Chemo-enzymatic synthesis of (S)-α-cyano-3-phenoxybenzyl alcohol

A chemo-enzymatic process for the preparation of (S)-α-cyano-3-phenoxybenzyl alcohol (S-CPBA), an important intermediate in the synthesis of many pyrethroids, was developed. The process consists of four stages, including lipase-mediated resolution. The first stage, the synthesis of racemic α-cyano-3-phenoxybenzyl acetate (CPBAc) from m-phenoxybenzaldehyde (m-PBA) and sodium cyanide in the presence of a phase transfer catalyst, resulted in a 75% yield with 95% purity. The second key step is the resolution of the racemic ester by a highly enantioselective lipase from Pseudomonas sp. The immobilized enzyme carried out the transesterification reaction to nearly full conversion (46% out of 50%) with an enantiomeric excess of >96%. The enzymatic reaction was accomplished in a batch system as well as in a fluidized bed column. The reaction was found to be inhibited by accumulation of the product and to a lesser extent, by the aldehyde. The separation of the enantiomerically pure alcohol from the undesired ester was performed by chromatographic techniques, as well as by extraction with hexane. The final racemization step of the (R)-ester was easily attained with the use of triethylamine in diisopropyl ether or toluene. The process was shown to be feasible on a gram scale and shows potential for scale up.     

Improved procedures for the synthesis of (S)-2-[N-(N′-benzylprolyl)amino]benzophenone (BPB) and Ni(II) complexes of Schiff's bases derived from BPB and amino acids

(S)-N-Benzylproline (BP) was obtained by the reaction of (S)-proline and benzylchloride in high chemical yield (89%). (S)-2-[N-(N′-Benzylprolyl)amino]benzophenone (BPB) was synthesized in amounts greater than 100 g by the SOCl₂ promoted condensation of BP with 2-aminobenzophenone (yield 82%). Ni(II) complexes of Schiff's bases derived from BPB and amino acids were prepared by an improved procedure involving the use of KOH as a base and MeOH as solvent (yield 90–91%).     

Chemical Composition and Antioxidant Activity of Essential Oils from Eugenia patrisii Vahl,E. punicifolia (Kunth) DC., and Myrcia tomentosa (Aubl.) DC., Leaf of Family Myrtaceae

Essential oils (EOs) were extracted from Eugenia patrisii, E. punicifolia, and Myrcia tomentosa, specimens A and B, using hydrodistillation. Gas chromatography coupled with mass spectrometry (GC/MS) was used to identify the volatile constituents present, and the antioxidant capacity of EOs was determined using diphenylpicryl-hydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays. For E. patrisii, germacrene D (20.03%), bicyclogermacrene (11.82%), and (E)-caryophyllene (11.04%) were identified as the major constituents of the EOs extracted from specimen A, whereas specimen B primarily comprised γ-elemene (25.89%), germacrene B (8.11%), and (E)-caryophyllene (10.76%). The EOs of E. punicifolia specimen A contained β-Elemene (25.12%), (E)-caryophyllene (13.11%), and bicyclogermacrene (9.88%), while specimen B was composed of (E)-caryophyllene (11.47%), bicyclogermacrene (5.86%), β-pinene (5.86%), and γ-muurolene (5.55%). The specimen A of M. tomentosa was characterized by γ-elemene (12.52%), germacrene D (11.45%), and (E)-caryophyllene (10.22%), while specimen B contained spathulenol (40.70%), α-zingiberene (9.58%), and γ-elemene (6.89%). Additionally, the chemical composition of the EOs was qualitatively and quantitatively affected by the collection period. Furthermore, the EOs of the studied specimens, especially specimen A of E. punicifolia, showed a greater antioxidant activity in DPPH rather than TEAC, as represented by a significantly high inhibition percentage (408.0%).     

Feasibility of Defatted Juice from Sea-Buckthorn Berries (Hippophae rhamnoides L.) as a Wheat Beer Enhancer

Juice made from sea-buckthorn berries (Hippophae rhamnoides L.) is a valuable source of bioactive compounds, vitamins, as well as micro- and macronutrients. By applying defatted sea-buckthorn juice, it is possible to enhance wheat beer and change its sensory properties and the contents of bioactive compounds in the finished product. A sensory assessment showed that wheat beers with a 5% v/v addition of sea-buckthorn juice were characterised by a balanced taste and aroma (overall impression). Physicochemical analyses showed that, compared to the control samples, wheat beers enhanced with defatted sea-buckthorn juice at a rate of 5% v/v or 10% v/v had high total acidity with respective mean values of 5.30 and 6.88 (0.1 M NaOH/100 mL), energy values lower on average by 4.04% and 8.35%, respective polyphenol contents of 274.1 mg GAE/L and 249.7 mg GAE/L, as well as higher antioxidant activity (measured using DPPH, FRAP, and ABTS assays). The findings show that the samples of wheat beer enhanced with sea-buckthorn juice had average ascorbic acid contents of 2.5 and 4.5 mg/100 mL (in samples with 5% v/v and 10% v/v additions, respectively) and contained flavone glycosides, e.g., kaempferol-3-O-glucuronide-7-O-hexoside. Based on the current findings, it can be concluded that wheat beer enhanced with sea-buckthorn juice could emerge as a new trend in the brewing industry.     

Volatiles and Antifungal-Antibacterial-Antiviral Activity of South African Salvia spp. Essential Oils Cultivated in Uniform Conditions

Spontaneous emissions of S. dentata Aiton and S. scabra Thunb., as well as the essential oil (EO) composition of the cited species, together with S. aurea L., were investigated. The chemical profile of the first two species is reported here for the first time. Moreover, in vitro tests were performed to evaluate the antifungal activity of these EOs on Trichophyton mentagrophytes, Microsporum canis, Aspergillus flavus, Aspergillus niger, and Fusarium solani. Secondly, the EO antibacterial activity against Escherichia coli, Staphylococcus aureus, and Staphylococcus pseudointermedius was examined, and their antiviral efficacy against the H1N1 influenza virus was assessed. Leaf volatile organic compounds (VOCs), as well as the EOs obtained from the arial part of Salvia scabra, were characterized by a high percentage of sesquiterpene hydrocarbons (97.8% and 76.6%, respectively), mostly represented by an equal amount of germacrene D (32.8% and 32.7%, respectively). Both leaf and flower spontaneous emissions of S. dentata, as well as the EO composition, showed a prevalence of monoterpenes divided into a more or less equal amount of hydrocarbon and oxygenated compounds. Interestingly, its EO had a non-negligible percentage of oxygenated sesquiterpenes (29.5%). S. aurea EO, on the contrary, was rich in sesquiterpenes, both hydrocarbons and oxygenated compounds (41.5% and 33.5%, respectively). S. dentata EO showed good efficacy (Minimal Inhibitory Concentration (MIC): 0.5%) against M. canis. The tested EOs were not active against E. coli and S. aureus, whereas a low inhibition of S. dentata EO was observed on S. pseudointermedius (MIC = 10%). Once again, S. dentata EO showed a very good H1N1 inhibition; contrariwise, S. aurea EO was completely inactive against this virus. The low quantity of S. scabra EO made it impossible to test its biological activity. S. dentata EO exhibited interesting new perspectives for medicinal and industrial uses.     

Chemistry of odorants: stereoselective synthesis of octahydronaphthalene-based perfumery Georgywood, (+,−)-1-[(1R,2S)-1,2,3,4,5,6,7,8-octahydro-1,2,8,8-tetramethylnaphthalen-2-yl]ethan-1-one

A straightforward synthesis of octahydronaphthalene-based fragrance, such as Georgywood, is described. The Lewis acid tin (IV) chloride catalyzed efficiently an original one-pot sequential cycloaddition-clyclization process by reaction of myrcene with 3-bromo-but-3-en-2-one, leading directly to the octahydronaphthalene skeleton in very good yields (85%). Then, dehydrohalogenation with DBU gave the key 2,4-dienone intermediate in excellent yield (85%). Regioselective Michael addition gave rise to the formation of the addition product as a trans/cis diastereoisomeric mixture, by reaction either with CH₃Cu·BF₃ (6:1 ratio, 70%) or (CH₃)₂CuLi/TMSCl reagents (3:1 ratio, 80%). The generation of thermodynamically more stable enolate by treatment of the diastereoisomeric mixture with sodium hydride in tetrahydrofuran in the presence of an excess of methyl iodide, allowed stereoselective introduction of the methyl group at C2, leading to the formation of Georgywood in good yield (60%), as the only diastereoisomer, with a trans stereochemistry of the two methyl groups as demonstrated by NMR experiments.     

Chemical Characterization and Nutritional Markers of South African Moringa oleifera Seed Oils

Moringa oleifera Lam (syn. M. ptreygosperma Gaertn.) leaves are globally acclaimed for their nutritional content and mitigation of malnutrition. In most impoverished rural communities including Limpopo, Mpumalanga and KwaZulu Natal of South Africa, powdered leaves of Moringa oleifera are applied as a nutritional supplement for readily available food such as porridge for malnourished children and even breast-feeding mothers. Widely practiced and admired is also the use of the plant seed in the do-it-yourself purification of water by rural South Africans. This study aimed at identifying the chemical and nutritional marker compounds present in South African Moringa oleifera seed oils using high resolution 1-2-dimension gas chromatography in order to give scientific validation to its uses in cosmetics and particularly in culinary practices. Results obtained from two-dimension tandem mass spectrometry chemical signature revealed over 250 compounds, five times more than those reported from one-dimension gas chromatography. Whereas previous reports from gas chromatography-mass spectrometry analysis reported oleic acid (70–78%) as the major compound from oil samples from other countries, M. oleifera seed oil from South Africa is marked by cis-13-octadeaconic acid with 78.62% and 41.9% as the predominant monounsaturated fatty acid in the hexane and dichloromethane extracts respectively. This was followed by cis-vaccenic acid, an isomer of oleic acid at 51% in the acetone extract, 9-octadecanoic acid-(z)-methyl ester at 39.18%, 21.34% and 10.06% in dichloromethane, hexane and acetone extracts respectively. However, a principal component analysis with R² = 0.98 of the two-dimension tandem mass spectrometry cum chemometric analysis indicated n-hexadecanoic acid, oleic acid, 9-octadecanoic acid-(z)-methyl ester and cis-vaccenic acid with a probability of 0.96, 0.88, 0.80 and 0.79 respectively as the marker compounds that should be used for the quality control of moringa seed oils from South Africa. This study demonstrates that South African Moringa oleifera oils contain C-18 monounsaturated fatty acids similar to oils from Egypt (76.2%), Thailand (71.6%) and Pakistan (78.5%) just to mention but a few. These fatty acids are sunflower and olive oil type-compounds and therefore place moringa seed oil for consideration as a cooking oil amongst its other uses.     

Preparation of (R)- and (S)-6-hydroxybuspirone by enzymatic resolution or hydroxylation

6-Hydroxybuspirone is an active metabolite of the antianxiety drug buspirone. The (R)- and (S)-enantiomers of 6-hydroxybuspirone were prepared using an enzymatic resolution process. l-Amino acid acylase from Aspergillus melleus (Amano Acylase 30000) was used to hydrolyze racemic 6-acetoxybuspirone to (S)-6-hydroxybuspirone in 95% ee after 45% conversion. The remaining (R)-6-acetoxybuspirone with 88% ee was converted to (R)-6-hydroxybuspirone by acid hydrolysis. The ee of both enantiomers could be improved to 99% by crystallization as a metastable polymorph. (S)-6-Hydroxybuspirone was also obtained in 88% ee and 14.5% yield by hydroxylation of buspirone using Streptomyces antibioticus ATCC 14890.     

Efficient resolution of prostereogenic arylaliphatic ketones using a recombinant alcohol dehydrogenase from Pseudomonas fluorescens

A broad range of arylaliphatic ketones is efficiently reduced to the corresponding optically active (R)-alcohols by a recombinant alcohol dehydrogenase from Pseudomonas fluorescens (PFADH) produced by overexpression in Escherichia coli. PFADH shows high activity and stereoselectivity in the reduction of acetophenone and various derivatives (45–99% e.e.), as well as in the reduction of 3-oxobutyric acid methyl ester (>99% e.e.). The highest activity was observed between 10 and 20°C. The cofactor NADH can be efficiently recycled by the addition of 10–20% (v/v) of iso-propanol.     

Antioxidant Activity and Molecular Docking Study of Volatile Constituents from Different Aromatic Lamiaceous Plants Cultivated in Madinah Monawara,Saudi Arabia

A comparative study of volatile constituents, antioxidant activity, and molecular docking was conducted between essential oils from Mentha longifolia L., Mentha spicata L., and Origanum majorana L., widely cultivated in Madinah. The investigation of volatile oils extracted by hydrodistillation was performed using Gas Chromatography-Mass Spectrometry (GC-MS). A total number of 29, 42, and 29 components were identified in M. longifolia, M. spicata, and O. majorana representing, respectively, 95.91, 94.62, and 98.42, of the total oils. Pulegone (38.42%), 1,8-cineole (15.60%), menthone (13.20%), and isopulegone (9.81%) were the dominant compounds in M. longifolia oil; carvone (35.14%), limonene (27.11%), germacrene D (4.73%), and β-caryophyllene (3.02%) were dominant in M. spicata oil; terpin-4-ol (42.47%), trans-sabinene hydrate (8.52%), γ-terpinene (7.90%), α-terpineol (7.38%), linalool (6.35%), α-terpinene (5.42%), and cis-sabinene hydrate (3.14%) were dominant in O. majorana oil. The antioxidant activity, assessed using DPPH free radical–scavenging and ABTS assays, was found to be the highest in O. majorana volatile oil, followed by M. spicata and M. longifolia, which is consistent with the differences in total phenolic content and volatile constituents identified in investigated oils. In the same context, molecular docking of the main identified volatiles on NADPH oxidase showed a higher binding affinity for cis-verbenyl acetate, followed by β-elemene and linalool, compared to the control (dextromethorphan). These results prove significant antioxidant abilities of the investigated oils, which may be considered for further analyses concerning the control of oxidative stress, as well as for their use as possible antioxidant agents in the pharmaceutical industry.     

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

Plant growth-promoting rhizobacteria (PGPR) mediate heavy metal tolerance and improve phytoextraction potential in plants. The present research was conducted to find the potential of bacterial strains in improving the growth and phytoextraction abilities of Brassica nigra (L.) K. Koch. in chromium contaminated soil. In this study, a total of 15 bacterial strains were isolated from heavy metal polluted soil and were screened for their heavy metal tolerance and plant growth promotion potential. The most efficient strain was identified by 16S rRNA gene sequencing and was identified as Bacillus cereus. The isolate also showed the potential to solubilize phosphate and synthesize siderophore, phytohormones (indole acetic acid, cytokinin, and abscisic acid), and osmolyte (proline and sugar) in chromium (Cr⁺³) supplemented medium. The results of the present study showed that chromium stress has negative effects on seed germination and plant growth in B. nigra while inoculation of B. cereus improved plant growth and reduced chromium toxicity. The increase in seed germination percentage, shoot length, and root length was 28.07%, 35.86%, 19.11% while the fresh and dry biomass of the plant increased by 48.00% and 62.16%, respectively, as compared to the uninoculated/control plants. The photosynthetic pigments were also improved by bacterial inoculation as compared to untreated stress-exposed plants, i.e., increase in chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoid was d 25.94%, 10.65%, 20.35%, and 44.30%, respectively. Bacterial inoculation also resulted in osmotic adjustment (proline 8.76% and sugar 28.71%) and maintained the membrane stability (51.39%) which was also indicated by reduced malondialdehyde content (59.53% decrease). The antioxidant enzyme activities were also improved to 35.90% (superoxide dismutase), 59.61% (peroxide), and 33.33% (catalase) in inoculated stress-exposed plants as compared to the control plants. B. cereus inoculation also improved the uptake, bioaccumulation, and translocation of Cr in the plant. Data showed that B. cereus also increased Cr content in the root (2.71-fold) and shoot (4.01-fold), its bioaccumulation (2.71-fold in root and 4.03-fold in the shoot) and translocation (40%) was also high in B. nigra. The data revealed that B. cereus is a multifarious PGPR that efficiently tolerates heavy metal ions (Cr⁺³) and it can be used to enhance the growth and phytoextraction potential of B. nigra in heavy metal contaminated soil.     

Chemical Composition and In Vitro Antioxidant Activity of Sida rhombifolia L. Volatile Organic Compounds

In the current study, the phytochemical constituents of volatile organic compounds (VOCs) obtained from Sida rhombifolia L. were identified by GC-FID and GC-MS analysis. A total of 73 volatile organic compounds were identified. The major components of S. rhombifolia VOCs were identified as palmitic acid (21.56%), phytol (7.02%), 6,10,14-trimethyl-2-pentadecanone (6.30%), oleic acid (5.48%), 2-pentyl-furan (5.23%), and linoleic acid (3.21%). The VOCs are rich in fatty acids (32.50%), olefine aldehyde (9.59%), ketone (9.41%), enol (9.02%), aldehyde (8.63%), and ketene (6.41%). The antioxidant capacity of S. rhombifolia VOCs was determined by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) diammonium salt (ABTS), and ferric reducing/antioxidant power (FRAP) methods with butylated hydroxytoluene (BHT) and Trolox as standard. The VOCs showed dose-dependent antioxidant activity with IC50 (50% inhibitory concentration) values of 5.48 ± 0.024 and 1.47 ± 0.012 mg/mL for DPPH and ABTS assays, respectively. FRAP antioxidant capacity was 83.10 ± 1.66 mM/g. The results show that the VOCs distilled from S. rhombifolia have a moderate antioxidant property that can be utilized as a natural botanical supplement or an antioxidant.     

A convenient resolution of racemic lavandulol through lipase-catalyzed acylation with succinic anhydride: simple preparation of enantiomerically pure (R)-lavandulol

(R)- and (S)-lavandulol and their esters are important compounds in perfumery and have recently become significant in pheromone research. (R)-Lavandulol and its esters, as well as the esters of (S)-lavandulol have been identified as sex and aggregation pheromones in two mealybugs, in thrips and in weevils. We report a convenient resolution of racemic lavandulol through lipase-catalyzed acylation with succinic anhydride. This method does not require tedious chromatographic separation and is particularly suitable for the preparation of enantiomerically pure (R)-lavandulol with 98% ee in one resolution cycle. The (S)-lavandulol with 90% ee can be obtained by a second resolution cycle.     

Chemical Composition of Essential Oils of Seven Polygonum Species from Turkey: A Chemotaxonomic Approach

Medicinal plants and herbal preparations are gaining attention in the scientific community today, as they are often used intermittently in the treatment of various diseases. The genus of Polygonum (Polygonaceae), known locally as “madimak”, is an aromatic plant widely used in world flavors. The chemical composition of the essential oils of dried aerial parts of seven of Polygonum was analyzed by GC-MS. These species are Polygonum lapathifolium L., Polygonum persicaria L., Polygonum arenastrum Bor., Polygonum bellardii All., Polygonum arenarium Waldst. Et Kit., Polygonum aviculare L., and Polygonum cognatum Meissn. Qualitative and quantitative differences were found in the essential oil analysis of the seven Polygonum species. The major compounds were determined as (E)-β-farnesene (19. 46%), dodecanal (15.92%), β-caryophyllene (12.95%), in P. aviculare; (E)-β-farnesene (25.00%), dodecanal (20.45%), β-caryophyllene (9.38%), and caryophyllene oxide (8. 26%) in P. persicaria; dodecanal (25.65%), caryophyllene oxide (13.35%), β-caryophyllene (7.95%), and (E)-β-farnesene (6.20%) in P. lapathifolium, and dodecanal (19.65%), (E)-β-farnesene (13.86%), β-caryophyllene (8.06%), and α-terpineol (7.2%) in P. arenarium, dodecanal (16.23%), β-caryophyllene (16.09%), (E)-β-farnesene (12.26%), caryophyllene oxide (7.94%) in P. bellardii, (E)-β-farnesene (20.75%), dodecanal (17.96%), β-caryophyllene (13.01%), α-terpineol (4.97%) in P. arenastrum, (E)-β-farnesene (9.49%), dodecanal (14.01%), β-caryophyllene (11.92%), geranyl acetate (9.49%), and undecanal (7.35%) in P. cognatum. This study is the most comprehensive study conducted to determine the essential oil components of Polygonum species. In addition, a literature review on the composition of the essential oils of these Polygonum taxa was performed. The essential oil components of the species in our study were revealed for the first time with this study.     

Changes in Isoflavone Profile from Soybean Seeds during Cheonggukjang Fermentation Based on High-Resolution UPLC-DAD-QToF/MS: New Succinylated and Phosphorylated Conjugates

In this study, thirty-eight isoflavone derivatives were comprehensively identified and quantified from the raw, steamed and fermented seeds of four selected soybean cultivars based on UPLC-DAD-QToF/MS results with reference to the previously reported LC-MS library and flavonoid database, and summarized by acylated group including glucosides (Glu), malonyl-glucosides (Mal-Glu), acetyl-glucosides (Ac-Glu), succinyl-glucosides (Suc-Glu) and phosphorylated conjugates (Phos) in addition to aglycones. Among them, Suc-Glu and Phos derivatives were newly generated due to fermentation by B. subtilis AFY-2 (cheonggukjang). In particular, Phos were characterized for the first time in fermented soy products using Bacillus species. From a proposed roadmap on isoflavone-based biotransformation, predominant Mal-Glu (77.5–84.2%, raw) decreased rapidly by decarboxylation and deesterification into Ac-Glu and Glu (3.5–8.1% and 50.0–72.2%) during steaming, respectively. As fermentation continued, the increased Glu were mainly succinylated and phosphorylated as well as gradually hydrolyzed into their corresponding aglycones. Thus, Suc-Glu and Phos (17.3–22.4% and 1.5–5.4%, 36 h) determined depending on cultivar type and incubation time, and can be considered as important biomarkers generated during cheonggukjang fermentation. Additionally, the changes of isoflavone profile can be used as a fundamental report in applied microbial science as well as bioavailability research from fermented soy foods.     

Phytochemistry,antioxidant and antibacterial activities of two Moroccan Teucrium polium L. subspecies: Preventive approach against nosocomial infections

The aim of the present study was to determine the chemical composition and antioxidant activity of essential oils (EOs) from two Teucrium polium subspecies, to evaluate, also their antibacterial activities, against some nosocomial-bacteria. The phytochemical screening of essential oils was analyzed using gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry analysis (GC-MS). The antibacterial activities were assessed by disc diffusion method and minimal inhibitory concentration (MIC), against Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Citrobacter koseri and Acinetobacter baumannii) and Gram-positive bacteria Staphylococcus aureus. The antioxidant potential was evaluated in vitro by three assays, namely free radical scavenging activity against 1,1-diphenyl-2-picrylhydrzyl (DPPH), ferric reducing activity power (FRAP) and total antioxidant capacity. Twenty-six components were identified in the EO of Teucrium polium subsp. aurum representing. Its major component was Caryophyllene (19.13%) followed by γ-Muurolene (13.02%), τ-cadinol, (11.01%), α-Gurjunene (9.2%), Rosifoliol (8.79%), 3-Carene (7.04%). However, twenty two components were identified in the EO of T. polium subsp. polium. Its major components are 3-carene (16.49%), γ-Muurolene (14.03%), α-pinene (9.94%), α-phellandrene (6.93%) and Caryophyllene (7.51%). The antibacterial activity of both essential oils showed a higher activity against tested nosocomial bacteria especially against S. aureus and A. baumannii. The EO of T. polium subsp. aureum showed better antioxidant activity as measured by DPPH and FRAP assays with IC₅₀ values of 3.7 ± 0.2 mg/ml and 2.31 ± 0.11 mg/ml, respectively. The total antioxidant capacity assay showed that T. polium subsp. aureum had a significant activity with value to 3308.27 mg equivalent to ascorbic acid/g of EO. The Moroccan T. polium essential oils could be exploited as an antimicrobial agent for the treatment of several infectious diseases caused by bacteria, especially, those who have developed resistance to conventional antibiotics.     

Novel diastereoselective synthesis of (E)- and (Z)-allylsilanes via organoboranes

A simple, novel diastereoselective synthesis of both (E)- and (Z)-allylsilanes via organoboranes is developed. (E)-1-Alkenylboronate esters easily prepared from the corresponding terminal alkynes via hydroboration with dibromoborane-methyl sulfide complex followed by treatment with 1,3-propane diol readily react with trimethylsilylmethyllithium at −78 °C in methanol followed by reaction with iodine in methanol to produce the corresponding (Z)-allylsilanes in high yields (72-80%) and in high stereochemical purities (98% as evidenced by CMR spectral data). Similarly, the (Z)-1-alkenylboronate esters react with trimethylsilylmethyllithium at −78 °C in methanol followed by treatment with iodine in methanol to produce the corresponding (E)-allylsilanes in moderate yields (57-65%) in high stereochemical purities (>98% as revealed by CMR spectral data).     

Nematicidal Activity of Essential Oil from Lavandin (Lavandula × intermedia Emeric ex Loisel.) as Related to Chemical Profile

Essential oils (EOs) from lavandin are known for a large spectrum of biological properties but poorly and contrastingly documented for their activity against phytoparasitic nematodes. This study investigated the toxicity of EOs from three different lavandin cultivars, Abrialis, Rinaldi Cerioni, and Sumiens, either to juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and to infective stages of the lesion nematode Pratylenchus vulnus. The suppressive activity of treatments with EOs from the three lavandin cultivars in soil infested by M. incognita was also investigated in a greenhouse experiment on potted tomato. The compositional profiles of tested EOs were also analyzed by GC-FID and GC-MS. Linalool was the major component of all the three EOs, as accounting for about 66%, 48%, and 40% of total EO from cv Rinaldi Cerioni, Sumiens, and Abrialis, respectively. Linalool acetate was the second most abundant compound in the EOs from cv Abrialis (18.3%) and Sumiens (14.9%), while significant amounts of camphor (11.5%) and 1,8-cineole (12.1%) were detected in cv Rinaldi Cerioni and Sumiens EOs, respectively. The mortality of M. incognita J2 peaked 82.0%, 95.8%, and 89.8% after a 24 h treatment with 100 mg·mL⁻¹ solutions of cv Abrialis, Rinaldi Cerioni, and Sumiens EOs, respectively. Infective specimens of P. vulnus were largely more sensitive than M. incognita J2, as there were peak mortality rates of 65.5%, 67.7%, and 75.7% after 4 h of exposure to Abrialis, Rinaldi Cerioni, and Sumiens EO, respectively. All three lavandin EOs significantly affected also M. incognita egg hatchability, which reduced to 43.6% after a 48 h egg mass exposure to a 100 µg·mL⁻¹ solution of cv Rinaldi Cerioni EO. Soil treatments with the three lavandin EOs strongly reduced, according to a dose–effect relationship, density of M. incognita eggs, and J2 both on tomato roots and in soil, as well as significantly reduced gall formation on tomato roots. Finally, almost all soil treatments with the lavandin EOs also resulted in a positive impact on tomato plant growth.     

Separation and identification of polyphenols in apple pomace by high-speed counter-current chromatography and high-performance liquid chromatography coupled with mass spectrometry

Apple pomace, a by-product in the processing of apple juice, was investigated as a potential source of polyphenols. Two methods of separation and purification of polyphenols from apple pomace extract were established by combination of gel chromatography with high-speed counter-current chromatography (HSCCC) and solvent extraction with HSCCC, respectively. The optimal separation was performed on a Sephadex LH-20 column using gradient aqueous ethanol as eluting solvent from 0% to 100% in increments of 10%. HPLC analysis indicated that main polyphenols existed in fractions eluted between 40% and 50% aqueous ethanol. The fractions of interest from column were separated by HSCCC with the solvent system hexane–ethyl acetate–1% aqueous acetic acid (0.5:9.5:10, v/v/v). Ethyl acetate fractionation of the apple pomace extract followed by direct HSCCC separation by the same solvent system in the volume ratio of 1:9:10 also produced a good separation of the main polyphenols of interest. Six high-purity polyphenols were achieved tentatively and identified by HPLC/MS: chlorogenic acid (1, m/z 354), quercetin-3-glucoside/quercetin-3-glacaside (2, m/z 464), quercetin-3-xyloside (3, m/z 434), phloridzin (4, m/z 436), quercetin-3-arabinoside (5, m/z 434), and quercetin-3-rhamnoside (6, m/z 448). These results provided a preliminary foundation for further development and exploration of apple pomace.