Separation of Enantiomeric Irones by Gas-Liquid Chromatography on Modified Cyclodextrins

Natural irones found in the essential oil of Iris rhizomes often are mixtures of enantiomers. The separation of all optical isomers of the irones by GLC on modified cyclodextrins and the determination of their composition within different Iris oils is described. The significance for the biosynthesis of the cycloiridals, C₃₁-triterpenoids, which serve as precursors of the irones, is discussed.     

Die absolute Konfiguration der Iridale und Cycloiridale unterschiedlicher Herkunft

The Absolute Configuration of Iridals and Cycloiridals of Different Origin Natural irones are known to occur in enantiomeric forms within Iris oils of different origin. They are formed by oxidative degradation of the cycloiridals (C₃₁-triterpenoids) found in rhizomes of various Iris species. The absolute configuration of iridals from different varieties is determined by ozonolysis of the triterpenoids and comparison of their degradation products with authentic samples of known configuration. It is shown that the initial cyclization of squalene resulting in the formation of a monocyclic seco-ring-A iridal has the same stereo-chemical course throughout all Iris species studied. The subsequent cyclization of the homofarnesyl side chain of the iridals, however, produces cycloiridals with enantiomeric irone moieties within different subspecies of the sword lilies.     

Phenolic Compounds and Bioactive Properties of Ruscus aculeatus L. (Asparagaceae): The Pharmacological Potential of an Underexploited Subshrub

Ruscus aculeatus L. is a subshrub used in traditional medicine in different parts of the world, namely in Europe and the Iberian Peninsula. According to reported folk knowledge, the aerial parts are mainly used as diuretics and the underground organs are used for the treatment of disorders of the urinary system and as a laxative. In this work, the aerial part and the roots and rhizomes of R. aculeatus were chemically characterized with regard to the content of phenolic compounds and bioactive properties. Aqueous (infusions and decoctions) preparations and hydroethanolic extracts from the two mentioned parts of the plant were prepared. Nine phenolic compounds were detected in all the extracts. Apigenin-C-hexoside-C-pentoside isomer II was the major compound in aqueous extracts and, in the hydroethanolic extract was quercetin-O-deoxyhexoside-hexoside followed by apigenin-C-hexoside-C-pentoside isomer II. All extracts revealed antioxidant activity and potential to inhibit some of the assayed bacteria; aqueous extracts of the aerial part and infusions of roots and rhizomes did not show cytotoxic effects on a non-tumor primary cell culture. This preliminary study provides suggestions of the biological potential associated with the empirical uses and knowledge of this species, in particular its bioactivities.     

Isoflavonoid Glycosides from the Rhizomes of Iris germanica

Five new di‐ and triglycosides, irigenin 7‐[O‐β‐D ‐glucopyranosyl‐(1→6)‐β‐D ‐glucopyranoside] ( 1 ), 6‐hydroxygenistein 4′‐[O‐β‐D ‐glucopyranosyl‐(1→6)‐β‐D ‐glucopyranoside] ( 2 ), nigricin 4′‐[O‐β‐D ‐glucopyanosyl‐(1→6)‐β‐D ‐glucopyranoside] ( 3 ), nigricin 4′‐[O‐β‐D ‐glucopyanosyl‐(1→2)‐O‐[α‐L ‐rhamnopyranosyl‐(1→6)]‐β‐D ‐glucopyranoside] ( 4 ), and 7‐{4′‐{[2″‐O‐(4′′′′‐acetyl‐2′′′′‐methoxyphenyl)‐β‐D ‐glucopyranosyl]oxy}‐3′‐(β‐D ‐glucopyranosyloxy)phenyl]‐9‐methoxy‐8H‐1,3‐dioxolo[4,5‐g]‐[1 benzopyran‐8‐one‐] ( 5 ), along with a known compound, nigricin 4′‐(β‐D ‐glucopyranoside) ( 6 ), were isolated from the rhizomes of Iris germanica. The structures of these compounds were established by spectroscopic methods, including 2D NMR spectroscopic techniques.     

Metabolite Profiling of In Vitro Cultured and Field Grown Rhizomes of Acorus calamus from Mongolia Using GC–MS

Acorus calamus (sweet flag) is used in the traditional Chinese and Indian medicines for various ailments. Due to its extensive use in herbal medicine, natural resources from the world’s forests are being depleted at an alarming rate. In the present study, an in vitro cell culture technique is being explored as an alternative to field grown A. calamus with respect to the metabolite profile, antioxidant properties, total phenol, and total flavonoid content. Gas chromatography mass spectrometry (GC–MS) was utilized to compare the metabolite profiling between methanolic extracts of in vitro and field grown rhizome tissues of A. calamus. A statistical analysis indicated an upregulation of α-selinene, which is representative of sesquiterpene ketones, and a cyclic polyol, d-pinitol, which has an insulin mimicking effect in the in vitro cultivated rhizome tissue when compared to field grown rhizomes. Significantly higher free-radical scavenging activity (IC₅₀ 69.32 μg mL⁻¹), total phenolic content (71.60 mg GAE g⁻¹), and total flavonoid content (42.34 mg CE g⁻¹) were observed in in vitro rhizome tissues compared with those from field grown rhizomes. These observations suggest that the in vitro cultivation of Acorus rhizomes could be exploited as an alternative to field grown A. calamus, as it is an endangered medicinal plant. The production of useful metabolites by the in vitro cultured rhizomes can be explored successfully for utilization by various food and drug industries.

     

On the Stereochemistry of Natural Irones,Dihydroirones, and their Precursors

Natural irones from the essential oil of Iris rhizomes develop by oxidative degradation of C₃₁-triterpenoids produced by the plant. Two enantiomeric forms of irones are found in Iris, oils of different origin. The optical properties and CD spectra of irones, dihydroirones and their C₃₁-precursors are reported and their absolute stereochemistry is determined.     

Bioactive compounds and antioxidant capacity of Chuquiraga jussieui J.F.Gmel from the highlands of Ecuador

Abstract

Chuquiraga jussieui J.F.Gmel is grown between 3000 and 5000 meters above sea level throughout the Andean region of Ecuador and used by the indigenous populations of the Andes for medicinal purposes. Here, we determined the total phenolic, flavonoids, vitamin C and carotenoids content of the leaves and flowers of Ch. jussieui J.F.Gmel from different highlands of Ecuador as well as the capacity of a crude methanolic extract from the both parts of the plant to scavenge free radicals and protect red blood cell membranes from lipid oxidation. The leaves showed a high bioactive compound content in comparison to the flowers. The crude extract from the leaves proved to be more effective than the flowers in reducing iron and scavenging the DPPH, O₂^? and H₂O₂ radicals, as well as in protecting cellular membrane against lipid oxidation, demonstrating that Ch. jussieui J.F.Gmel represents an important source of bioactive compounds with relevant healthy properties.     

Metabolic Profiling of Zingiber zerumbet Following Pythium myriotylum Infection: Investigations on the Defensive Role of the Principal Secondary Metabolite,Zerumbone

Induced biosynthesis of bioactive secondary metabolites constitutes one of the mechanisms of plant basal innate immunity to fungal infection. Metabolic changes were studied in rhizomes of Zingiber zerumbet, a wild congener of ginger, after infection with soft rot-causative necrotrophic phytopathogen, Pythium myriotylum, by gas chromatography-mass spectrometry (GC-MS) analysis. Infection triggered a considerable alteration in the relative content of zerumbone and α-caryophyllene (humulene) with enhancement in zerumbone content (81.59 %) and that of α-caryophyllene (11.91 %) compared to 9.97 and 1.11 %, respectively, in uninfected rhizomes. While zerumbone is the principal secondary metabolite in Z. zerumbet, α-caryophyllene is its immediate precursor. Principal component analysis (PCA) identified the correlations between metabolite changes in Z. zerumbet rhizomes and P. myriotylum infection. Radial diffusion assay with zerumbone indicated a concentration-dependent P. myriotylum growth inhibition with 93.75 % inhibition observed at 700 μg and 50 % maximal effective concentration (EC₅₀) value of 206 μg. Scanning electron microscopy (SEM) analysis revealed that the mechanistic basis of zerumbone’s antagonistic action on P. myriotylum growth involved the induction of aberrant morphology including severe hyphal deformities and membrane disruption. Results are discussed highlighting the critical role played by sesquiterpenoid zerumbone in affording resistance in Z. zerumbet and could expedite the development of appropriate strategies for biocontrol of Pythium spp., thus reducing the usage of broad-spectrum fungicides.     

Phytochemistry and Biological Activities of Iris Species Growing in Iraqi Kurdistan and Phenolic Constituents of the Traditional Plant Iris postii

A dozen Iris species (Iridaceae) are considered traditional remedies in Kurdistan, especially for treating inflammations. Phytochemical studies are still scarce. The information reported in the literature about Iris species growing in Kurdistan has been summarized in the first part of this paper, although, except for Iris persica, investigations have been performed on vegetal samples collected in countries different from Kurdistan. In the second part of the work, we have investigated, for the first time, the contents of the methanolic extracts of Iris postii aerial parts and rhizomes that were collected in Kurdistan. Both extracts exhibited a significant dose-dependent free radical scavenging and total antioxidant activities, comparable to those of ascorbic acid. Medium-pressure liquid chromatographic separations of the two extracts afforded l-tryptophan, androsin, isovitexin, swertisin, and 2″-O-α-l-rhamnopyranosyl swertisin from the aerial parts, whereas ε-viniferin, trans-resveratrol 3,4′-O-di-β-d-glucopyranoside, and isotectorigenin were isolated from the rhizomes. This is the first finding of the last three metabolites from an Iris species. The various remarkable biological activities of isolated compounds scientifically sustain the traditional use of I. postii as a medicinal plant.     

Hoogianal,a β‐Irone Precursor from Iris hoogiana Dykes (Iridaceae)

Fractionation of the lipid extract from rhizomes of Iris hoogiana Dykes resulted in the isolation of one new and several known iridals. The latter were identified by comparison with authentic standards as 1 – 5 . The structure of the new natural product, hoogianal ( 11 ), was elucidated by spectroscopic analysis. Oxidative degradation yielded β‐irone ( 10 ), identified by GC‐ and LC‐MS. The (−)‐(2S)‐configuration of this oxidation product was determined by enantioselective GC on a chiral cyclodextrin phase and by comparison with the corresponding ketones in laevo‐ and dextrorotatory commercial Iris oils.     

Spatial and Temporal Bioactive Compound Contents and Chlorophyll Fluorescence of Kale (Brassica oleracea L.) Under UV-B Exposure Near Harvest Time in Controlled Environments

UV-B irradiation has been used to enhance the secondary metabolite content in plants, but its spatial effect on plants has not been considered. The objective of this study was to compare spatial photosynthetic traits and bioactive compound accumulation in kale (Brassica oleracea L. var Acephala) according to the distribution and length of UV-B exposure near harvest. Plants were exposed to UV-B of 0–3, 3–6 and 6–9 W m⁻² for 4 h per day at 5 days (Exp. 1) and 4.2 W m⁻² at 5, 4, 3, 2 or 1 days (Exp. 2) before harvest. In spatial distribution, the higher the UV-B intensity, the lower the mean F_v/F_m (maximal photochemical efficiency of PSII) and the higher the concentration of total flavonoid compound (TFC). With UV-B stress, F_v/F_m and fluorescence transient parameters decreased except for DI₀/CS (dissipated energy flux per cross section) and PI_abs (performance index of PSII). When exposed to UV-B radiation for 2 days before harvest, the total phenolic compounds and TFC per plant were highest, not always proportional to the local F_v/F_m but affected by dry weight. Short-term UV-B stress near harvest would be more efficient for the accumulation of bioactive compounds by minimizing the loss of plant weight.     

Assessment of the bioactive compounds,antioxidant and antibacterial activities of Isodon rubescens as affected by drying methods

The influence of natural drying (ND), hot-air drying (HD), vacuum drying (VD), infrared drying (ID) and freeze drying (FD) on bioactive compounds and bioactivities of Isodon rubescens (Hemsl.) was investigated in this study. The results showed that different drying methods resulted in the differences in bioactive compositions’ content, antioxidant and antibacterial activities of extracts from I. rubescens. FD sample possessed the highest content of total phenolics, total flavonoids and several main phenolic compounds, as well as the stronger antioxidant and antibacterial activities, followed by ND, HD and VD, the lowest for ID samples. For this reason, freeze drying would seem to be more advisable for the drying I. rubescens, and future studies could focus on the quality evaluation and optimising various drying parameters.     

In vitro antioxidant and antiproliferative activities of six international basil cultivars

The total phenolic, flavonoid and tannin contents in leaves extracts of Ocimum basilicum (OB) (Lamiaceae) international cultivars, as well as their overall antioxidant activities using DPPH and linoleic acid assays, were investigated. Furthermore, the antiproliferative and cytotoxic activities against line HeLa, MCF-7, Jurkat, HT-29, T24, MIAPaCa-2 cancer cells and one normal human cell line HEK-293 were examined. DPPH and linoleic acid assays ranged from 75.8% to 93.3% and from 74.5% to 97.1%; respectively. O. b. ‘purple ruffle’, O. b. ‘dark opale’, O. b. ‘genovese’, O. b. ‘anise’, O. b. ‘bush green’ and O. b. L. (OBL) varied in their antiproliferative and cytotoxic activities, influenced cell cycle progression and stimulated apoptosis in most cancer cells. OBL exhibited the highest antioxidant and antiproliferative activities. OB extracts not only improve taste but also have certain anticancer activity against diverse cancer cells due to the presence of compounds such as rosmarinic acid, chicoric acid and caftaric acid. Thus, OB represents a potent source of anticancer materials.     

Preparation and quantification of the total phenolic products in Citrus fruit using solid‐phase extraction coupled with high‐performance liquid chromatography with diode array and UV detection

Citrus fruit is an important health‐promoting food that is rich in dietary phenolic metabolites. Traditional Chinese medicines, such as Zhishi and Zhiqiao, come from young and immature fruits of Citrus cultivars. The preparation of diversified bioactive phenolic products and establishment of the corresponding quality control methodology are challenging and necessary. In the current study, four types of solid‐phase extraction sorbents for the enrichment and clean‐up of the phenolic matrix were evaluated. A solid‐phase extraction column coated with Strata‐X was finally used in the procedure. Twenty phenolic compounds were selected to evaluate the extraction performances of the sorbents using high‐performance liquid chromatography analysis. Under the optimized conditions, good linearities were obtained with R² more than 0.9996 for all analytes with LODs of 0.04–1.012 μg/g. Intra‐ and interday relative standard deviation values were less than 3%, and the recovery was equal to or higher than 90.02%. Compared to non‐solid‐phase extraction process, the content of total phenolic products was elevated 35.55–68.48% with solid‐phase extraction. Finally, the developed and validated method was successfully applied to the discrimination of Zhishi samples from different species as well as Zhishi and Zhiqiao samples in different development stages.     

Simultaneous determination of pyrroquinazoline alkaloids and flavonoids in Adhatoda beddomei and Adhatoda vasica and their marketed herbal formulations using ultra‐high‐performance liquid chromatography coupled with triple quadrupole linear ion trap mass spectrometry

Adhatoda beddomei and Adhatoda vasica leaf, known as ‘Vasaka ’ and/or ‘Vasa ’ in Ayurveda and ‘Malabar nut’ in English, is an official drug in the Indian Pharmacopoeia . The medicinal properties of these plants are due to the presence of pyrroquinazoline alkaloids. An UHPLC–ESI/MS/MS method in both positive and negative electrospray ionization in multiple‐reaction‐monitoring mode was developed and validated for the estimation of alkaloids and flavonoids in Adhatoda species and their marketed herbal formulations. Chromatographic separation was achieved on an Acquity UPLC® BEH C₁₈‐column using a gradient elution with 0.1% formic acid in water and methanol. The developed method was validated as per International Conference on Harmonization guidelines and found to be accurate with overall recovery in the range 94.2–105.0% (RSD ≤ 1.71%), precise (RSD ≤ 3.44%) and linear (R ² ≥ 0.9992) over the concentration range of 0.5–1000 ng/mL. The total content of alkaloids and flavonoids were highest in the chloroform and aqueous fraction of A. vasica leaf, respectively. The results indicated that the developed method was simple, rapid, sensitive, selective and accurate for the estimation of multiple bioactive constituents in crude mixture, and therefore could make a contribution to the quality control of Adhatoda species and its derived herbal formulations.     

Microwave‐assisted extraction and rapid isolation of ursolic acid from the leaves of Eucalyptus × hybrida Maiden and its quantification using HPLC‐diode array technique

Ursolic acid (UA) is the most important bioactive phytoconstituent of Eucalyptus × hybrida Maiden leaves and exhibits anticancer, antimutagenic, anti‐inflammatory, antioxidative, and antiprotozoal activities. In this study, microwave‐assisted extraction technique was employed for rapid isolation of UA from the leaves of Eucalyptus × hybrida and simultaneously HPLC‐diode array method was developed for the quantification of UA. Effects of several experimental parameters on the extraction efficiencies of UA, such as type and volume of extraction solvents, microwave power and extraction time, were evaluated. The optimal extraction conditions were found to be 20 mL of a mixture of chloroform/methanol, 60:40; liquid‐to‐material ratio, 4:1; preleaching time, 10 min; microwave power, 600 W; temperature, 50°C; and microwave irradiation time, 5 min. Under the optimum conditions, the yield of UA was found to be 1.95 ± 0.08% in the dry leaves of Eucalyptus × hybrida. The results showed that microwave‐assisted extraction is a more rapid extraction method with higher yield and lower solvent consumptions than the conventional method. It is a faster, convenient, and appropriate method and it may be used for rapid isolation and quantification of UA and other important phytoconstituents present in the leaves of Eucalyptus × hybrida.     

Chemical Composition of Hydrilla Verticillata （L. f.） Royle in Taihu Lake

Hydrilla verticillata （Linn. f.） Royle is a submerged plant for phytoremediation on Taihu Lake, China. The planted submerged plant should be harvested in every autumn to reduce the nutrition burden of the lake. Five compounds were firstly isolated by column chromatography and purified from the extractions of Hydrilla verticillata （Linn. f.） Royle. 1-（5＇-Hydroxy-4＇-hydroxymethyl-1＇-methyl-1H-pyrrol-2＇-yl）-henicosa-2,12,15-trien-1-one （2） and thymidine （3） were identified by EIMS, 1H NMR, laC NMR and IR spectra. Crystal loliolide （1） and sulfur-gamma （4） were identified by X-ray diffraction. Octadecanedioic acid （5） was also elucidated. Among them, compound 2 is a new natural compound, loliolide （1） and thymidine （3） are known bioactive substances. The results provided basic research data for exploring their application as medical materials.     

A New Oligostilbenoid from Rhizomes of Curculigo Sinensis

Curcusinol ( 1 ), a new resveratrol trimer, was isolated and identified from the rhizomes of Curculigo sinensis (Hypoxidaceae), together with five known phenolic compounds: curcapital ( 2 ), pilosidine ( 3 ), crassifoside A ( 4 ), curculigoside I ( 5 ) and phegopolin ( 6 ). The new compound 1 was determined as an oligostilbenoid on the basis of various spectroscopic methods, especially intensive 2D‐NMR (COSY, HMQC, HMBC and NOESY) techniques.     

Separation and identification of bioactive compounds in Anabasis articulata (Forsk) Moq. roots

In the present paper, for the first time, we are interested to separate and identify some bioactive fractions isolated from the roots of a Saharan plant Anabasis articulata, which is widely used in traditional medicine against cancer. The crude methanolic extract of the roots was fractionated on column chromatography, and eluted with dichloromethane/methanol each time with increasing polarity of methanol; 17 fractions were separated. One of these fractions named F12 showed more antioxidant activity to scavenge DPPH free radical with percentage inhibition of 95.29%. F12 was separated by thin-layer chromatography (TLC) to give 12 compounds. A second preparative TLC of compound 2, which has antioxidative activity of 74.92%, provided the three phenolic acids M1, M2 and M3, analysed by high-performance liquid chromatography and UV–visible spectrophotometry.