Garcinia kola: a critical review on chemistry and pharmacology of an important West African medicinal plant.

Garcinia kola Heckel (Clusiaceae) is a tree indigenous to West and Central Africa. All plant parts, but especially the seeds, are of value in local folklore medicine. Garcinia kola is used in treatment of numerous diseases, including gastric disorders, bronchial diseases, fever, malaria and is used to induce a stimulating and aphrodisiac effect. The plant is now attracting considerable interest as a possible source of pharmaceutically important drugs. Several different classes of compounds such as biflavonoids, benzophenones, benzofurans, benzopyran, vitamin E derivatives, xanthones, and phytosterols, have been isolated from G. kola, of which many appears to be found only in this species, such as garcinianin (found in seeds and roots), kolanone (fruit pulp, seeds, roots), gakolanone (stem bark), garcinoic acid, garcinal (both in seeds), garcifuran A and B, and garcipyran (all in roots). They showed a wide range of pharmacological activities (e.g. analgesic, anticancer, antidiabetic, anti-inflammatory, antimalarial, antimicrobial, hepatoprotective and neuroprotective effects), though this has only been confirmed in animal models. Kolaviron is the most studied compound and is perceived by many studies as the active principle of G. kola. However, its research is associated with significant flaws (e.g. too high doses tested, inappropriate positive control). Garcinol has been tested under better conditions and is perhaps showing more promising results and should attract deeper research interest (especially in the area of anticancer, antimicrobial, and neuroprotective activity). Human clinical trials and mechanism-of-action studies must be carried out to verify whether any of the compounds present in G. kola may be used as a lead in the drug development.

Stereochemistry of two pheromonal components of the bumblebee wax moth, Aphomia sociella.

The bumblebee wax moth, Aphomia sociella, is a parasite of bumblebees. In this species, males produce sexual pheromone to attract females, while females produce an aphrodisiac pheromone that initiates male courtship. Both pheromones contain 6,10,14-trimethylpentadecan-2-one (TMPD-one) and the corresponding alcohol, 6,10,14-trimethylpentadecan-2-ol (TMPD-ol) in sex specific quantities. Male sex pheromone consists of 7 components with TMPD-one as a minor one and traces of TMPD-ol. In female aphrodisiac pheromone, TMPD-ol is the major component, while TMPD-one is present in traces. Here we report on the absolute configuration of TMPD-one in male sex pheromone and TMPD-ol in female aphrodisiac pheromone of A. sociella. The configuration was determined from GC/MS of prepared (S)-acetoxypropionyl esters of TMPD-ol. TMPD-one was first reduced to the alcohol that was then derivatized with (S)-acetoxypropionyl chloride. The GC/MS data of obtained diastereoisomers were compared with synthetic standards. The absolute configuration of TMPD-one in the male pheromone was (6R,10R). The configuration of TMPD-ol in the female pheromone was (2R,6R,10R). Electrophysiological experiments showed that TMPD-one and TMPD-ol are perceived by both sexes. The synthetic standards of naturally produced stereoisomers elicited higher responses than mixtures of all stereoisomers.

Sexual attraction: a review of bumblebee male pheromones.

Males of many bumblebee species exhibit a conspicuous pre-mating behavior with two distinct behavioral components: scent marking and patrol flying. The marking pheromone is produced by the cephalic part of the labial gland (CLG). As far as is known, the CLG secretion is species specific, and it usually consists of two types of compounds: (i) straight-chain aliphatic alcohols, aldehydes or esters, and (ii) acyclic mono-, sesqui- and diterpenes (alcohols or acetates). Here, we summarize data from the literature reporting chemical composition of the CLG secretions of more than 80 bumblebee species. Similarities and differences within and between subgenera are discussed in the context of biosynthetic pathways and evolution.

Expansion of the fatty acyl reductase gene family shaped pheromone communication in Hymenoptera.

Fatty acyl reductases (FARs) are involved in the biosynthesis of fatty alcohols that serve a range of biological roles. Insects typically harbor numerous FAR gene family members. While some FARs are involved in pheromone biosynthesis, the biological significance of the large number of FARs in insect genomes remains unclear.Using bumble bee (Bombini) FAR expression analysis and functional characterization, hymenopteran FAR gene tree reconstruction, and inspection of transposable elements (TEs) in the genomic environment of FARs, we uncovered a massive expansion of the FAR gene family in Hymenoptera, presumably facilitated by TEs. The expansion occurred in the common ancestor of bumble bees and stingless bees (Meliponini). We found that bumble bee FARs from the expanded FAR-A ortholog group contribute to the species-specific pheromone composition. Our results indicate that expansion and functional diversification of the FAR gene family played a key role in the evolution of pheromone communication in Hymenoptera.

The cephalic labial gland secretions of two socially parasitic bumblebees Bombus hyperboreus (Alpinobombus) and Bombus inexspectatus (Thoracobombus) question their inquiline strategy.

Social parasitic Hymenopterans have evolved morphological, chemical, and behavioral adaptations to overcome the sophisticated recognition and defense systems of their social host to invade host nests and exploit their worker force. In bumblebees, social parasitism appeared in at least 3 subgenera independently: in the subgenus Psithyrus consisting entirely of parasitic species, in the subgenus Alpinobombus with Bombus hyperboreus, and in the subgenus Thoracobombus with B. inexspectatus. Cuckoo bumblebee males utilize species-specific cephalic labial gland secretions for mating purposes that can impact their inquiline strategy. We performed cephalic labial gland secretions in B. hyperboreus, B. inexspectatus and their hosts. Males of both parasitic species exhibited high species specific levels of cephalic gland secretions, including different main compounds. Our results showed no chemical mimicry in the cephalic gland secretions between inquilines and their host and we did not identify the repellent compounds already known in other cuckoo bumblebees.

Variability in Sexual Pheromones Questions their Role in Bumblebee Pre-Mating Recognition System.

Sex-specific chemical secretions have been widely used as diagnostic characters in chemotaxonomy. The taxonomically confused group of bumblebees has reaped the benefit of this approach through the analyses of cephalic labial gland secretions (CLGS). Most of currently available CLGS descriptions concern species from the West-Palearctic region but few from the New World. Here, the CLGS of four East-Palearctic species Bombus deuteronymus, B. filchnerae, B. humilis, and B. exil (subgenus Thoracobombus) are analysed. Our results show high levels of variability in the major compounds in B. exil. In contrast, we describe a low differentiation in CLGS compounds between B. filchnerae and its phylogenetically closely related taxon B. muscorum. Moreover, the chemical profiles of B. filchnerae and B. muscorum are characterized by low concentrations of the C16 component, which is found in higher concentrations in the other Thoracobombus species. This raises the possibility that courtship behavior as well as environmental constraints could affect the role of the bumblebee males' CLGS.

Biotechnological potential of insect fatty acid-modifying enzymes.

There are more than one million described insect species. This species richness is reflected in the diversity of insect metabolic processes. In particular, biosynthesis of secondary metabolites, such as defensive compounds and chemical signals, encompasses an extraordinarily wide range of chemicals that are generally unparalleled among natural products from other organisms. Insect genomes, transcriptomes and proteomes thus offer a valuable resource for discovery of novel enzymes with potential for biotechnological applications. Here, we focus on fatty acid (FA) metabolism-related enzymes, notably the fatty acyl desaturases and fatty acyl reductases involved in the biosynthesis of FA-derived pheromones. Research on insect pheromone-biosynthetic enzymes, which exhibit diverse enzymatic properties, has the potential to broaden the understanding of enzyme specificity determinants and contribute to engineering of enzymes with desired properties for biotechnological production of FA derivatives. Additionally, the application of such pheromone-biosynthetic enzymes represents an environmentally friendly and economic alternative to the chemical synthesis of pheromones that are used in insect pest management strategies.

Qualitative analyses of less-volatile organic molecules from female skin scents by comprehensive two dimensional gas chromatography-time of flight mass spectrometry.

Instrumental human scent analysis is undoubtedly desirable for many forensic as well medical applications. Most of the previous human scent studies were focused on volatile organic compounds (VOCs) which were analysed by head space solid phase micro-extraction gas chromatography/mass spectrometry (HS-SPME-GC/MS). This method is, however, significantly less sensitive to "heavier" less volatile compounds emitted from the human skin. These less volatile organic scent molecules probably create the basis of the individual human scent signature, and therefore, our attention is focused mainly on these "heavier" compounds. The human scent was adsorbed onto purified glass beads and samples were prepared as hexane solutions obtained by extraction from the sampled glass beads. To resolve a lot of very similar molecules, the comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometer (GCxGC-TOFMS) was used to analyse the hexane scent solutions. Using this technique, more than 137 less volatile molecules including organic fatty acids, ketones, aldehydes, simple esters, alcohols, and especially various fatty acid esters with different carbon chains were identified. A considerable number of these molecules were identified in the scent samples for the first time.

Chemical reproductive traits of diploid Bombus terrestris males: Consequences on bumblebee conservation.

The current bumblebee decline leads to inbreeding in populations that fosters a loss of allelic diversity and diploid male production. As diploid males are viable and their offspring are sterile, bumblebee populations can quickly fall in a vortex of extinction. In this article, we investigate for the first time a potential premating mechanism through a major chemical reproductive trait (male cephalic labial gland secretions) that could prevent monandrous virgin queens from mating with diploid males. We focus our study on the cephalic labial gland secretions of diploid and haploid males of Bombus terrestris (L.). Contrary to initial expectations, our results do not show any significant differentiation of cephalic labial gland secretions between diploid and haploid specimens. Queens seem therefore to be unable to avoid mating with diploid males based on their compositions of cephalic labial gland secretions. This suggests that the vortex of extinction of diploid males could not be stopped through premating avoidance based on the cephalic labial gland secretions but other mechanisms could avoid mating between diploid males and queens.

Gene Expression Dynamics in Major Endocrine Regulatory Pathways along the Transition from Solitary to Social Life in a Bumblebee, Bombus terrestris.

Understanding the social evolution leading to insect eusociality requires, among other, a detailed insight into endocrine regulatory mechanisms that have been co-opted from solitary ancestors to play new roles in the complex life histories of eusocial species. Bumblebees represent well-suited models of a relatively primitive social organization standing on the mid-way to highly advanced eusociality and their queens undergo both, a solitary and a social phase, separated by winter diapause. In the present paper, we characterize the gene expression levels of major endocrine regulatory pathways across tissues, sexes, and life-stages of the buff-tailed bumblebee, Bombus terrestris, with special emphasis on critical stages of the queen's transition from solitary to social life. We focused on fundamental genes of three pathways: (1) Forkhead box protein O and insulin/insulin-like signaling, (2) Juvenile hormone (JH) signaling, and (3) Adipokinetic hormone signaling. Virgin queens were distinguished by higher expression of forkhead box protein O and downregulated insulin-like peptides and JH signaling, indicated by low expression of methyl farnesoate epoxidase (MFE) and transcription factor Krüppel homolog 1 (Kr-h1). Diapausing queens showed the expected downregulation of JH signaling in terms of low MFE and vitellogenin (Vg) expressions, but an unexpectedly high expression of Kr-h1. By contrast, reproducing queens revealed an upregulation of MFE and Vg together with insulin signaling. Surprisingly, the insulin growth factor 1 (IGF-1) turned out to be a queen-specific hormone. Workers exhibited an expression pattern of MFE and Vg similar to that of reproducing queens. Males were characterized by high Kr-h1 expression and low Vg level. The tissue comparison unveiled an unexpected resemblance between the fat body and hypopharyngeal glands across all investigated genes, sexes, and life stages.

Regulation of Isoprenoid Pheromone Biosynthesis in Bumblebee Males.

Males of the closely related species Bombus terrestris and Bombus lucorum attract conspecific females by completely different marking pheromones. MP of B. terrestris and B. lucorum pheromones contain mainly isoprenoid (ISP) compounds and fatty acid derivatives, respectively. Here, we studied the regulation of ISP biosynthesis in both bumblebees. RNA-seq and qRT-PCR analyses indicated that acetoacetyl-CoA thiolase (AACT), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), and farnesyl diphosphate synthase (FPPS) transcripts are abundant in the B. terrestris labial gland. Maximal abundance of these transcripts correlated well with AACT enzymatic activity detected in the LG extracts. In contrast, transcript abundances of AACT, HMGR, and FPPS in B. lucorum were low, and AACT activity was not detected in LGs. These results suggest that transcriptional regulation plays a key role in the control of ISP biosynthetic gene expression and ISP pheromone biosynthesis in bumblebee males.

Seasonal Dynamics in the Chemistry and Structure of the Fat Bodies of Bumblebee Queens.

Insects' fat bodies are responsible for nutrient storage and for a significant part of intermediary metabolism. Thus, it can be expected that the structure and content of the fat body will adaptively change, if an insect is going through different life stages. Bumblebee queens belong to such insects as they dramatically change their physiology several times over their lives in relation to their solitary overwintering, independent colony foundation stage, and during the colony life-cycle ending in the senescent stage. Here, we report on changes in the ultrastructure and lipid composition of the peripheral fat body of Bombus terrestris queens in relation to seasonal changes in the queens' activity. Six life stages are defined and evaluated in particular: pharate, callow, before and after hibernation, egg-laying, and senescence. Transmission electron microscopy revealed that the fat body contained two main cell types-adipocytes and oenocytes. Only adipocytes reveal important changes related to the life phase, and mostly the ration between inclusion and cytoplasm volume varies among particular stages. Both electron microscopy and chemical analyses of lipids highlighted seasonal variability in the quantity of the stored lipids, which peaked prior to hibernation. Triacylglycerols appeared to be the main energy source during hibernation, while the amount of glycogen before and after hibernation remained unchanged. In addition, we observed that the representation of some fatty acids within the triacylglycerols change during the queen's life. Last but not least, we show that fat body cell membranes do not undergo substantial changes concerning phospholipid composition in relation to overwintering. This finding supports the hypothesis that the cold-adaptation strategy of bumblebee queens is more likely to be based on polyol accumulation than on the restructuring of lipid membranes.

First Chemical Analysis and Characterization of the Male Species-Specific Cephalic Labial-Gland Secretions of South American Bumblebees.

The evolution of signals and reproductive traits involved in the pre-mating recognition has been in focus of abundant research in several model species, such as bumblebees (genus Bombus). However, the most-studied bumblebee reproductive trait, the male cephalic labial gland secretions (CLGS), remains unknown among bumblebee species from South America. In this study, the CLGS of five South American bumblebees of the subgenera Thoracobombus (Bombus excellens and B. atratus) and Cullumanobombus (B. rubicundus, B. hortulanus, and B. melaleucus) were investigated, by comparing the chemical compositions of their secretions to those of closely related European species. The results showed an obvious interspecific differentiation in both subgenera. The interspecific differentiation among the species of the Thoracobombus subgenus involved different compounds present at high contents (main compounds), while those of the Cullumanobombus subgenus shared the same main components. This suggests that among the species of the Cullumanobombus subgenus, the differentiation in minor components could lead to species discrimination.

Characterisation of Acetyl-CoA Thiolase: The First Enzyme in the Biosynthesis of Terpenic Sex Pheromone Components in the Labial Gland of Bombus terrestris.

Buff-tailed bumblebees, Bombus terrestris, use a male sex pheromone for premating communication. Its main component is a sesquiterpene, 2,3-dihydrofarnesol. This paper reports the isolation of a thiolase (acetyl-CoA thiolase, AACT_BT), the first enzyme involved in the biosynthetic pathway leading to formation of isoprenoids in the B. terrestris male sex pheromone. Characterisation of AACT_BT might contribute to a better understanding of pheromonogenesis in the labial gland of B. terrestris males. The protein was purified to apparent homogeneity by column chromatography with subsequent stepwise treatment. AACT_BT showed optimum acetyltransferase activity at pH 7.1 and was strongly inhibited by iodoacetamide. The enzyme migrated as a band with an apparent mass of 42.9 kDa on SDS-PAGE. MS analysis of an AACT_BT tryptic digest revealed high homology to representatives of the thiolase family. AACT_BT has 96 % amino acid sequence identity with the previously reported Bombus impatiens thiolase.

Effect of heat treatment on the n-3/n-6 ratio and content of polyunsaturated fatty acids in fish tissues.

The aim of this study was to compare the effect of different heat treatments (pan-frying, oven-baking, and grilling) on the contents of polyunsaturated fatty acids (PUFAs) in fish tissue. Four fish species were examined: pike, carp, cod, and herring. High performance liquid chromatography, coupled with electrospray ionization and mass spectrometric detection (HPLC/ESI/MS), was employed for determination of intact lipid molecules containing n-3 and n-6 PUFAs. Although mostly non-polar lipids (triacylglycerols, TGs) were present in the fish tissue, the PUFAs were present preferentially in the phospholipid fraction. Omnivorous fish species (carp, herring) contained more TGs than did predatory ones (pike, cod). Higher amounts of PUFAs were detected in the marine species than in the freshwater ones. The impact of heat treatments on the lipid composition in the fish tissue seems to be species-specific, as indicated by multivariate data analysis. Herring tissue is most heat-stable, and the mildest heat treatment for PUFA preservation was oven-baking.

Biosynthetic Studies of the Male Marking Pheromone in Bumblebees by Using Labelled Fatty Acids and Two-Dimensional Gas Chromatography with Mass Detection.

Two-dimensional comprehensive gas chromatography (GC×GC) coupled with mass detection was used as a tool for biosynthetic studies of bumblebee pheromones. Prior to biosynthetic experiments, the chromatographic behaviour of isotopically modified esters in the GC×GC system as well as their behaviour in mass detection was studied. The male marking pheromones of Bombus lucorum, Bombus lapidarius and Bombus terrestris were investigated. Main pheromonal components are ethyl tetradec-9-enoate (53 %) and ethyl dodecanoate (6 %) in B. lucorum, hexadec-9-en-1-ol (52 %) and hexadecan-1-ol (31 %) in B. lapidarius, and 2,3-dihydrofarnesol (58 %) and ethyl dodecanoate (15 %) in B. terrestris. The research strategy was based on 1) in vivo incubation of isotopically (2 H, 13 C) modified fatty acids (FAs) and analysis of their metabolites and 2) feeding experiments with 2 H- and 13 C-labelled FAs mixed with food. It was observed that labelled FAs were modified into the most abundant aliphatic compounds present in labial gland secretions. In feeding experiments, the labelled FAs were transformed into pheromone components. Transport of the FA precursors from the fat body through haemolymph was confirmed. The results show that FAs, stored in the form of triacylglycerols in the fat body, are likely to participate in the biosynthesis of some aliphatic pheromone components.

Fatty acids from pool lipids as possible precursors of the male marking pheromone in bumblebees.

Triacylglycerols (TGs) stored in the fat bodies of bumblebee males have a species-specific composition. The striking structural similarities between TG fatty acids (FAs) and components of the male marking pheromone in certain species led to the hypothesis that FAs may serve as precursors in pheromone biosynthesis. Here, we analysed TGs from B. ruderatus, B. bohemicus, and B. campestris. Nonadec-9-ene and icos-15-en-1-ol are the main components of B. ruderatus labial gland secretion, forming up to 92% of the gland extract. The corresponding icos-11-enic and icos-15-enic acids were found in TGs at levels higher than usual for bumblebee species. We found similar relationships in B. campestris and B. bohemicus. These results suggest that FAs might be precursors of aliphatic compounds in the male pheromones. Furthermore, we report for the first time the pheromone structure of B. ruderatus males.

Scent of a break-up: phylogeography and reproductive trait divergences in the red-tailed bumblebee (Bombus lapidarius).

BACKGROUND: The Pleistocene climatic oscillations are considered as a major driving force of intraspecific divergence and speciation. During Ice Ages, populations isolated in allopatric glacial refugia can experience differentiation in reproductive traits through divergence in selection regimes. This phenomenon may lead to reproductive isolation and dramatically accentuates the consequences of the climatic oscillations on species. Alternatively, when reproductive isolation is incomplete and populations are expanding again, further mating between the formerly isolated populations can result in the formation of a hybrid zone, genetic introgression or reinforcement speciation through reproductive trait displacements. Therefore changes in reproductive traits driven by population movements during climatic oscillations can act as an important force in promoting pre-zygotic isolation. Notwithstanding, divergence of reproductive traits has not been approached in the context of climatic oscillations. Here we investigate the impact of population movements driven by climatic oscillations on a reproductive trait of a bumblebee species (Bombus lapidarius). We characterise the pattern of variation and differentiation across the species distribution (i) with five genes (nuclear and mitochondrial), and (ii) in the chemical composition of male marking secretions (MMS), a key trait for mate attraction in bumblebees. RESULTS: Our results provide evidence that populations have experienced a genetic allopatric differentiation, in at least three main refugia (the Balkans, Centre-Eastern Europe, and Southern Italy) during Quaternary glaciations. The comparative chemical analyses show that populations from the Southern Italian refugium have experienced MMS differentiation and an incipient speciation process from another refugium. The meeting of Southern Italian populations with other populations as a result of range expansion at a secondary contact zone seems to have led to a reinforcement process on local MMS patterns. CONCLUSIONS: This study suggests that population movement during Quaternary climatic oscillations can lead to divergence in reproductive traits by allopatric differentiation during Ice Ages and by reinforcement during post-glacial recolonization.

Cytotoxic constituents of Pachyrhizus tuberosus from Peruvian amazon.

Investigations into the chemical constituents of the seeds of the neglected tuber crop Pachyrhizus tuberosus (Leguminosae) resulted in the isolation of seven components: five rotenoids [12a-hydroxyerosone (1), 12a-hydroxydolineone (2), erosone (3), 12a-hydroxyrotenone (4) and rotenone (6)], a phenylfuranocoumarin [pachyrrhizine (5)] and an isoflavanone [neotenone (7)]. The compounds were isolated using several chromatography techniques and characterized and verified by NMR and HPLC/MS. The MTT assay was used to examine the selective cytotoxic effects of the methanolic P. tuberosus extract and isolated compounds in two human cancer cell lines [breast (MCF-7) and colorectal (HCT-116)] and in non-transformed human fibroblasts (MRC-5); IC50 values were calculated. The methanolic P. tuberosus extract displayed respectable cytotoxic effects against HCT-116 and MCF-7 cells with IC50 values of 7.3 and 6.3 microg/mL, respectively. Of the compounds, 6 exacted greatest cytotoxicity and selectivity towards the cancer cell lines tested, yielding IC50 values of 0.3 microg/mL against both MCF-7 and HCT-116 cells, and a 6-fold reduced activity against MRC-5 fibroblasts. Compound 4 also demonstrated cytotoxicity against MCF-7 and HCT-116 (1.1 and 1.8 microg/mL, respectively), and reduced cytotoxicity towards MRC-5 cells (7.5 mirog/mL). The results revealed from the in vitro cytotoxic MTT assay are worthy of further antitumor investigation.

Characterization of neutral lipase BT-1 isolated from the labial gland of Bombus terrestris males.

BACKGROUND: In addition to their general role in the hydrolysis of storage lipids, bumblebee lipases can participate in the biosynthesis of fatty acids that serve as precursors of pheromones used for sexual communication. RESULTS: We studied the temporal dynamics of lipolytic activity in crude extracts from the cephalic part of Bombus terrestris labial glands. Extracts from 3-day-old males displayed the highest lipolytic activity. The highest lipase gene expression level was observed in freshly emerged bumblebees, and both gene expression and lipase activity were lower in bumblebees older than 3 days. Lipase was purified from labial glands, further characterized and named as BT-1. The B. terrestris orthologue shares 88% sequence identity with B. impatiens lipase HA. The molecular weight of B. terrestris lipase BT-1 was approximately 30 kDa, the pH optimum was 8.3, and the temperature optimum was 50°C. Lipase BT-1 showed a notable preference for C8-C10 p-nitrophenyl esters, with the highest activity toward p-nitrophenyl caprylate (C8). The Michaelis constant (Km) and maximum reaction rate (Vmax) for p-nitrophenyl laurate hydrolysis were Km = 0.0011 mM and Vmax = 0.15 U/mg. CONCLUSION: This is the first report describing neutral lipase from the labial gland of B. terrestris. Our findings help increase understanding of its possible function in the labial gland.