections were pre-treated with 0.1 M sodium carbonate and with the enzyme pectate lyase indicated that the heteromannans have O-acetyl groups that limit LM21 binding and the cell walls contain pectic homogalacturonan that masks detection of heteromannans using LM21. Therefore, to fully detect heteromannans in the cell walls, it was essential to use these pre-treatments to remove the O-acetyl groups from the heteromannans and pectic homogalacturonan from the cell walls. Fluorescence microscopy experiments with a second monoclonal antibody, LM22, also specific for heteromannans, showed similar results, but the binding was considerably weaker than with LM21, possibly as a result of subtle structural differences in the epitopes of the two antibodies. Although heteromannans occur abundantly in the cell walls of many species in basal lineages of tracheophytes, prior to the present study, research on the distribution of these polysaccharides in the walls of different cell types in mosses was confined to the model species Physcomitrium patens.

Complementary Analytical Platforms of NMR Spectroscopy and LCMS Analysis in the Metabolite Profiling of Isochrysis galbana.

This study was designed to profile the metabolites of Isochrysis galbana, an indigenous and less explored microalgae species. 1H Nuclear Magnetic Resonance (NMR) spectroscopy and Liquid Chromatography-Mass Spectrometry (LCMS) were used to establish the metabolite profiles of five different extracts of this microalga, which are hexane (Hex), ethyl acetate (EtOAc), absolute ethanol (EtOH), EtOH:water 1:1 (AqE), and 100% water (Aq). Partial least square discriminant analysis (PLS-DA) of the generated profiles revealed that EtOAc and Aq extracts contain a diverse range of metabolites as compared to the other extracts with a total of twenty-one metabolites, comprising carotenoids, polyunsaturated fatty acids, and amino acids, that were putatively identified from the NMR spectra. Meanwhile, thirty-two metabolites were successfully annotated from the LCMS/MS data, ten of which (palmitic acid, oleic acid, α-linolenic acid, arachidic acid, cholesterol, DHA, DPA, fucoxanthin, astaxanthin, and pheophytin) were similar to those present in the NMR profile. Another eleven glycerophospholipids were discovered using MS/MS-based molecular network (MN) platform. The results of this study, besides providing a better understanding of I.galbana's chemical make-up, will be of importance in exploring this species potential as a feed ingredient in the aquaculture industry.

Biological Activities of Selected Plants and Detection of Bioactive Compounds from Ardisia elliptica Using UHPLC-Q-Exactive Orbitrap Mass Spectrometry.

Plants and plant-based products have been used for a long time for medicinal purposes. This study aimed to determine the antioxidant and anti-α-glucosidase activities of eight selected underutilized plants in Malaysia: Leucaena leucocephala, Muntingia calabura, Spondias dulcis, Annona squamosa, Ardisia elliptica, Cynometra cauliflora, Ficus auriculata, and Averrhoa bilimbi. This study showed that the 70% ethanolic extract of all plants exhibited total phenolic content (TPC) ranging from 51 to 344 mg gallic acid equivalent (GAE)/g dry weight. A. elliptica showed strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) scavenging activities, with half maximal inhibitory concentration (IC50) values of 2.17 and 49.43 µg/mL, respectively. Most of the tested plant extracts showed higher inhibition of α-glucosidase enzyme activity than the standard, quercetin, particularly A. elliptica, F. auriculata, and M. calabura extracts with IC50 values of 0.29, 0.36, and 0.51 µg/mL, respectively. A total of 62 metabolites including flavonoids, triterpenoids, benzoquinones, and fatty acids were tentatively identified in the most active plant, i.e., A. elliptica leaf extract, by using ultra-high-performance liquid chromatography (UHPLC)-electrospray ionization (ESI) Orbitrap MS. This study suggests a potential natural source of antioxidant and α-glucosidase inhibitors from A. elliptica.