Xylans extracted from branches and leaves of Protium puncticulatum: antioxidant, cytotoxic, immunomodulatory, anticoagulant, antitumor, prebiotic activities and their structural characterization.

This work aimed to isolate and characterize xylans from branches and leaves of Protium puncticulatum, in addition to evaluating its in vitro biological and prebiotic potential. The results showed that the chemical structure of the obtained polysaccharides is similar being classified as homoxylans. The xylans presented an amorphous structure, in addition to being thermally stable and presenting a molecular weight close to 36 g/mol. With regard to biological activities, it was observed that xylans were able to promote low antioxidant activity (< 50%) in the different assays evaluated. The xylans also showed no toxicity against normal cells, in addition to being able to stimulate cells of the immune system and showing promise as anticoagulant agents. In addition to presenting promising antitumor activity in vitro. In assays of emulsifying activity, xylans were able to emulsify lipids in percentages below 50%. Regarding in vitro prebiotic activity, xylans were able to stimulate and promote the growth of different probiotics. Therefore, this study, in addition to being a pioneer, contributes to the application of these polysaccharides in the biomedical and food areas. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03506-1.

Biological activities and physicochemical characterization of alkaline lignins obtained from branches and leaves of Buchenavia viridiflora with potential pharmaceutical and biomedical applications.

In this work, we investigated in vitro different biological activities of alkaline lignins extracted from the species Buchenavia viridiflora, a tree from the Amazon rainforest used as a wood product. The chemical composition results for the twig and leaves were, respectively (%): cellulose (30.88 and 24. 28), hemicellulose (21.62 and 23.03), lignin (29.93 and 25.46), extractives (13.06 and 20.52), and ash (4.51 and 6.72). The yield was higher for the lignin of the branches (67.9 %) when compared to the leaves (60.2 %). Lignins are of the GSH type, low molecular weight and thermally stable. They promoted moderate to low antioxidant activity, highlighting the lignin of the branches, which presented an IC50 of 884.56 µg/mL for the DPPH assay and an IC50 of 14.08 µg/mL for ABTS. In the cytotoxicity assays, they showed low toxicity against macrophage cells (IC50 28.47 and 22.58 µg/mL). In addition, they were not cytotoxic against splenocytes and erythrocytes at concentrations ranging from 100 to 6.25 µg/mL. These were able to promote splenocyte proliferation and induce the production of anti-inflammatory cytokines. And inhibit the growth of tumor cells with IC50 ranging from 12.63 to values >100 µg/mL and microbial at a concentration of 512 µg/mL. Finally, they showed antiparasitic activity by inhibiting the growth of chloroquine-sensitive and resistant Plasmodium falciparum strains. These findings reinforce that the lignins in this study are promising for potential pharmaceutical and biomedical applications.

Lignin from Morinda citrifolia leaves: Physical and chemical characterization, in vitro evaluation of antioxidant, cytotoxic, antiparasitic and ultrastructural activities.

In this work, we investigated in vitro the antioxidant, cytotoxic and anti-leishmanial activities of a lignin extracted from the leaves of Morinda citrifolia. Initially, an analysis of the composition of the sheets was performed, then the lignin was obtained by alkaline delignification and characterized by different techniques: elemental analysis, FT-R, UV-vis, HSQC-NMR, thermal analysis, Py-GC/MS and by GPC. The results showed that the leaves had in their composition cellulose (31.29%), hemicellulose (25.01%), lignin (18.34%), extractives (14.39%) and ash (10.03%). The lignin extraction yield was 89.8%. The lignin obtained is of the GSH type with the following contents 79.39%, 13.58% and 7.03% respectively. Furthermore, it is low molecular weight and thermally stable. It had a phenolic content of 93.3 mg GAE/g and low antioxidant activity. In macrophage cytotoxicity assays, it presented a CC50 of 31.0 µg/mL, showing less toxicity than amphotericin B. In assays against the promastigote forms of Leishmania amazonensis, lignin presented an IC50 of 29.56 µg/mL, a less effective concentration than amphotericin B (IC50 = 0.14 µg/mL). However, it was able to promote inhibition of the parasites, a fact confirmed by structural changes. These findings reinforce that M. citrifolia lignin is a promising macromolecule for use as an antiparasitic and antioxidant agent.