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Mystroxylon aethiopicum (Thumb.) Loes subsp. schlechteri (loes.) R. H. Archeris, a member of the Celastracea family, is widely used in traditional medicine to treat several diseases, such as hemorrhagic diarrhoea and respiratory tract infections. The study aimed to isolate the biologically active compounds from the leaves of M. aethiopicum. The leaves were ground to a fine powder and sequentially extracted with n-hexane, dichloromethane, acetone and methanol using serial exhaustive extraction (SEE) method. The bioautography and broth micro-dilution methods were used to analyse the antibacterial activities. The bioautography assay revealed that the compounds in the n-hexane, dichloromethane and acetone extracts have activity against all tested microorganisms. In contrast, the methanol extracts exhibited no antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli. The n-hexane extract had the lowest average MIC of 0.08 mg/mL, followed by the acetone (0.71 mg/mL) and dichloromethane (0.82 mg/mL) extracts. The bioassay-guided fractionation of dichloromethane and acetone extracts led to the isolation of 3-Oacetyloleanolic acid. The structure of the isolated compound was elucidated using NMR data and comparison with literature data. This is the first report on the isolation of 3-O-acetyloleanolic acid from the leaves of M. aethiopicum. [ABSTRACT FROM AUTHOR]

6H-Benzo[c]chromen-6-ones serve as core structures of secondary metabolites and are of considerable pharmacological importance. Natural sources produce limited quantities, hence the need for synthetic procedures for 6H-benzo[c ]chromen-6-ones, which are herein reviewed. The literature describes protocols such as the Suzuki coupling reactions for the synthesis of biaryl, which then undergoes lactonization, reactions of 3-formylcoumarin (chromenones) with 1,3-bis(silylenol ethers), radical mediated cyclization of arylbenzoates, metal or base catalyzed cyclization of phenyl- 2-halobenzoates and 2-halobenzyloxyphenols, and benzoic acid coupling with benzoquinone using electrophilic metal- based catalyst. The efficient and simple procedures are those involving the reactions of Michael acceptor (chromenones and chalcones) with 1,3- and 1,5-dicarbonyl compounds. [ABSTRACT FROM AUTHOR]

A series of 3-nitrochalcones have been synthesized enroute towards fused ring pyrazolones and isoxazolones. Base catalyzed condensation of the chalcones with ethylacetoacetate yielded cyclohexenones in good yields (74–76%). The treatment of cyclohexenones with hydrazine hydrate or hydroxylamine chloride in the presence of a base afforded the corresponding fused-ring pyrazolinones (70–78% yield) and isoxazolinones (58–66% yield). The newly synthesized compounds were characterized by IR, 1D and 2D NMR and HRMS spectral analysis. The compounds were screened for their antioxidant and antimicrobial activities. Pyrazolinones showed good DPPH radical scavenging and iron metal chelating properties. The para -hydroxy group was important for a compound to have enhanced antioxidant activity. Pyrazolinones and isoxazolinone exhibited a wider range of antimicrobial activities compared to cyclohexenones. Pyrazolinones and isoxazolinone bearing a thiophene ring were the most potent type of compounds against B acillus subtilis and C andida albicans with MIC values of 0.313–1.25 μg/mL. Some of the synthesized compounds were found to have promising antioxidant, metal chelation and antimicrobial activities. [ABSTRACT FROM AUTHOR]

The reaction of ethyl acetoacetate and 2'-hydroxychalcones under atmospheric air to furnish a series of functionalized 6H-benzo[c]chromen-6-ones in moderate yields is reported. The reaction proceeds through trans-esterification, intra-molecular Michael addition, Robinson annulation and oxidative aromatization. [ABSTRACT FROM AUTHOR]

Abstract: The investigation of Tylosema esculentum (Morama) husks, cotyledons, and tuber yielded griffonilide 2, compound 1, griffonin 3, gallic acid 4, protocatechuic acid 5, β-sitosterol 6, behenic acid 7, oleic acid 8, sucrose 9, 2-O-ethyl-α-d-glucopyranoside 10, kaempferol 11 and kaempferol-3-O-β-d-glucopyranoside 12. The structures of the isolates were determined by NMR, HR-TOF EIMS, IR and UV–vis spectroscopy, and by comparison with literature data. The husk EtOAc and n-butanol extracts demonstrated >90% DPPH radical scavenging activity at concentrations of 25, 50 and 250μg/mL. Furthermore the husk extracts showed higher total phenolic content (233mg GAE/g). The extractives exhibited minimum inhibitory quantities of 50–100μg or no activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Candida albicans. The tuber extracts were inactive against Caco-2 and Hela cell lines, while the husk extracts showed low activity against Caco-2 and Vero cell line with IC50 values >400μg/mL. The GC–MS analysis showed the beans and tuber non-polar (n-hexane) extracts major constituents as fatty acids. [Copyright &y& Elsevier]

The structure of pyridin-4-ylmethyl 4-aminobenzoate was determined using single crystal X-ray diffraction. The compound was also characterized by elemental analysis, which showed the product was pure, and Fourier-transform infrared spectroscopy, which showed all important functional groups associated with the molecule. The compound crystallized in the orthorhombic space group Pna21, and the unit cell parameters were: a = 11.1735(16) Å, b = 8.3548(13) Å, c = 12.3831(17) Å, V = 1156.0(3) Å3, Z = 4. The crystal structure was solved by intrinsic phasing and refined to the final values R1 = 0.0429 and wR2 = 0.1312. [ABSTRACT FROM AUTHOR]

Abstract: An efficient total synthesis of flavans from the reactions of salicylaldehyde and acetophenone derivatives is reported. The synthesis involves preparation of chalcones through an aldol reaction followed by reduction of both the double bond and the ketone using NaBH4 and an acetic acid mediated cyclization. Methoxy groups on the aromatic rings did not affect significantly the yields of the procedure. [Copyright &y& Elsevier]

Abstract: A 1,2-hydride shift in the phosphoric acid-promoted cyclodimerization of styrene oxide and its chloro derivatives under solvent-free conditions leading to 2,4-disubstituted 1,3-dioxolanes is described. Methoxy substituents on the aromatic ring of the styrene oxide prevent the 1,2-hydride shift reaction leading to substituted 1,4-dioxanes. A possible mechanism for the formation of the 1,3-dioxolanes is proposed. [Copyright &y& Elsevier]

Background: Grewia flava infusions are consumed to assist with kidney problems and stomach ailments. However, there are no scientific data on the phytochemical profile or biological properties to validate its folklore use. Thus, the study aimed to assess the phytochemical profile, antioxidant, and antimicrobial activities of Grewia flava twig extracts. Methodology: The antioxidant activities of the extracts were assayed using 1,1-diphenyl-2-picrylhydrazyl radical scavenging, reducing power, metal chelation, and total phenolic and flavonoid content assays. The agar well diffusion and microdilution methods were used for crude extracts and fractions (from 80% methanol extract) for antimicrobial screening against P. aeruginosa, S. aureus, E. coli, B. subtilis, A. niger, and R. oryzae. Results: The 80% methanol twig extract (250.00 ± 2 GAE/g) exhibited a high concentration of phenolic content, followed by the distilled water extract (192.00 ± 2 mg GAE/g) and the hexane extract (43.10 ± 0.2 mg GAE/g). Fraction 14 of the methanol twig extract exhibited MIC values of 0.21–0.31 mg/mL against all test microorganisms. The root and twig extracts exhibited significant antioxidant and antimicrobial activities, which were attributed to the extracts of bioactive phytochemical compounds such as alkaloids, flavonoids, saponins, steroids, glycosides, anthraquinones, and tannins that were detected in the extracts. Also, the root and twig non-polar extracts were subjected to gas chromatography–mass spectrometry analysis, which identified several bioactive compounds like betulin, β-amyrin, palmitic acid, lupenone, and phytol, highlighting the potential of the plant species as a botanical drug. Conclusions: The study supports the traditional use of plant roots and twigs for treating various ailments, indicating their medicinal value. The twigs can be used in place of the roots to guarantee Grewia flava harvesting that is sustainable. However, a comparison of the quantities of the active compound in the twigs and roots using LC–MS is crucial. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six cobalt complexes were synthesized and characterized using diverse physicochemical techniques, with co-grinding method yielding pure products and higher yields. • Various characterization analysis confirmed successful synthesis of cobalt complexes, supporting successful synthesis. • Cobalt complexes exhibited enhanced activity against Gram-negative bacteria, notably K. pneumoniae , with some showing potent bacteriostatic effects against MDR- K. pneumoniae. • CoL2 disrupted folate biosynthesis of K. pneumoniae , while CoL3 affected MRSA's folate biosynthesis. While CoL3, Co4PY-H, Co4PY, CoL2, and CoL3 disrupted cell membrane integrity of K. pneumoniae ; CoL3 also affected MRSA's cell membrane. • Molecular docking calculations provided strong evidence supporting experimental modes of action of active complexes. This study describes the synthesis and characterization of four cobalt complexes using diverse physicochemical techniques. Notably, the co-grinding method was predominantly employed, resulting in higher yields and increased purity of the products. Thermal studies provided insights into the stability of the cobalt complexes, with dichoro-bis-4-((4-nitrophenoxy)methyl)pyridine cobalt(II) (CoL4) demonstrating the highest stability based on transformations and high melting points. High resolution electrospray ionization mass spectrometry (HRESI-MS) analysis further confirmed the successful synthesis of the cobalt complexes, reinforcing the characterization results. The dichloro-bis(pyridin-4ylmethyl-4aminobenzoate) cobalt (II) (CoL3) exhibited a cis tetrahedral structure with a high-symmetry monoclinic crystal system and a primitive lattice centering of an I2/a space group. The cobalt complexes displayed enhanced activity against Gram-negative bacteria, particularly Klebsiella pneumoniae , with some exhibiting potent bacteriostatic effects against Multidrug resistant K. pneumoniae (MDR- K. pneumoniae). Additionally, dichoro-bis-(4-[(pyridin-4-yl)methoxy] aniline) cobalt(II) (CoL2) and CoL3 were found to disrupt the folate biosynthesis of K. pneumoniae and Methicillin resistant Staphylococcus aureus (MRSA), respectively. Moreover, 4-chloromethylpyridinium tetrachlorocobaltate (II) (Co4PY-H) , dichloro-bis-4-picolyl cobalt (II) (Co4PY) , CoL2 , and CoL3 showed significant disruption of the cell membrane integrity of K. pneumoniae , with CoL3 also affecting MRSA's cell membrane. Lastly, molecular docking calculations provided compelling evidence supporting the experimental modes of action of these active complexes. [ABSTRACT FROM AUTHOR]

Review: 68 refs. [ABSTRACT FROM AUTHOR]

Review: 112 refs. [ABSTRACT FROM AUTHOR]

Highlights: [•] We compare ESI of florfenicol and thiamphenicol in CH3OH and THF. [•] THF was better than CH3OH or CH3CN that are traditionally used for LC–MS. [•] THF:H2O solvent system can replace the CH3OH:H2O/CH3CN:H2O for better sensitivity. [•] We report the use of THF:H2O solvent system for ESI/HPLC of the phenicols. [Copyright &y& Elsevier]

The synthesis, antibacterial screening and mode of action copper pyridyl complexes towards drug resistant bacteria. [Display omitted] • Novel series of copper complexes with pyridyl-based ligands were successfully synthesized using mechanochemical methods, resulting in favorable yields of 80–90%. • Characterization data confirmed the successful synthesis of the complexes and the electronic spectra and magnetic susceptibility data indicated that the copper complexes were d9 tetrahedral complexes with parallel spin electrons. • The copper complexes exhibited promising antibacterial activity, with higher efficacy against Gram-positive bacteria, particularly CuL4 , which showed exceptional activity against MRSA and S. aureus. • Time-kill kinetics analysis indicated that the copper complexes displayed bacteriostatic activity at their minimum inhibitory concentrations (MIC) but exhibited bactericidal tendencies after 24 h. • Cell membrane disruption studies revealed that CuL4 , the nitro group complex, was the most effective in disrupting the cell membrane of S. aureus , followed by Cu4PY-H and the control AgSD , indicating potential modes of action. A series of four new copper complexes containing pyridyl-based ligands of the type [Cu(Cl) 2 (L) 2 ] were prepared by solid-state methods and evaluated for antibacterial activity. Their elemental analysis showed that the grinding method produced pure complexes. FTIR spectroscopy confirmed the coordination of ligands to copper ions by identifying shifts in vibrational frequencies. Furthermore, their successful synthesis was confirmed by the coordinating bonds being shifted to lower frequencies. Electronic spectra and magnetic susceptibility data proved the complexes to be d9 tetrahedral complexes. Thermal studies of the copper complexes indicated that they had good thermal stability. In the thermal analysis, a recurring pattern emerges as each copper complex experiences multiple mass losses and exhibits characteristic transitions in DSC profiles, shedding light on their distinct thermal behaviors. The mass spectra of the copper complexes showed that the data agreed with the elemental analysis and other elucidation techniques. The complexes displayed characteristic molecular ion peaks and adducts consistent with their calculated masses, substantiating the successful synthesis of these complexes and enhancing understanding of their composition and stability. The copper complexes also displayed solubility in highly polar and heavy solvents thus reduced the chances of forming good-quality crystals. The copper complexes were more effective against Gram-positive bacteria, with CuL4 performing best, notably against MRSA and S. aureus. All of the active complexes were bacteriostatic against MRSA and S. aureus based on the time kill kinetics. Additionally, it was shown that the CuL4 and Cu4PY-H disrupted the S. aureus cell membrane more effectively than the AgSD control. Finally, the CuL4 membrane disruption studies were not significantly different to the AgSD control on MRSA. The results of cell membrane disruption were supported by molecular docking scores, where CuL4 outperformed the other active compounds, and the trends corroborated the experimental results. [ABSTRACT FROM AUTHOR]

The synthesis of datively bonded complexes to 4-picloyl chloride and their acido complex counterparts of the type [MCl 4 ]2− were synthesized, characterized using SC-XRD, UV/Vis, FTIR, Computational methods, Thermal techniques and elemental analysis. These techniques helped describe their physicochemical properties. Further, their antibacterial properties towards Gram-negative and positive drug resistant bacteria is discussed. [Display omitted] The physicochemical and antibacterial properties of compounds of copper and cobalt of the type (4PY-H) 2 [MCl 4 ] and [M(Cl) 2 (4PY) 2 ] were studied. The conventional coordination compounds and the acido complex crystals were prepared in a 1:2 mol ratio. The magnetic and electronic spectra data of the copper compounds showed that the two behave similarly to each other, even though, the copper acido complex had better absorptive properties. The copper acido complex crystalized in the monoclinic Ia space group, while the copper complex crystalized in the triclinic P 1 space group. The cobalt complex similarly crystalized in the triclinic P 1 space group while its acido complex crystalized also crystalized in a monoclinic crystal system, but contrary to the copper acido complex crystal, it was under P 2 1 / c space group. FTIR indicated that the compounds were structurally different where the acido complexes and the free ligand both displayed N H peak in their IR spectra. This proved the existence of a protonated pyridyl nitrogen. Additionally, In silico geometry and FTIR data of all the 4 compounds corroborated well with the experimental data. The two compounds had very different melting points where the complex melted at higher temperatures than the acido complex. The compounds were thermally stable with melting points above 100 °C with complexes having higher melting points than acido complex crystals for both copper and cobalt. Also, DSC profiles showed that with increase in heat the acido complex crystals transformed to their complex forms. The antibacterial activity studies showed that the cobalt compounds were more active against the Gram-negative bacteria with more activity towards K. pneumoniae while the copper compounds were more active against the Gram-positive especially towards S. aureus. The time kill kinetics showed all the copper compounds to be bactericidal while the cobalt compounds were bacteriostatic. [ABSTRACT FROM AUTHOR]