Cysteine Sulfoxide Research Articles

Free Amino Acid and Cysteine Sulfoxide Composition of 11 Garlic (Allium sativum L.) Cultivars by Gas Chromatography with Flame Ionization and Mass Selective Detection

Two garlic subspecies (n = 11), Allium sativum L. var. opioscorodon (hardneck) and Allium sativum L. var. sativum (softneck), were evaluated for their free amino acid composition. The free amino acid content of garlic samples analyzed ranged from 1121.7 to 3106.1 mg/100 g of fresh weight (mean = 2130.7 +/- 681.5 mg/100 g). Hardneck garlic had greater methiin, alliin, and total free amino acids contents compared to softneck garlic. The major free amino acid present in all but one subspecies was glutamine (cv. Mother of Pearl had aspartic acid as the major free amino acid). Cv. Music Pink garlic (a rocambole hardneck variety) contained the most methiin, alliin, and total free amino acids. The solid-phase extraction, alkylchloroformate derivatization, GC-FID, and GC-MS methods used in this study were simple and rapid, allowing 18 free amino acids in garlic to be separated within 10 min.

Chemical Characterization of Allium ursinum L. Depending on Harvesting Time

Sulfur-containing compounds of ramson (Allium ursinum L.) are responsible for its traditional use in terms of culinary and medicinal purposes. Leaves and bulbs were investigated for their contents of cysteine sulfoxides (volatile precursors) as well as volatile compounds released from minced plant material. Plants were analyzed during the whole vegetation period, focused on the months from March to June. Additionally, within the dormancy period bulbs were analyzed again and alliinase activity was determined. The pattern of volatile compounds was analyzed both by SPME/GC-MS and by SDE/GC-MS. Compared to each other, SDE exhibited a wider spectrum of detectable volatile compounds. The quality and quantity of volatiles significantly depended on the time of harvest. The highest amounts of volatile precursors can be gained in March and April, shortly before flowering time (up to 0.4% of total cysteine sulfoxides). The main cysteine sulfoxides were alliin and isoalliin. It has been found that alliinase of A. ursinum exhibited properties similar to those of alliinase of garlic (Allium sativum L.), but differing in terms of substrate specificity.

Bioactive S‐Alk(en)yl Cysteine Sulfoxide Metabolites in the Genus Allium: The Chemistry of Potential Therapeutic Agents

AbstractFor Abstract see ChemInform Abstract in Full Text.

Purification and cloning of a γ-glutamyl transpeptidase from onion ( Allium cepa)

γ-Glutamyl transpeptidase (E.C. 2.3.2.2; GGT) catalyses hydrolysis of γ-glutamyl linkages in γ-glutamyl peptides and transfer of the γ-glutamyl group to amino acids and peptides. Although plant γ-glutamyl peptide metabolism is important in biosynthesis and metabolism of secondary products and xenobiotics, plant GGTs are poorly characterised. We purified a membrane-associated GGT from sprouting onion bulbs that catalyses transpeptidation of methionine by the synthetic substrate γ-glutamyl- p-nitroanilide (GGPNA) and obtained N-terminal peptide sequence. We also cloned the full-length coding region of an onion GGT by homology with the Arabidopsis enzyme and confirmed that this shared the same N-terminal sequence. Enzyme kinetic studies show that the enzyme has high affinity for glutathione and glutathione conjugates, and that affinity for S-substituted glutathione analogs decreases as the substituted chain length increases. The major onion γ-glutamyl peptide, γ-glutamyl trans- S-1-propenyl cysteine sulfoxide (GGPrCSO) exhibited uncompetitive inhibition of transpeptidation by GGPNA. This suggests that GGPrCSO is a poor glutamyl donor and therefore unlikely to be an in vivo substrate for peptidase activity by this enzyme.

Sulfur and nitrogen fertility affects flavour of field-grown onions

Although glasshouse studies have conclusively demonstrated that S nutrition can affect onion (Allium cepaL.) pungency this has been rarely observed in field-based studies due to difficulties in controlling S nutrition and lack of efficient methods for measurement of flavour bioactives. We have developed a rapid automated method for determination of onion lachrymatory factor ((Z, E)-thiopropanal-S-oxide; LF) based on juice extraction into dichloromethane and gas chromatography (GC) analysis with flame photometric detection. We evaluated this in a field trial of a mild (cv. ‘Encore’) and a pungent (cv. ‘Kojak’) onion cultivar grown on a low S soil with and without S addition, under high or low N treatments. No treatments significantly affected bulb fresh weight but S fertilisation significantly increased bulb total S, sulfate, pungency, LF and flavour precursor levels in both varieties. Analysis of bulb flavour precursors by HPLC confirmed that juice LF levels paralleled levels of the flavour precursor S-1-propenyl cysteine sulfoxide. The pungent cultivar also exhibited significant N main effects on bulb LF, total S and sulfate. We also assayed the key S-assimilatory enzyme, APS reductase (APR) in leaves before and during bulbing. Specific activities in the range of 1 to 11 nmol mg−1·min−1 were observed in youngest leaves, but only the milder cultivar exhibited significant stage × N × S effects. These findings suggest that sulfur metabolism of mild and pungent onions respond differently to N fertility, and that GC of LF is practical for field-based studies of onion flavour.

Bioactive S-alk(en)yl cysteine sulfoxide metabolites in the genus Allium: the chemistry of potential therapeutic agents

S-Alk(en)yl cysteine sulfoxides are odourless, non-protein sulfur amino acids typically found in members of the family Alliaceae and are the precursors to the lachrymatory and flavour compounds found in the agronomically important genus Allium. Traditionally, Allium species, particularly the onion (Allium cepa) and garlic (A. sativum), have been used for centuries in European, Asian and American folk medicines for the treatment of numerous human pathologies, however it is only recently that any significant progress has been made in determining their mechanisms of action. Indeed, our understanding of the role of Allium species in human health undoubtedly comes from the combination of several academic disciplines including botany, biochemistry and nutrition. During tissue damage, S-alk(en)yl cysteine sulfoxides are converted to their respective thiosulfinates or propanethial-S-oxide by the action of the enzyme alliinase (EC 4.4.1.4). Depending on the Allium species, and under differing conditions, thiosulfinates can decompose to form additional sulfur constituents including diallyl, methyl allyl, and diethyl mono-, di-, tri-, tetra-, penta-, and hexasulfides, the vinyldithiins and (E)- and (Z)-ajoene. Recent reports have shown onion and garlic extracts, along with several principal sulfur constituents, can induce phase II detoxification enzymes like glutathione-S-transferases (EC 2.5.1.18) and quinone reductase (QR) NAD(P)H: (quinine acceptor) oxidoreductase (EC 1.6.99.2) in mammalian tissues, as well as also influencing cell cycle arrest and apoptosis in numerous in vitro cancer cell models. Moreover, studies are also beginning to highlight a role of Allium-derived sulfur compounds in cardiovascular protection. In this review, we discuss the chemical diversity of S-alk(en)yl cysteine sulfoxide metabolites in the context of their biochemical and pharmacological mechanisms.

Sodium Chloride in Nutrient Solutions Can Affect Onion Growth and Flavor Development

Onion is classified as a salt-sensitive crop, though it is found in production on saline soils around the world. While onion flavor intensity has been studied in response to various growing conditions, little is known about its response to salt stress. To understand if NaCl affects growth, flavor development, and mineral content in onion, `Granex 33' plants were grown to maturity with six different concentrations of NaCl ranging from 0 (control) to 125 mm in nutrient solutions. NaCl affected onion fresh weight and altered onion flavor intensity and quality. Plants did not survive the 125 mm NaCl treatments and are not included in the results. As bulb Na+ and Cl- content increased in response to increasing NaCl concentrations, leaf and bulb fresh weight of mature plants decreased. Total bulb S content also decreased with increasing NaCl solution concentrations, while bulb SO42- content increasing linearly, indicating that less S was entering the S metabolic stream. Though bulb soluble solids content was not influenced by NaCl concentrations, pungency increased, but only at the highest NaCl concentration. Total flavor precursors and methyl cysteine sulfoxide content increased in response to NaCl, but only at the 100 mm treatment. 1-Propenyl cysteine sulfoxide was generally unresponsive to the salt treatment. Propyl cysteine sulfoxide content decreased then increased in responses to increasing NaCl levels, but was found as a minor flavor precursor. Peptide intermediates measured in the pathway leading to 1-propenyl cysteine sulfoxide and propyl cysteine sulfoxide decreased linearly with increasing NaCl exposure. While NaCl affected onion flavor in this study, severe reductions in growth would prevent onion production under similar saline conditions. For practical purposes, the effects of NaCl on flavor are, therefore, minimal.

Influence of Nitrogen and Sulfur Fertilization on the Alliin Content of Onions and Garlic

Onion (Allium cepa L.) and garlic (Allium sativum L.) were among the earliest cultivated crops and have been popular in folk medicine for centuries. Alliins (cysteine sulfoxides) are the characteristic sulfur (S) containing secondary metabolites of Allium species like onions, shallot, garlic, leek and chives and they cause taste and sharpness and are criteria for the pharmaceutical quality. The influence of the S nutritional status on the content of secondary S containing metabolites was shown for different crops such as oilseed rape, mustard, nasturtium, and allium species. It was the aim of this study to investigate the influence of the S and nitrogen (N) supply on the alliin content of onion and garlic and to evaluate the significance for crop quality. In a greenhouse experiment three levels of N and S were applied in factorial combinations of 0, 50, and 250 mg pot−1 S and 250, 500, and 1000 mg pot−1 N. 8 plants were grown in a Mitscherlich pot containing 8 kg sand. Leaves and bulbs were sampled twice during the growth period in order to follow up translocation processes. The first sampling was carried out when leaves were developed, but bulb growth had not yet started and the second one during main bulb growth. An increasing S supply was related to an increasing alliin content in leaves and bulbs of both crops, whereas nitrogen fertilization had only a minor influence. The alliin content in bulbs could be doubled by S fertilization. A translocation of alliin from leaves to bulbs was found so that time of harvest has a strong influence on the alliin content. At the beginning of plant development high alliin contents were found in leaves, while with bulb development they were translocated into this plant organ. The results show that the potential health benefits of Allium species could be distinctly improved by S fertilization.

Chemical characterization of interspecific hybrids between Allium cepa L. and Allium kermesinum Rchb.

Interspecific hybridization between wild and cultivated species of the genus Allium has been performed to generate plant material possessing biochemical properties of both parental plants. These cross-breeding experiments should lead to Allium plants with higher amounts of valuable constituents. The chemical characterization of interspecific hybrids between A. cepa and A. kermesinum is described on the basis of their sulfur-containing constituents and secondary metabolites. In addition, the hybrid character has been proven by random amplified polymorphic DNA (RAPD) analysis of the progenies obtained from the crosses. It has been shown that the distribution of the cysteine sulfoxides as well as the volatile secondary metabolites in the hybrids is not uniform. The profiles are mainly determined by the paternal wild species A. kermesinum. It has been ascertained that the gas chromatography profiles of the hybrids show increasing amounts of unsymmetrical substituted oligosulfides, which are known to be physiologically active substances. On the basis of statistical calculations, three different types of hybrids can be separated. The chemical analysis of cysteine sulfoxides and volatile sulfur-containing substances is shown to be a useful tool for breeding purposes as it allows an effective selection with regard to optimal distribution and amount of valuable constituents.

Allium discoloration: precursors involved in onion pinking and garlic greening.

Precursors involved in the formation of pink and green-blue pigments generated during onion and garlic processing, respectively, have been studied. It has been confirmed that the formations of both pigments are of very similar natures, with (E)-S-(1-propenyl)cysteine sulfoxide (isoalliin) serving as the primary precursor. Upon disruption of the tissue, isoalliin and other S-alk(en)ylcysteine sulfoxides are enzymatically cleaved, yielding 1-propenyl-containing thiosulfinates [CH3CH=CHS(O)SR; R = methyl, allyl, propyl, 1-propenyl] among others. The latter compounds have been shown to subsequently react with amino acids to produce the pigments. Whereas the propyl, 1-propenyl, and methyl derivatives form pink, pink-red, and magenta compounds, those containing the allyl group give rise to blue products after reacting with glycine at pH 5.0. The role of other thiosulfinates [RS(O)SR'] (R, R' = methyl, allyl, propyl) and (Z)-thiopropanal S-oxide (the onion lachrymatory principle) in the formation of the pigments is also discussed.

Evaluation of Methanethiol and Dimethyl Disulfide in the Homogenate Fractions of Fresh and Frozen Broccoli Tissues

The emission of methanethiol (MT) and dimethyl disulfide (DMDS) from homogenate fractions of fresh and frozen broccoli tissues was analyzed using gas chromatography coupled with flame photometric detector after incubating for 2 h at 30 °C in a water bath. Both sulfur compounds were detected in the headspace of the residue fraction of fresh broccoli but not frozen tissues. Only DMDS was formed in the filtrate and supernatant fractions of fresh tissues but their emission was also suppressed in frozen tissues. Phosphate buffer treatment reduced the amount of MT formed on the residue of fresh tissues, whereas treatment of enzyme co-factor, pyridoxal phosphate, and its substrate, S-methyl-L-cysteine sulfoxide, in the residue fraction of frozen broccoli did not induce the formation of MT except for DMDS. Both compounds were also inhibited in the residue fraction of the fresh tissues by aminooxyacetic acid, a potential inhibitor of pyridoxal phosphate-dependent enzymes, indicating that these objectionable odors were produced upon the action of cysteine sulfoxide lyase. This enzyme, which yielded strong activity in the residue upon extraction with buffer containing Triton X-100, is highly likely to be a bound enzyme. Inhibition of MT and DMDS in frozen broccoli tissues is likely attributed to the retardation of the enzyme action due in part to the loss of the co-factor and its substrate, and owing to the solubility of MT and its affinity to gaseous condition.

Quantitative determination of allicin in garlic: supercritical fluid extraction and standard addition of alliin.

A quantitative method is described for the determination of allicin (2-propene-1-sulfinothioic acid S-2-propenyl ester) in garlic, using standard additions of alliin (l-(+)-S-allylcysteine sulfoxide) in conjunction with supercritical fluid extraction (SFE) and high performance liquid chromatography analysis with UV-vis absorbance detection. Optimum CO(2)-SFE conditions provided 96% recovery for allicin with precision of 3% (RSD) for repeat samples. The incorporation of an internal standard (allyl phenyl sulfone) in the SFE step resulted in a modest improvement in recovery (99%) and precision (2% RSD). Standard additions of alliin were converted to allicin in situ by endogenous alliinase (l-(+)-S-alk(en)ylcysteine sulfoxide lyase, EC 4.4.1.4). Complete conversion of the spiked alliin to allicin was achieved by making additions after homogenization-induced conversion of the naturally occurring cysteine sulfoxides to thiosulfinates had taken place, thus eliminating the likelihood of competing reactions. Concentration values for allicin determined in samples of fresh garlic (Allium sativum L. and Allium ampeloprasum) and commercially available garlic powders (Allium sativum L.) by standard addition of alliin were found in all cases to be in statistical agreement (95% confidence interval) with values determined using a secondary allicin standard (concentration determined using published extinction coefficients). This method provides a convenient alternative for assessing the amount of allicin present in fresh and powdered garlic, as alliin is a far more stable and commercially prevalent compound than allicin and is thus more amenable for use as a standard for routine analysis.

Allium discoloration: the nature of onion pinking and garlic greening

Precursors involved in the formation of pink and green-blue pigments during onion and garlic processing, respectively, have been studied. It has been confirmed that the formation of both pigments is of a very similar nature, with (E)-S-(1-propenyl)cysteine sulfoxide (isoalliin) serving as the primary precursor. Upon disruption of the tissue, isoalliin and other S-alk(en)ylcysteine sulfoxides are enzymatically cleaved, yielding prop-1-enylcontaining thiosulfinates [CH<sub>3</sub>CH = CHS(O)SR; R = methyl, allyl, propyl, 1-propenyl], among others. The latter compounds subsequently react with amino acids to produce the pigments. Whereas the onion and leek-related propyl, prop-1-enyl and methyl derivatives can form pink, pink-red and magenta compounds, those containing the allyl group yield dark blue products after reacting with glycine at pH 5.0.

Controlled atmosphere and regular storage-induced changes in S-alk(en)yl-l-cysteine sulfoxides and alliinase activity in onion bulbs (Allium cepa L. cv. Hysam)

Abstract Onion bulbs (Allium cepa L. cv. Hysam) were stored under regular atmosphere (RA: 21% O2/0.1% CO2) and controlled atmospheres (CA2/2: 2% O2/2% CO2; and CA2/8: 2% O2/8% CO2) with 80±3% relative humidity (RH) at 0.5±0.5 °C for 9 weeks. Total pyruvic acid content (PY), changes in S-alk(en)yl- l -cysteine sulfoxide (ACSO) flavour precursors and alliinase activity were quantified before and after storage. Both PY and total ACSO contents were significantly increased by RA storage (9–11%) and significantly depleted by CA storage. PY and total ACSO contents were depleted by 4.8 and 19%, respectively under CA2/2, and by 13.5 and 22%, respectively under CA2/8. The proportion of individual ACSOs also changed during storage. Before storage, trans-(+)-S-(1-propenyl)- l -cysteine sulfoxide (PRENCSO) was the major ACSO (49.2%), followed by (+)-S-methyl- l -cysteine sulfoxide (MCSO) (31.5%) and (+)-propyl- l -cysteine sulfoxide (PSCO) (19.3%). The proportion of PCSO was reduced under RA and CA2/2, with a concomitant increase in the proportion of MCSO. The reverse occurred under CA2/8. The protein content declined under all treatments, although alliinase specific activity increased under RA and CA2/2 and declined under CA2/8. Thus in cv. Hysam, CA storage reduced pungency and flavour by reducing both flavour precursors and enzyme activity.

Development of a biosensor specific for cysteine sulfoxides

S-Alk(en)yl cysteine sulfoxides have been observed in several plants, mainly belonging to the onion family ( Alliaceae), which are of high commercial interest (e.g. garlic, Allium sativum). The quality of most garlic containing herbal remedies produced from garlic powder is determined by their content of the cysteine sulfoxide alliin. Therefore, a comprehensive method for the documentation of alliin amounts present in the fresh plant material through to the final remedy is desirable. The newly developed biosensoric method described in this paper was designed in order to fulfil these demands. In contrast to conventional HPLC-methods, neither a pre-column derivatization nor a chromatographic separation are required allowing a high throughput of samples. This technique is based on immobilized alliinase (EC 4.4.1.4), which was combined with an ammonia-gas electrode. The enzyme was either placed in a small cartridge or was immobilized in direct contact of the electrode surface giving detection limits of 3.7×10 −7 and 5.9×10 −6 M. Founded on these experiments, a pH-sensitive electrolyte/insulator/semiconductor (EIS) layer structure made of Al/p-Si/SiO 2/Si 3N 4 was also combined with immobilized alliinase. Measurements could be performed in a range between 1×10 −5 and 1×10 −3 M alliin. All sensors were operated in the flow-through modus. A high specificity for alliin could be demonstrated for the electrode and a number of garlic samples were analyzed. Results gained with the new method showed a good correlation with those obtained with conventional HPLC-methods. In addition, onion and a variety of wild Allium species were analyzed in order to determine the amount of isoalliin or total cysteine sulfoxides present, respectively.

Temperature Influences Flavor Intensity and Quality in `Granex 33' Onion

The effects of temperature and developmental age on flavor intensity and quality were tested by growing `Granex 33' onions (Allium cepa L.) at 16.5, 22.1, 26.7, and 32.2 (±0.4) °C for 50 days and to maturity. Plants were harvested and evaluated for growth characteristics. Bulbs were then analyzed for sulfur (S) assimilation and flavor development parameters. Total bulb S increased linearly with temperature regardless of bulb age. Bulb sulfate changed little over temperatures, indicating that organically bound S increased with temperature. Total pyruvic acid content (pungency), total S-alkenyl cysteine sulfoxide (ACSO) content and individual ACSOs increased linearly in response to temperature when measured at the two developmental stages. Though trans-(+)-S-(1-propenyl)-L-cysteine sulfoxide was the predominant ACSO at most temperatures, (+)-S-methyl-L-cysteine sulfoxide accumulation was greatest among the individual ACSOs in mature bulbs grown at 32.2 °C. Additionally, (+)-S-propyl cysteine sulfoxide was present in the least amount at all treatment levels and developmental stages. Gamma glutamyl propenyl cysteine sulfoxide and 2-carboxypropyl glutathione peptides in the flavor biosynthetic pathway also increased linearly with temperature. When ACSOs were assessed in onion macerate as a measure of alliinase activity, levels of degraded ACSOs increased linearly with growing temperature. The relative percentage of most ACSOs hydrolyzed, however, did not change in response to growing temperature. This suggested that the activity of alliinase was proportional to the amounts of flavor precursors synthesized. Growing temperature, therefore, should be considered when evaluating and interpreting yearly and regional variability in onion flavor.

A Comparative Study of Antioxidants S-Allyl Cysteine Sulfoxide and Vitamin E on the Damages Induced by Nicotine in Rats

The dietary consumption of antioxidant-rich fruits and vegetables is inversely correlated with the incidence of various diseases like cardiovascular diseases and lung cancer. We have tried to find out how far the S-allyl cysteine sulfoxide (SACS) isolated from garlic (Allium sativum L.) can combat the nicotine-induced peroxidative damage in rats. The effects have been compared with the standard antioxidant vitamin E. Administration of SACS or vitamin E (100 mg/kg) to nicotine (0.6 mg/kg) treated rats for 21 days showed decreased concentrations of thiobarbituric acid reactive substances, hydroperoxides, and conjugated dienes in liver, lungs, and heart as compared with the values found in rats treated with nicotine alone. The activities of catalase and superoxide dismutase increased. The levels of the antioxidants like vitamins A, C, and E in the liver and glutathione in all tissues increased significantly in SACS-treated or vitamin E fed rats. However, the antioxidant status was higher when vitamin E was administered as compared with SACS administered to nicotine-treated rats.

S-Substituted cysteine derivatives and thiosulfinate formation in Petiveria alliacea—part II

Three cysteine derivatives, ( R)- S-(2-hydroxyethyl)cysteine, together with ( R S R C)- and ( S S R C)- S-(2-hydroxyethyl)cysteine sulfoxides, have been isolated from the roots of Petiveria alliacea. Furthermore, three additional amino acids, S-methyl-, S-ethyl-, and S-propylcysteine derivatives, were detected. They were present only in trace amounts (<3 μg g −1 fr. wt), precluding determination of their absolute configurations and oxidation states. In addition, four thiosulfinates, S-(2-hydroxyethyl) (2-hydroxyethane)-, S-(2-hydroxyethyl) phenylmethane-, S-benzyl (2-hydroxyethane)- and S-benzyl phenylmethanethiosulfinates, have been found in a homogenate of the roots. The formation pathways of various benzyl/phenyl-containing compounds previously found in the plant were also discussed.

Biosensoric flow-through method for the determination of cysteine sulfoxides

Abstract Cysteine sulfoxides are known for their canceroprotective and antioxidant potential and have been detected in several plants, mainly those belonging to the leek family ( Alliaceae ). A number of these plants are used as herbal remedies, spices, or vegetables, including garlic ( Allium sativum ), onion ( Allium cepa ) and leek ( Allium porrum ). Determination of the quality and pharmacological activity of garlic-containing herbal remedies produced from garlic powder is by measurement of their content of the cysteine sulfoxide alliin. A convenient method allowing reliable routine estimation of the alliin levels present in the fresh plant material through to the final remedy is urgently required. The newly developed flow-through method described in this paper was designed in order to fulfill this demand. In contrast to conventional HPLC methods, neither a pre-column derivatization nor a chromatographic separation are required allowing a high throughput of samples. This technique is based on immobilized alliinase (EC 4.4.1.4), which was combined with an ammonia gas electrode mounted in a miniaturized flow-through cell. The lower detection limit obtained for alliin was 3.7×10 −7 M alliin. High specificity for alliin was demonstrated for the electrode and a variety of garlic samples including garlic powders, dry extracts and garlic tablets were analyzed successfully. Results obtained with the new method showed a good correlation with those obtained with conventional HPLC methods. In conclusion, the flow-through method provides a valuable method for quality control of garlic preparations and screening plant materials for their cysteine sulfoxide-related health potential.

Isolation of S-n-butylcysteine sulfoxide and six n-butyl-containing thiosulfinates from Allium siculum.

Isolation and identification of (S(S)R(C))-S-n-butylcysteine sulfoxide (1) from the bulbs of Allium siculum is reported. This compound was found in all parts of the plant (bulbs, stem, leaves, and flowers) along with known compounds (S(S)R(C))-S-methyl- and (R(S)R(C))-(E)-S-(1-propenyl)cysteine sulfoxides (2 and 3, respectively). In addition, six n-butyl-containing thiosulfinates (4-9) have been found in a CH2Cl2 extract of the bulbs. Structures were determined by a combination of spectral methods (primarily NMR and MS) and by comparison with authentic compounds obtained by synthesis. Antimicrobial activities of 4-7 and 9 are reported.