Asian Pacific Journal of Tropical Biomedicine

Issue 8,2020 Table of Contents

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  • 1  Vector-borne diseases: Mosquito holobiont and novel methods for vector control
    Upasana Shyamsunder Singh Aparup Das
    2020(8):341-342. DOI: 10.4103/2221-1691.287160
    [Abstract](18) [HTML](0) [PDF 592.88 K](257)
    2  Isolation and characterization of five novel mini-M conotoxins from the venom of mollusk-hunter snail Conus bandanus
    Nguyen Bao Jean-Piere LE CAER Phan Thi Khanh Vinh
    2020(8):343-352. DOI: 10.4103/2221-1691.287161
    [Abstract](51) [HTML](0) [PDF 2.83 M](222)
    Objective: To determine the new M-superfamily conotoxins from molluscivorous snail Conus bandanus in Vietnam. Methods: Conus bandanus venom was fractionated and purified on HPLC system with an analytical reversed-phase C18 column in order to screen small conotoxins. The primary structure of peptide was analyzed by matrix-assisted laser desorption/ionization time of flight tandem mass spectrometry using collision-induced dissociation and confirmed by Edman's degradation method. Results: Five new conotoxins were biochemically characterized from the crude venom of the mollusk-hunting cone snail Conus bandanus, which were collected at Ke Ga reef of the Nha Trang Bay (Vietnam). Each conotoxin had 15 or 16 amino acid residues and shared the same characteristic cysteine framework V as –CC–C– C–CC–. They were termed as Bn3b, Bn3c, Bn3d, Bn3e and Bn3f following the conotoxins nomenclature. Conclusions: The conotoxins Bn3b, Bn3e, and Bn3f are categorized in the mini-M conotoxins of the M1 branch, while conotoxins Bn3c and Bn3d are categorized in the mini-M conotoxins of the M2 branch. The homological analysis reveals that these conotoxins could serve as promising probe compounds for voltage-gated sodium channels.
    3  Metabolite profiling and antidiabetic attributes of ultrasonicated leaf extracts of Conocarpus lancifolius
    Syed Ali Raza Ayoub Rashid Chaudhary Muhammad Waseem Mumtaz Ahmad Adnan Hamid Mukhtar Muhammad Tayyab Akhtar
    2020(8):353-360. DOI: 0.4103/2221-1691.284430
    [Abstract](59) [HTML](0) [PDF 849.18 K](233)
    Objective: To profile the secondary metabolites and to evaluate the antidiabetic potential of hydroethanolic leaf extracts of Conocarpus lancifolius. Methods: The various hydroethanolic extracts of Conocarpus lancifolius leaf were prepared by ultrasonication assisted freezedrying. Total phenolic contents, flavonoid contents, antioxidant activity, alpha-glucosidase and alpha-amylase inhibitions of leaf extracts were determined. The metabolite profiling was accomplished by UHPLC-Q-TOF-MS/MS analysis. The antidiabetic assessment of the most potent extract was carried out by measuring the hypoglycemic and hypolipidemic effect in the high fat diet-fed diabetic albino mice. The blood glucose level, haemoglobin, total cholesterol, high-density lipoproteins (HDL) and low-density lipoproteins (LDL) were determined. Results: The 60% ethanolic extract exhibited the highest phenolic and flavonoid contents of (349.39 ± 2.13) mg GAE/g dry extract and (116.95 ± 2.34) mg RE/g dry extracts, respectively, and the highest DPPH scavenging activity with an IC50 value of (32.87 ± 1.11) μg/mL. The IC50 values for alpha-glucosidase and alpha-amylase inhibitions were (38.64 ± 0.93) μg/mL and (44.80 ± 1.57) μg/mL, respectively. UHPLC-Q-TOF-MS/MS analysis confirmed the presence of gallic acid, ellagic acid, corilagin, kaempherol-3-O-rutinoside, caffeic acid derivative, isorhamnetin and galloyl derivatives in the 60% ethanolic extract. Plant extract at a dose of 450 mg/kg body weight reduced blood glucose level, total cholesterol, LDL and HDL, and increased haemoglobin in alloxan-induced diabetic mice. Conclusions: Conocarpus lancifolius leaves are proved as a good source of biologically functional metabolites and possess antidiabetic activity which may be further explored to treat diabetes.
    4  Immunosuppressive and antibacterial activities of dihydromorin and norartocarpetin isolated from Artocarpus heterophyllus heartwoods
    Abdi Wira Septama Ibrahim Jantan Pharkphoom Panichayupakaranant Mohd Fadhlizil Fasihi Mohd Aluwi Eldiza Puji Rahmi
    2020(8):361-368. DOI: 10.4103/2221-1691.287162
    [Abstract](50) [HTML](0) [PDF 1.05 M](229)
    Objective: To evaluate the immunosuppressive effect on human phagocytes and antibacterial activity of dihydromorin and norartocarpetin isolated from Artocarpus heterophyllus heartwoods. Methods: Dihydromorin and norartocarpetin were isolated from Artocarpus heterophyllus heartwoods. A modified Boyden chamber was used to determine the chemotactic activity of human phagocyte. The respiratory burst was evaluated by chemiluminescence assay. Myeloperoxidase (MPO) activity was quantified using a colorimetric assay. The broth microdilution method was performed to assess their antibacterial activity. Results: Dihydromorin exhibited potent inhibitory effect on the chemotactic activity of polymorphonuclear neutrophils (PMNs) with an IC50 value of 5.03 μg/mL. Dihydromorin also inhibited reactive oxygen species production of whole blood cells, PMNs, and monocytes with IC50 values of 7.88, 7.59 and 7.24 μg/mL, respectively. Interestingly, dihydromorin also strongly inhibited the MPO activity of PMNs with an IC50 value of 5.24 μg/mL, which was lower than indomethacin (24.6 μg/mL). Molecular docking of dihydromorin and crystal structure of MPO showed that dihydromorin had close interaction with key amino acid residues such as Arg239 and Gln91. Antibacterial activity assay showed that only dihydromorin had a strong effect against Streptococcus pyogenes with MIC and MBC values of 15.62 and 31.25 μg/mL, respectively. Conclusions: The results suggest that dihydromorin could be developed as an anti-inflammatory and antibacterial agent.
    5  Peanut testa extracts enhance anticancer effect of cisplatin against human cholangiocarcinoma cells via modulation of histone deacetylase inhibitory activity
    Somprasong Saenglee Gulsiri Senawong Jarckrit Jeeunngoi Sanun Jogloy Albert J. Ketterman Banchob Sripa Thanaset Senawong
    2020(8):369-378. DOI: 10.4103/2221-1691.287163
    [Abstract](78) [HTML](0) [PDF 884.49 K](234)
    Objective: To investigate the effect of combination treatments of cisplatin and KK4 and ICG15042 peanut testa extracts against cholangiocarcinoma cells in vitro. Methods: The growth inhibition, cell cycle arrest and apoptosis of cholangiocarcinoma cells were determined by 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry analysis, respectively. The levels of proteins involved in apoptosis were assessed using Western blotting assays. The caspase activity was assessed using a colorimetric caspase activity assay. Results: Cisplatin and peanut (KK4 and ICG15042) testa extracts inhibited the growth of cholangiocarcinoma cell lines (KKUM214 and KKU-100 cells) in a dose- and time-dependent manner. The combination treatments reduced cell viability and induced apoptosis of cholangiocarcinoma cells more efficiently than singledrug treatments. Cancer cell death synergistically mediated by cisplatin and peanut testa extracts was observed in KKU-M214 cells (combination index < 1.0) but not in KKU-100 cells (combination index > 1.0). The combination treatments also increased the sub-G1 population and caused KKU-M214 cell cycle arrest at S and G2/M phases, which were the combined effects of cisplatin (S phase arrest) and peanut testa extracts (G2/M phase arrest). In addition, pERK1/2, Ac-H3, Bcl-2 and proteins related to apoptosis, including Bax and caspases 3, 8, 9, exhibited enhanced expression in KKUM214 cells. The combination treatments caused down-regulation of p53, whereas the expression of p21 was fairly constant when compared with cisplatin single drug treatment. Conclusions: Peanut testa extracts in combination with cisplatin synergistically reduce cell viability and induce apoptosis through stimulation of caspases 3, 8 and 9 in KKU-M214 cells.
    6  Gymnema montanum improves endothelial function via inhibition of endoplasmic reticulum stress by activating Nrf2 signaling
    Dornadula Sireesh Natarajan Suganya Suvro Chatterjee Kunka Mohanram Ramkumar
    2020(8):379-386. DOI: 10.4103/2221-1691.287164
    [Abstract](46) [HTML](0) [PDF 1.07 M](230)
    Objective: To investigate the effects of Gymnema montanum leaf extract against endoplasmic reticulum (ER) stress-induced toxicity in endothelial cells. Methods: The immortalized endothelial hybrid cell, EA.hy926 was treated with different concentrations of Gymnema montanum leaf extract (0–100 μg/mL) and the ER stress inducer, tunicamycin. The cytotoxicity was assessed by MTT as well as lactate dehydrogenase and malondialdehyde levels were determined. The levels of ER stress markers, GRP78 and CHOP were analysed by Western blot assay. The Gymnema montanum leaf extract-mediated activation of nuclear factor erythroid 2-related factor 2 (Nrf2) was assessed by cell-based luciferase enzyme fragment complementation assay and antioxidant responsive element driven luciferase reporter assay. The levels of phosphoproteins of the MAPK pathway were analyzed using the Bioplex system. Results: A dose-dependent cytoprotective effect of Gymnema montanum leaf extract was observed in tunicamycin-induced toxicity. Gymnema montanum leaf extract significantly reduced lactate dehydrogenase activity and malondialdehyde levels in ER stress-induced endothelial cells. It also suppressed ER stress markers dose dependently and inhibited the phosphorylation of JNK, ERK, MEK and p38 MAPK in tunicamycin-induced endothelial cells. Moreover, Gymnema montanum leaf extract increased the expression of Nrf2 and its downstream targets in endothelial cells. Conclusions: Gymnema montanum leaf extract attenuates ER stress by increasing the expression of Nrf2 and its downstream genes.

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