Please login first

List of accepted submissions

 
 
Show results per page
Find papers
 
  • Open access
  • 111 Reads
Effective Synthesis of a Novel Betulinic Acid Conjugate with Mitochondria-Targeting Cation F16.

Currently, mitochondria are considered as an attractive universal target in the development of new anticancer drugs. These organelles are essential in energy production, regulation of cell death pathways, generation of reactive oxygen species, as well as maintenance of calcium homeostasis. Various approaches are being developed to deliver biologically active compounds into the mitochondria of tumour cells, including conjugation of cytotoxic substances with mitochondria-targeted lipophilic cations. Among the currently known low molecular weight lipophilic cationic molecules, (E)-4(1H-indol-3-ylvinyl)-N-methylpyridinium iodide (F16) is of great interest. This mitochondria-toxic cationic compound with luminescent properties is selectively accumulated in mitochondria and can selectively trigger apoptosis and necrosis of tumour cells, making it an attractive targeted agent for theranostic use. Meanwhile, betulinic acid, an available natural pentacyclic triterpenoid, has been considered as a promising scaffold for development of new anticancer agents in recent years. The antitumour effect of this natural product arises from affecting the mitochondria of tumour cells through formation of reactive oxygen species. The present article details an efficient synthesis of a novel multifunctional hybrid agent in which a cytotoxic triterpenoid, betulinic acid, is carbon-carbon bonded to the cationic F16 fragment at the C-2 position of ring A through a phenylethynyl spacer. The starting substrates in the synthesis were C-2 propynyl derivative of betulinic acid and N-aryl-substituted 4-(1H-indol-3-ylvinyl)-pyridine. The derivative of betulinic acid with a terminal acetylenic group was prepared by the reaction of C-alkylation with propargyl bromide of potassium enoxytriethylborate generated from betulonic acid. To obtain the N-aryl-substituted analogue of F16, CuI-catalyzed Ullmann-Goldberg reaction was applied. The synthesis of the target conjugate was successfully completed by the cross-coupling of the terpene and heterocyclic components according to Sonogashira in the presence of CuI/Pd(PPh3)2 catalyst.

  • Open access
  • 84 Reads
Ti(O-iPr)4-EtMgBr-catalyzed reaction of dialkyl-substituted alkynes with Et2Zn

For the first time, Ti(O-iPr)4-EtMgBr carbozincation of dialkyl-substituted alkynes with Et2Zn was carried out. It was found that the reaction of 1,2-disubstituted alkynes (5-decyne, 4-octyne, 3-hexyne) with Et2Zn is accompanied by the regioselective formation of stereoisomeric tetraalkyl-substituted hexa-1,3-diene derivatives in high yield. It was found that 2-zincoethylzincation of dialkyl-substituted alkynes in the presence of catalytic amounts of Ti(O-iPr)4 and EtMgBr does not stop at the stage of ethylzincation of the triple bond, but is accompanied by the involvement of a second alkyne molecule with the formation of two stereoisomeric hexa-1,3-diene derivatives. The effect of the nature of the solvent on the carbozincation of dilkyl-substituted acetylenes under the conditions of titanium-magnesium catalysis was studied.

  • Open access
  • 56 Reads
An Overview of Biotransformation for the Sustainability of Sweet Tasting Proteins as Natural Sugar Replacers

According to WHO, sugar intake rates should be reduced to less than 10 % per day due to the connection of sugar with diseases (WHO, 2020a). Natural substitutes of sugar such as sweet-tasting proteins may solve the overconsumption problems with a sweet taste, health benefits, and without caloric content. Known natural sweet-tasting proteins are brazzein, curculin, thaumatin, monellin, miraculin, and mabinlin. Natural sources of sweet proteins might be extinct in the future due to overconsumption of sweet proteins. Hence, biotransformation studies are promising for sweet protein production with more yield rates, better quality, fewer by-products, and more sustainable solutions. For instance, Bacillus licheniformis has produced 57 mg/L of brazzein at 36 h (Hung et al., 2019). Heterodimeric forms of curculin via Escherichia coli has demonstrated a characteristic sweet taste (Masuda & Kitabatake, 2006). Gene expression of thaumatin via Lactococcus lactis has been approved as GRAS (Yeh et al., 2009). Biotransformation of monellin via Saccharomyces cerevisiae has yielded about 54 g of purified monellin (Kaul et al., 2018). However, the first biotransformation study of miraculin via E. coli did not demonstrate any sweet taste (Kurihara, 1994), then via transgenic plants, miraculin has exhibited a high amount of sweet taste (Hiwasa-Tanase et al., 2012). Biotransformation studies of Mabinlin ll via E. coli and L. lactis provide availabilities to produce mabinlin in wide spectrums for food applications (Gu et al., 2015). Thus, sweet proteins can be produced more sustainably by biotransformation which provides advantages both for human health and a sustainable future.

  • Open access
  • 78 Reads
Profiling the nematicidal activity of linear and cyclic compounds on the pinewood nematode

The pinewood nematode (PWN), Bursaphelenchus xylophilus, has become one of the most damaging pests to forest health, in Asia and Europe. This phytoparasite causes Pine Wilt Disease (PWD) by attacking susceptible Pinus trees and inducing shoot yellowing (chlorosis) and wilting (caused by embolism), which can lead to the death of an adult tree in less than 50 days. In the search for sustainable biopesticides, research has focused on plant derived natural products, e.g., essential oils and extracts, known to be comprised of highly active secondary metabolites. Many of these compounds have shown promising results in direct contact bioassays, depending on their chemical structure. In the present work, 25 linear and aromatic pure compounds, commonly found in essential oils and extracts, were preliminarily tested in direct contact bioassays, against the PWN, to understand how distinct chemical structures can be related to a stronger nematicidal activity. Fifteen compounds showed complete mortality (100%) at 1 µL per mL of assay solution. Activity appeared to be strongly related with specific functional groups, isomerism or with the length of the linear carbon chain. In this context, compounds containing an alcohol group showed high activity, e.g., the linear geraniol, linalool or menthol. For the enantiomers of the aldehyde citronellal, complete mortality was only attained by its (-)-citronellal enantiomer. Additionally, the aliphatic decanoic (C10 carbon chain) and undecanoic acids (C11 carbon chain) induced complete mortality but not dodecanoic acid (C12 carbon chain). Uncovering the variation in the structure-activity relationships of anti-PWN compounds contributes to the identification of the nematicidal mechanisms of action. This knowledge is useful for improving sustainable pest management in forest ecosystems.

  • Open access
  • 57 Reads
Green synthesis of fluorescent carbon dots through solvothermal treatment of Buchnania lanzan leaves extract

In the present work we have synthesized fluorescent carbon dots (CDs) through solvothermal
treatment of Buchnania lanzan leaves extract at 160 °C for 4h in oven. Here, Buchnania lanzan
leaves serve as a renewable source of carbon. The obtained blackish-brown CDs solution was
centrifuged and the supernatant was filtered through syringe filter (0.22 µm). Further, the CDs
solution was dried in vacuum oven to obtain powder. The synthesized CDs were characterized
by different techniques including UV-Vis spectroscopy, fluorescence spectroscopy, fourier
transform infrared (FTIR), zeta potential, x-ray diffraction (XRD). The as prepared CDs
solution was found brownish colored in day light while exhibited green fluorescence under UV
light. UV-Vis absorption spectrum displayed a characteristic peak of CDs at 268 nm and a
shoulder peak at 365 nm. In the fluorescence spectra, excitation dependent emission behaviour
of CDs was seen, which is one of the distinct characteristic of CDs. The negative zeta
potential and characteristic peaks in FTIR, suggested presence of carboxyl functional group on
the CDs surface. XRD spectrum exhibited broad peaks suggesting amorphous nature of CDs
similar as reported in earlier works. As we have synthesized carboxyl group surface
functionalized carbon nanoparticles from a renewable and abundant precursor, this method can
be highly useful in synthesis of large quantity of carbon dots with reduced cost and will find
potential applications in the field of targeted drug delivery, bioimaging, etc.

  • Open access
  • 140 Reads
Investigation of Selected Piperazine-2,5-diones on Their Effect on Cartilage-Related Cells

Various chronic inflammatory diseases have become a problem, especially in the Western world. Whether it is inflammation of visceral organs, joints, bones, etc., it is always a physiological reaction of the body, which always tries to eradicate harmful substances and restore tissue homeostasis. Unfortunately, prolonged or chronic inflammation often results in damage to the affected tissues. Cartilage damage, diseases such as osteoarthritis, rheumatoid arthritis and arthrosis, are very common. In addition to suppressing inflammation in the joints and around the cartilage, it is advantageous to administer compounds that are capable of stimulating cartilage growth and regenerate damaged tissue. Variously substituted piperazine-2,5-dione derivatives were investigated as compounds with a potential effect on cartilage regeneration. A series of assays were performed to evaluate their cytotoxicity, anti-inflammatory activity, ability to potentiate chondrocyte proliferation, and suppress synovial cell growth. The compounds proved to be completely non-toxic for all used types of cells up to the concentration of 20 µM. Unfortunately, their evaluated biological activity proved to be insignificant in comparison with untreated cells.

  • Open access
  • 71 Reads
Investigation of interactions of ortho- and para-N-aryl-substituted 2-trifluoromethylcinnamanilides

Unsubstituted (2E)-N-phenyl-3-[2-(trifluoromethyl)phenyl]prop-2-enamide and six other ortho- or para-halogen-substituted anilides of 2-(trifluoromethyl)cinnamic acid were prepared. As the benzene nucleus of cinnamic acid itself is substituted in C(2) position with a trifluoromethyl moiety that is spatially close to both the amide bond and the halogen (F, Cl, CF3) ortho-substitution of the anilide ring, interesting intramolecular interactions can be expected. Other derivatives are substituted at the para-position of the anilide ring, so that intermolecular interactions can be expected. Thus, it can be assumed that the predicted properties, especially lipophilicity, will differ significantly from the experimentally determined values. All the discussed compounds were analyzed using the reversed-phase high performance liquid chromatography method. The procedure was performed under isocratic conditions with methanol as an organic modifier in the mobile phase using an end-capped non-polar C18 stationary reversed-phase column. In the present study, the structure-lipophilicity relationships of the studied compounds are discussed.

  • Open access
  • 53 Reads
Photosynthesis-Inhibiting Activity of Fluorinated 2‑Hydroxynaphthalene-1-carboxanilides

2-Hydroxy-N-phenylnaphthalene-1-carboxamide, three fluoro monosubstituted and five fluoro disubstituted 2-hydroxynaphthalene-1-carboxanilides were prepared by microwave-assisted synthesis and characterized. All the compounds were evaluated for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The PET inhibitory activity of the discussed compounds proved to be in a wide range, from inactive N-(2,6-difluorophenyl)-2-hydroxynaphthalene-1-carboxamide with an IC50 = 904 μM to N-(2,5-difluorophenyl)-2-hydroxynaphthalene-1-carboxamide with an IC50 of 44.2 μM, which was the most potent isomer of the series of evaluated compounds. Based on previous studies, it can be assumed that the mechanism of PET inhibition of these compounds is the inhibition of photosystem II in the thylakoid membrane.

  • Open access
  • 73 Reads
Patentability of biopolymer-based hydrogels

Biopolymer-based hydrogels are used in the field of tissue engineering, in the form of matrix capable of sustaining the life of differentiated and non-differentiated cells in three-dimensional structure that they can develop there and produce all the compounds for which they are programmed. Biopolymer-based hydrogels can be created by supramolecular chemistry from a large number of water-soluble polymers including proteins (e.g., collagen, gelatin, fibrin, etc.) and polysaccharides (e.g., cellulose, alginate, chitosan, etc.). The three-dimensional structure of these hydrogels is due to physical or chemical crosslinking which forms a structure which is insoluble in the biofluid of the environment. The elasticity of these structures, the presence of a large amount of water and the flexibility allow a resemblance to different living biological tissues, which allows them to be used in many biomedical applications.

This work, in the form of a patentability study of biopolymer-based hydrogels, englobes information present within patents (i.e., patent applications and granted patents). The patentability study describes the state of the art by introducing what has been patented in relation to biopolymer-based hydrogels regarding to preparation methods/process, formulations and applications. A detailed analysis is then given regarding to publication year, international patent classifications, inventors, applicants, owners, and jurisdiction. Furthermore, this work gives a competitive analysis of the past, present and future trends in the biological control and leads to various recommendations that could help one to plan and innovate research strategy.

Top