Headspace volatile composition of the flowers of Caralluma europaea N.E.Br. (Apocynaceae)

Labellum Features and Chemical Composition of Floral Scent in Bulbophyllum carunculatum Garay, Hamer & Siegrist (Section Lepidorhiza Schltr., Bulbophyllinae Schltr., Orchidaceae Juss.)

The vast majority of fly-pollinated Bulbophyllum species use a combination of visual and olfactory clues to mimic food sources and brood/oviposition sites of pollinators. The aims of the present work were to characterize the floral secretory tissue and the floral scent and compare them with those previously described in B. echinolabium. Based on the histochemical results, the labellar secretion in B. carunculatum is the protein-rich mucilage. The adaxial epidermal cells of the labellum showed typical features of secretory activity. Plastids contained plastoglobuli, which are thought to be the places for scent production in osmophores. Juxtaposed with FeCl₃ staining, the presence of dihydroxyphenolic globules in the cytoplasm of the epidermis and sub-epidermis was confirmed. Phenolic derivatives were also described with GC/MS analysis of the floral scent. The number of aromatic compounds and hydrocarbons was indicated in the floral scent of B. carunculatum. Moreover, pregnane-3,20-dione, occurring in the highest percentage in the floral fragrance of B. carunculatum, is a biologically active, 5-alpha-reduced metabolite of plasma progesterone. Progesterone is a mammalian gonadal hormone, but, like other steroid hormones, has been found in plants as intermediates in different biosynthetic pathways. The research on biosynthesis and functions of progesterone and its derivatives in flowers is still lacking.

Lipids Fraction from Caralluma europaea (Guss.): MicroTOF and HPLC Analyses and Exploration of Its Antioxidant, Cytotoxic, Anti-Inflammatory, and Wound Healing Effects

Caralluma europaea is a medicinal plant used in Morocco to cure a variety of illnesses. This study was conducted to determine the chemical composition, the antioxidant, antiproliferative, anti-inflammatory, and wound healing activities of C. europaea lipids. The chemical composition of C. europaea was analyzed using time-of-flight mass spectrometry and high-performance liquid chromatography. The antioxidant potential was determined using the 2,2-di-phenyl-1-picryl hydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) tests. The antiproliferative effect was evaluated by MTT assay against HL60, K562, Huh-7 cancer cells, and normal Vero cells. The anti-inflammatory potential was conducted against carrageenan-induced paw edema. The wound healing effect was evaluated against skin burns for 21 days. The identified phytochemical compounds were docked for their effect on nicotinamide adenine dinucleotide phosphate oxidase, caspase-3, lipoxygenase, glycogen synthase kinase-3-β, and protein casein kinase-1. The results showed the presence of some lipids, such as linoleic acid and vitamin D3. The DPPH (IC50 = 0.018 mg/mL) and FRAP (EC50 = 0.084 mg/mL) of C. europaea lipids showed an important antioxidant effect. For the anti-inflammatory test, an inhibition of 83.50% was recorded after 6 h of treatment. Our extract showed the greatest wound retraction on the 21st day (98.20%). C. europaea lipids showed a remarkable antitumoral effect against the K562 cell line (IC50 = 37.30 µg/mL), with no effect on Vero cells (IC50 > 100 µg/mL). Lignoceric acid was the most active molecule against caspase-3 (−6.453 kcal/mol). The findings indicate the growing evidence of C. europaea as a potential treatment for several diseases.

Floral attractants in the black orchid Brasiliorchis schunkeana (Orchidaceae, Maxillariinae): clues for presumed sapromyophily and potential antimicrobial activity

BACKGROUND

Orchids have evolved various strategies that aim to ensure their reproduction success. These may include the production of rewards for pollinators, or on the contrary, deception. Specific sets of features such as flower morphology, color, nectar, and odor presence (or lack thereof) are considered to determine suitability for pollination by different groups of animals. Stingless bees are thought to be the primary pollinators of the orchids of the Neotropical subtribe Maxillariinae. However, almost black flowered Brasiliorchis schunkeana at first glance presents floral adaptations that may suggest another pollination syndrome-sapromyophily.

RESULTS

A few traces of secretion were noticed on the glabrous lip callus and lip apex built by conical to villiform papillae (SEM analysis). Histochemical studies revealed huge amounts of lipids in the epidermis, subepidermis, and some parenchyma cells (SBB test) with various stages of lipids accumulation between cells. Further TEM analysis showed a heterogeneous (lipoid and phenolic) nature of secretion. The dense osmiophilic cytoplasm contained organelles (RER, free ribosomes, dictyosomes, plastids with plastoglobuli, nucleus) and vesicles migrating to plasmalemma. The vesicles, osmiophilic globules, and flocculent material were visible in periplasmic space. The central vacuole possessed osmiophilic phenolic content and flocculent material. GC-MS analysis revealed in floral extract the presence of 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione (77.06%) and 2,5-di-tert-butyl-1,4-benzoquinone (16.65%). Both compounds are known for their biological activity.

CONCLUSIONS

The juxtaposition of results led us to the conclusion that the labellar tissue produces lipoid and phenolic material, which is responsible for the glossiness and rotten herring scent. This type of secretion could be classified as a phenolic resin. The chemical analysis revealed the presence of five semiochemicals that are known to be attractants for some Diptera, which together with the rest of the results constitutes a strong premise that representatives of this order could be potential pollinators of B. schunkeana. Field observations however are still needed to confirm this pollination syndrome.

Odor-Pollution From Fungicides Disrupts Learning and Recognition of a Common Floral Scent in Bumblebees (Bombus impatiens)

Background and Aims

Bumblebees provide vital pollination services to both natural and agricultural ecosystems. Consequently their declines in species-diversity and population size over the last five decades is alarming. Direct contributors to these declines include pesticides, habitat loss, and disease. However, given that colony fitness is linked to foraging success, successful conservation requires mitigation of any anthropogenic practices that negatively impact foraging. Previous work has shown that agrochemical odor-pollution, including that of fungicides, can modulate bumblebee foraging behavior. This study investigates how odor pollution from three common fungicides (Safer® Brand Garden Fungicide II, Scotts® Lawn Fungus Control, and Reliant® Systemic Fungicide) affects Bombus impatiens’ floral-odor learning and recognition using an associative learning paradigm.

Methods

The effects of fungicide-odor pollution were tested in three ways: (1) background pollution during floral-odor learning; (2) background pollution during floral-odor recognition; and (3) point (localized) pollution during floral-odor recognition. Electroantennogram (EAG) recordings from B. impatiens confirmed the salience of all odor-stimuli and examined impacts of background fungicide-odor on antennal responses to floral-odor. To better understand how fungicide-odor structure related to behavioral data, scents were sampled (Solid Phase Microextraction) and analyzed using gas chromatography–mass spectrometry. Odors were then characterized using the Compounds Without Borders (CWB) vectorization method.

Conclusion

All fungicides tested disrupted floral-odor learning and recognition for at least one concentration tested, and Scotts® was universally disruptive at all tested concentrations. All fungicides induced EAG responses, indicating they provide perceivable odor stimuli. Interestingly, two of three tested fungicides (Scotts® and Reliant®) inhibit antennal responses to Monarda fistulosa odor. Odor characterization supports previous findings that sulfurous scents could be disruptive to odor-driven foraging behaviors. Inability for foraging bumblebees to associate to rewarding floral odors in the presence of fungicidal odor pollution could have negative large-scale implications for colony health and reproductive fitness.

Plant in vitro cultures: A promising and emerging technology for the feasible production of antidiabetic metabolites in Caralluma tuberculata

Caralluma tuberculata, a medicinal and edible plant of the genus Caralluma, belongs to the family Asclepiadaceae. Traditionally, its succulent stems are used as folk medicine for life-threatening diabetes mellitus (DM) disease. Its antidiabetic potential is ascribed to the presence of various secondary metabolites (e.g., pregnane glycosides, flavone glycosides, megastigmane glycosides, polyphenols, ferulic acid, quercetin, and bitter principles, among others) that act as effective and safe antidiabetic agents. The mechanisms of these bioactive secondary metabolites in C. tuberculata herbal medicine include lowering the blood glucose level, stimulating B cells of the pancreas to release more insulin, enhancing the sensitivity of the insulin receptor, inhibiting the action of glucagon and the hydrolysis of glycogen, and increasing the use of glucose in tissues and organ. However, overexploitation, alterations in natural environmental conditions, lower seed viability, and slow growth rate are responsible for the extinction of species from natural habitats, then becoming critically endangered species according to the International Union for Conservation of Nature Red List categories. Therefore, its limited availability does not meet the higher worldwide market demand of C. tuberculata as an antidiabetic drug. Thus, for its conservation and sustainable utilization, researchers across the globe are working on devising strategies to conserve and improve biomass along with the secondary metabolite profiles of C. tuberculata using in vitro approaches. The current review describes the recent progress on antidiabetic phytoconstituents, their cellular mechanisms, and their subsequent clinical outcomes in the drug discovery management of DM. Moreover, in vitro methods such as callus culture, micropropagation, and nano-elicitation strategies for conserving and producing bioactive secondary metabolites have been concisely reviewed and discussed.

Caralluma europaea (Guss) N.E.Br.: A review on ethnomedicinal uses, phytochemistry, pharmacological activities, and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Caralluma europaea (Guss) N.E.Br. (Apocynaceae), is a medicinal plant distributed in Morocco, Algeria, Tunisia, Libya, Egypt, Jordan, Spain, and Italy. The different parts of the plant are used traditionally to treat various diseases such as diabetes mellitus, flu, caught, kidney stones, cysts, respiratory infection, cancer, digestives disorders, urogenital infections, metabolic disorders, and cardiovascular problems.

AIM OF THE REVIEW

In this review, previous reports on C. europaea concerning its morphological description, geographical distribution, ethnomedicinal uses, phytochemistry, pharmacological properties, and toxicological studies were critically summarized.

MATERIALS AND METHODS

A systematic review of the literature on C. europaea was performed by searching the scientific databases Science Direct, PubMed, Scopus, and Google Scholar.

RESULTS

In traditional medicine, C. europaea used to treat several illnesses including diabetes, cancer, and kidney stones. Our analysis of the previous reports confirmed the scientific evidence of C. europaea ethnomedicinal uses, especially the antidiabetic activity. However, there was no clear correlation between previous pharmacological reports on C. europaea and its other ethnomedicinal uses in the treatment of kidney stones, flu, caught, metabolic, digestive, cardiovascular and respiratory disorders. The essential oils and extracts of C. europaea exhibited several in vitro and in vivo pharmacological properties such as antidiabetic, antioxidant, anti-inflammatory, analgesic, anti-proliferative, antibacterial, antimicrobial, toxicological, and immunomodulatory effects. Phytochemical characterization of C. europaea revealed the presence of several classes of secondary metabolites such as terpenoids, polyphenols, and flavonoids compounds. Finally, the food preservative ability of the extracts and essential oil obtained from C. europaea has been fully discussed.

CONCLUSION

Ethnomedicinal surveys indicated the use of C. europaea for the treatment of numerous diseases. Pharmacological reports showed that C. europaea exhibited significant antidiabetic, antioxidant, anti-inflammatory, analgesic, anti-proliferative, antibacterial, antimicrobial, and immunomodulatory effects. Further studies on the phytochemistry of bioactive compounds should be performed by using bioactivity-guided isolation strategy and improve their biological potency as well as scientific exploitation of traditional uses. An in-depth investigation is needed to valid the food preservative properties.

Volatile and Semi-Volatile Organic Compounds May Help Reduce Pollinator-Prey Overlap in the Carnivorous Plant Drosophyllum lusitanicum (Drosophyllaceae)

Most carnivorous plants show a conspicuous separation between flowers and leaf-traps, which has been interpreted as an adaptive response to minimize pollinator-prey conflicts which will reduce fitness. Here, we used the carnivorous subshrub Drosophyllum lusitanicum (Drosophyllaceae) to explore if and how carnivorous plants with minimal physical separation of flower and trap avoid or reduce a likely conflict of pollinator and prey. We carried out an extensive field survey in the Aljibe Mountains, at the European side of the Strait of Gibraltar, of pollinating and prey insects of D. lusitanicum. We also performed a detailed analysis of flower and leaf volatile and semi-volatile organic compounds (VOCs and SVOCs, respectively) by direct thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) to ascertain whether this species shows different VOC/SVOC profiles in flowers and leaf-traps that might attract pollinators and prey, respectively. Our results show a low overlap between pollinator and prey groups as well as clear differences in the relative abundance of VOCs and SVOCs between flowers and leaf-traps. Coleopterans and hymenopterans were the most represented groups of floral visitors, whereas dipterans were the most diverse group of prey insects. Regarding VOCs and SVOCs, while aldehydes and carboxylic acids presented higher relative contents in leaf-traps, alkanes and plumbagin were the main VOC/SVOC compounds detected in flowers. We conclude that D. lusitanicum, despite its minimal flower-trap separation, does not seem to present a marked pollinator-prey conflict. Differences in the VOCs and SVOCs produced by flowers and leaf-traps may help explain the conspicuous differences between pollinator and prey guilds.

Antidiabetic and antihyperlipidemic effect of Duvalia corderoyi in rats with streptozotocin-induced diabetes

Diabetes mellitus (DM) is a metabolic syndrome distinguished with glucose increasing in blood, insulin resistance, and hyperlipidemia. It results in decease of millions of people yearly. Duvalia corderoyi is a traditional diabetes and hypertension medicine from the Arabian region. D. corderoyi extract was administered to diabetes rats for estimate its anti-diabetic and antihyperlipidemic activities in Wistar rats were induced using (60 mg/kg) of streptozotocin (STZ) intraperitoneally. The rats were randomly divided into five groups: control, diabetic, diabetic receiving glibenclamide, and two diabetic D. corderoyi-treatment groups. Rats were weighted weekly, and the biochemical analysis were carried out in serum, and liver homogenate samples. Body weight of diabetic rats was lessening significantly D. corderoyi improved body weight, glucose concentration, lipid profiles, hepatic enzymes, urea, creatinine, insulin, and HDL-C. These results are the first to indicate the potential antidiabetic and antihyperlipidemic activities of D. corderoyi.

Labellum structure of Bulbophyllum echinolabium J.J. Sm. (section Lepidorhiza Schltr., Bulbophyllinae Schltr., Orchidaceae Juss.)

This micromorphological, chemical and ultrastructural study is a continuation of research conducted on the section Lepidorhiza. The Bulbophyllum echinolabium flowers comprised features that characterize a sapromyophilous syndrome, having large, glistening parts that emit an intense scent of rotten meat. The secretory activity was described in the hypochile (nectary in longitudinal groove and in the prickles) and the epichile (putative osmophore). The ultrastructural studies revealed a dense cytoplasm in the epidermis and subepidermal tissue with large nuclei and numerous mitochondria, the profiles of SER and RER, and dictyosomes. Large amounts of heterogeneous residues of secreted material (possibly phenolic) were present on the cuticle surface, similar to the unusual prominent periplasmic space with flocculent secretory material. The chemical analysis (GC/MS) of the scent profile of lips comprised carbohydrates and their derivatives (29.55% of all compounds), amino acids (1.66%), lipids (8.04%) and other organic compounds (60.73%). A great number of identified compounds are Diptera attractants (mainly Milichiidae, Tephritidae, Drosophilidae, Muscidae, Sarcophagidae, Tachinidae). The examination of visual and olfactory features indicates correlation between colour of flowers and the type of olfactory mimicry, where a dark colour labellum emits strong smell of rotten waste.

Toxicological Evaluation of the Aqueous Extract of Caralluma europaea and Its Immunomodulatory and Inflammatory Activities

Background:

Caralluma europaea (CE) has been studied for its chemical constituents, and no information is available on its toxicity or its pharmacological activities.

Objective:

To determine the toxicity of an aqueous extract of CE stems in vitro and in vivo after acute and subchronic oral gavages in Swiss albino's mice and its immunomodulatory and inflammatory activities.

Materials and Methods:

The extract was administrated in single oral dose at 5 g/kg body weight for the acute toxicity test and by gavages daily at doses of 1, 2.5, or 5 g/kg for 30 consecutive days for the subchronic toxicity test. The immunomodulatory activities and inflammatory activities were tested by the evaluation of hemagglutination antibodies (HAs) titers and delayed-type hypersensitivity (DTH) response.

Results:

For the dose of 1 g/kg, no visible toxic effects were observed. However, for the higher doses, clinical observations of toxicity were noted after 1 week of treatment. This was confirmed by the biochemical parameters values and the histology analyses of the spleen, liver, and kidney tissues. The high cellular mortality rate in vitro when treated with CE extract confirmed their toxicity potential. There was also increase of “HA titer” and “DTH” response in mice treated with nontoxic dose of CE (1 g/kg) compared to control group. This immune activity was confirmed by the high number of lymphocytes infiltrates noted in the different organs.

Conclusion:

We conclude that CE at the dose up of 1 g/kg produced toxic effect in mice that induced an immune inflammatory reaction.

SUMMARY

Caralluma europaea (CE) has been studied for its chemical constituents, and no information is available on its toxicity or its pharmacological activities. The objective is to determine the toxicity of an aqueous extract of CE stems in vitro and in vivo after acute and subchronic oral gavages in Swiss albino's mice and its immunomodulatory and inflammatory activities. For the dose of 1 g/kg, no visible toxic effects were observed. However, for the higher doses, clinical observations of toxicity were noted after 1 week of treatment. This was confirmed by the biochemical parameters values and the histology analyses of the spleen, liver, and kidney tissues. The high cellular mortality rate in vitro confirmed their toxicity potential. There was also increase of “hemagglutination antibody titer” and “delayed-type hypersensitivity” response in mice treated with nontoxic dose of CE (1 g/kg) compared to control group. This immune activity was confirmed by the high number of lymphocytes infiltrates noted in the different organs. We conclude that CE at the dose up of 1 g/kg produced toxic effect in mice that induced an immune inflammatory reaction.

Abbreviations Used: CE: Caralluma europaea, ALT: Alanine aminotransferase, AST: Aspartate aminotransferase, RRBCs: Rat red blood cells, DTH: Delayed-type hypersensitivity response, PBS: Phosphate buffer solution.

Olfactory attraction of the hornet Vespa velutina to honeybee colony odors and pheromones

Since the beginning of the last century, the number of biological invasions has continuously increased worldwide. Due to their environmental and economical consequences, invasive species are now a major concern. Social wasps are particularly efficient invaders because of their distinctive biology and behavior. Among them, the yellow-legged hornet, Vespa velutina, is a keen hunter of domestic honeybees. Its recent introduction to Europe may induce important beekeeping, pollination, and biodiversity problems. Hornets use olfactory cues for the long-range detection of food sources, in this case the location of honeybee colonies, but the exact nature of these cues remains unknown. Here, we studied the orientation behavior of V. velutina workers towards a range of hive products and protein sources, as well as towards prominent chemical substances emitted by these food sources. In a multiple choice test performed under controlled laboratory conditions, we found that hornets are strongly attracted to the odor of some hive products, especially pollen and honey. When testing specific compounds, the honeybee aggregation pheromone, geraniol, proved highly attractive. Pheromones produced by honeybee larvae or by the queen were also of interest to hornet workers, albeit to a lesser extent. Our results indicate that V. velutina workers are selectively attracted towards olfactory cues from hives (stored food, brood, and queen), which may signal a high prey density. This study opens new perspectives for understanding hornets’ hunting behavior and paves the way for developing efficient trapping strategies against this invasive species.

A review on ethnobotany, phytochemistry and pharmacology of plant genus C aralluma R. Br

Objectives

C aralluma is a xerophytic genus used as traditional medicine for the treatment of diabetes, inflammation, leprosy, obesity and rheumatism. Objectives of this review are to establish a relationship between traditional uses and scientific studies by critically evaluating the available fragmented literature on ethnobotany, pharmacology, phytochemistry and toxicology of genus Caralluma.

Key findings

Ethnomedical uses of Caralluma have been recorded from various countries such as China, India, Iran and Pakistan for six major classes of diseases including diabetes and gastrointestinal disorders. This review indicated the efficacy of genus Caralluma in several in vitro and in vivo pharmacological properties such as antimicrobial, antioxidant and anticancer activity. These bioactivity might be due to the presence of certain classes of compounds in genus Caralluma including pregnane glycosides, flavonoid glycosides and flavones.

Summary

Traditional uses and scientific evaluation of Caralluma indicates that it is one of the most widely used genus in some parts of the world. Further studies on the structural activity relationship of some of the isolated compound may improve their biological potency as well as scientific exploitation of traditional uses of the genus.

Essential oil composition of stems and fruits of Caralluma europaea N.E.Br. (Apocynaceae)

The essential oil of the stems and fruits of Caralluma europaea (Guss.) N.E.Br. (Apocynaceae) from Lampedusa Island has been obtained by hydrodistillation and its composition analyzed. The analyses allowed the identification and quantification of 74 volatile compounds, of which 16 were aromatic and 58 non-aromatic. Stems and fruits contained 1.4% and 2.7% of aromatic compounds respectively, while non-aromatic were 88.3% and 88.8%. Non-aromatic hydrocarbons were the most abundant compounds in both organs, followed by fatty acids. Data showed differences in the profiles between stems and fruits which shared only eighteen compounds; stems accounted for 38 compounds while fruits for 53. Fruits showed a higher diversity especially in aromatic compounds with twelve versus four in stems. Among the volatiles identified in stems and fruits of C. europaea 26 are present in other taxa of Apocynaceae, 52 are semiochemicals for many insects, and 21 have antimicrobial activity. The possible ecological role of the volatiles found is briefly discussed.