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Amino acids have been identified in extraterrestrial materials such as meteorites and returned samples from asteroids and comets. Some of these amino acids or their precursors may have formed on icy interstellar dust grains or at a later phase when these grains became incorporated into larger parent bodies. In this work, we simulated parent body aqueous alteration of the residues from irradiated interstellar ice analogs in the presence of relevant minerals (pulverized serpentinite and Allende meteorite). We tracked the change in amino acid abundances as a function of hydrothermal processing time and examined how these differed based on the presence of minerals. We find that the presence of minerals and their mineralogy can have a significant impact on the formation and destruction of amino acids during simulated aqueous alteration experiments.

We report primordial aqueous alteration signatures in water-soluble organic molecules from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 spacecraft of JAXA. Newly identified low-molecular-weight hydroxy acids (HO-R-COOH) and dicarboxylic acids (HOOC-R-COOH), such as glycolic acid, lactic acid, glyceric acid, oxalic acid, and succinic acid, are predominant in samples from the two touchdown locations at Ryugu. The quantitative and qualitative profiles for the hydrophilic molecules between the two sampling locations shows similar trends within the order of ppb (parts per billion) to ppm (parts per million). A wide variety of structural isomers, including α- and β-hydroxy acids, are observed among the hydrophilic molecules. We also identify pyruvic acid and dihydroxy and tricarboxylic acids, which are biochemically important intermediates relevant to molecular evolution, such as the primordial TCA (tricarboxylic acid) cycle. Here, we find evidence that the asteroid Ryugu samples underwent substantial aqueous alteration, as revealed by the presence of malonic acid during keto-enol tautomerism in the dicarboxylic acid profile. The comprehensive data suggest the presence of a series for water-soluble organic molecules in the regolith of Ryugu and evidence of signatures in coevolutionary aqueous alteration between water and organics in this carbonaceous asteroid., (© 2024. The Author(s).)

Polycyclic aromatic hydrocarbons (PAHs) contain ≲20% of the carbon in the interstellar medium. They are potentially produced in circumstellar environments (at temperatures ≳1000 kelvin), by reactions within cold (~10 kelvin) interstellar clouds, or by processing of carbon-rich dust grains. We report isotopic properties of PAHs extracted from samples of the asteroid Ryugu and the meteorite Murchison. The doubly- 13 C substituted compositions (Δ2× 13 C values) of the PAHs naphthalene, fluoranthene, and pyrene are 9 to 51‰ higher than values expected for a stochastic distribution of isotopes. The Δ2× 13 C values are higher than expected if the PAHs formed in a circumstellar environment, but consistent with formation in the interstellar medium. By contrast, the PAHs phenanthrene and anthracene in Ryugu samples have Δ2× 13 C values consistent with formation by higher-temperature reactions.

Samples from the carbonaceous asteroid (162173) Ryugu provide information on the chemical evolution of organic molecules in the early solar system. Here we show the element partitioning of the major component ions by sequential extractions of salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition of the primitive asteroid. Sodium is the dominant electrolyte of the salt fraction extract. Anions and NH 4 + are more abundant in the salt fraction than in the carbonate and phyllosilicate fractions, with molar concentrations in the order SO 4 2-  > Cl -  > S 2 O 3 2-  > NO 3 -  > NH 4 + . The salt fraction extracts contain anionic soluble sulfur-bearing species such as S n -polythionic acids (n < 6), C n -alkylsulfonates, alkylthiosulfonates, hydroxyalkylsulfonates, and hydroxyalkylthiosulfonates (n < 7). The sulfur-bearing soluble compounds may have driven the molecular evolution of prebiotic organic material transforming simple organic molecules into hydrophilic, amphiphilic, and refractory S allotropes., (© 2023. Springer Nature Limited.)

The Hayabusa2 spacecraft collected samples from the surface of the carbonaceous near-Earth asteroid (162173) Ryugu and brought them to Earth. The samples were expected to contain organic molecules, which record processes that occurred in the early Solar System. We analyzed organic molecules extracted from the Ryugu surface samples. We identified a variety of molecules containing the atoms CHNOS, formed by methylation, hydration, hydroxylation, and sulfurization reactions. Amino acids, aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-heterocyclic compounds were detected, which had properties consistent with an abiotic origin. These compounds likely arose from an aqueous reaction on Ryugu's parent body and are similar to the organics in Ivuna-type meteorites. These molecules can survive on the surfaces of asteroids and be transported throughout the Solar System.

The stable isotope composition of soluble and insoluble organic compounds in carbonaceous chondrites can be used to determine the provenance of organic molecules in space. Deuterium enrichment in meteoritic organics could be a residual signal of synthetic reactions occurring in the cold interstellar medium or an indicator of hydrothermal parent-body reactions. δD values have been measured in grains and bulk samples for a wide range of meteorites; however, these reservoirs are highly variable and may have experienced fractionation during thermal and/or aqueous alteration. Among the plethora of organic compounds in meteorites are polycyclic aromatic hydrocarbons (PAHs), which are stable and abundant in carbonaceous chondrites, and their δD ratio may preserve evidence about their formation environment as well as the influence of parent-body processes. This study tests hypotheses about the potential links between PAHs-deuteration concentrations and their formation conditions by examining the δD ratio of PAHs in three CM carbonaceous chondrites representing an aqueous alteration gradient. We use deuterium enrichments in soluble 2-5-ring PAHs as an indicator of either photon-driven deuteration due to unimolecular photodissociation in warm regions of space, gas-phase ion-molecule reactions in cold interstellar regions of space, or UV photolysis in ices. We also test hypothesized reaction pathways during parent-body processing that differ between partially and fully aromatized PAHs. New methodological approaches were developed to extract small, volatile PAHs without fractionation. Our results suggest that meteoritic PAHs could have formed through reactions in cold regions, with possible overprinting of deuterium enrichment during aqueous parent-body alteration, but the data could not rule out PAH alteration in icy mantles as well.

Recent findings, in vitro and in silico, are strengthening the idea of a simpler, earlier stage of genetically encoded proteins which used amino acids produced by prebiotic chemistry. These findings motivate a re-examination of prior work which has identified unusual properties of the set of twenty amino acids found within the full genetic code, while leaving it unclear whether similar patterns also characterize the subset of prebiotically plausible amino acids. We have suggested previously that this ambiguity may result from the low number of amino acids recognized by the definition of prebiotic plausibility used for the analysis. Here, we test this hypothesis using significantly updated data for organic material detected within meteorites, which contain several coded and non-coded amino acids absent from prior studies. In addition to confirming the well-established idea that "late" arriving amino acids expanded the chemistry space encoded by genetic material, we find that a prebiotically plausible subset of coded amino acids generally emulates the patterns found in the full set of 20, namely an exceptionally broad and even distribution of volumes and an exceptionally even distribution of hydrophobicities (quantified as logP) over a narrow range. However, the strength of this pattern varies depending on both the size and composition the library used to create a background (null model) for a random alphabet, and the precise definition of exactly which amino acids were present in a simpler, earlier code. Findings support the idea that a small sample size of amino acids caused previous ambiguous results, and further improvements in meteorite analysis, and/or prebiotic simulations will further clarify the nature and extent of unusual properties. We discuss the case of sulfur-containing amino acids as a specific and clear example and conclude by reviewing the potential impact of better understanding the chemical "logic" of a smaller forerunner to the standard amino acid alphabet., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Amino acids and polycyclic aromatic hydrocarbons (PAHs) belong to the range of organic compounds detected in meteorites. In this study, we tested empirically and theoretically if PAHs are precursors for amino acids in carbonaceous chondrites, as previously suggested. We conducted experiments to synthesize amino acids from fluoranthene (PAH), with ammonium bicarbonate as a source for ammonia and carbon dioxide under mimicked asteroidal conditions. In our thermodynamic calculations, we extended our analysis to additional PAH-amino acid combinations. We explored 36 reactions involving the PAHs naphthalene, anthracene, fluoranthene, pyrene, triphenylene, and coronene and the amino acids glycine, alanine, valine, leucine, phenylalanine, and tyrosine. Our experiments do not show the formation of amino acids, whereas our theoretical results hint that PAHs could be precursors of amino acids in carbonaceous chondrites at low temperatures., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The abundances, relative distributions, and enantiomeric and isotopic compositions of amines, amino acids, and hydroxy acids in Miller Range (MIL) 090001 and MIL 090657 meteorites were determined. Chiral distributions and isotopic compositions confirmed that most of the compounds detected were indigenous to the meteorites and not the result of terrestrial contamination. Combined with data in the literature, suites of these compounds have now been analyzed in a set of six CR chondrites, spanning aqueous alteration types 2.0-2.8. Amino acid abundances ranged from 17 to 3300 nmol g -1 across the six CRs; hydroxy acid abundances ranged from 180 to 1800 nmol g -1 ; and amine abundances ranged from 40 to 2100 nmol g -1 . For amino acids and amines, the weakly altered chondrites contained the highest abundances, whereas hydroxy acids were most abundant in the more altered CR2.0 chondrite. Because water contents in the meteorites are orders of magnitude greater than soluble organics, synthesis of hydroxy acids, which requires water, may be less affected by aqueous alteration than amines and amino acids that require nitrogen-bearing precursors. Two chiral amino acids that were plausibly extraterrestrial in origin were present with slight enantiomeric excesses: L-isovaline (~10% excess) and D-β-amino- n -butyric acid (~9% excess); further studies are needed to verify that the chiral excess in the latter compound is truly extraterrestrial in origin. The isotopic compositions of compounds reported here did not reveal definitive links between the different compound classes such as common synthetic precursors, but will provide a framework for further future in-depth analyses., (© 2020 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals LLC on behalf of The Meteoritical Society (MET).)

The search for evidence of extraterrestrial life in our Solar System is currently guided by our understanding of terrestrial biology and its associated biosignatures. The observed homochirality in all life on Earth, that is, the predominance of "left-handed" or l-amino acids and "right-handed" or d-sugars, is a unique property of life that is crucial for molecular recognition, enzymatic function, information storage and structure and is thought to be a prerequisite for the origin or early evolution of life. Therefore, the detection of l- or d-enantiomeric excesses ( ee ) of chiral amino acids and sugars could be a powerful indicator for extant or extinct life on another world. However, studies of primitive meteorites have revealed they contain extraterrestrial amino acids and sugar acids (aldonic acids) with large enantiomeric excesses of the same chirality as terrestrial biology resulting from nonbiological processes, complicating the use of chiral asymmetry by itself as a definitive biosignature. Here we review our current knowledge of the distributions and enantiomeric and isotopic compositions of amino acids and polyols found in meteorites compared to terrestrial biology and propose a set of criteria for future life detection missions that can be used to help establish the origin of chiral asymmetry.

Soluble organic compositions of extraterrestrial samples offer valuable insights into the prebiotic organic chemistry of the solar system. This review provides a summary of the techniques commonly used for analyzing amino acids, amines, monocarboxylic acids, aldehydes, and ketones in extraterrestrial samples. Here, we discuss possible effects of various experimental factors (e.g., extraction protocols, derivatization methods, and chromatographic techniques) in order to highlight potential influences on the results obtained from different methodologies. This detailed summary and assessment of current techniques is intended to serve as a basic guide for selecting methodologies for soluble organic analyses and to emphasize some key considerations for future method development.

Aliphatic aldehydes and ketones are essential building blocks for the synthesis of more complex organic compounds. Despite their potentially key role as precursors of astrobiologically important molecules, such as amino acids and carboxylic acids, this family of compounds has scarcely been evaluated in carbonaceous chondrites. The paucity of such analyses likely derives from the low concentration of aldehydes and ketones in the meteorites and from the currently used chromatographic methodologies that have not been optimized for meteorite analysis. In this work, we report the development of a novel analytical method to quantify the molecular distribution and compound-specific isotopic analysis of 29 aliphatic aldehydes and ketones. Using this method, we have investigated the molecular distribution and 13 C-isotopic composition of aldehydes and ketones in 10 carbonaceous chondrites from the CI, CM, CR, and CV groups. The total concentration of carbonyl compounds ranged from 130 to 1000 nmol g -1 of meteorite with formaldehyde, acetaldehyde, and acetone being the most abundant species in all investigated samples. The 13 C-isotopic values ranged from -67 to +64‰ and we did not observe clear relationships between 13 C-content and molecular weight. Accurately measuring the relative abundances, determining the molecular distribution, and isotopic composition of chondritic organic compounds is central in assessing both their formation chemistry and synthetic relationships., Competing Interests: The authors declare no competing financial interest.

The water-soluble organic compounds in carbonaceous chondrite meteorites constitute a record of the synthetic reactions occurring at the birth of the solar system and those taking place during parent body alteration and may have been important for the later origins and development of life on Earth. In this present work, we have developed a novel methodology for the simultaneous analysis of the molecular distribution, compound-specific δ 13 C and enantiomeric compositions of aliphatic monocarboxylic acids (MCA) extracted from the hot-water extracts of sixteen carbonaceous chondrites from CM, CR, CO, CV and CK groups. We observed high concentrations of meteoritic MCAs, with total carbon weight percentages which in some cases approached those of carbonates and insoluble organic matter. Moreover, we found that the concentration of MCAs in CR chondrites is higher than in the other meteorite groups, with acetic acid exhibiting the highest concentration in all samples. The abundance of MCAs decreased with increasing molecular weight and with increasing aqueous and/or thermal alteration experienced by the meteorite sample. The δ 13 C isotopic values of MCAs ranged from -52 to +27‰, and aside from an inverse relationship between δ 13 C value and carbon straight-chain length for C 3 -C 6 MCAs in Murchison, the 13 C-isotopic values did not correlate with the number of carbon atoms per molecule. We also observed racemic compositions of 2-methylbutanoic acid in CM and CR chondrites. We used this novel analytical protocol and collective data to shed new light on the prebiotic origins of chondritic MCAs.

Compound-specific carbon isotope analysis (δ 13 C) of meteoritic organic compounds can be used to elucidate the abiotic chemical reactions involved in their synthesis. The soluble organic content of the Murchison carbonaceous chondrite has been extensively investigated over the years, with a focus on the origins of amino acids and the potential role of Strecker-cyanohydrin synthesis in the early solar system. Previous δ 13 C investigations have targeted α-amino acid and α-hydroxy acid Strecker products and reactant HCN; however, δ 13 C values for meteoritic aldehydes and ketones (Strecker precursors) have not yet been reported. As such, the distribution of aldehydes and ketones in the cosmos and their role in prebiotic reactions have not been fully investigated. Here, we have applied an optimized O -(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) derivatization procedure to the extraction, identification and δ 13 C analysis of carbonyl compounds in the Murchison meteorite. A suite of aldehydes and ketones, dominated by acetaldehyde, propionaldehyde and acetone, were detected in the sample. δ 13 C values, ranging from -10.0‰ to +66.4‰, were more 13 C-depleted than would be expected for aldehydes and ketones derived from the interstellar medium, based on interstellar 12 C/ 13 C ratios. These relatively 13 C-depleted values suggest that chemical processes taking place in asteroid parent bodies (e.g. oxidation of the IOM) may provide a secondary source of aldehydes and ketones in the solar system. Comparisons between δ 13 C compositions of meteoritic aldehydes and ketones and other organic compound classes were used to evaluate potential structural relationships and associated reactions, including Strecker synthesis and alteration-driven chemical pathways.

We previously reported on the isolation and biological activities of plagiochiline A ( 1 ), a 2,3-secoaromadendrane-type sesquiterpenoid from the Peruvian medicinal plant, Plagiochila disticha . This compound was found to have antiproliferative effects on a variety of solid tumor cell lines, as well as several leukemia cell lines. Other researchers have also noted the cytotoxicity of plagiochiline A (isolated from different plant species), but there are no prior reports regarding the mechanism for this bioactivity. Here, we have evaluated the effects of plagiochiline A on cell cycle progression in DU145 prostate cancer cells. A cell cycle analysis indicated that plagiochiline A caused a significant increase in the percentage of cells in the G₂/M phase when compared with control cells. When cells were stained and observed by fluorescence microscopy to examine progress through the mitotic phase, we found a significant increase in the proportion of cells with features of late cytokinesis (cells connected by intercellular bridges) in the plagiochiline A-treated samples. These results suggest that plagiochiline A inhibits cell division by preventing completion of cytokinesis, particularly at the final abscission stage. We also determined that plagiochiline A reduces DU145 cell survival in clonogenic assays and that it induces substantial cell death in these cells.

The organic compounds found in carbonaceous chondrite meteorites provide insight into primordial solar system chemistry. Evaluating the formation and decomposition mechanisms of meteoritic amino acids may aid our understanding of the origins of life and homochirality on Earth. The amino acid glycine is widespread in meteorites and other extraterrestrial environments; other amino acids, such as isovaline, are found with enantiomeric excesses in some meteorites. The relationship between meteoritic amino acids and other compounds with similar molecular structures, such as aliphatic monoamines and monocarboxylic acids is unclear; experimental results evaluating the decomposition of amino acids have produced inconclusive results about the preferred pathways, reaction intermediates, and if the conditions applied may be compatible with those occurring inside meteoritic parent bodies. In this work, we performed extensive tandem metadynamics, umbrella sampling, and committor analysis to simulate the neutral mild hydrothermal decomposition mechanisms of glycine and isovaline and put them into context for the origins of meteoritic organic compounds. Our ab initio simulations aimed to determine free energy profiles and decomposition pathways for glycine and isovaline. We found that under our modeled conditions, methylammonium, glycolic acid, and sec -butylamine are the most likely decomposition products. These results suggest that meteoritic aliphatic monocarboxylic acids are not produced from decomposition of meteoritic amino acids. Our results also indicate that the decomposition of L-isovaline prefers an enantioselective pathway resulting in the production of ( S )- sec -butylamine.

OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and <180 ng/cm 2 of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.

The analysis of water-soluble organic compounds in meteorites provides valuable insights into the prebiotic synthesis of organic matter and the processes that occurred during the formation of the solar system. We investigated the concentration of aliphatic monoamines present in the hot acid-water extracts of the unaltered Antarctic carbonaceous chondrites DOM 08006 (CO3) and MIL 05013 (CO3), and the thermally altered meteorites Allende (CV3), LAP 02206 (CV3), GRA 06101 (CV3), ALH 85002 (CK4), and EET 92002 (CK5). We have also reviewed and assessed the petrologic characteristics of the meteorites studied here, to evaluate the effects of asteroidal processing on the abundance and molecular distributions of monoamines. The CO3, CV3, CK4, and CK5 meteorites studied here contain total concentrations of amines ranging from 1.2 to 4.0 nmol/g of meteorite; these amounts are one to three orders of magnitude below those observed in carbonaceous chondrites from the CI, CM and CR groups. The low amine abundances for CV and CK chondrites may be related to their extensive degree of thermal metamorphism and/or to their low original amine content. Although the CO3 meteorites DOM 08006 and MIL 05013 do not show signs of thermal and aqueous alteration, their monoamine contents are comparable to those observed in moderately/extensively thermally altered CV3, CK4, and CK5 carbonaceous chondrites. The low content of monoamines in pristine CO carbonaceous chondrites suggests that the initial amounts, and not asteroidal processes, play a dominant role in the content of monoamines in carbonaceous chondrites. The primary monoamines, methylamine, ethylamine and n -propylamine constitute the most abundant amines in the CO3, CV3, CK4, and CK5 meteorites studied here. Contrary to the predominance of n -ω-amino acid isomers in CO3 and thermally altered meteorites, there appears to be no preference for the larger n -α-amines.

Glycine and methylamine are meteoritic water-soluble organic compounds that provide insights into the processes that occurred before, during, and after the formation of the Solar System. Both glycine and methylamine and many of their potential synthetic precursors have been studied in astrophysical environments via observations, laboratory experiments, and modeling. In spite of these studies, the synthetic mechanisms for their formation leading to their occurrence in meteorites remain poorly understood. Typical 13 C-isotopic values (δ 13 C) of meteoritic glycine and methylamine are 13 C-enriched relative to their terrestrial counterparts; thus, analyses of their stable carbon isotopic compositions ( 13 C/ 12 C) may be used not only to assess terrestrial contamination in meteorites, but also to provide information about their synthetic routes inside the parent body. Here, we examine potential synthetic routes of glycine and methylamine from a common set of precursors present in carbonaceous chondrite meteorites, using data from laboratory analyses of the well-studied CM2 meteorite Murchison. Several synthetic mechanisms for the origins of glycine and methylamine found in carbonaceous chondrites may be possible, and the prevalence of these mechanisms will largely depend on (a) the molecular abundance of the precursor molecules and (b) the levels of processing (aqueous and thermal) that occurred inside the parent body. In this work, we also aim to contextualize the current knowledge about gas-phase reactions and irradiated ice grain chemistry for the synthesis of these species through parent body processes. Our evaluation of various mechanisms for the origins of meteoritic glycine and methylamine from simple species shows what work is still needed to evaluate both, the abundances and isotopic compositions of simpler precursor molecules from carbonaceous chondrites, as well as the effects of parent body processes on those abundances and isotopic compositions. The analyses presented here combined with the indicated measurements will aid a better interpretation of quantitative analysis of reaction rates, molecular stability, and distribution of organic products from laboratory simulations of interstellar ices, astronomical observations, and theoretical modeling.

The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work.

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) have become increasingly popular in dietary supplements worldwide and global demand for higher purity ω-3 PUFAs in clinical applications has been rising rapidly in the recent years. Traditional methods for isolating ω-3 PUFAs however, generally require multiple, cumbersome steps to obtain high purity (>95%) products. In this study, we report an efficient liquid chromatography method for purifying individual omega-3 fatty acid ethyl esters (FAEEs), eicosapentaenoic acid (EPA, C20:5) and docosahexaenoic acid (DHA, C22:6), at >95% purity using a silver(I)-mercaptopropyl stationary phase, otherwise known as silver-thiolate chromatographic material (AgTCM). We demonstrate the key variables controlling separation of FAEEs with a silver(I)-thiolate stationary phase and examine important similarities and differences between silver-thiolate and silver-ion chromatography in regards to the separation mechanism taking place. We demonstrate the separation behavior of FAEEs under various conditions such as mobile phase composition, flow rate and sample injection amount. Purification of EPA and DHA was carried out on an analytical and semi-preparative scale and the resulting purity was determined by GC-FID. We report high attainable purity for EPA (>95%) and DHA (>99%) from a single isocratic separation of fish oil FAEEs within 5-10min using a mobile phase of heptane/acetone (95:5, % v/v)., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Silver(I) and copper(I) are known to form reversible complexes with π bonds, which have been exploited in LC for separating unsaturated organic compounds. Prominent examples include the use of AgNO3-impregnated silica gel in LC, and the use of copper(I) salts for selective extraction of alkenes from hydrocarbon mixtures. The Dewar-Chatt-Duncanson model is often invoked to explain the interaction between Ag(I) and Cu(I) and π bonds. However, it is unclear if such a reversible interaction is directly related to their d(10) outer electronic configurations. Particularly, Au(I) has not been reported to separate olefins with different numbers of double bonds in LC. Also, there has not been a systematic comparison of the liquid chromatographic properties of other d(10) transition metal salts (e.g., Zn(II), Cd(II)), making it difficult to fully understand the observed reversible interactions of Ag(I) and Cu(I) with π bonds. We demonstrate for the first time that silica gel impregnated with all three Group 11 transition metals with 1+ oxidation state strongly and similarly retain olefin compounds in LC, while transition metals from Groups 10 and 12 do not. We also tested a range of functionalized silica gels to improve the stability of Cu(I) and Au(I) ions on the surface of the silica., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the use of silver-thiolate chromatographic material (AgTCM) as a stable material for use in TLC. The AgTCM stationary phase operates under the same principles as silver-ion chromatography, separating compounds by degree of unsaturation; however, the AgTCM stationary phase shows considerable advantages over Ag-TLC in terms of light stability and shelf lifetime. We demonstrate the light stability of the AgTCM-TLC and its application for separations based on the degrees of unsaturation using fatty acid methyl esters (FAMEs) and polycyclic aromatic hydrocarbons (PAHs)., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Separation of organic compounds containing various numbers of double bonds (DB) can be readily achieved by using silver ion impregnated silica gel, often called silver-ion or argentation chromatography. However, the practical application of silver-ion liquid chromatography in analytical and preparative separations has been limited by the concerns about the stability and mobility of silver ions and the widespread use of reversed phase high performance liquid chromatography. Silver covalently anchored onto the thiol moiety of mercaptopropyl modified silica gel has been tested for the separation of polycyclic aromatic hydrocarbons by ring numbers, but has never been shown to separate mixtures of alkenes having different number of double bonds. We report here that silver-thiolate chromatographic material (AgTCM; including, but not limited to, silver(I) mercaptopropyl silica gel) is also highly efficient in liquid chromatographic separation of alkane/alkenes differing by one double bond. AgTCM displays exceptionally high selectivity for unsaturated compounds and high stability under extended heat and light exposure, while silver is virtually immobile during solvent elution. Compared to ionic silver, silver-thiolate interacts with double bonds less strongly, allowing AgTCM to efficiently separate olefins using less polar (and often less viscous and lower cost) solvents. The interaction energy between silver and ethylene is calculated using established computational methods and the results are in full agreement with our experimental results. Importantly, the exceptional stability of AgTCM gives rise to much higher compound recovery than conventional silver-ion silica gel during the chromatographic elution. Our results pave the way for the development of novel covalently bonded, transition metal-containing chromatographic materials., (Copyright © 2012 Elsevier B.V. All rights reserved.)

We show that the characterization of mono-, di- and triglycerols can be readily accomplished by high performance liquid chromatography (HPLC) with silver(I)-mercaptopropyl modified silica gel, or silver thiolate chromatographic material (AgTCM), which can be used with evaporative light scattering detection (ELSD) or atmospheric pressure chemical ionization mass spectroscopy (APCI-MS). Separation of triglycerols varying by degrees of unsaturation and cis/trans configuration in common oil samples can be achieved using a simple linear gradient of hexane and acetone. In addition to double bonds, AgTCM also displays major selectivity for compounds with different levels of polarity, allowing for efficient separation between mono-, di- and triglycerols. In comparison to conventional reversed phase columns, AgTCM produces simple chromatograms for rapid assessment of degrees of unsaturation and the amount of trans fats in triglycerides, which are central issues to food quality determination. In comparison to previous silver-ion based HPLC separations, AgTCM-HPLC based column offers greatly enhanced stability, inertness, durability, and reproducibility allowing routine coupling of the HPLC with a mass spectrometer for detection., (Copyright © 2012 Elsevier B.V. All rights reserved.)

An anticancer-bioassay guided isolation of the ethanol extract and fractions of two plants from the Peruvian rainforest, Mikania decora and Cremastosperma microcarpum, led to the characterization of one abundant diterpene, ent-pimara-8(14),15-dien-19-oic acid (1), three thymol derivatives, 10-acetoxy-8,9-dehydro-6-methoxythymol butyrate (2), 10-acetoxy-8,9-epoxy-6-methoxythymol isobutyrate (3), and acetylschizoginol (4), as well as one neolignan, (±)-trans-dehydrodiisoeugenol (5). Only the latter was isolated from C. microcarpum. These compounds exhibited significant cytotoxic activity against a panel of human tumor cell lines. Compounds 3 and 4 were also investigated for their in vitro antileishmanial and trypanocidal activity against Leishmania amazonensis axenic amastigotes and Trypanosoma cruzi trypomastigotes., (© Georg Thieme Verlag KG Stuttgart · New York.)

The synthesis of 2-(5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4-yl)hydrazone-derivatives (BTPs) and their in vitro evaluation against Trypanosoma cruzi trypomastigotes, Mycobacterium tuberculosis, Leishmania amazonensis axenic amastigotes, and six human cancer cell lines is described. The in vivo activity of the most active and least toxic compounds against T. cruzi and L. amazonensis was also studied. BTPs constitute a new family of drug leads with potential activity against infectious diseases. Due to their drug-like properties, this series of compounds can potentially serve as templates for future drug-optimization and drug-development efforts for use as therapeutic agents in developing countries., (Copyright 2010 Elsevier Ltd. All rights reserved.)

The in vitro screening of 43 polysubstituted chalcones against Leishmania amazonensis axenic amastigotes, led to the evaluation of 9 of them in a macrophage-infected model with the two other most infectious Leishmania species prevalent in Peru (L. braziliensis and L. peruviana). The five most active and selective chalcones were studied in vivo, resulting on the identification of two chalcones with high reduction parasite burden percentages., (Copyright 2009 Elsevier Ltd. All rights reserved.)

The aldol reaction of beta-allenoate with use of a commercial THF solution of tetrabutylammonium fluoride (TBAF) yielded polyfunctionalized (2E,4E)-4-carbinol alkadienoate-a valuable building block-in highly regio- and stereoselective fashion.

A multidisciplinary and international team of scientists was assembled in the early 1990s to conduct an ethnobotanical study of plants used by the Aguaruna people of the Peruvian Amazon forest. The initial ethnobotanical project, carried out under the auspices of an International Cooperative Biodiversity Grant (ICBG), led to the collection of approximately 4000 plant species. Some members of the original team of scientists have continued this collaboration by focusing on potential sources of new anticancer, anti-infective, and wound-healing agents. This effort has uncovered several secondary metabolites representing a wide variety of chemical diversity. In this short review we describe some bioactive compounds of interest as part of our continuing collaboration.

Synthesis of a cytotoxic dihydrochalcone, first isolated from a traditional Amazonian medicinal plant Iryanthera juruensis Warb (Myristicaceae), followed by a comprehensive SAR analysis of saturated and unsaturated chalcone synthetic intermediates, led to the identification of analogues with selective and significant in vitro anti- Trypanosoma cruzi activity. Further SAR studies were undertaken with the synthesis of 21 new chalcones containing two allyloxy moieties that resulted in the discovery of 2',4'-diallyloxy-6'-methoxy chalcones with improved selectivity against this parasite at concentrations below 25 microM, four of which exhibited a selectivity index greater than 12.

A pharmacological screening of the ethanol extract and fractions of Blepharodon nitidum led to the isolation of fourteen compounds, two of which, 24-hydroperoxycycloart-25-en-3beta-ol and 25-hydroperoxycycloart-23-en-3beta-ol, exhibited in vitro anti- Mycobacterium tuberculosis and antileishmanial activities, as well as significant cytotoxic activity against a panel of human tumor cell lines.

The antiproliferative bioassay-guided fractionation of five Peruvian plants, Doliocarpus dentatus, Picramnia sellowii, Strychnos mitscherlichii, Iryanthera juruensis, and Croton alnifolius, led to the isolation and identification of their different major cytotoxic constituents, betulinic acid (1), nataloe-emodin (2), bisnordihydrotoxyferine (4), 2',4'-dihydroxy-6'-methoxy-3,4-methylenedioxydihydrochalcone (5), and 2',4'-dihydroxy-4,6'-dimethoxydihydrochalcone (6) and 12-O-tetradecanoylphorbol-13-acetate (7), respectively. Eight human tumor cell lines and two nontumorigenic cell lines were used in this investigation. Their in vitro activity against Mycobacterium tuberculosis is also reported.

An ethanol extract of the Peruvian plant Clavija procera, a member of the rare Theophrastaceae family, was fractionated using a colorimetric bioassay-guided protocol against Mycobacterium tuberculosis (MTB), yielding the oleanane triterpenoid aegicerin (1) as the active constituent. Its MIC values ranged between 1.6 and 3.12 microg/mL against 37 different sensitive and resistant MTB strains (1 H37Rv, 21 susceptible clinical isolates, 2 INH-resistant clinical isolates, and 13 MDR clinical isolates).