Search Results (38)

The [2+2]-photocycloaddition of 2-acetoxy-1,4-naphthoquinone with 1,1-diphenylethylene, styrene and cyclopentene was conducted in a conventional batch reactor. Prolonged irradiation selectively produced the corresponding anti and head-to-head cyclobutanes in acceptable to good yields. The batch process was subsequently transferred to continuous-flow operation in a simple capillary device. Likewise, the photocycloaddition with diphenylacetylene gave the corresponding cyclobutene and a benzoanthracenone derivative in acceptable yields. The crystal structures of all main photoproducts were successfully determined. Full article

Discovering new yeast species can be crucial for creating new types of beers. In this study, we investigated three new yeast species, Saccharomyces bayanus, Schizosaccharomyces japonicus and Schizosaccharomyces pombe var. malidevorans, which have not been previously used in the brewing industry. Colour, total acidity, bitterness, aroma profile, total phenolic, flavonoid, mineral content and organoleptic characteristics of beers fermented by these strains were analysed to discover their applicability in the brewing industry. They did not significantly affect the nutritional value and colour of the beers, but showed increased acidity compared to the control Saccharomyces cerevisiae. GC-MS (Gas Chromatography-Mass Spectrometry) analysis revealed 33 aroma compounds, some of which were identical and some unique. S. cerevisiae and S. bayanus produced a similar number (19–20) of aroma compounds, while S. japonicus produced the fewest, including some undesirable compounds. Isobutyl alcohol, isoamyl alcohol, acetol, dimethylpyrazine, acetic acid, 4-cyclopentene-1,3-dione, butyrolactone, 2-furanmethanol, phenylethyl alcohol, maltol and pyranone that provide desired aromas in beers could be found in every sample. The new yeasts significantly increased polyphenols and decreased flavonoid content. Based on the results above and the taste scores, the strains S. bayanus and S. pombe var. malidevorans may be suitable for brewing, while S. japonicus is less or only suitable for combined fermentation. Full article

The quality of pudding using different types of sugar (sucrose at 5% by weight or isomaltulose 5% or 10% by weight) in a formulation was studied. Adding isomaltulose resulted in less water being separated (syneresis) from the pudding structure after 15 days of storage and increased texture firmness. The pudding product containing 10% isomaltulose received the highest scores for consumer acceptance for texture, taste, and overall liking (7.00–7.60; moderately to very much liked). The effects of gamma irradiation at different doses (0, 2, 4, and 6 kGy) on taro flour were studied. All doses of irradiation did not significantly (p > 0.05) affect the proximate chemical composition of taro flour. The irradiation dose used to treat taro flour significantly affected (p ≤ 0.05) the syneresis of the puddings, with increasing doses decreasing the observed syneresis after 15 days of storage while increasing texture firmness. The effects of gamma irradiation on taro flour at 6 kGy resulted in a more pleasant odor, including sweet (toluene), jasmine/sweet (2-cyclopenten-1-one), almond (benzaldehyde), and nutty (2-methyl-3-methylthio-pyrazine) in the pudding sample. Furthermore, such a sample was the most liked (7.30) compared to other pudding samples. This study demonstrated that isomaltulose and irradiated taro flour could be used to produce pudding samples with desirable quality and sensory liking. Full article

Microalgae represent promising biotechnological platforms for bioactive compound production with pharmaceutical applications. This study investigated the phytochemical composition and biological activities of lipid extracts from three Chlorella species to evaluate their potential as antioxidant and antidiabetic sources. Lipid extraction using chloroform–methanol (2:1) followed by GC–MS analysis revealed distinct compound distributions: 29 compounds in C. ellipsoidea, 33 in C. sorokiniana, and 19 in C. vulgaris. Major bioactive compounds included 2-hexanol, 1,3,6-heptatriene, 4-(2,3-dimethyl-2-cyclopenten-1-yl)-4-methylpentanal, n-hexadecanoic acid, and octadecanoic acid. Biological activity screening encompassed antioxidant assessment through DPPH• and •NO radical scavenging assays and FRAP analysis, while antidiabetic potential was evaluated using α-glucosidase and α-amylase inhibition assays. C. sorokiniana exhibited superior bioactivity with the highest antioxidant capacity (DPPH• IC₅₀ = 329.03 ± 4.30 µg/mL; •NO IC₅₀ = 435.53 ± 10.20 µg/mL; FRAP = 94.74 ± 5.72 mg TE/g) and strongest enzyme inhibition (α-glucosidase IC₅₀ = 752.75 ± 57.95 µg/mL; α-amylase IC₅₀ = 3458.50 ± 104.01 µg/mL). This is the first report on C. sorokiniana strain KU.B2′s biological properties and phytochemical profile. These findings establish C. sorokiniana as a valuable biotechnological platform for pharmaceutical bioactive compound development. Full article

Saline environments shape plant metabolism, driving ecological and biochemical adaptations. This study investigated the impact of salinity on Adenosma indiana (Indian scent-wort), a medicinal herb known for its volatile organic compounds (VOCs) and anti-inflammatory and antimicrobial properties, to elucidate its adaptive strategies. During the flowering stage, samples were collected from four saline microhabitats in Kalasin Province, Thailand. We analyzed soil properties, plant growth, photosynthetic pigments, compatible solutes (anthocyanins, proline, total sugars), and elemental concentrations (K, Na, Ca, Mg) across different tissues. Results showed that A. indiana maintained stable growth while enhancing chlorophyll and β-carotene levels under increasing salinity. GC-MS identified 47 VOCs, including 3-cyclopenten-1-one (first reported in this species) and β-bisabolene, both strongly linked to soil salinity. In low-salinity soils, leaves accumulated high sodium, inducing osmoprotectants (proline, total sugars) and VOCs (D-limonene, α-pinene, terpinolene, 1-octen-3-ol) in peltate glandular trichomes. Conversely, in high-salinity soils, lower leaf sodium levels were associated with increased β-bisabolene and β-caryophyllene production, suggesting distinct biochemical pathways. These findings reveal salinity-driven VOC modulation in A. indiana, highlighting its adaptive potential for medicinal applications in saline environments and its role as a source of salt-tolerant bioactive compounds. Full article

A previously unknown reduction of carbonyl compounds with dicyclopentylzinc is reported. Aldehydes react in mild conditions yielding corresponding primary alcohols and cyclopentene. Although cyclohexanone and acetophenone are inert to dicyclopentylzinc, a variety of heterocyclic ketones reacted readily, yielding reasonable to high yields of corresponding secondary alcohols. When the reaction was catalyzed with (–)-(1R,2S)-ephedrine, 3-acetylpyridine (10) resulted in a high yield of (S)-1-(pyridin-3-yl)ethanol (19) with >99% ee. 5-Acetyl-2-bromopyridine (11) also provided the corresponding optically active alcohol 20, albeit with a much lower optical yield. When 10% of 19 with 92% ee was used as an autocatalyst, 55% yield of the same compound was obtained, with 95% ee and 96% ee in two independent experiments. A three-stage reaction sequence starting from “no chirality” reaction yielded 19 with 6% ee. Thus, amplifying autocatalysis was detected in the reaction of ketone 10 with dicylopentylzinc. Full article

A variety of ribo-, 2′-deoxyribo-, and 5′-norcarbocyclic derivatives of the 8-aza-7-deazahypoxanthine fleximer scaffolds were designed, synthesized, and screened for antibacterial activity. Both chemical and chemoenzymatic methods of synthesis for the 8-aza-7-deazainosine fleximers were compared. In the case of the 8-aza-7-deazahypoxanthine fleximer, the transglycosylation reaction proceeded with the formation of side products. In the case of the protected fleximer base, 1-(4-benzyloxypyrimidin-5-yl)pyrazole, the reaction proceeded selectively with formation of only one product. However, both synthetic routes to realize the fleximer ribonucleoside (3) worked with equal efficiency. The new compounds, as well as some 8-aza-7-deazapurine nucleosides synthesized previously, were studied against Gram-positive and Gram-negative bacteria and M. tuberculosis. It was shown that 1-(β-D-ribofuranosyl)-4-(2-aminopyridin-3-yl)pyrazole (19) and 1-(2′,3′,4′-trihydroxycyclopent-1′-yl)-4-(pyrimidin-4(3H)-on-5-yl)pyrazole (9) were able to inhibit the growth of M. smegmatis mc2 155 by 99% at concentrations (MIC₉₉) of 50 and 13 µg/mL, respectively. Antimycobacterial activities were revealed for 4-(4-aminopyridin-3-yl)-1H-pyrazol (10) and 1-(4′-hydroxy-2′-cyclopenten-1′-yl)-4-(4-benzyloxypyrimidin-5-yl)pyrazole (6). At concentrations (MIC₉₉) of 40 and 20 µg/mL, respectively, the compounds resulted in 99% inhibition of M. tuberculosis growth. Full article

This study focused on the assessment of the antimicrobial resistance of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) isolated from bovine mastitis milk samples and the revealing anti-mastitis potential of phytocompounds of Ziziphus jujube and Acacia nilotica through molecular docking analysis. The mastitis milk samples were collected from various dairy farms for the isolation of the bacteria (S. aureus and E. coli) and their response to antibiotics. Ethanolic extracts of both plants were prepared. Their antibacterial activity was evaluated, and they were processed for phytochemical analysis after which, molecular docking analysis with pathogenic proteins of the bacteria was carried out. Parametric and non-parametric statistical analyses were performed to reach the conclusions of this study. The findings of the study revealed a higher drug resistance (≥40%) of E. coli against ampicillin, amikacin, and vancomycin, while S. aureus exhibited the highest resistance to ampicillin, erythromycin, and ciprofloxacin. The ethanolic extracts of the Ziziphus jujube and Acacia nilotica plants produced a ZOI between 18 and 23 mm against multidrug-resistant S. aureus and E. coli. Gas chromatography–mass spectrophotometry (GC–MS) was used to explore 15 phytocompounds from Ziziphus jujube and 18 phytocompounds from Acacia nilotica. The molecular docking analysis of 2cyclopenten−1-one,3,4,4 trimethyl and Bis (2ethylhexyl) phthalate of Ziziphus jujube showed a binding affinity of −4.8 kcal/mol and −5.3 kcal/mol and −5.9 kcal/mol and −7.1 kcal/mol against the DNA Gyrase and toxic shock syndrome toxin-1 proteins of S. aureus and E. coli, respectively. The suberic acid monomethyl ester of Acacia nilotica showed a binding affinity of −5.9 kcal/mol and −5 kcal/mol against the outer membrane protein A and Topoisomerase IV protein of E. coli and −5.1 kcal/mol and −5.8 kcal/mol against the toxic shock syndrome toxin-1 and Enterotoxin B proteins of S. aureus. Similarly, 2,2,4-trimethyl-1,3-pentanediol di-iso-butyrate showed a binding affinity of −6.5 kcal/mol and −5.3 kcal/mol against the outer membrane protein A and Topoisomerase IV of E. coli and −5.2 kcal/mol and −5.9 kcal/mol against the toxic shock syndrome toxin-1 and Enterotoxin B proteins of S. aureus, respectively. The study concluded that there was an increasing trend for the antimicrobial resistance of S. aureus and E. coli, while the Ziziphus jujube and Acacia nilotica plant extracts expressed significant affinity to tackle this resistance; hence, this calls for the development of novel evidence-based therapeutics. Full article

To discriminate the aroma-active compounds in dried jujube slices through microwave-dried treatments and understand their sensory attributes, odor activity value (OAV) and detection frequency analysis (DFA) combined with sensory analysis and analyzed through partial least squares regression analysis (PLSR) were used collaboratively. A total of 21 major aromatic active compounds were identified, among which 4-hexanolide, 4-cyclopentene-1,3-dione, 5-methyl-2(5H)-furanone, 4-hydroxy-2,5-dimethyl-3(2H)furanone, 3,5-dihydroxy-2-methyl-4-pyrone were first confirmed as aromatic compounds of jujube. Sensory evaluation revealed that the major characteristic aromas of dried jujube slices were caramel flavor, roasted sweet flavor, and bitter and burnt flavors. The PLSR results showed that certain compounds were related to specific taste attributes. 2,3-butanedione and acetoin had a significant positive correlation with the roasted sweet attribute. On the other hand, γ-butyrolactone, 4-cyclopentene-1,3-dione, and 4-hydroxy-2,5-dimethyl-3(2H)furanone had a significant positive impact on the caramel attributes. For the bitter attribute, 2-acetylfuran and 5-methyl-2(5H)-furanone were positively correlated. Regarding the burnt flavor, 5-methyl-2-furancarboxaldehyde and 3,5-dihydroxy-2-methyl-4-pyrone were the most influential odor-active compounds. Finally, 2-furanmethanol and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one were identified as the primary sources of the burnt and bitter flavors. Importantly, this work could provide a theoretical basis for aroma control during dried jujube slices processing. Full article

In this research, a metal-free diastereoselective formal 1,3-dipolar cycloaddition of N-2,2,2-trifluoroethylisatin ketimines and cyclopentene-1,3-diones which can efficiently lead to the desymmetrization of cyclopentene-1,3-diones is developed. With the developed protocol, a series of tetracyclic spirooxindoles containing pyrrolidine and cyclopentane subunits can be smoothly obtained with good results (up to 99% yield and 91:9 dr). Furthermore, the methodology can be extended to trifluoromethyl-substituted iminomalonate, and the corresponding formal [3+2] cycloaddition reaction affords bicyclic heterocycles containing fused pyrrolidine and cyclopentane moieties in moderate yields with >20:1 dr. The synthetic potential of the methodology is demonstrated by the scale-up experiment and by versatile transformations of the products. Full article

Terminalia chebula Retz. (Fam. Combretaceae), locally called Manahei, is a well-known medicinal plant that grows wildly in Manipur, a Northeastern state of India. It is used as a mild laxative, an anti-inflammatory agent, and a remedy for piles, colds, and ulcers by ethnic communities of the state. The hydroalcoholic extract obtained from four fruit samples of T. chebula collected from different locations in Manipur were analyzed using gas chromatography–mass spectrometry (GC-MS) and high-performance thin-layer chromatography (HPTLC) for their chemical constituents and evaluated for their anticancer activity against the colon cancer cell HCT 116. GC-MS analysis results indicated significant variation in the composition and percentage of major compounds present in the extracts. 1,2,3-Benzenetriol was the most abundant chemical constituent present in all four extracts of T. chebula, ranging from 20.95 to 43.56%. 2-Cyclopenten-1-one, 5-hydroxymethylfurfural, and catechol were commonly present in all extracts. Two marker compounds, gallic acid and ellagic acid, were also quantified usingHPTLC in all four extracts of T. chebula. The highest content of gallic acid (22.44 ± 0.056 µg/mg of dried extract) was observed in TCH, and that of ellagic acidwas found in TYH (11.265 ± 0.089 µg/mg of dried extract). The IC₅₀ value of TYH for the DPPH and ABTS assays (12.16 ± 0.42 and 7.80 ± 0.23 µg/mL) was found to be even lower than that of Trolox (18 ± 0.44 and 10.15 ± 0.24 µg/mL), indicating its strong antioxidant properties among the four extracts of T. chebula. The MTT assay determined the effect of T. chebula extracts on the viability of HCT 116 cells. TYH showed the highest activity with anIC₅₀ value of 52.42 ± 0.87 µg/mL, while the lowest activity was observed in TCH (172.05 ± 2.0 µg/mL). The LDH assay confirmed the cytotoxic effect of TYH in HCT 116 cells. TYH was also found to induce caspase-dependent apoptosis in HCT 116 cells after 48 h of treatment. Our study provides insight into the diversity of T. chebula in Manipur and its potential activity against colon cancer. Full article

We have realized a Pd-catalyzed ring-opening of diazabicyclic olefins with 4-halo-1,3-dicarbonyl compounds. This reaction resulted in the formation of 3(2H)-furanone-appended hydrazino cyclopentenes. The reaction proceeds via the formation of a π-allylpalladium intermediate which is attacked by the active methylene species, and an intramolecular nucleophilic substitution in the 4-halo-1,3-dicarbonyl moiety furnishes the 3(2H)-furanone-substituted cyclopentene. We could extend this methodology to cyclopropane-appended spirotricyclic olefin for synthesizing 3(2H)-furanone-substituted spiro[2.4]hept-5-ene. Full article

Ornithine aminotransferase (OAT) is overexpressed in hepatocellular carcinoma (HCC), and we previously showed that inactivation of OAT inhibits the growth of HCC. Recently, we found that (3S,4S)-3-amino-4-fluorocyclopentenecarboxylic acid (5) was a potent inactivator of γ-aminobutyric acid aminotransferase (GABA-AT), proceeding by an enamine mechanism. Here we describe our investigations into the activity and mechanism of 5 as an inactivator of human OAT. We have found that 5 exhibits 10-fold less inactivation efficiency (k_inact/K_I) against hOAT than GABA-AT. A comprehensive mechanistic study was carried out to understand its inactivation mechanism with hOAT. pK_a and electrostatic potential calculations were performed to further support the notion that the α,β-unsaturated alkene of 5 is critical for enhancing acidity and nucleophilicity of the corresponding intermediates and ultimately responsible for the improved inactivation efficiency of 5 over the corresponding saturated analogue (4). Intact protein mass spectrometry and the crystal structure complex with hOAT provide evidence to conclude that 5 mainly inactivates hOAT through noncovalent interactions, and that, unlike with GABA-AT, covalent binding with hOAT is a minor component of the total inhibition which is unique relative to other monofluoro-substituted derivatives. Furthermore, based on the results of transient-state measurements and free energy calculations, it is suggested that the α,β-unsaturated carboxylate group of PLP-bound 5 may be directly involved in the inactivation cascade by forming an enolate intermediate. Overall, compound 5 exhibits unusual structural conversions which are catalyzed by specific residues within hOAT, ultimately leading to an enamine mechanism-based inactivation of hOAT through noncovalent interactions and covalent modification. Full article

In this paper, Grubbs- and Hoveyda–Grubbs-type olefin metathesis catalysts featuring N-cyclopentyl/N’-mesityl backbone-substituted N-heterocyclic carbene (NHC) ligands were synthesized. Their propensity to promote the alternating ring-opening metathesis copolymerization (ROMP) of norbornene (NBE) with cyclooctene (COE) or cyclopentene (CPE) was evaluated and compared to that shown by analogous N-cyclohexyl complexes. High degrees of chemoselectivity were achieved in both copolymerizations. The presence of the N-cyclopentyl substituent allowed for the achievement of up to 98% and 97% of alternating diads for NBE-COE and NBE-CPE copolymers, respectively, at low comonomer ratios. Density functional theory (DFT) studies showed that both the sterical and electronic effects of NHC ligands influence catalyst selectivity. Full article

Gold catalysts possess the advantages of water and oxygen resistance, with the possibility of catalyzing many novel chemical transformations, especially in the syntheses of small-molecule skeletons, in addition to achieving the rapid construction of multiple chemical bonds and ring systems in one step. In this feature paper, we summarize recent advances in the construction of small-molecule scaffolds, such as benzene, cyclopentene, furan, and pyran, based on gold-catalyzed cyclization of arylalkyne derivatives within the last decade. We hope that this review will serve as a useful reference for chemists to apply gold-catalyzed strategies to the syntheses of related natural products and active molecules, hopefully providing useful guidance for the exploration of additional novel gold-catalyzed approaches. Full article