Correction: Professor (Dr) Sukh Dev: an iconic scientist with an innate sixth sense who radicalized natural product synthesis & organic chemistry.

Correction for 'Professor (Dr) Sukh Dev: an iconic scientist with an innate sixth sense who radicalized natural product synthesis & organic chemistry' by Harry Kochat et al., Org. Biomol. Chem., 2024, 22, 5466-5469, https://doi.org/10.1039/D4OB90071E.

TALSPEAK process on hollow fiber renewable liquid membrane apropos to the remedial maneuver of high level nuclear waste.

In concurrence with objectives of advanced high level nuclear waste(HLW) management, separation of chemically similar trivalent actinides and lanthanides is accomplished using TALSPEAK (Trivalent Actinide - Lanthanide Separation by Phosphorous reagent Extraction from Aqueous Komplexes) process on hollow fibre renewable liquid membrane (HFRLM). Permeability coefficient(Kf) of metal ions are determined under varying concentrations of diethylene triamine pentacaetic acid (DTPA) and H+ in the feed solution, containing 241Am with other metal impurities usually occurred in the HLW, and di(2-ethylhexyl) phosphoric acid (HDEHP) in liquid membrane and receiving emulsion phase. Optimized process conditions obtained are: 5 ± 0.25 L feed solution: containing 0.05 M DTPA, 1 M lactic acid and metal ions under the agitation of 400 ± 15 rpm, receiving phase: emulsion of 400 ± 15 mL 2 M HNO3 + 100 mL 0.2 M HDEHP/dodecane under stirring at 650 ± 25 rpm. The Kf of metal ions obtained under optimized process conditions are in the order: Am(III)<

Silver(i)-catalyzed sequential hydroamination and Prins type cyclization for the synthesis of fused benzo-δ-sultams.

An intramolecular annulation strategy has been developed for the synthesis of tetrahydrobenzo[e]pyrano[4,3-c][1,2]thiazine derivatives by means of coupling of aldehydes with 2-(4-hydroxybut-1-yn-1-yl)-N-arylsulfonamides using a catalytic amount of silver hexafluoroantimonate in toluene at 80 °C. This is the first report on the synthesis of fused benzo-δ-sultam derivatives through C-N, C-O, and C-C bond formations. The reaction proceeds through a cascade of hydroamination and Prins type cyclization.

Unique reversibility in extraction mechanism of U compared to solvent extraction for sorption of U(VI) and Pu(IV) by a novel solvent impregnated resin containing trialkyl phosphine oxide functionalized ionic liquid.

Novel Solvent Impregnated Resin (SIR) material was prepared by impregnating a trialkyl phosphine oxide functionalized ionic liquid (IL) into an inert polymeric material XAD-7. A series of SIR materials were prepared by varying the IL quantity. Sorption of both U(VI) and Pu(IV) were found to increase with increasing IL concentration in SIR up to an optimum IL concentration of 435 mg g-1 of SIR beyond which no effect of IL concentration was observed. A change of mechanism of sorption for U(VI) by SIR was observed in comparison to solvent extraction. The dependency of U(VI) sorption with nitric acid concentration showed a reverse trend compared to solvent extraction studies while for Pu(IV) the trend remained same as observed with solvent extraction. Sorption of both the radionuclides was found to follow pseudo second order mechanism and Langmuir adsorption isotherm. Distribution co-efficient measurements on IL impregnated SIR showed highly selective sorption of U(VI) and Pu(IV) over other trivalent f-elements and fission products from nitric acid medium.

Synthesis and biological evaluation of 1-amino isochromans from 2-bromoethyl benzaldehyde and amines in acid medium.

We have developed a facile and efficient synthetic route to substituted isochromans for the first time by reacting 2-(2-bromoethyl)benzaldehyde with a variety of aryl, heteroaryl amines in AcOH. The reaction is catalyst/additive free and takes place at reflux conditions with short reaction time to furnish products in good to excellent yields. All the compounds have been characterized by spectral techniques such as IR, 1H NMR and Mass etc. Synthesized compounds were evaluated for antimicrobial activity against specific bacterial like 1) Staphylococcus strains aureus 2) Bacillus subtilis 3) Escherichia coli 4) Pseudomonas aeruginosa. Compounds 3e, 3n, 3 m, 3 l, 3 k, 3j and 3b showed most potent in vitro activity against bacterial strains.

Carbon nano tubes functionalized with novel functional group- amido-amine for sorption of actinides.

The manuscript presents the results on the sorption of U(VI), Am(III) & Eu(III) from pH medium by a novel amido-amine functionalized multiwalled carbon nanotube (MWCNT). The novel functional group was introduced in the MWCNT by two step processes and characterized by various instrumental techniques like Scanning Electron Microscopy (SEM), Raman and X-ray Photoelectron Spectroscopy (XPS). The sorption process was found to be highly dependent on the pH of the solution with maximum sorption for both 233U, 241Am & 152+154Eu at pH 7.0. Kinetics of sorption was found to be fast with equilibrium reached in ∼15min and the sorption was found to be following pseudo 2nd order kinetics for the radionuclides. The sorption for both 233U and 152+154Eu followed Langmuir sorption model with maximum sorption capacity of 20.66mg/g and 16.1mg/g respectively. This has been explained by DFT calculations which shows that more negative solvation energy of U(VI) compared to Am(III) and Eu(III) and stronger U-MWCNT-AA complex is responsible for higher sorption capacity of U(VI) compared to Am(III) and Eu(III).The synthesized amido-amine functionalized MWCNT is a very promising candidate for removal of actinides and lanthanides from waste water solution with high efficiency.

Total syntheses of Prelactone V and Prelactone B.

The total syntheses of natural products Prelactone-V and Prelactone-B have been accomplished by a novel Chiron approach starting from d-glucose. The synthesis involves isopropylidene acetal formation of d-glucose using Poly(4-vinylpyridine) supported iodine as a catalyst, Tebbe olefination, Grignard reaction, Wittig olefination, selective mono deprotection of acetal using PMA/SiO2, hydrogenation and anti-1,3-diol formation are as key steps.

Simultaneous delivery of Paclitaxel and Bcl-2 siRNA via pH-Sensitive liposomal nanocarrier for the synergistic treatment of melanoma.

pH-sensitive drug carriers that are sensitive to the acidic (pH = ~6.5) microenvironments of tumor tissues have been primarily used as effective drug/gene/siRNA/microRNA carriers for releasing their payloads to tumor cells/tissues. Resistance to various drugs has become a big hurdle in systemic chemotherapy in cancer. Therefore delivery of chemotherapeutic agents and siRNA's targeting anti apoptotic genes possess advantages to overcome the efflux pump mediated and anti apoptosis-related drug resistance. Here, we report the development of nanocarrier system prepared from kojic acid backbone-based cationic amphiphile containing endosomal pH-sensitive imidazole ring. This pH-sensitive liposomal nanocarrier effectively delivers anti-cancer drug (Paclitaxel; PTX) and siRNA (Bcl-2), and significantly inhibits cell proliferation and reduces tumor growth. Tumor inhibition response attributes to the synergistic effect of PTX potency and MDR reversing ability of Bcl-2 siRNA in the tumor supporting that kojic acid based liposomal pH-sensitive nanocarrier as efficient vehicle for systemic co-delivery of drugs and siRNA.

Substitution dependent stereoselective construction of bicyclic lactones and its application to the total synthesis of pyranopyran, tetraketide and polyrhacitide A.

A novel bicyclization strategy has been developed for the stereoselective synthesis of bicyclic lactones, i.e. 7-aryl or alkyl-2,6-dioxabicyclo[3.3.1]nonan-3-ones through a domino cyclization of (R)-3-hydroxyhex-5-enoic acid with an aldehyde in the presence of 10 mol% trimethylsilyltriflate under mild conditions. The salient features of this methodology are high yields, excellent selectivity, low catalyst loading and faster reaction times. This method has been successfully applied to the total synthesis of pyranopyran, tetraketide and polyrhacitide A.

Para amino benzoic acid-derived self-assembled biocompatible nanoparticles for efficient delivery of siRNA.

A number of diseases can result from abnormal gene expression. One of the approaches for treating such diseases is gene therapy to inhibit expression of a particular gene in a specific cell population by RNA interference. Use of efficient delivery vehicles increases the safety and success of gene therapy. Here we report the development of functionalized biocompatible fluorescent nanoparticles from para amino benzoic acid nanoparticles for efficient delivery of short interfering RNA (siRNA). These nanoparticles were non-toxic and did not interfere with progression of the cell cycle. The intrinsic fluorescent nature of these nanoparticles allows easy tracking and an opportunity for diagnostic applications. Human Bcl-2 siRNA was complexed with these nanoparticles to inhibit expression in cells at both the transcriptional and translational levels. Our findings indicated high gene transfection efficiency. These biocompatible nanoparticles allow targeted delivery of siRNA, providing an efficient vehicle for gene delivery.

Cooperative Multicatalytic System for the One-Pot Synthesis of Octahydrospiro-ß-carbolines.

A domino cyclization of 3-((3-(2-aminophenyl)prop-2-ynylamino)methyl)but-3-en-1-ol with aldehydes has been accomplished employing 5 mol % of the Ph3PAuCl/AgSbF6/In(OTf)3 system to afford the corresponding octahydrospiro[pyran-4,4'-pyrido[3,4-b]indole] derivatives in good yields with high selectivity. This is the first report on the synthesis of spiro-ß-carbolines through a multicatalytic cascade process.

Tandem Prins/Wagner/Ritter process for the stereoselective synthesis of (3-oxabicyclo[4.2.0]octanyl)amide and (1-(5-aryltetrahydrofuran-3-yl)cyclobutyl)amide derivatives.

Three-component coupling of aldehydes, vinylcyclopropyl carbinols, and nitriles in the presence of 10 mol% TMSOTf at -40 to 0 °C in dichloromethane affords a novel class of (3-oxabicyclo[4.2.0]octanyl)amides in high yields with excellent selectivity, whereas (1-vinylcyclobutyl)methanol provides the corresponding (1-(5-aryltetrahydrofuran-3-yl)cyclobutyl)amides under similar conditions. This is the first report on the synthesis of oxabicycles through a sequential Prins/Wagner/Ritter process.

The protecting-group directed diastereoselective Nozaki-Hiyama-Kishi (NHK) reaction: total synthesis and biological evaluation of zeaenol, 7-epi-zeaenol and its analogues.

The stereoselective total synthesis of zeaenol and 7-epi-zeaenol is achieved in a convergent manner using Julia-Kocienski olefination, protecting group-directed intermolecular diastereoselective Nozaki-Hiyama-Kishi (NHK) reaction, De Brabander's lactonization reaction and CBS reduction as the key steps. In this article, we have observed the most suitable protecting groups with respect to selectivity during the protecting group directed intermolecular asymmetric Nozaki-Hiyama-Kishi reaction. The zeaenol, 7-epi-zeaenol and its derivatives were analyzed for their biological activity and screened in four cancer cell lines.

Synthesis and determination of absolute configuration of α-pyrones isolated from Penicillium corylophilum.

The first total synthesis of (S)-6-(2,9-dihydroxynonyl)-4-hydroxy-3-methyl-2H-pyran-2-one, 4-hydroxy-3-methyl-6-((2S,4R)-2,4,11-trihydroxyundecyl)-2H-pyran-2-one, and its unnatural 2R,4R-isomer starting from commercially available 1,8-octanediol is described. The synthesis led to the revision of the proposed structural assignment of the natural product as (R)-6-(2,9-dihydroxynonyl)-4-hydroxy-3-methyl-2H-pyran-2-one. The key steps include chiral auxiliary mediated asymmetric acetate aldol reaction, dianion addition, and base mediated cyclization to form an α-pyrone ring.

Thee-component, one-pot synthesis of hexahydroazepino[3,4-b]indole and tetrahydro-1H-pyrido[3,4-b]indole derivatives and evaluation of their cytotoxicity.

A three-component, four-center Ugi reaction has been developed to produce a novel class of 2-aryl-3-oxo-hexahydroazepino[3,4-b]indole and 2-aryl-3-oxo-tetrahydro-1H-pyrido[3,4-b]indole derivatives in good to high yields. A few of them exhibit moderate cytotoxicity against various cancer cell lines such as HeLa (human epithelial cervical cancer), A549 (human lung carcinoma epithelial), DU145 (human prostate carcinoma epithelial) and MCF-7 (human breast adenocarcinoma).

Extracellular polymeric substances of bacteria and their potential environmental applications.

Biopolymers are considered a potential alternative to conventional chemical polymers because of their ease of biodegradability, high efficiency, non-toxicity and non-secondary pollution. Recently, extracellular polymeric substances (EPS, biopolymers produced by the microorganisms) have been recognised by many researchers as a potential flocculent for their applications in various water, wastewater and sludge treatment processes. In this context, literature information on EPS is widely dispersed and is very scarce. Thus, this review marginalizes various studies conducted so far about EPS nature-production-recovery, properties, environmental applications and moreover, critically examines future research needs and advanced application prospective of the EPS. One of the most important aspect of chemical composition and structural details of different moieties of EPS in terms of carbohydrates, proteins, extracellular DNA, lipid and surfactants and humic substances are described. These chemical characteristics of EPS in relation to formation and properties of microbial aggregates as well as degradation of EPS in the matrix (biomass, flocs etc) are analyzed. The important engineering properties (based on structural characteristics) such as adsorption, biodegradability, hydrophilicity/hydrophobicity of EPS matrix are also discussed in details. Different aspects of EPS production process such as bacterial strain maintenance; inoculum and factors affecting EPS production were presented. The important factors affecting EPS production include growth phase, carbon and nitrogen sources and their ratio, role of other nutrients (phosphorus, micronutrients/trace elements, and vitamins), impact of pH, temperature, metals, aerobic versus anaerobic conditions and pure and mixed culture. The production of EPS in high concentration with high productivity is essential due to economic reasons. Therefore, the knowledge about all the aspects of EPS production (listed above) is highly essential to formulate a logical and scientific basis for the research and industrial activities. One of the very important issues in the production/application/biodegradation of EPS is how the EPS is extracted from the matrix or a culture broth. Moreover, EPS matrix available in different forms (crude, loosely bound, tightly bound, slime, capsular and purified) can be used as a bioflocculant material. Several chemical and physical methods for the extraction of EPS (crude form or purified form) from different sources have been analyzed and reported. There is ample information available in the literature about various EPS extraction methods. Flocculability, dewaterability and biosorption ability are the very attractive engineering properties of the EPS matrix. Recent information on important aspects of these properties qualitatively as well as quantitatively has been described. Recent information on the mechanism of flocculation mediated by EPS is presented. Potential role of EPS in sludge dewatering and biosorption phenomenon has been discussed in details. Different factors influencing the EPS ability to flocculate and dewaterability of different suspensions have been included. The factors considered for the discussion are cations, different forms of EPS, concentration of EPS, protein and carbohydrate content of EPS, molecular weight of EPS, pH of the suspension, temperature etc. These factors were selected for the study based upon their role in the flocculation and dewatering mechanism as well the most recent available literature findings on these factors. For example, only recently it has been demonstrated that there is an optimum EPS concentration for sludge flocculation/dewatering. High or low concentration of EPS can lead to destabilization of flocs. Role of EPS in environmental applications such as water treatment, wastewater flocculation and settling, colour removal from wastewater, sludge dewatering, metal removal and recovery, removal of toxic organic compounds, landfill leachate treatment, soil remediation and reclamation has been presented based on the most recent available information. However, data available on environmental application of EPS are very limited. Investigations are required for exploring the potential of field applications of EPS. Finally, the limitations in the knowledge gap are outlined and the research needs as well as future perspectives are highlighted.

Mixed culture of Kluyveromyces marxianus and Candida krusei for single-cell protein production and organic load removal from whey.

The study was conducted to evaluate the potential of mixed culture of Kluyveromyces marxianus and Candida krusei to enhance COD removal efficiency, minimize contamination at extreme conditions (high temperature 40°C and low pH 3.5) during batch and continuous aerobic fermentation and to obtain improved quality single-cell protein (SCP) using whey as substrate. The batch fermentation of mono-culture and mixed culture result showed that the mixed culture resulted in 8.8% higher COD removal efficacy with 19% higher biomass yield and 33% increased productivity. The maximum COD removal 80.2% (including residual protein) was obtained at 24h HRT with biomass productivity of 0.17 g/L/h; however, maximum biomass productivity of 0.38 g/L/h and 34% COD removal were obtained at 6h HRT. The results showed that the mixed culture of acid resistance and thermo-tolerant yeasts was a potential way to produce SCP (animal feed) and simultaneous COD removal under extreme operating conditions.

Recovery of residual soluble protein by two-step precipitation process with concomitant COD reduction from the yeast-cultivated cheese whey.

The present study was conducted to recover the residual soluble protein after cultivation of yeast (K. marxianus) in cheese whey. Cheese whey continuous fermentation with cell recycle system was carried out at 40 °C and pH 3.5. The yeast biomass was separated from the fermented broth by centrifugation and residual soluble protein from fermented whey supernatant was precipitated by heat treatment (at 100 °C, pH 4.5 and 10 min incubation). The maximum soluble protein recovery up to 53 % was achieved at pH 4.5 with 54 % residual COD removal. However, gravity sedimentable precipitates were obtained at pH 3.5 with 47 % protein recovery. Therefore, the reactor (scale up) study was conducted at pH 3.5 with agitation, which resulted in 68 % of residual soluble protein recovery and simultaneously residual COD removal of 62 %. Further precipitation/coagulation of soluble protein was also evaluated using carboxymethylcellulose (CMC) and then two precipitation (thermal followed by CMC precipitation) processes were combined to increase the protein precipitation, which finally reached up to 81 % of total soluble protein recovery from the supernatant. This optimized process could be applied to recover the residual protein left after fermentation of cheese whey without centrifugation.