Search Results (19)

The high demand for sustainable biodiesel feedstocks has led to the exploration of innovative strategies to enhance lipid productivity in microalgae. This study introduces a push–pull strategy to optimize lipid accumulation in Nannochloropsis oculata. The benzyl amino purine (BAP) and naphthalene acetic acid (NAA) stimulation, acting as the ‘push’ component, significantly boost growth and nutrient stress tolerance. Meanwhile, the ‘pull’ component, nitrogen (N) deficiency, triggers lipid biosynthesis. A Box–Behnken design was employed to optimize the factors named BAP fraction (0–1), total phytohormone (PH) BAP/NAA mix dose (0–20 ppm), and N-concentration (0–50%). The combined BAP/NAA treatment significantly increased biomass (15% higher than the control) and mitigated N-stress with higher doses (20 ppm). Lipid yield surged from 12.4% to 38.87% under optimized conditions (23.25% N, 39.5 ppm NAA, and BAP fraction 0). The push–pull strategy contributed to boosting lipid synthesis and balancing biomass production. N-limitation and total PH dosage were the determining factors in this strategy. This work demonstrates the potential of the push–pull strategy in increasing lipid accumulation, offering a promising and optimistic solution for biodiesel production at scale from microalgae. By reducing dependence on fossil fuels, N. oculata emerges as a reliable feedstock for oil extraction and biodiesel. Full article

The ‘Yuluxiang’ pear is a key cultivated variety in China, celebrated for its high quality. However, it exhibits a low leaf regeneration frequency of only 35.0%, which hinders its transgenic breeding process. To establish an efficient regeneration system, we utilized tissue culture seedlings of the ‘Yuluxiang’ pear and investigated various factors influencing leaf regeneration: plant growth regulators, natural organic materials, leaf wounding and positioning methods, duration of dark culture, ages and lines of plantlets, as well as culture containers. Our results indicated that the optimal medium for leaf regeneration consisted of MS supplemented with 6-BA (6-Benzyl Aminopurine) 1.5 mg/L, NAA (α-Naphthalene acetic acid) 0.4 mg/L along with 10% (v/v) coconut water. Suitable wounding involved ensuring no damage to leaves while placing the abaxial side facing down on the medium; the ideal duration for dark culture was determined to be 21 days; optimal plantlet age was found to be 20 days; both plantlet line 1 and line 2 demonstrated effectiveness; triangle bottles were identified as appropriate culture containers. In summary, we successfully established an efficient leaf regeneration system for the ‘Yuluxiang’ pear that achieved a maximum regeneration frequency of 96.70% with an average bud number of 5.15 per explant. This system also proved effective for the ‘Qiuyue’ pear, yielding a regeneration frequency of 88.89% and an average bud number of 3.44 per explant. After investigating the germination methods of 200 leaves from this screened leaf regeneration system of ‘Yuluxiang’, it was found that there were both direct and indirect regeneration methods, and the germination rate of direct and indirect regeneration was 68.00% and 70.50%, respectively. Therefore, this study also laid a solid foundation for the future genetic transformation of ‘Yuluxiang’ pear. Full article

The unusual reactivity of key enamine intermediates led to the formation of 3-methylamino-2-(2-nitrobenzoyl)-4H-naphthalen-1-one as an unexpected product in an attempted synthesis of the P. aeruginosa metabolite 2-benzyl-4(1H)-quinolone. Although the synthesis of the natural product has not been successful, this methodology allows for the easy preparation of novel derivatives carrying a carboxamide moiety at the C3 position. Full article

Liquid organic hydrogen carriers (LOHCs) are aromatic molecules that are being considered for the safe storage and release of hydrogen. The thermodynamic properties of a range of aromatic ethers were investigated using various experimental and theoretical methods to assess their suitability as LOHC materials. The absolute vapour pressures were measured for benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene using the transpiration method. The standard molar enthalpies and entropies of vaporisation/sublimation were derived from the temperature dependence of the vapour pressures. The combustion energies of benzyl phenyl ether and dibenzyl ether were measured using high-precision combustion calorimetry, and their standard molar enthalpies of formation were derived from these data. High-level quantum chemical calculations were used to calculate the standard molar enthalpies of formation in the gas phase for benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene. The latter values agreed very well with the experimental results obtained in this work. The thermodynamic properties of the hydrogenation/dehydrogenation reactions in liquid phase in LOHC systems based on methoxy–benzene, diphenyl ether, benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene were derived and compared with the data for similarly structured hydrogen carriers based on benzene, diphenylmethane, 1,2-diphenylethane, 1,3-diphenylpropane and naphthalene. The influence of the oxygen functionality on the thermodynamic properties of the hydrogenation/dehydrogenation reactions was evaluated. Full article

Human Galectin-3 (hGal-3) is a protein that selectively binds to β-galactosides and holds diverse roles in both normal and pathological circumstances. Therefore, targeting hGal-3 has become a vibrant area of research in the pharmaceutical chemistry. As a step towards the development of novel hGal-3 inhibitors, we synthesized and investigated derivatives of thiodigalactoside (TDG) modified with different aromatic substituents. Specifically, we describe a high-yielding synthetic route of thiodigalactoside (TDG); an optimized procedure for the synthesis of the novel 3,3′-di-O-(quinoline-2-yl)methyl)-TDG and three other known, symmetric 3,3′-di-O-TDG derivatives ((naphthalene-2yl)methyl, benzyl, (7-methoxy-2H-1-benzopyran-2-on-4-yl)methyl). In the present study, using competition Saturation Transfer Difference (STD) NMR spectroscopy, we determined the dissociation constant (K_d) of the former three TDG derivatives produced to characterize the strength of the interaction with the target protein (hGal-3). Based on the K_d values determined, the (naphthalen-2-yl)methyl, the (quinolin-2-yl)methyl and the benzyl derivatives bind to hGal-3 94, 30 and 24 times more strongly than TDG. Then, we studied the binding modes of the derivatives in silico by molecular docking calculations. Docking poses similar to the canonical binding modes of well-known hGal-3 inhibitors have been found. However, additional binding forces, cation–π interactions between the arginine residues in the binding pocket of the protein and the aromatic groups of the ligands, have been established as significant features. Our results offer a molecular-level understanding of the varying affinities observed among the synthesized thiodigalactoside derivatives, which can be a key aspect in the future development of more effective ligands of hGal-3. Full article

Naphtho[1,8-de][1,2]oxazin-4-ol and its acyl or benzyl derivatives ring open to various 2,8-dihydroxy-1-naphthonitriles, which, through (de)protection protocols and reduction, afford the target (E)-2-hydroxy-8-methoxy-1-naphthaldehyde. This was converted to its corresponding oxime, which was oxidatively o-cyclized with phenyliodine(III) diacetate (PIDA) to 9-methoxynaphtho[1,2-d]isoxazole 2-oxide. The latter, in deuterated DMSO at room temperature, was rearranged to its isomer 2-hydroxy-8-methoxy(naphthalen-1-yl)nitrile oxide. The isomerization was detected by time-course plot ¹H NMR spectroscopy and further identified from its ¹³C NMR and HRMS spectra. The nitrile oxide was stable in (non)deuterated DMSO for at least 18 h. A 3,4-bis(2-hydroxy-8-methoxynaphthalen-1-yl)-1,2,5-oxadiazole 2-oxide, as a dimerization product or an isocyanate as a rearrangement isomer, was ruled out, the former by its HRMS spectrum and the latter by its 1,3-dipolar cycloaddition reactions to substituted isoxazoles. Full article

The aim of this study is to develop an efficient method for micropropagation of Pennisetum × advena ‘Rubrum’. Agar cultures containing Murashige and Skoog (MS) medium supplemented with 6-benzyl-amino-purine (BAP) in various concentrations (0.5 mg/L to 2 mg/L) and a temporary immersion bioreactor system (TIS) using liquid medium MS with an addition of 1 mg/L BAP were tested. Rooting was performed using ½ MS medium supplemented with different auxin combinations (indole-3-butyric acid IBA and α-naphthalene acetic acid NAA) and activated charcoal. The TIS method was found to be the most efficient, producing 36.9 new plants within four weeks. The resulting plantlets were thin and bright green in color, with no signs of hyperhydricity. The most suitable agar medium yielded 19.5 new plants within eight weeks. For rooting, ½ MS supplemented with 0.5 mg/L IBA and 0.5 mg/L NAA exhibited an 84% rooting rate, whereas the addition of activated charcoal inhibited rooting. Full article

Chicory (Cichorium intybus L.) is a low-height perennial or biennial herb from the family of Asteraceae. Investigation of different in vitro regeneration strategies of Cichorium intybus and increasing the number of secondary metabolites in vitro regenerated plant samples were the aims of the research. Callus and plant regenerations were achieved in basal plant growth media supplemented with plant growth regulators (PGRs). Whole plant regeneration was carried out by direct organogenesis from leaf explant in Murashige and Skoog (MS) and B5 media supplemented with naphthalene acetic (NAA) acid and indole-3-butyric acid (IBA). The highest callus quantity was produced in MS medium supplemented with indole-3-acetic acid (IAA) and benzyl amino purine (BAP). The combination and concentrations of PGRs used in MS and B5 media not only provided root and shoot formation with callus, but also caused a change in the amounts of phenolic components. In addition, some PGRs used caused an increase in the number of phenolic compounds in callus and shoots developed from the leaf explant. When plants that grow in vitro and in vivo are compared with each other, it has been determined that plants grown in vivo contain higher amounts of some phenolic compounds. In vivo and in vitro samples were extracted in ethanol/water (80:20 v/v). The analysis of phenolic compounds (caftaric, chicoric, and chlorogenic acids and esculin) were performed in high-performance liquid chromatography (HPLC) and inulin was in UV spectrophotometry. The caftaric and chlorogenic acids and inulin concentrations were higher in vivo samples than that in vitro. Contrarily, esculin, and chicoric acid concentrations were higher in the in vitro regenerated samples. The higher concentration of valuable compounds in the in vitro regenerated samples, especially in callus tissue, gives hope for large-scale production of secondary metabolites under laboratory conditions. Full article

Achillea fragrantissima Forssk. (Family: Asteraceae) has been used as a natural remedy in the Arabian region for its antihyperglycemic activity. As a result of the intensive demand for this plant in folk medicinal uses, its scarcity has become problematic. This study has explored methods that produce an efficient in vitro culture protocol for the conservation of this plant as well as the enhancement of its hypoglycemic activity. A. fragrantissima cultures on Murashige and Skoog (MS) medium supplemented with 3.6 µM/L of 6-benzyl aminopurine (BAP) for a two month period resulted in maximum in vitro shoot proliferation (12.33 shoots/explant) while MS medium supplemented with 2.4 µM/L 1-naphthalene acetic acid (NAA) provided maximum in vitro adventitious root formation (2.46 roots/shoot tip explant). Callus induction was favored by leaf explants cultured on MS medium and supplemented with 3 µM/L BAP and 3 µM/L IAA media in dark conditions. Further in vivo study of some selected feedings determined that the best hypoglycemic activity was obtained in either indole-3-butyric acid (IBA)-fed plants (24%) or NAA-fed plants (22%). Both treatments enhanced insulin-like activity in STZ-treated diabetic Sprague-Dawley rats when compared with the wild plant (10%). Moreover, the IBA-fed plants showed significant antioxidant activity while the NAA-fed plants inhibited salivary alpha amylase. The framework of this study provides in vitro culture methods that can sustain the cultivation of this over-exploited A. fragrantissima plant as well as increase its antioxidant and insulin-like activities. Full article

A plant tissue culture protocol from stevia was optimized for the production of planting materials and the natural sweetener, rebaudioside A. The highest survivability (88.90% ± 5.55) of explants was achieved at 15 and 30 days after culture initiation (DACI) on Murashige and Skoog (MS) media by sterilization with 30% Clorox (5 min) and 10% Clorox (10 min), respectively. Supplementation of MS with 0.50 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D) and 0.10 mg/L zeatin produced 50% callus at 15 DACI while 1.50 mg/L 2,4-D and 0.10 mg/L zeatin at 30 DACI increased callus production to 76.67%. The highest shoot proliferation per callus was achieved with 10.00 mg/L 6-benzyl amino purine (BAP) in MS at 15 DACI (5.80) and 30 DACI (12.33). The longest shoots of 4.31 cm and 6.04 cm at 15 and 30 DACI, respectively, were produced using BAP (10.00 mg/L) and 1.00 mg/L naphthalene acetic acid (NAA). MS media (0.50 strength) induced 2.86 and 6.20 roots per shoot and produced 3.25 cm and 7.82 cm long roots at 15 and 30 DACI, respectively. Stevia grown on 0.25 MS accumulated the highest concentration of rebaudioside A (6.53%), which correlated with the expression level of its biosynthetic gene uridine-diphosphate-dependent (UDP)-glycosyltransferase (UGT76G1). Full article

It is well known that the products of encapsulation (multifunctional beads and synthetic seeds) can be used as innovative technological tools to integrate micropropagation both for plant germplasm conservation and to simplify the management of propagation materials in nurseries. Nevertheless, the usual concept of encapsulation concerns the use of initial in vitro derived explants. In this study, for the first time, in vivo derived organs of Mentha spicata L., obtained through the excision of fragments (nodes) from stolons of cultivated mother plants, were employed. The artificial endosperm had a tenfold reduced concentration of Murashige and Skoog (MS) substrate, with the addition of sucrose (5 g L⁻¹), 6-benzyl-aminopurine (BAP) (0.1 mg L⁻¹) and 1-naphthalene acetic acid (NAA) (0.01 mg L⁻¹). Moreover, the calcium alginate matrix was enriched with different thiophanate-methyl (TM) concentrations (0, 10, 50, 100 and 200 mg L⁻¹) in order to prevent possible contamination during the conversion in nonsterile conditions. Interesting results were obtained encapsulating every single node of fresh stolon as a bipolar propagule able to develop a whole plantlet (conversion), as the coated seed in other species. The synthetic seeds of spearmint without TM in the artificial endosperm showed a satisfactory ability to convert (56.7%) into plantlets after sowing in soil under nonsterile conditions. TM at 100 and 200 mg L⁻¹ negatively affected the total emergence, which decreased to 30.0 and 33.3%, respectively. In general, in the artificial seeds without TM, higher values for most of the aboveground and belowground plants parameters were recorded compared to naked nodes. Full article

Despite the established treatment regimens, tuberculosis remains an alarming threat to public health according to WHO. Novel agents are needed to overcome the increasing rate of resistance and perhaps achieve eradication. As part of our long-term research on pyrazine derived compounds, we prepared a series of their ortho fused derivatives, N-phenyl- and N-benzyl quinoxaline-2-carboxamides, and evaluated their in vitro antimycobacterial activity. In vitro activity against Mycobacterium tuberculosis H37Ra (represented by minimum inhibitory concentration, MIC) ranged between 3.91–500 µg/mL, with most compounds having moderate to good activities (MIC < 15.625 µg/mL). The majority of the active compounds belonged to the N-benzyl group. In addition to antimycobacterial activity assessment, final compounds were screened for their in vitro cytotoxicity. N-(naphthalen-1-ylmethyl)quinoxaline-2-carboxamide (compound 29) was identified as a potential antineoplastic agent with selective cytotoxicity against hepatic (HepG2), ovarian (SK-OV-3), and prostate (PC-3) cancer cells lines. Molecular docking showed that human DNA topoisomerase and vascular endothelial growth factor receptor could be potential targets for 29. Full article

High cannabidiol (CBD) and cannabigerol (CBG) varieties of Cannabis sativa L., a species with medicinal properties, were regenerated in vitro. Explants of nodal segments including healthy axillary bud, after sterilization, were placed in Murashige-Skoog (MS) culture medium. The shoots formed after 30 days were subcultured in full- or half-strength MS medium supplemented with several concentrations of 6-benzyl-amino-purine (BA) or thidiazuron (TDZ). The highest average number and length of shoots was achieved when both full and half-strength MS media were supplemented with 4.0 μM BA. The presence of 4.0 μM TDZ showed also comparable results. BA and TDZ at concentrations of 4.0, 8.0 μM and 2.0, 4.0 μM respectively, displayed the maximum shooting frequency. The new shoots were transferred on the same media and were either self-rooted or after being enhanced with different concentrations of indole-3-butyric acid (IBA) or α-naphthalene acetic acid (NAA). Presence of 2.0 or 4.0 μM IBA or 4.0 μM NAA resulted to the optimum rooting rates. The maximum average number and length of roots per shoot was observed when the culture media was supplemented with 4.0 μM IBA or NAA. Approximately 92% of the plantlets were successfully established and acclimatized in field. The consistency of the chemical profile of the acclimatized in vitro propagated clones was assessed using quantitative ¹H-NMR high throughput screening. In each variety, analysis of the micropropagated plant in comparison with the mother plant showed no statistically significant differences (p ≤ 0.05) in CBD+ cannabidiolic acid (CBDA) and CBG+ cannabigerolic acid (CBGA) content respectively, thus indicating stability of their chemical profile. Full article

To improve the catalytic performance of zeolite catalysts in reactions involving bulky molecules, a series of mesoporous Beta zeolite were prepared using organic functionalized fumed silica as the silicon source, which were thoroughly characterized in terms of porosity and acidity. The peaks in X-ray diffraction (XRD) patterns showed broadening, and the external surface area and mesoporosity increased progressively when the content of organic functionalization increased. An infrared (IR) spectroscopy study of adsorbed probe molecules, including pyridine (Py-IR), 2,6-ditertbutylpyridine (DTBPy-IR) and pivalonitrile (Pn-IR), showed that the improvement of mesoporosity increased the accessibility of acidic sites. In the catalytic benzylation of naphthalene with benzyl chloride (BC) over the mesoporous Beta zeolite catalysts, the conversion of BC was significantly increased when the accessibility of Brönsted acid sites improved. The increase of mesoporosity not only improved the diffusion ability of the reactants and products, but also increased the accessibility of acid sites, which greatly enhanced the activity of the mesoporous Beta zeolite catalysts. It is highlighted that the interdependence of mesoporosity, acid type, acid concentration, and strength of the mesoporous Beta zeolites on the catalytic performance in the benzylation of naphthalene with BC was comprehensively studied. Full article

A practical synthesis of both enantiomers of unnatural phenylalanine derivatives by using two pseudoenantiomeric phase transfer catalysts is described. Through asymmetric α-alkylation of glycine Schiff base with substituted benzyl bromides and 1-(bromomethyl)naphthalene under the catalysis of O-allyl-N-(9-anthracenmethyl) cinchoninium bromide (1f) and O-allyl-N-(9-anthracenylmethyl)cinchonidium bromide (1i), respectively, a series of both (R)- and (S)-enantiomers of unnatural α-amino acid derivatives were obtained in excellent yields and enantioselectivity. The synthetic method is simple and scalable, and the stereochemistry of the products is fully predictable and controlled: the cinchonine-type phase transfer catalyst 1f resulted in (R)-α-amino acid derivatives, and the cinchonidine-type phase transfer catalyst 1i afforded (S)-α-amino acid derivatives. Full article