Search

Abstract: The demand for natural product-based drugs with less cost and efficient procedures has become a challenge for researchers. Benzalacetophenone is a natural product-based species that is modified into numerous heterocyclic compounds, including isoxazoline and isoxazole derivatives. The utility of isoxazoline and oxazole derivatives has been increased for the synthesis of new and effective chemical entities to serve medicinal chemistry in the past few years. Isoxazoline and isoxazole are fascinating classes of heterocyclic compounds, which belong to N- and O-heterocycles, and are widely used as precursors for the development of drugs. This review highlights the recent work on the synthesis of mono and bis isoxazoline and isoxazole derivatives using stable benzalacetophenone and functionalization of isoxazoline and isoxazole, along with the prevailing biological properties.

Silica-based heterogeneous catalyst derived from rice husk ash (RHA) was used for the transformation of palm fatty acid distillate (PFAD) into biodiesel. The production of the biodiesel from PFAD was conducted via esterification and transesterification employing Huskcatacid and Huskcatbase, respectively. The biodiesel was analyzed from different parameters, i.e., amount of catalyst, oil to methanol ratio, temperature, and reaction times. The outcomes depicted Huskcatacid was efficient for PFAD esterification to produce 91.6% ester with 5 wt% catalysts and 5:1 (MeOH:PFAD), followed by the transesterification using 1 wt% Huskcatbase in 3:1 (MeOH:oil) to generate 99.73% biodiesel with a high percentage of methyl oleate (57.86%) and methyl palmitate (34.43%). Huskcatacid and Huskcatbase depicted a high surface area (7.362 m2/g and 14.493 m2/g) and high porosity (2.726 × 10−3 cm3/g and 4.985 × 10−3 cm3/g), respectively, that contributed to the efficient esterification and the easy separation of glycerol. The PFAD-derived biodiesel was tested on the Megatech®-Mark III engine and confirmed the proportional torque (ɽ) increment with the loading of B100 biodiesel. Rice husk showed promising outcomes as solid-support heterogeneous catalysts and the production of value-added products to reduce the agricultural waste management issues.

In this study, coconut shells were converted into biochar via pyrolysis and chemically modified via an acid-base treatment to enrich its adsorption capabilities. Batch experiments were carried out to analyze the adsorption potential of the modified coconut shell (MCSC) or removal of chromium, nickel, and copper from aqueous solution. The chemical modification increased the surface area of MCSC to 185.712 m2/g. Batch adsorption study using MCSC resulted in 99% removal of copper, 95% (nickel), and 39% (chromium). The adsorption of studied metal ions fitted well with Langmuir isotherm, showing a monolayer adsorption process. A kinetic analysis showed that all the samples match a strong correlation coefficient in pseudo-second-order (R2>0.95), indicating the occurrence of a chemical adsorption process.

The rise of antimicrobial resistance for infectious bacteria has become an alarming issue to human health. New antimicrobial drugs are in dire need and pivotal to overcome this issue. In this study, aspirinate azo ligands bearing different halogens L1-5 has been prepared via diazo-coupling reaction. The ligands L1-5 were coordinated with silver, Ag (I) metal to produce Ag (I) aspirin-azo complexes C1-5. The antibacterial properties of L1-5 and C1-5 were evaluated against Staphylococcus aureus and Escherichia coli using turbidimetric kinetic method. The complexes C1-5 showed comparable growth inhibition activity towards E. coli (MIC 82-105 ppm) and S. aureus (MIC 80-105 ppm) compared to ligands L1-5 with E. coli (MIC 83-200 ppm), S. aureus (80-131 ppm) and ampicillin (MIC 93 and 124 ppm, respectively). The excellent bacterial resistance of both L1-5 and C1-5 indicates the potential of aspirinate azo and their complexes as new antibacterial agents, which significantly benefit to the pharmaceutical industries.

The use of agricultural by-products has been widely studied to develop effective and inexpensive adsorbent for heavy metal removal. In this study, sago (M.sagu) fly ash (FA) was chemically modified to afford an operational adsorbent for Pb (II) elimination from water. Chemical modification was carried out via acid-base treatment using NaOH and HCl. The chemically modified fly ash (MFA) was characterized via proximate, surface morphology, and functional groups' surface area analyses. The effects of adsorption parameters, namely, Pb (II) initial concentration, sorbent dosage and contact time on the eradication of Pb (II) by MFA was analyzed in batch experiments with Langmuir and Freundlich isotherms. Optimization of Pb (II) removal by MFA was studied via response surface methodology (RSM) approach. Results revealed that chemical modification has successfully enhanced the adsorptive properties of MFA (BET surface area: 231.4 m2/g, fixed carbon: 55.83%). MFA exhibits better Pb (II) removal efficiency (90.8%) compared to FA (63.6%) at the following adsorption condition: Pb (II) initial concentration (5 ppm), contact time (30 min) and agitation speed (150 rpm). The adsorption of Pb (II) by FA and MFA fitted well with Freundlich isotherm (R2>0.9). RSM study suggested that the optimum Pb (II) removal was 99.4% at the following conditions: Pb (II) initial concentration (20 ppm), contact time (2 h) and sorbent dosage (0.6 g/50 mL). The results concluded the potential optimum operational condition for Pb (II) removal from aqueous environment by MFA as a low cost adsorbent, at larger scale.

Eleusine indica, a perennial herb that belongs to the Poaceae family, is locally known as “rumput sambau”. The species can be found in the tropical regions and it is the only species of Eleusine in Malaysia. In India, some parts of the plant such as the roots and the seeds are used as food and can be eaten raw or cooked. The young seedling is also used as a side dish with rice, while the seeds are sometimes used as a famine food. Although this grass is not considered as food in Malaysia, the local people utilise it to treat various ailments such as hastening the placenta delivery after childbirth, pain relieve for vaginal bleeding, asthma, fever, urinary infection, haemorrhoids, and tonic for flu related symptoms. Due to wide spectrum of traditional usage, a complete review of E. indica which focusing on food and medicinal perspectives is necessary to organize and evaluate its potential for further studies and commercial exploitation. The information on the species was collected from scientific journals, books, and reports searched through available databases such as Google Scholar, PubMed, Directory of Open Access Journals, Science Direct, Bioline International, and Reaxys. Contextually, the present review reveals that apart from the roots, the plant is relatively safe to ingest. It represents a rich source of nutrients and contains therapeutic phytochemicals such as flavonoids, steroids, essential oils, cardiac glycosides, coumarins, fatty acids, anthraquinones, anthrones, triterpenes, tannins, and alkaloids. Thus, E. indica can be considered as a natural reservoir for both food and medicine.

Latest progress in the liquid crystal (LC) field related to azo molecules incorporated into natural product- based moieties for the improvement of LC texture and mesomeric phases has received great interest among researchers. A LC containing natural product-based moieties i.e. menthol, kojic acid, cholesterol and chalcone with stable azo and azobenzene scaffolds with specific optical tunability, has been widely used in photo-active materials such as Liquid Crystal Display (LCD), LC films, smart windows and other devices. This review discusses the influence of azobenzene, a renowned photo-responsive and stable LC scaffold, in mesogenic phases due to photo-isomerization and optical switching. The incorporation of mesomeric phases of natural product moieties to azo molecules has improved the properties of LC, i.e, from the nematic phase to the smectic phase with proper magnetic field alignment. Natural product-based LC can be useful in numerous applications, especially practical electronic or optic devices such as optical image storage, display devices, solar cells, optical switching.

Stingless bee honey is a unique edible natural product and has been used by humankind for millenniums for various purposes, mostly as food and for therapeutic uses. The compositions of honey and pr...

Chalcone-derived pyrimidine is a well-known heterocyclic compound that is commonly present in ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) bio-isosteres. Pyrimidine derivatives are effective in both the electronic industry and drug industries. This review highlights the synthesis of pyrimidines, namely mono-pyrimidine, bis-pyrimidine, fused pyrimidine, symmetric, and asymmetric pyrimidine via one-pot and two-pot methods. The one-pot method is the direct reaction of amino derivatives with aldehydes and acetophenones, whereas the two-pot method is frequently reported for the synthesis of chalcone before the cyclization to a pyrimidine. This review is important in organic synthesis, particularly in the heterocyclic field, regarding pyrimidines and their significance in therapeutic and electronic industries.

Coronavirus disease 2019 (COVID-19) has become a global pandemic in a short period, where a tragically large number of human lives being lost. It is an infectious pandemic that recently infected more than two hundred countries in the world. Many potential treatments have been introduced, which are considered potent antiviral drugs and commonly reported as herbal or traditional and medicinal treatments. A variety of bioactive metabolites extracts from natural herbal have been reported for coronaviruses with some effective results. Food and Drug Administration (FDA) has approved numerous drugs to be introduced against COVID-19, which commercially available as antiviral drugs and vaccines. In this study, a comprehensive review is discussed on the potential antiviral remedies based on natural and synthetic drugs. This review highlighted the potential remedies of COVID-19 which successfully applied to patients with high cytopathic inhibition potency for cell-to-cell spread and replication of coronavirus.

Metal-organic frameworks (MOFs) bearing a number of organic ligands of various functional groups and substituents give rise to MOFs of unique crystal structures and topologies. A number of potential applications have been considered for these materials in a wide array of scientific fields, such as in the adsorption of industrially-relevant gases, as heterogeneous catalysts for various organic reactions, as photoluminescent materials, and as antibacterial agents. This review highlights the utility of select groups of organic ligands in the assembly of main group metals, transition metals, as well as lanthanides and actinides, to generate MOFs of diverse structures in the solid state, with special attention paid on ligands bearing the carboxylate-, pyridyl-, ether-, imine (Schiff base) moieties, as well as mechanically interlocked molecules (MIMs).

In the present work, the surface morphology and electrical characteristic of different doping ratio of reduced Graphene Oxide (rGO) in Titanium Oxide solution with different organic dyes (turmeric and beetroot) were studied. The Titanium Dioxide (TiO2) solution and reduced Graphene Oxides (rGO) were synthesized by using precipitation-peptization method and chemical reagent, respectively. The TiO2-rGO thin film was deposited on the glass substrate by using doctor-blade technique. The surface morphology and electrical characteristic were measured by using Scanning Electron Microscope (SEM) and Keitheley 2450 Source Meter, respectively. Experimental results showed that 0.3 wt% rGO with turmeric dye resulted the highest value of open voltage (Voc) and short circuit current (Isc) of Dye-sensitized Solar Cells (DSSC).

A series of mono-substituted thiourea (2a–i) and bis-substituted thiourea-azo (3a–f) derived from paracetamol derivatives were prepared from isothiocyanates with one and two equivalents of halogenated azo dyes, respectively. The incorporation of azo-derived paracetamol via thiourea moiety in 2a–i depicted excellent microbial activity on Staphylococcus aureus, and 2-(((3-((2-bromophenyl)diazenyl)-4-hydroxyphenyl)carbamothioyl)carbamoyl)phenyl acetate, 2a showed equivalent inhibition properties to the standard ampicillin (10 mm). The structure–activity relationship studies of 2a were supported via molecular docking interaction against S. aureus tyrosyl-tRNA synthetase protein which displayed a free energy interaction of −7.7 kcal/mol compared to aspirin (−6.4 kcal/mol).

Utilizing agricultural wastes into value-added products of a low-cost adsorbent has become of interest in recent years. In this study, sago-silica composite with a ratio of 80:20 (w/w%) was prepared via chemical grafting of abundantly available sago waste and rice husk. The physicochemical properties of the composites were characterized, and their efficiencies as adsorbents on the removal of chromium (Cr), lead (Pb), and copper (Cu) in aqueous media were studied as a function of pH, adsorbent dosage, initial concentration, and contact time. Results showed that the sago-silica composite has a more extensive surface area of 227.7 m2/g compared to SAC (167.3 m2/g). The adsorption of Cr and Cu gave excellent monolayer and heterolayer adsorption on sago-silica composite represented by Langmuir and Freundlich’s isotherm based on coefficient regression, R2 > 0.9. Pseudo-second-order kinetics model showed best fitted with excellent adsorption capacity qe of Cr, Pb, and Cu adsorption on sago-silica composites, which demonstrated the occurrence of chemisorption process between the composite and metal ions. The composite from carbon–silica is one of the cost-effective natural sorbents which demonstrate excellent removal of heavy metal from the aqueous environment.

Epoxy chalcone is a heterocyclic molecule and an important precursor for the synthesis of biologically active compounds. This mini-review is elucidating the synthetic strategies of chalcone epoxide via one pot and two pot routes including nature of reactants, nature of catalyst and variety of catalyst to improve yield of desired product, biological applications and advantages and drawbacks of these synthetic strategies. One pot route has wide variety of reactants and efficient one is the condensation of aldehyde and ketone. However, two pot route is consisted of chalcone synthesis preceding to epoxy chalcone. The synthetic routes for the preparation of epoxy chalcone and the usage as a precursor for the synthesis of various organic molecules with biological application is comprehensively discussed. This review is outstanding in organic chemistry and pharmaceutical industries to produce new molecules with various applications.

The evolution of drug resistant bacteria has now becoming a major concern in the search for new antibacterial agent. Ongoing interest has also developing to find a new class of compounds with antioxidant properties. Herein, a series of hydroxylated chalcones 1a-g and aspirin-chalcone derivatives 2a-g were successfully synthesised for antibacterial and antioxidant properties. Chalcones 1a-g were prepared by Claisen-Schmidt condensation of 4-hydroxyacetophenone and benzaldehyde derivatives, while 2a-g were synthesised viaesterification of aspirin with 1a-g. All the synthesised compounds were elucidated using CHNS elemental analysis, FTIR, 1H and 13C NMR spectroscopy, and X-ray crystallography. All compounds were evaluated for antibacterial assay via disc diffusion method and antioxidant assay using stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Only 1ashowed moderate activity against Escherichia coli, while 1b-gand 2a-gshowed no inhibition against E. coliand Staphylococcus aureusin comparison ampicillin as standard antibiotic. Compounds 1b-g and 2a-g having various substituents contributed to bulky molecular structures and caused difficult penetration into the cell membrane thus, unable to inhibit the bacterial growth. Compounds 1a-gand 2a-g also displayed poor antioxidant properties on DPPH in comparison to ascorbic acid due to low phenolic pharmacophore. The formation of bulky structures for 2a-g have hindered the antioxidant properties compared to 1a-g.

A novel trimetallic W-Mg-Al oxide composites immobilised onto starch were synthesized via sol-gel method. W-Mg-Al oxide composites were synthesized by first preparing WO3 using incipient wetness method, followed by immobilising onto MgO-Al2O3 support using starch as binder. The effects of starch addition on the crystal properties and morphology were investigated by X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). In the presence of hydrogen peroxide and acetic acid as oxidant system, W-Mg-Al oxide starch composites exhibited higher catalytic performances for oxidative desulphurisation (ODS) of dibenzothiophene (DBT) at 95% compared to W-Mg-Al oxide composites. The catalytic activity observed could be correlated to the distribution of active phases on starch as well as the higher crystallinity of the metal oxide composites.

An up-to-date short review of the chalcone methodologies is presented, which is the most interesting and beneficial for choosing the desired protocol to synthesize suitable derivatives of chalcones. Chalcones are fluorescent, stable compounds which contribute to the synthesis of various pharmacologically important heterocyclic structure-based derivatives. Chalcone has displayed a remarkable curative efficiency to cure several diseases. Several schemes and methodologies have been reported for employing different catalysts and reagents. The development of improved methodologies of α, β-unsaturated carbonyl compounds is still on going. In this review, synthetic methodologies and their recent modification in designing new methods with efficient, economical, eco-friendly and high yield are discussed.