Sesquiterpenes from lippia integrifolia essential Oil

Mechanistic characterisation of a sesquiterpene synthase for asterisca-1,6-diene from the liverwort Radula lindenbergiana and implications for pentalenene biosynthesis

A sesquiterpene synthase from the liverwort Radula lindenbergiana was characterised and shown to produce the new sesquiterpene hydrocarbon (3R,9R)-asterisca-1,6-diene, besides small amounts of pentalenene. The biosynthesis of asterisca-1,6-diene was studied through isotopic labelling experiments, giving additional insights into the long discussed biosynthesis of pentalenene.

Bicyclo [6.3.0] Undecane Sesquiterpenoids: Structures, Biological Activities, and Syntheses

Sesquiterpenoids constitute a marvelously varied group of natural products that feature a vast array of molecular architectures. Among them, the unusual bicyclo [6.3.0] undecane sesquiterpenoids are one of the most representative. To date, only approximately 42 naturally occurring compounds with this unique scaffold, which can be classified into seven different groups, have been reported. As the first-found member of each type, dactylol, asteriscanolide, dumortenol, toxicodenane C, and capillosanane S are characteristic of the four methyl groups on the five-eight-membered ring system. Only 11-hydroxyjasionone and sinuketal decorate the core with an isopropyl group. These natural products exhibit a wide range of bioactivities, including antifouling, anti-inflammatory, immune suppression, cytotoxic, antimutagenic, antiplasmodial, and antiviral activities. It was noted that some total syntheses of precapnellane-sesquiterpenoids (dactylol, poitediol, precapnelladiene), asteriscanolide, and 11-hydroxyjasionone have been achieved, because their cyclooctanoid core represents an important target for the development of synthetic strategies to prepare eight-membered ring-containing compounds. This review focuses on these natural sesquiterpenoids and their biological activities and synthesis, and aims to provide a foundation for further research of these interesting compounds.

Isoafricanol synthase from Streptomyces malaysiensis

A terpene cyclases from Streptomyces malaysiensis was characterised as (+)-isoafricanol synthase and its mechanism was investigated using isotopically labelled substrates.

Pristinol, a Sesquiterpene Alcohol with an Unusual Skeleton from Streptomyces pristinaespiralis

A terpene cyclase from Streptomyces pristinaespiralis was characterized as the synthase for (+)-(2S,3S,9R)-pristinol. The structure of this sesquiterpene alcohol, which has a new carbon skeleton, was established by NMR spectroscopy and single-wavelength anomalous-dispersion X-ray crystallography. Extensive isotopic labelling experiments were performed to distinguish between various possible cyclization mechanisms of the terpene cyclase and to decipher the EI-MS fragmentation mechanism for pristinol.

Intraspecific variation in essential oil composition of the medicinal plant Lippia integrifolia (Verbenaceae). Evidence for five chemotypes

The aerial parts of Lippia integrifolia (incayuyo) are widely used in northwestern and central Argentina for their medicinal and aromatic properties. The essential oil composition of thirty-one wild populations of L. integrifolia covering most of its natural range was analyzed by GC and GC-MS. A total of one hundred and fifty two terpenoids were identified in the essential oils. Sesquiterpenoids were the dominant components in all but one of the collections analyzed, the only exception being a sample collected in San Juan province where monoterpenoids amounted to 51%. Five clearly defined chemotypes were observed. One possessed an exquisite and delicate sweet aroma with trans-davanone as dominant component (usually above 80%). Another with an exotic floral odour was rich in oxygenated sesquiterpenoids based on the rare lippifoliane and africanane skeletons. The trans-davanone chemotype is the first report of an essential oil containing that sesquiterpene ketone as the main constituent. The absolute configuration of trans-davanone from L. integrifolia was established as 6S, 7S, 10S, the enantiomer of trans-davanone from 'davana oil' (Artemisia pallens). Wild plants belonging to trans-davanone and lippifolienone chemotypes were propagated and cultivated in the same parcel of land in Santa Maria, Catamarca. The essential oil compositions of the cultivated plants were essentially identical to the original plants in the wild, indicating that the essential oil composition is largely under genetic control. Specimens collected near the Bolivian border that initially were identified as L. boliviana Rusby yielded an essential oil practically identical to the trans-davanone chemotype of L. integrifolia supporting the recent view that L. integrifolia (Gris.) Hieron. and L. boliviana Rusby are synonymous.

Gastroprotection as an example: antiadhesion against Helicobacter pylori, anti-inflammatory and antioxidant activities of aqueous extracts from the aerial parts of Lippia integrifolia Hieron

ETHNOPHARMACOLOGICAL RELEVANCE

The aerial parts of Lippia integrifolia (Gris.) Hieronymus (Verbenaceae), known as incayuyo, are used by the peasant population of Argentina for treatment of diseases related to a gastrointestinal system, mainly for inflammation of the stomach and have also been included into the Argentina Food Code. This study aimed to investigate the phytochemical profile of hydrophilic extracts from the herbal material by LC-MS and to evaluate potential pharmacological mechanisms rationalizing the traditional use of incayuyo aqueous extracts potential anti-inflammatory treatment of gastrointestinal disorders.

MATERIALS AND METHODS

Phytochemical profiling: LC-MS of an aqueous decoction. Antiadhesive effects against Helicobacter pylori: in vitro FACS assay using FITC-labeled bacteria and AGS human stomach cells. Influence of extracts on stomach cells and RAW 264.7 macrophages: MTT viability assay and BrdU proliferation ELISA. Influence of extracts on IL-6 and IL-8 secretion from stomach cells was quantitated by ELISA after infection of the cells with Helicobacter pylori. Influence of test extracts on macrophages: phagocytosis of FITC-labeled Zymosan particles and NO production. Antioxidative capacity: DPPH assay and O2-induced caroten oxidation.

RESULTS

LC-MS profiling indicated the presence of compounds 1-20 with flavonoid hexosides, phenylethanoides (acteoside, isoacteoside) and sesquiterpenes [(epi)lippidulcine, peroxylippidulcine] in the decoction extract and subfraction PhF. The extract exhibits strong in vitro antioxidative capacity and inhibited adhesion of Helicobacter pylori to stomach cells up to 40%, while an EtOH-soluble fraction showed inhibition rates of up to 60%. Decoction increased the cellular viability of AGS cells significantly at >10 μg/mL, while proliferation rate was not influenced. Helicobacter pylori induced IL-8 secretion was significantly reduced by coincubation of AGS cells with the extracts. Aqueous extracts stimulated phagocytosis rate of macrophages and inhibited the LPS-induced NO-secretion.

CONCLUSIONS

The traditional use of aqueous extracts from Lippia integrifolia for gastric inflammation seems to be rationalized: besides anti-inflammatory effects on stomach cells antiadhesive properties of the extracts against the main bacterial inductor of gastritis Helicobacter pylori were identified. Additional effects for stimulation of innate immunity and potential radical scavenging effects may additionally contribute to the activity of the extracts.

Asteriscane-type sesquiterpenoids from the soft coral Sinularia capillosa

Chemical examination of the soft coral Sinularia capillosa collected from the South China Sea resulted in the isolation of 14 new asteriscane-type sesquiterpenoids, namely, capillosananes A-N (1-14), four new seco-asteriscanes, capillosananes O-R (15-18), and (-)-sinularone A and sinularone A. Their structures were determined on the basis of extensive spectroscopic analyses, while the absolute configurations were determined by CD and ECD calculation, Mosher's method, and chemical conversion. This is the first report of asteriscane-type sesquiterpenoids from soft corals, and capillosananes Q (17) and R (18) represent new seco-asteriscane skeletons. Capillosanane A exhibited potent antifouling activity against Balanus amphitrite, with an IC₅₀ value of 9.70 μM, while capillosananes B and I and (-)-sinularone A inhibited inflammation-related TNF-α in vitro.

Effect of isotopically sensitive branching on product distribution for pentalenene synthase: support for a mechanism predicted by quantum chemistry

Mechanistic proposals for the carbocation cascade reaction leading to the tricyclic sesquiterpene pentalenene are assessed in light of the results of isotopically sensitive branching experiments with the H309A mutant of pentalenene synthase. These experimental results support a mechanism for pentalenene formation involving a 7-protoilludyl cation whose intermediacy was first predicted using quantum-chemical calculations.

Evaluation of the analgesic and anti-inflammatory effects of the essential oil of Lippia gracilis leaves

AIM OF THE STUDY

The aim of the present study is to investigate the antinociceptive, anti-inflammatory, and antioxidant activities of essential oil (EO) of Lippia gracilis Schauer (Verbenaceae) leaves to support the medicinal uses claimed by folklore practitioners in the caatinga region (semi-arid) of Northeastern Brazil.

MATERIALS AND METHODS

The chemical composition and antinociceptive and anti-inflammatory activities of the EO of Lippia gracilis leaves (50-200 mg/kg) were investigated. Antinociceptive activity of the EO was evaluated by writhing test. Anti-inflammatory activity of the EO was evaluated using paw oedema and peritonitis methods.

RESULTS

Oral treatment with the EO of Lippia gracilis leaves elicited inhibitory activity on acetic acid effect at 50, 100, and 200 mg/kg (30.33+/-2.36, 25.20+/-1.48, and 21.00+/-1.54 abdominal writhes, respectively, P<0.05), as compared with the control group (36.73+/-1.92 writhes). The compound acetylsalicylic acid (ASA, 300 mg/kg) inhibited the acetic acid-induced writhing (12.67+/-0.50 abdominal writhes, P<0.001). Carrageenan-induced oedema formation was reduced with the EO of Lippia gracilis leaves at 200 mg/kg (0.72+/-0.06 mL h, P<0.001) and by the reference compound ASA (300 mg/kg, 0.85+/-0.04 mL h, P<0.001), as compared with the control group (1.76+/-0.06 mL h). Leukocyte migration into the peritoneal cavity induced by carrageenan was reduced with the EO of Lippia gracilis leaves at 50, 100, and 200 mg/kg (13.81+/-0.61, 11.77+/-0.91, and 10.30+/-0.60 leukocytes x 10(6)/mL, respectively, P<0.01), and by the compound dexamethasone (2 mg/kg, 5.34+/-0.33 leukocytes x 10(6)/mL, P<0.001), as compared with the control group (16.71+/-0.54 leukocytes x 10(6)/mL). The analyses of the essential oil allowed the identification of Lippia gracilis as a thymol-p-cymene chemotype (32.68% and 17.82%, respectively).

CONCLUSIONS

The EO of Lippia gracilis leaves shows antinociceptive and anti-inflammatory activities.

Vibrational circular dichroism of Africanane and lippifoliane sesquiterpenes from Lippia integrifolia

The agreement between theoretical and experimental vibrational circular dichroism curves of (4R,9R,10R)-(+)-african-1(5)-ene-2,6-dione (1) and (4R,9S,10R)-lippifoli-1(6)-en-5-one (2), isolated from the widely used plant Lippia integrifolia, allowed the determination of the conformation and absolute configuration of 1 and confirmed both structural features for 2. Molecular modeling of 1 and 2 was carried out by means of a systematic and a Monte Carlo search protocol followed by geometry optimization employing density functional theory calculations with the B3LYP/6-31G(d), B3LYP/DGDZVP, and/or B3PW91/DGDZVP2 functionals/basis sets. Validation of the minimum energy conformations for both tricyclic substances was achieved by comparison of the experimental and theoretical vicinal (1)H-(1)H NMR coupling constants obtained by DFT-GIAO calculations.

Theoretical Studies on Farnesyl Cation Cyclization: Pathways to Pentalenene

In this article, we describe studies, using quantum chemical computations, on possible polycyclization pathways of the farnesyl cation leading to the complex sesquiterpene pentalenene. Two distinct pathways to pentalenene with similar activation barriers are described, each differing from previous mechanistic proposals, and each involving unusual and unexpected intermediates. Direct deprotonation of intermediates on these pathways leads to sesquiterpene byproducts, such as humulene, protoilludene, and asteriscadiene, supporting the notion that a key function of pentalenene synthase, the enzyme that produces pentalenene in Nature, is to regulate the timing and location of proton removal. The implications of the computational results for experimental studies on pentalenene synthase are discussed.

In vitro evaluation of trypanocidal activity in plants used in Argentine traditional medicine

Thirty-two organic and aqueous extracts, belonging to 12 Argentine medicinal plants were tested for their in vitro trypanocidal activity on epimastigote forms of Trypanosoma cruzi. Among the selected species, the organic extracts of Ambrosia scabra, Ambrosia tenuifolia, Baccharis spicata, Eupatorium buniifolium, Lippia integrifolia, Mulinum spinosum and Satureja parvifolia, and the aqueous extracts of E. buniifolium, L. integrifolia, M. spinosum and S. parvifolia showed trypanocidal activity with a percentage of growth inhibition higher than 70% at a concentration of 100 microg/ml.

In vitro antifungal assay of traditional Argentine medicinal plants

Methanol extracts from 11 traditionally used Argentine medicinal plants were assayed in vitro for antifungal activity against yeasts, hialohyphomycetes as well as dermatophytes with the microbroth dilution method. Among them, the strongest effect was presented by Eupatorium buniifolium and Terminalia triflora, Trichophyton mentagrophytes and Trichophyton rubrum being the most susceptible species with MICs ranging from 100 to 250 microg/ml. Lithrea molleoides showed the broadest spectrum of action inhibiting all of the tested dermatophytes with MIC=250 microg/ml.

Absolute configuration of lippifoliane and africanane derivatives

The absolute configuration of naturally occurring lippifoliane derivatives isolated from the widely used plant Lippia integrifolia was assigned by analysis of the circular dichroism data in combination with density functional theory minimum energy molecular models of (1S,4R,6S,9S,10R)-lippifolian-1-ol-5-one (1), (4R,9S,10R)-lippifoli-1(6)-en-5-one (2), and (4S,9S,10R)-lippifoli-1(6)-en-4-ol-5-one (3) and application of the octant rule for saturated ketone 1 and the helicity rules for alpha,beta-unsaturated ketones 2 and 3. The results were reinforced by the anomalous dispersion effect observed in the X-ray diffraction analysis of (4S,9S,10R)-4,10,11-tribromo-10,11-seco-lippifoli-1(6)-en-5-one (4) prepared from 2. The biogenetic relationships between lippifolianes 1-3 and africanane derivatives 7-9 and 13 isolated from the same species, together with chiroptical data for africananes isolated from the Hepaticae family, complete a stereochemical scenario in relation to the absolute configuration of africananes from L. integrifolia.

Seco-sethukarailin, a novel diterpenoid from the soft coral Sinularia dissecta

Seco-sethukarailin (1), a novel diterpenoid, has been isolated along with known sesquiterpenes Delta(9(15))africanene, beta-elemene, african-1-ene, 6R,7R-6,7-epoxycaryophyll-3(15)-ene, and known diterpenoids sethukarailin and isomandapamate, from the soft coral Sinularia dissecta collected from Mandapam Coast, South India. The structure of the novel diterpenoid seco-sethukarailin (1) was characterized by interpretation of spectral data.

Lippia: traditional uses, chemistry and pharmacology: a review

The chemical composition, pharmacological activity and traditional uses of 52 species attributed to the genus Lippia (Verbenaceae) as used in the South and Central America, and Tropical Africa, were revised and compared. A survey of the available literature shows that these species are used mostly for the treatment of gastrointestinal and respiratory disorders and as seasoning. Additionally, some of these Lippia species showed antimalarial, spasmolitic, sedative, hypotensive and, anti-inflammatory activities. Generally, the essential oil or the phenolic compounds (flavonoids) from these plant extracts are assumed to be the active principles.