Synthesis and Biological Screening of 2‐Substituted 5,6‐Dihydro‐5‐oxo‐ 4H‐1,3,4‐oxadiazine‐4‐propanenitriles and of Their Intermediates

To evaluate the effect of substituents on biological activities of electron‐rich N‐containing heterocycles, the variably 2‐substituted 5,6‐dihydro‐5‐oxo‐4H‐1,3,4‐oxadiazine‐4‐propanenitriles 26 – 33 were synthesized and evaluated for antibacterial, antifungal, and enzyme‐inhibition activities. The target compounds were obtained from alkyl 4‐ or 3‐hydroxy benzoates 1 and 2 , respectively, and from methyl indoleacetate 3 . The phenolic OH group of benzoates 1 and 2 were substituted with p‐toluenesulfonyl (→ 4 and 5 ), benzoyl (→ 6 and 7 ), and benzyl groups (→ 8 and 9 ) and then converted to 5,6‐dihydro‐5‐oxo‐4H‐1,3,4‐oxadiazine‐4‐propanenitriles. To establish structure‐activity relationships (SAR), a pharmacological screening of the intervening intermediates was also conducted, which revealed that the intermediate hydrazide 11 possesses significant antimicrobial and MAO‐A inhibiting properties and intermediates 12, 24, 28 , and 29 appreciable antifungal activities. Compound 7 inhibits α‐chymotrypsin.     

Novel Synthetic Routes to Prepare Biologically Active Quinoxalines and Their Derivatives: A Synthetic Review for the Last Two Decades

Quinoxalines, a class of N-heterocyclic compounds, are important biological agents, and a significant amount of research activity has been directed towards this class. They have several prominent pharmacological effects like antifungal, antibacterial, antiviral, and antimicrobial. Quinoxaline derivatives have diverse therapeutic uses and have become the crucial component in drugs used to treat cancerous cells, AIDS, plant viruses, schizophrenia, certifying them a great future in medicinal chemistry. Due to the current pandemic situation caused by SARS-COVID 19, it has become essential to synthesize drugs to combat deadly pathogens (bacteria, fungi, viruses) for now and near future. Since quinoxalines is an essential moiety to treat infectious diseases, numerous synthetic routes have been developed by researchers, with a prime focus on green chemistry and cost-effective methods. This review paper highlights the various synthetic routes to prepare quinoxaline and its derivatives, covering the literature for the last two decades. A total of 31 schemes have been explained using the green chemistry approach, cost-effective methods, and quinoxaline derivatives’ therapeutic uses.     

High-Performance Thin-Layer Chromatographic Determination of Three Therapeutic Phenolic Components in Leucas Species

JPC – Journal of Planar Chromatography – Modern TLC - This study was designed to develop a simple, sensitive, selective, and precise high-performance thin-layer chromatography (HPTLC)...     

Qualitative and Quantitative Standardization of Myrica esculenta Buch.-Ham. Stem Bark by Use of HPTLC

JPC – Journal of Planar Chromatography – Modern TLC - Bark of Myrica esculenta Buch.-Ham., commonly known as ‘Kaphal’ in indigenous systems of medicine, is used for...     

Radiochemical separation of110mAg,210Pb,127Te and131I from aqueous nitric acid solution by bis-2-(butoxyethyl ether)

A bis-2-(butoxyethyl ether) (DBC) solvent extraction method has been developed for the radiochemical separation of^110mAg,²¹⁰Pb,¹²⁷Te and¹³¹I in varying concentrations of aqueous HNO₃. Various factors were examined to determine the optimum conditions of extraction. The effect of various masking agents has been studied. The extraction of¹³¹I is enhanced to 99% at 2.4M HNO₃ in the presence of KSCN.¹³¹I was stripped into aqueous sodium hydroxide from the oxygenated organic extractant. The method was then applied for the recovery of¹³¹I from neutron irradiated tellurium metal. The mechanism and reactivity of DBC with metal ions is described.     

Multielemental determination in platinum rocks by nondestructive neutron activation analysis

Na, Zn, Re, Sc, Ir, Ru, Pt, Fe and Co have been determined in Pt-rock samples from different parts of the state by thermal neutron-activation analysis followed by nondestructive analysis on a MCA. The accuracy and precision of the method have been determined.     

Two new triterpenoids and a steroidal glycoside from the aerial parts of Ocimum basilicum

Studies on the chemical constituents of the aerial parts of Ocimum basilicum have led to the isolation of three new compounds, basilol (1), ocimol (2), and basilimoside (3), along with two known constituents betulinic acid and oleanolic acid. The structures of the new constituents have been elucidated through spectral studies including 2D-NMR experiments (HMQC, HMBC, COSY, NOESY, and J-resolved) and chemical transformation, as p-formylphenyl 3beta-hydroxyolean-12-en-28-oate (1), 2-methoxy-4-carbomethoxyphenyl 3beta-hydroxy-lup-20(29)-en-28-oate (2), and (22E)-24xi-ethyl-25-methylcholesta-5,22-diene-3beta-ol-3-O-D-glucopyranoside (3).     

Phase Separation Phenomenon in Non-ionic Surfactant TX-114 Micellar Solutions: Effect of Added Surfactants and Polymers

Clouding (or phase separation) in non-ionic surfactants is a well-known phenomenon. Clouding is to be avoided in some applications whereas in others it is preferred. Herein the results of CP (cloud point—the temperature at which solution separates into two phases) measurements of the non-ionic surfactant Triton X-114 (TX-114) in the presence of surfactants and polymers are presented. Cationic and nonionic surfactants, in the absence and presence of the quaternary salt tetrabutylammonium bromide (TBAB), increase the CP of TX-114. Anionic surfactants, in the absence of TBAB, increase the CP; in the presence of TBAB, these surfactants decrease the CP. Polymers of PEG and PVP series have been found to decrease the CP. The results are discussed by taking into consideration the nature of the added surfactants and polymers.     

Chiral Lewis Base-Catalysed Asymmetric Syntheses of Benzo-fused ϵ-Lactones

We herein report a two-step protocol for the asymmetric synthesis of novel chiral benzofused ϵ-lactones starting from O-protected hydroxymethyl-para-quinone methides and activated aryl esters. By using chiral isothiourea Lewis base catalysts a broad variety of differently substituted products could be obtained in yields of around 50 % over both steps with high levels of enantioselectivities, albeit low diastereoselectivities only.