Aliphatic Constituents Research Articles

Aliphatic acetogenin constituents of avocado fruits inhibit human oral cancer cell proliferation by targeting the EGFR/RAS/RAF/MEK/ERK1/2 pathway

Avocado (Persea americana) fruits are consumed as part of the human diet and extracts have shown growth inhibitory effects in various types of human cancer cells, although the effectiveness of individual components and their underlying mechanism are poorly understood. Using activity-guided fractionation of the flesh of avocado fruits, a chloroform-soluble extract (D003) was identified that exhibited high efficacy towards premalignant and malignant human oral cancer cell lines. From this extract, two aliphatic acetogenins of previously known structure were isolated, compounds 1 [(2S,4S)-2,4-dihydroxyheptadec-16-enyl acetate] and 2 [(2S,4S)-2,4-dihydroxyheptadec-16-ynyl acetate]. In this study, we show for the first time that the growth inhibitory efficacy of this chloroform extract is due to blocking the phosphorylation of EGFR (Tyr1173), c-RAF (Ser338), and ERK1/2 (Thr202/Tyr204) in the EGFR/RAS/RAF/MEK/ERK1/2 cancer pathway. Compounds 1 and 2 both inhibited phosphorylation of c-RAF (Ser338) and ERK1/2 (Thr202/Tyr204). Compound 2, but not compound 1, prevented EGF-induced activation of the EGFR (Tyr1173). When compounds 1 and 2 were combined they synergistically inhibited c-RAF (Ser338) and ERK1/2 (Thr202/Tyr204) phosphorylation, and human oral cancer cell proliferation. The present data suggest that the potential anticancer activity of avocado fruits is due to a combination of specific aliphatic acetogenins that target two key components of the EGFR/RAS/RAF/MEK/ERK1/2 cancer pathway.

Gas-chromatographic analysis of the aliphatic fractions of brown coal wax

The individual composition of the fractions of wax isolated from brown coal from the Sergeevskoe deposit was studied using gas chromatography. It was found that the aliphatic constituents of wax are C14–C42n-alkanes with high coefficients of oddness, C14–C30 saturated alcohols, C14–C36 higher fatty acids, and esters. The contribution of unsaturated compounds was found. The structure and formation conditions of coal are considered.

Evidence of aliphatics in nascent soot particles in premixed ethylene flames

Chemical composition of nascent soot in burner-stabilized, premixed ethylene–oxygen–argon flames was studied using micro-FT-IR spectroscopy. The flames have an identical unburned gas composition with equivalence ratio equal to 2.07, but they differ in cold gas velocity. Nascent soot was sampled using a dilution probe over a range of burner surface-to-probe separation. The particles were deposited on thin-film substrates in a cascade impactor at two cut sizes of D50=10 and 56nm. The micro-FT-IR spectra revealed the presence of aliphatic C–H, aromatic C–H and a number of oxygenated functionalities. Spectral analyses were made to quantify variations of the aliphatic and aromatic C–H groups with flame temperature and sampling position. Results show that the aliphatic-to-aromatic C–H ratio is greater than unity in all cases, indicating the presence of an appreciable amount of aliphatic C–H bonds in nascent soot. The relative content of aliphatic components was found to increase with an increase in the maximum flame temperature. To examine the nature of these aliphatic constituents, a thermal desorption–chemical ionization time-of-flight mass spectrometry was used to softly fragment a soot sample and ionize the fragments. Results suggest that the aliphatic constituents are alkylated aromatics with molecular weights spanning from 200 to 900amu. This work provides definitive and quantitative observations that aliphatics are abundant at early stages of soot mass and size growth.

Characterization of military fog oil by comprehensive two-dimensional gas chromatography

The most commonly used military fog oil is characterized by comprehensive two-dimensional gas chromatography (GC×GC) coupled to either Flame Ionization Detection (FID) or Time-of-Flight Mass Spectrometric Detection (TOFMS) to advance the knowledge regarding the complete chemical makeup of this complex matrix. Two different GC×GC column sets were investigated, one employing a non-polar column combined with a shape selective column and the other an inverse column set (medium-polar/non-polar). The inverse set maximizes the use of the two-dimensional separation space and segregates aliphatic from aromatic fractions. The shape selective column best separates individual polycyclic aromatic hydrocarbons (PAHs) from the bulk oil. The results reveal that fog oil (FO) is composed mainly of aliphatic compounds ranging from C 10 to C 30, where naphthenes comprise the major fraction. Although many different species of aromatics are present, they constitute only a minor fraction in this oil, and no conjugated PAHs are found. The composition of chemically similar aliphatic constituents limits the analytical power of silica gel fractionation and GC–MS analysis to characterize FO. Among the aliphatic compounds identified are alkanes, cyclohexanes, hexahydroindanes, decalins, adamantanes, and bicyclohexane. The aromatic fraction is composed of alkylbenzene compounds, indanes, tetrahydronaphthalenes, partially hydrogenated PAHs, biphenyls, dibenzofurans and dibenzothiophenes. This work represents the best characterization of military fog oil to date. As the characterization process shows, information on such complex samples can only be parsed using a combination of sample preprocessing steps, multiple detection schemes, and an intelligent selection of column chemistries.

Surface activity of new invertible amphiphilic polyesters based on poly(ethylene glycol) and aliphatic dicarboxylic acids

The surface active properties of aqueous solutions of invertible amphiphilic alternated polyesters differing by hydrophilic–lipophilic balance (HLB) and molecular weight have been determined over the wide concentration range. The polyesters are based on poly(ethylene glycol) (PEG) of two molecular weights and aliphatic dicarboxylic acids (decanedioic and dodecanedioic). The surface activity of the polyesters and their ability to form micellar assemblies (which was recently shown for organic solvents) has been confirmed in water. The central role of the balance of hydrophilic to hydrophobic groups ratio in the formation of polymeric arrangements having hydrophobic pockets and external hydrophilic shell has been shown. The effect of molecular weight has been found considerable as well. Two changes in slope have been observed for the more hydrophobic polyesters in the surface tension vs log concentration curve. The change at low concentration is believed to originate from the formation of polyester assemblies with a hydrophobic interior and hydrophilic exterior due to the interaction of hydrophobic fragments and macromolecular flexibility. The higher concentration region exhibits behavior consistent with a cmc, which was confirmed by additional dye solubilization experiments. Molecular structure of the polyester micelles is determined by the solubilization of a solvatochromic dye. The experiment confirmed that micellization of polyesters is accompanied by the association of more hydrophobic (aliphatic) constituents forming the micelle interior. The hydrophilic fragments (ethylene oxide groups) are involved in the formation of micelle exterior.

In situ analysis by microspectroscopy reveals triterpenoid compositional patterns within leaf cuticles of Prunus laurocerasus

The cuticular waxes on the leaves of Prunus laurocerasus are arranged in distinct layers differing in triterpenoid concentrations (Jetter et al., Plant Cell Environ 23:619-628, 2000). In addition to this transversal gradient, the lateral distribution of cuticular triterpenoids must be investigated to fully describe the spatial distribution of wax components on the leaf surfaces. In the present investigation, near infrared (NIR) Raman microspectroscopy, coherent anti-Stokes Raman scattering (CARS) microscopy, and third harmonic generation (THG) spectroscopy were employed to map the triterpenoid distribution in isolated cuticles from adaxial and abaxial sides of P. laurocerasus leaves. The relative concentrations of ursolic acid and oleanolic acid were calculated by treating the cuticle spectra as linear combinations of reference spectra from the major compounds found in the wax. Raman maps of the adaxial cuticle showed that the triterpenoids accumulate to relatively high concentrations over the periclinal regions of the pavement cells, while the very long chain aliphatic wax constituents are distributed fairly evenly across the entire adaxial cuticle. In the analysis of the abaxial cuticles, the triterpenoids were found to accumulate in greater amounts over the guard cells relative to the pavement cells. The very long chain aliphatic compounds accumulated in the cuticle above the anticlinal cell walls of the pavement cells, and were found at low concentrations above the periclinals and the guard cells.

Molecular Taphonomy of Metasequoia

Abstract Chemical analysis of the leaves of modern Metasequoia and other gymnosperms revealed the presence of structural polyesters, guaiacyl lignin units and polysaccharides, but no long chain recalcitrant aliphatic constituent. Analysis of Tertiary fossil Metasequoia showed the presence of polysaccharides, lignin and a long chain aliphatic polymer. Tertiary fossil conifers similarly revealed the preservation of lignin and a long chain aliphatic polymer (up to C33) with limited preservation of polysaccharides. Experimental maturation of modern pine needles generated a composition with a long chain aliphatic polymer and additional phenolic compounds similar to those seen in the fossils. Experimental maturation of the structural polyester cutin and a pure model C16 and C18 fatty acid mixture yielded fatty acids and an aliphatic polymer less than C20 suggesting that polymers greater than C20 may be incorporated into the fossil macromolecule from longer-chain plant waxes. Thermochemolysis of the fossil conif...

Molecular features of organic matter in diagnostic horizons from andosols as seen by analytical pyrolysis

Andosols are usually formed from volcanic substrates, with thick A horizons high in organic carbon mainly in the form of stabilized humic fractions. The peculiar properties of these soils are, to large extent, affected by poorly crystalline materials like allophanes, imogolite and other Fe and Al oxyhydroxides that induce intense organo-mineral interactions which are considered to play a relevant role in OM protection against biodegradation as regards other soils developed under similar climatic conditions. Little is known about the molecular composition of this stabilized OM in a soil scenario often considered as an efficient C-sink in terms of C sequestration processes. Whole soil samples in addition to isolated humic and fulvic acids from organic A horizons of three soils with andic properties and one non-andic soil (Sodic Cambisol) from the island of Tenerife (Canary Islands, Spain) were analysed by double shot pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS) in order to get some insight on the molecular composition of different structural domains of progressive structural stability. Clear differences were found between soils, both in thermal desorption and pyrolysis behaviour of humic substances. In general the results suggest large yields of aliphatic (both alkyl and carbohydrate-derived pyrolysis compounds) pointing to high-performance processes of incorporation of aliphatic humic constituents in andosols probably favoured by interactions with amorphous minerals, whereas in non-andic soils the latter are comparatively less stabilized and are removed in early pyrolysis stages as if they occurred as loosely joined, thermoevaporation-released products. In fact, compared to Cambisol, humic and fulvic acids from andic soils led to comparatively richer pyrograms and compound assemblages. The lack of similar amounts of these loosely joined, mainly aliphatic structures after thermal desorption of the whole andic soils indicate an origin for humic substances based on rapid sequestration of C-forms of recent (litter or microbial) origin.

Genetic and ultrastructural analysis of different mutants of Pseudomonas putida affected in the poly‐3‐hydroxy‐n‐alkanoate gene cluster

Functional analyses of the different proteins involved in the synthesis and accumulation of polyhydroxyalkanoates (PHAs) in P. putida U were performed using a mutant in which the pha locus had been deleted (PpUDeltapha). These studies showed that: (i) Pha enzymes cannot be replaced by other proteins in this bacterium, (ii) the transformation of PpDeltapha with a plasmid containing the locus pha fully restores the synthesis of bioplastics, (iii) the transformation of PpDeltapha with a plasmid harbouring the gene encoding the polymerase PhaC1 (pMCphaC1) permits the synthesis of polyesters (even in absence of phaC2ZDFI); however, in this strain (PpUDeltapha-pMCphaC1) the number of PHAs granules was higher than in the wild type, (iv) the expression of phaF in PpUDeltapha-pMCphaC1 restores the original phenotype, showing that PhaF is involved in the coalescence of the PHAs granules. Furthermore, the deletion of the phaDFI genes in P. putida U considerably decreases (> 70%) the biosynthesis of PHAs consisting of hydroxyalkanoates with aliphatic constituents, and completely prevents the synthesis of those ones containing aromatic monomers. Additional experiments revealed that the deletion of phaD in P. putida U strongly reduces the synthesis of PHA, this effect being restored by PhaF. Moreover, the overexpression of phaF in P. putida U, or in its DeltafadBA mutant, led to the collection of PHA over-producer strains.

Bound volatile compounds and essential oil from the fruit of Maclura pomifera (Raf.) Schneid. (osage orange)

AbstractThe bound and free volatile compounds from Maclura pomifera (Raf.) Schneid. (osage orange fruit) have been studied by GC and GC–MS. The free volatiles amounted to 230 mg/kg and the content of bound volatiles was 10 mg/kg. Identified compounds consist of aliphatic constituents (free, 28.3%; bound, 27.6%), phenylpropane derivatives along with related compounds (free, 5.1%; bound, 36.0%), monoterpenes along with sesquiterpenes (free, 54.9%; bound, 15.5%) and other compounds (bound, 1.6%). In total, 39 bound volatiles were identified, with eugenol (9.9%) and p‐cresol (9.6%) being the major components. As far as we know, this is the first report on bound volatiles of osage orange fruit and 12 compounds were established to be identical by comparison with the free volatiles. The principal constituents of the essential oil were elemol (19.2%), 1‐dodecanol (9.7%), trans‐caryophyllene (5.6%) and n‐hexyl hexanoate (5.4%). Copyright © 2006 John Wiley & Sons, Ltd.

CHARACTERIZATION OF HUMIC ACID-LIKE MATERIAL ISOLATED FROM THE HUMIN FRACTION OF A TOPSOIL

A humic acid-like material (HALM) was obtained by base extraction of a demineralized humin. The objective of this study was to investigate how HALM differs from the humic acids (HAs) associated with the same soil by systematically characterizing the chemical, structural, and molecular properties of both HALM and HA fractions. The methods used for characterization included elemental analysis, high performance size exclusion chromatography, solid state 13C-nuclear magnetic resonance spectroscopy, pyrolysis-gas chromatography-mass spectrometry, and tetramethyl ammonium hydroxide pyrolysis-gas chromatography-mass spectrometry. The results showed that the HALM fraction constituted 8.8% of the total organic carbon of the original soil and that it had O/C and H/C atomic ratios of 0.32 and 0.96, respectively, compared with 0.46 and 0.89 for the HA. The high performance size exclusion chromatography chromatograms indicated that both HA and HALM had two subunits of macromolecules with average molecular weight values of 3.38 to 3.47 and 40.1 to 45.8 kDa for the smaller and the larger size subunits, respectively, and that the relative contents of the larger size subunits was 26.9% and 41.4% for HA and HALM, respectively. The CP-magic-angle-spinning 13C-nuclear magnetic resonance spectroscopy and pyrolysis data indicated that compared with HA, HALM was characterized by lower contents of oxygen-containing groups and higher contents of aliphatic carbons. The study suggests that HALM may have undergone a greater degree of biogeochemical alterations and that its larger apparent molecular weight and higher H/C and lower O/C atomic ratios may result from hydrophobic aliphatic constituents that were incorporated to HALM under water-flooded conditions.

How the polarity of the separation column may influence the characterization of compost organic matter by pyrolysis-GC/MS

Characterizing the chemical composition of compost organic matter (OM) may help to understand short- and long-term effect of compost spreading on soils. Pyrolysis-GC/MS is a powerful tool to study compost OM. However, the choice of the chromatographic conditions may induce selectivity for some pyrolysis products. This study aimed at comparing the information given by two columns of contrasted polarities. A polar (wax) column was better suited to characterize pyrolysis products originating from less humified OM, such as polysaccharide, protein and lignin-derived products. Alkanoic acids were also better analyzed on this column. By contrast, the use of a non-polar column was more satisfactory to characterize the distribution of aliphatic structures producing alkanes and alkenes upon pyrolysis. This study suggested that a polar column should be the most useful to evaluate compost OM stability and fertilizing properties (N availability), whereas their potential use as organic amendments for long-term carbon storage in soils, requiring information on the most refractory aliphatic constituents, should be better evaluated with a non-polar column. Information on compost hydrophobicity, influencing soil structural stability, should require the combination of both columns.

Effect of In Vivo Jet Fuel Exposure on Subsequent In Vitro Dermal Absorption of Individual Aromatic and Aliphatic Hydrocarbon Fuel Constituents

The percutaneous absorption of topically applied jet fuel hydrocarbons (HC) through skin previously exposed to jet fuel has not been investigated, although this exposure scenario is the occupational norm. Pigs were exposed to JP-8 jet fuel-soaked cotton fabrics for 1 and 4 d with repeated daily exposures. Preexposed and unexposed skin was then dermatomed and placed in flow-through in vitro diffusion cells. Five cells with exposed skin and four cells with unexposed skin were dosed with a mixture of 14 different HC consisting of nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, ethyl benzene, o-xylene, trimethyl benzene (TMB), cyclohexyl benzene (CHB), naphthalene, and dimethyl naphthalene (DMN) in water + ethanol (50:50) as diluent. Another five cells containing only JP-8-exposed skin were dosed solely with diluent in order to determine the skin retention of jet fuel HC. The absorption parameters of flux, diffusivity, and permeability were calculated for the studied HC. The data indicated that there was a two-fold and four-fold increase in absorption of specific aromatic HC like ethyl benzene, o-xylene, and TMB through 1- and 4-dJP-8 preexposed skin, respectively. Similarly, dodecane and tridecane were absorbed more in 4-d than 1-dJP-8 preexposed skin experiments. The absorption of naphthalene and DMN was 1.5 times greater than the controls in both 1- and 4-d preexposures. CHB, naphthalene, and DMN had significant persistent skin retention in 4-d preexposures as compared to 1-d exposures that might leave skin capable of further absorption several days postexposure. The possible mechanism of an increase in HC absorption in fuel preexposed skin may be via lipid extraction from the stratum corneum as indicated by Fourier transform infrared (FTIR) spectroscopy. This study suggests that the preexposure of skin to jet fuel enhances the subsequent in vitro percutaneous absorption of HC, so single-dose absorption data for jet fuel HC from naive skin may not be optimal to predict the toxic potential for repeated exposures. For certain compounds, persistent absorption may occur days after the initial exposure. This work was supported by U.S. Air Force Office of Scientific Research, grant F49620-01-1-0080.

Tomato fruit cuticular waxes and their effects on transpiration barrier properties: functional characterization of a mutant deficient in a very-long-chain fatty acid beta-ketoacyl-CoA synthase.

Cuticular waxes play a pivotal role in limiting transpirational water loss across the plant surface. The correlation between the chemical composition of the cuticular waxes and their function as a transpiration barrier is still unclear. In the present study, intact tomato fruits (Lycopersicon esculentum) are used, due to their astomatous surface, as a novel integrative approach to investigate this composition- function relationship: wax amounts and compositions of tomato were manipulated before measuring unbiased cuticular transpiration. First, successive mechanical and extractive wax-removal steps allowed the selective modification of epi- and intracuticular wax layers. The epicuticular film consisted exclusively of very-long-chain aliphatics, while the intracuticular compartment contained large quantities of pentacyclic triterpenoids as well. Second, applying reverse genetic techniques, a loss-of-function mutation with a transposon insertion in a very-long-chain fatty acid elongase beta-ketoacyl-CoA synthase was isolated and characterized. Mutant leaf and fruit waxes were deficient in n-alkanes and aldehydes with chain lengths beyond C30, while shorter chains and branched hydrocarbons were not affected. The mutant fruit wax also showed a significant increase in intracuticular triterpenoids. Removal of the epicuticular wax layer, accounting for one-third of the total wax coverage on wild-type fruits, had only moderate effects on transpiration. By contrast, reduction of the intracuticular aliphatics in the mutant to approximately 50% caused a 4-fold increase in permeability. Hence, the main portion of the transpiration barrier is located in the intracuticular wax layer, largely determined by the aliphatic constituents, but modified by the presence of triterpenoids, whereas epicuticular aliphatics play a minor role.

Biodegradation of diesel oil by an Arabian Sea sediment culture isolated from the vicinity of an oil field

Laboratory scale batch studies were performed to test the diesel oil biodegradation ability of ES1 cultures isolated from Arabian Sea sediments obtained from the vicinity of an oil field. This culture could utilize diesel as the sole source of carbon and energy. Under aerobic conditions, 39% loss of diesel oil was observed over 8 days where 80% of the loss was due to aliphatic constituents. Under anoxic nitrate reducing conditions the rate and extent of degradation was significantly lower, i.e., 18% over 50 days. Salt acclimatized cultures could tolerate salinities up to 3.5% and demonstrated optimal performance at a salinity of 0.5%. The optimum N/P ratio for these cultures was found to be in the range of 2:1–5:1. Addition of two trace elemental substance formulations exhibited a significant inhibitory effect on culture growth. This culture has good potential for decontamination of oil-contaminated marine and subsurface environments.

Essential oil constituents of aerial parts of Artemisia scoparia Waldst. & Kit.

AbstractHydrodistilled oil obtained from the aerial parts of Artemisia scoparia Waldst. & Kit. was analysed by capillary GC and GC–MS. The volatile oil of the 10–15 cm high herb was composed mainly of eight monoterpenes (ca. 68.5%), and the predominant constituents were β‐myrcene (24.4%), γ‐terpinene (18.3%), neral (12.5%) and cis‐p‐mentha‐2‐en‐1‐ol (5.1%). Among seven sesquiterpenes (6.9%) present in the oil, the prominent one was β‐caryophyllene (3.4%). p‐Cymene (17.4%) and p‐cymene‐8‐ol were the characterized aromatic compounds in the volatile oil. Three aliphatic constituents, identified as n‐octane, n‐heptadecane and n‐eicosane, occurred in trace amounts. Copyright © 2004 John Wiley & Sons, Ltd.

X-Ray Raman Spectroscopy—A New Tool to Study Local Structure of Aromatic Hydrocarbons and Asphaltenes

Polycyclic aromatic hydrocarbons (PAHs) are essential components in numerous natural and man made organic compounds. In asphaltenes, knowledge of the electronic structure of both its aromatic and aliphatic components is of crucial importance, when trying to understand and predict its macroscopic properties. Theoretical studies of complex PAHs have led to simple rules to describe their π electron distribution, but systematic experimental support is still needed. A novel approach to directly probe carbon type in PAHs is described here, namely the technique of X-ray Raman spectroscopy (XRS). Conventional X-ray absorption spectroscopy (XAS) has been used for many years for element specific characterization of local structure and chemistry. However, in the soft X-ray region (relevant for light elements) its application to numerous carbonaceous systems including asphaltenes encounters problems. Most of the difficulties, including surface sensitivity and restricted sample environments, stem from the submicron path lengths of soft X-rays and/or electrons. XRS provides a means for obtaining the information content of soft X-ray absorption spectra while maintaining the experimental benefits of hard X-ray techniques (˜mm path length). In the XRS process an incident photon is inelastically scattered and part of its energy is transferred to excite an inner shell electron into an unoccupied state. Under the dipole approximation, the resulting features are identical to the corresponding XAS spectrum. In the past, the extremely low cross-section of XRS has made this technique impractical, but intense new X-ray facilities and improvements in X-ray optics have helped to advance this unique spectroscopic tool. We have applied XRS to a series of PAHs and several asphaltenes. The results directly support the simple ideas contained in the “sextet-double bond” description of PAHs. Furthermore, we show that XRS can probe the geometrry of aromatic ring systems in asphaltenes, as well as its ratio of aromatic and aliphatic constituents.

Volatile Constituents of Rhizomes of Alpinia galanga (Linn.) Willd

A hydro-distilled volatile oil obtained from the rhizome of Alpinia galanga (Linn.) Willd. belonging to the family Zingiberaceae, was analysed by GC and GC-MS. The oil was found to contain 11 components of which 10 constituents, comprising 98.5% were identified. The most abundant class of compounds were 4 monoterpenes comprising about 74% of the total volatiles. The predominant monoterpene was 1, 8–cineole (57%) followed by geranyl acetate (10.2%), citronellyl acetate (3.4%) and linalool (3.1%). Only one sesquiterpene viz; β-caryophyllene (5.4%) was identified. Five higher aliphatic constituents namely n-tridecane (1.5%), eicosanol (3.5%), n-docosane (4.3%), n-docosan-8-ol (4.9%) and n-tricosanol (5.2%) were also found in the oil.

Aerobic short-term microbial utilization and degradation of humic acids extracted from soils of long-term field experiments

A humic acid (HA) fraction of the soil organic matter (SOM) was extracted with alkali from soil samples originated in non-fertilized and fertilized (NPK + organic manure) plots of long-term (45 years) field experiments. The HA preparations served as supplemental sources of nutrients or as sole source of either C or N for soil micro-organisms indigenous to the same soils. Under aerobic conditions (shake cultures) between 15% and 45% of HA were degraded in 21 days. The degradation was minimum if HAs were added supplementary, although the biomass formation was strongly enhanced. Preparations of HA from long-term fertilized soils appeared somewhat less susceptible to microbial degradation but they were capable of supporting microbial growth. Under copious nutritional conditions some novel HA-like substances were formed. The HA preparations re-isolated from individual cultures exhibited differences in elemental and structural characteristics. The FTIR spectra indicated an increasing proportion of aromatic structures that appeared as associated with mineral moieties. Conclusively, HAs from long-term fertilized and manured soils could be considered as more resistant to microbial activities than those from control soil, but under limited nutrient conditions their aliphatic constituents appear utilizable by micro-organisms.

Clustering of comb and propolis waxes based on the distribution of aliphatic constituents

Chemical composition data for 41 samples of propolis waxes and 9 samples of comb waxes of Apis mellifera collected mainly in Brazil were treated using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). For chemometrical analysis, the distribution of hydrocarbons and residues of alcohols and carboxylic acids of monoesters were considered. The clustering obtained revealed chemical affinities and differences not previously grasped by simple eye-inspection of the data. No consistent differences were detected between comb and propolis waxes. These and previous results suggest that hydrocarbons, carboxylic acids, aliphatic alcohols and esters from both comb and propolis waxes are bee-produced compounds and, hence, the differences detected between one and another region are dependent on genetic factors related to the insects rather than the local flora. The samples analyzed were split into two main clusters, one of them comprising exclusively material collected in the State of Sao Paulo. The results are discussed with respect to the africanization of honeybees that first took place in that State and therefrom irradiated to other parts of Brazil.