Asian Pacific Journal of Tropical Biomedicine

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Objective: To investigate the effect of Gracilaria fisheri oligosaccharides (GFO) on inflammation and colonic epithelial barrier dysfunction in colitis mice. Methods: The animals were treated by oral gavage with distilled water, 1 000 mg/kg inulin, 100, 500, or 1 000 mg/kg GFO for 14 d, or treated with 50 mg/kg mesalamine for 5 d after colitis induction (on day 10). Histopathology, inflammatory cytokines, colonic permeability, and tight junction proteins were investigated by hematoxylin and eosin staining, immunohistochemical staining, Ussing chamber technique, and Western blotting assays, respectively. Results: GFO ameliorated histological damage in colitis mice when compared to untreated colitis mice. Treatments with 100, 500, and 1 000 mg/kg GFO reduced TNF-α expression, while IL-1β was significantly reduced in colitis mice treated with 500 and 1 000 mg/kg. Compared to untreated colitis mice, GFO increased transepithelial electrical resistance, reduced fluorescein isothiocyanate-dextran paracellular flux, and modulated tight junction proteins (occludin and claudin 2) in colitis mice. Conclusions: GFO has anti-inflammatory activity and could modulate colonic epithelial barrier dysfunction in acetic acid-induced colitis mice. Furthermore, GFO could modulate the expression of tight junction proteins that play important roles in colonic barrier function.

Objective: To evaluate antioxidant, cytotoxic, and anti-venom capacity of crude bark extracts of Alstonia parvifolia Merr. Methods: Gas chromatography-mass spectrometry (GC-MS) and energy dispersive X-ray analyses were accomplished to characterize the chemical constituents of Alstonia parvifolia. Biochemical characterization was evaluated using an inhibitory phospholipase A₂ (PLA₂) assay, DPPH, and cytotoxicity assays. Using the constituents listed in the GC-MS analyses, molecular docking was conducted to inspect the binding energies between the chosen compounds and selected PLA₂ isoforms. Results: GC-MS analyses showed that the Alstonia parvifolia crude extract consisted predominantly of acetylmarinobufogenin (14.89%), γ-sitosterol (10.44%), 3-O-methyl-D-glucose (5.88%), 3,5-dimethoxy-4-hydroxyphenylacetic acid (5.30%), (2α,5α)-17-methoxyaspidofractinin-3-one (AFM) (4.08%), and 2,3,5,6,7,8,9-heptahydro-1-phenyl-5-(p-chlorophenylimino)-1H-benzo[e]^[1],[4]thiazepine (HPT) (1.37%). The principal elemental components of Alstonia parvifolia were Ca (4.012%) and K (1.496%), as exhibited by energy dispersive X-ray examination. Alstonia parvifolia showed significant free radical scavenging ability (IC₅₀: 0.287 mg/mL) and was non-cytotoxic to normal HDFn cells (IC₅₀ >100 μg/mL). Moreover, Alstonia parvifolia was favorably cytotoxic to MCF-7 (IC₅₀: 4.42 μg/mL), followed by H69PR, HT-29, and THP-1, with IC₅₀ values of 4.94, 5.07, and 6.27 μg/mL, respectively. Alstonia parvifolia also displayed notable inhibition against PLA₂ activity of Naja philippinensis Taylor venom with IC₅₀ of (15.2 ± 1.8) μg/mL. Docking and cluster analyses projected negative binding energies from AFM (-6.36 to -9.68 kcal/mol), HPT (-7.38 to -9.77 kcal/ mol), and acetylmarinobufogenin (-7.22 to -9.59 kcal/mol). These calculations were for the particular interactions of Alstonia parvifolia constituents to PLA₂ homologues where the utmost affinity was detected in HPT owing to the dipole interactions with amino acid residues. Conclusions: The bark extract of Alstonia parvifolia shows great potential as an anti-venom agent due to its low cytotoxic profile, remarkable PLA₂ inhibition, and docking binding energies between its bioactive constituents and PLA₂ homologues.

The ongoing outbreak of novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused an unprecedented global health crisis. Development of a cure for this devastating disease is currently at full speed, with several vaccines against COVID-19 already authorized and administered. Currently, demand for these vaccines far exceeds supply. As such, boosting immunity represents a viable route to halt the rapid spread of SARS-CoV-2 and limit fatalities until vaccines become more readily and widely available. The use of phytochemicals appears to be a promising panacea. Sesamin, a lignan isolated from Sesamum indicum seeds, is known for its potent pharmacological properties, and is therefore hypothesized as a potential candidate in the therapeutic regimen against COVID-19. Herein, we highlight the confirmed therapeutic anti-inflammatory and immune-modulatory potential of sesamin against myriads of respiratory disorders, and tentatively suggest that sesamin may exert similar potent effects against COVID-19. Precisely, we speculate that sesamin may help alleviate COVID-19 via restoring Th1/Th2 balance and preventing inflammation and cytokine storm development. Additionally, we further support the promising role of sesamin against COVID-19 by underscoring the direct evidence, which suggests that sesamin may demonstrate promising inhibitory potential against three important SARS-CoV-2 targets, namely main protease, spike protein, and angiotensin-converting enzyme 2 receptor. Although preliminary, there is ample evidence to propose sesamin as a potential phytotherapeutic and prophylactic candidate against COVID-19. Further in vitro, in vivo, and preclinical studies are required to further substantiate the role of sesamin in the prevention and/or treatment of COVID-19.

Objective: To investigate whether the ethanol extract of Chondracanthus tenellus (Harvey) Hommersand, a type of red algae, could exhibit anti-inflammatory potential in lipopolysaccharide (LPS)-stimulated macrophages. Methods: The ethanol extract of Chondracanthus tenellus was applied to 100 ng/mL LPS-stimulated RAW 264.7 cells, and cell viability, phagocytic ability, levels of pro-inflammatory factors, and the production of reactive oxygen species were measured. To identify the underlying mechanism of the ethanol extract of Chondracanthus tenellus, the expression of inflammation-regulated genes was estimated. Results: The ethanol extract of Chondracanthus tenellus had no cytotoxic effect at concentrations below 300 μg/mL, and reduced the LPS-induced production of inflammatory mediators including nitric oxide (NO) and prostaglandin E₂. Furthermore, the extract markedly suppressed the expression of inducible NO synthase and cyclooxygenase-2, as well as the production of reactive oxygen species. The LPS-induced up-regulation of pro-inflammatory cytokines was attenuated by treatment with the ethanol extract of Chondracanthus tenellus, reducing their extracellular secretion. The Chondracanthus tenellus extract also inhibited LPS-mediated activation of nuclear factor-kappa B (NF-κB). In addition, the phosphorylation of mitogen activated protein kinases (MAPKs) and phosphatidylinositol 3 kinase (PI3K)/Akt was markedly increased by LPS, which was significantly abolished by the Chondracanthus tenellus extract. Conclusions: Our findings indicate that the ethanol extract of Chondracanthus tenellus exhibited potential anti-inflammatory and antioxidant effects through downregulating the NF-κB, MAPKs, and PI3K/Akt signaling pathways in LPS stimulated RAW 264.7 macrophages.

Objective: To explore the effect of Sirt1 on the function of endothelial progenitor cells (EPCs) in rats with chronic obstructive pulmonary disease (COPD). Methods: A rat COPD model was established via smoking and endotoxin administration for three months. The peripheral circulating EPCs were isolated by gradient centrifugation, and their functions, cell cycle distribution, apoptosis, and Sirt1 expression were examined. The function changes of EPCs in the presence or absence of Sirt1 agonist and inhibitor were estimated; meanwhile, the expressions of Sirt1, FOXO3a, NF-κB, and p53 were also evaluated. Results: The proliferation, adhesion, and migration of EPCs decreased while the apoptosis rate was increased in the COPD rats. The expression of Sirt1 protein in EPCs of the COPD group was significantly lower than that in the control group (P<0.01). The overexpression of the Sirt1 gene using a gene transfection technique or Sirt1 agonists (SRT1720) improved the proliferation, migration, and adhesion, and decreased the apoptosis of EPC. However, Sirt1 inhibitor (EX527) decreased EPC functions in the COPD group. The effect of Sirt1 expression on EPC function may be related to reduction of FOXO3a and increase of NF-κB and p53 activity. Conclusions: Increased expression of Sirt1 can improve the proliferation and migration of EPCs and reduce their apoptosis in COPD rats. This change may be related to FOXO3a, NF-κB, and p53 signaling pathways.

Online since 13^th December 2017