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PubMed1994

Detection of N-(deoxyguanosin-8-yl)-2-fluorenamine in DNA of peritoneal serosa and liver after intraperitoneal exposure of rats to N-hydroxy-N-2-fluorenylbenzamide or N-hydroxy-N-2-fluorenylacetamide.

DNA adduct formation was examined in rat peritoneal serosa, a tumor target for i.p. administered aqueous suspensions of N-hydroxy-N-2-fluorenylbenzamide (N-OH-2-FBA) and N-hydroxy-N-2-fluorenylacetamide (N-OH-2-FAA), and compared to that in the liver, which is a tumor target for N-OH-2-FAA in the male rat. 32P-Postlabeling analyses showed the presence of a single adduct, N-(deoxyguanosin-8-yl)-2-fluorenamine (dG-C8-FA), from activation of both hydroxamic acids by the serosa and liver in vitro and in vivo. The relatively low levels of dG-C8-FA (60-80 fmol/micrograms DNA) from N-OH-2-FBA in vitro were increased 2.7- and 35-fold upon the addition of acetyl coenzyme A (AcCoA) to the serosal cytosol and hepatic cytosol or microsomes respectively. By contrast, addition of AcCoA led to a decrease (approximately 34%) in the high level of dG-C8-FA (4330 fmol/micrograms DNA) from activation of N-OH-2-FAA by hepatic cytosol and did not alter the levels from activation by hepatic microsomes and serosal cytosols (530 and 78.3 fmol/micrograms DNA respectively). These data and the previously reported hydroxamic acid activation enzyme activities in the serosa and liver indicated that the precursor of dG-C8-FA, N-acetoxy-N-2-fluorenamine, was formed from N-OH-2-FAA chiefly via an intramolecular N,O-acetyltransfer and from N-OH-2-FBA via a two-step sequence of N-debenzoylation and AcCoA-dependent O-acetylation. The levels of dG-C8-FA were approximately 2- to 3-fold higher in the serosal DNA (up to 515 and 1012 fmol/micrograms DNA) after one (30 mumol/rat) and ten or eleven (cumulative dose of approximately 275 mumol/rat) injections of N-OH-2-FBA or N-OH-2-FAA than in the hepatic DNA. This correlated with the carcinogenicities of the hydroxamic acids, but was inversely proportional to the rates and extents of their activation in vitro. Multiple injections affected hepatic enzyme activities related to the activation of the hydroxamic acids in that the cytosolic N-debenzoylation of N-OH-2-FBA increased (approximately 1.7-fold) whereas N-OH-2-FAA acetyltransferase and sulfotransferase activities decreased. The effect of treatment with N-OH-2-FBA was greater than that with N-OH-2-FAA and was greater on the sulfotransferase activity (approximately 88% decrease). The latter suggested that N-OH-2-FBA, although a poor acceptor for an enzymatic sulfate transfer, may be carcinogenic for the rat liver.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetyl Coenzyme A↗
PubMed2001

Shedding of growth hormone-binding protein is inhibited by hydroxamic acid-based protease inhibitors: proposed mechanism of activation of growth hormone-binding protein secretase.

The present study describes events postulated to be involved in the regulated mechanism of proteolytic shedding of growth hormone (GH)-binding protein (GHBP). Using Chinese hamster ovary (CHO) cell lines stably transfected either with the full-length human GH receptor (hGHR) or with the cytoplasmic domain-truncated hGHR (hGHR(tr)), we show that the phorbol ester, phorbol 12-myristate 13-acetate (PMA), caused a rapid time- and dose-dependent increase in GHBP secretion, which, as expected, was matched by a corresponding decrease in cell-surface GHR. Furthermore, PMA equally enhanced GHBP release from CHO/hGHR(tr) cells, suggesting that the cytoplasmic domain of hGHR is not essential for PMA-induced shedding. PMA is known to specifically activate protein kinase C and, indeed, the stimulatory effects of PMA in both cell lines were completely inhibited by the protein kinase inhibitor, staurosporine (100 nM), suggesting that activation of protein kinase C (PKC) may mediate PMA-induced GHBP shedding. Since proteolytic cleavage of several cell-surface proteins was shown to be stimulated by modulators of PKC activity and inhibited by metalloprotease inhibitors, we studied the effects of two hydroxamic acid-based inhibitors of zinc-dependent metalloproteases, BB-3103 and Ro31-9790, on GHBP proteolysis. Pretreatment of CHO/hGHR cells with both these inhibitors reduced PMA-enhanced shedding of GHBP, in a dose-dependent manner, with IC(50) values of approximately 0.41 microM for BB-3103 and approximately 0.97 microM for Ro31-9790. In addition, these inhibitors dose-dependently reduced the shedding enhanced by the sulfhydryl alkylator, N-ethylmaleimide (NEM), with IC(50) values of approximately 0.32 microM and approximately 0.58 microM for BB-3103 and Ro31-9790 respectively. It was of interest to find out that Ro31-9790 acted not only to modulate PMA- or NEM-induced shedding processes, but also markedly reduced the spontaneous, time-dependent accumulation of GHBP released from CHO/hGHR cells growing in serum-containing medium. Taken together, these results suggest that one or more zinc-dependent metalloprotease(s), acting at the cell surface, may be involved in GHBP secretase activity. A scheme is proposed whereby at least part of the regulated maturation and/or activation of the protease activity may involve a cysteine-switch mechanism and/or PKC-dependent phosphorylation. In the long run, specific inhibitors of these processes could be applied in the regulation of GHBP levels and, thus, of GH availability and/or activity.

Animals↗
PubMed1994

Novel bishydroxamic acids as 5-lipoxygenase inhibitors.

Two series of novel bishydroxamic acids 2 and 3 (types A and B) were synthesized and tested for inhibition of 5-lipoxygenase from rat basophile leukemia (RBL) cells. Both series were potent inhibitors of the isolated enzyme but only the type B reverse hydroxamic acids possessed significant oral activity. The most potent compound, orally, was 3a, [IC50 = 270 nM; ED50 = 1.86 mg/kg], which compares favorably with the clinically useful 5-lipoxygenase inhibitor, zileuton. Unlike known hydroxamic acid inhibitors, the oral activity in this series appears to be associated with the second hydroxamic acid group. The corresponding monohydroxamic acids retained inhibitor potency, in vitro, with reduced oral activity in a mouse zymosan peritonitis model. Compound 4e [IC50 = 7 nM], a monohydroxamic acid derivative related to 3a, is among the most potent inhibitors of the isolated enzyme yet to be reported.

Animals↗
PubMed2000

Design and synthesis of acidic dipeptide hydroxamate inhibitors of procollagen C-proteinase.

Procollagen C-proteinase (PCP) is essential for the cleavage of procollagen to collagen in the extracellular matrix of animals and is, therefore, of major relevance to studies of ectopic deposition of collagen during fibrosis. In this study, we describe the design and synthesis of acidic side chain hydroxamate dipeptide inhibitors of PCP having IC50 values in the range 0.1-10 microM that mimic the location of aspartic acid residues in the P1' and P2' positions (i.e. immediately C-terminal) of the PCP cleavage site in procollagen. Assays of PCP using purified human type I procollagen (a natural substrate of PCP) showed that the structure activity relationship of the inhibitors was improved with a glutamic acid mimic at the P1' position. The results also showed that the presence of an acidic side chain at the P2' position was not necessary for PCP inhibition. Marimastat and BB3103, which are highly effective inhibitors of matrix metalloproteinases and ADAMS proteinases, respectively, did not inhibit PCP.

Amino Acid Sequence↗
PubMed1991

Purification and some properties of protease I having transfer action from Streptomyces griseus var. alcalophilus.

Streptomyces griseus var. alcalophilus was selected because it secreted a unique protease (protease I) that catalyzed the transfer reaction forming the hydroxamic acids of various amino acids. Protease I was purified to the electrophoretically homogeneous state and an activity of more than 125-fold that of the culture broth. The molecular weight of the enzyme was estimated to be 25,000 by gel filtration. The enzyme was most active in neutral pH for the transfer reaction forming phenylalanine hydroxamic acid, although for the hydrolytic reaction with casein as substrate it was most active in alkaline pH. The enzyme was inhibited by diisopropylfluorophosphate. Protease I catalyzed the transfer reaction synthesizing the hydroxamic acids of hydrophobic, acidic, basic, and small aliphatic amino acids such as Phe, Tyr, Leu, Asp, Glu, Arg, Lys, Ala, and Gly. These results indicate that protease I has broad donor specificity. It is also considered that protease I is a unique enzyme with transfer activity, and distinct from the alkalophilic proteinase reported previously [Yamamoto et al., Agric. Biol. Chem., 38, 37 (1974)].

Amino Acid Sequence↗
PubMed1993

Substituted chromenes as potent, orally active 5-lipoxygenase inhibitors.

A series of chromene derivatives was synthesized and evaluated for their in vitro and ex vivo 5-lipoxygenase (5-LO) inhibitory activity. These compounds were prepared by condensation of appropriate salicyl aldehydes with alpha, beta-unsaturated carbonyl compounds, followed by transformation to the corresponding hydroxamic acids or N-hydroxyureas. Placement of phenoxy or p-fluorophenoxy substituents at the 6 position of the chromene ring led to a dramatic increase in the in vitro potency as demonstrated by the guinea pig PMN 5-LO assay. Chromene hydroxamic acids, in general, behaved poorly in the ex vivo dog model. On the other hand, replacement of the hydroxamic acid function with N-hydroxyurea yielded potent and long-lasting 5-LO inhibitors in the dog model. In most cases, the oral efficacy of the chromene N-hydroxyureas correlated very well with their in vitro activity. Compounds 43 (CGS 23885) and 55 (CGS 24891) are among the most potent inhibitors prepared, showing IC50 values of 48 and 51 nM, respectively. The values for the duration of action (DA) for compounds 43 and 55 are 21 and 20 h, respectively, following intravenous (i.v.) administration of 1.0 mg/kg. In the oral (po) experiments, 43 and 55 have DA's of 14 and 15 h, respectively, at a 1.0 mg/kg dose. In both iv and po experiments, 43 and 55 showed sustained maximal inhibition (> 95%) at earlier time points. The oral ED50 values of 43 and 55 in the ex vivo dog model are 0.23 and 0.23 mg/kg, respectively, at 6.0 h, and 2.37 and 1.63 mg/kg, respectively, at 24 h. Compound 43, which inhibits sheep seminal vesicle cyclooxygenase (CO) with an IC50 value of 36 microM, was shown to be a selective 5-lipoxygenase inhibitor in the ex vivo study. These compounds compare favorably with zileuton (A-64077) in all the parameters examined.

Animals↗
PubMed2004

Proteasome inhibition sensitizes non-small cell lung cancer to histone deacetylase inhibitor-induced apoptosis through the generation of reactive oxygen species.

OBJECTIVES: The histone deacetylase inhibitor suberoylanilide hydroxamic acid induces apoptosis in some malignancies through mitochondrial injury and generation of reactive oxygen species. Histone deacetylase inhibitors also activate the antiapoptotic transcription factor nuclear factor kappaB. We hypothesize that proteasome inhibition with bortezomib (Velcade; Millennium Pharmaceuticals, Inc, Cambridge, Mass)will inhibit nuclear factor kappaB activation, enhance suberoylanilide hydroxamic acid-induced mitochondrial injury, and sensitize non-small cell lung cancer cells to apoptosis. METHODS: Four tumorigenic non-small cell lung cancer cell lines were treated with nothing, suberoylanilide hydroxamic acid, bortezomib, or both drugs. Nuclear factor kappaB-dependent transcription was determined by reporter gene assays and endogenous interleukin 8 transcription. Reactive oxygen species were quantified by using the fluorophore H 2 DCFDA. Cell viability was determined on the basis of clonogenic survival, and apoptosis was measured by quantifying caspase-3 activity and DNA fragmentation. Apoptosis and cell-survival assays were repeated in similarly treated cells incubated in the presence or absence of N-acetyl cysteine. Statistical significance was determined by means of analysis of variance. RESULTS: Suberoylanilide hydroxamic acid significantly enhanced interleukin 8 and nuclear factor kappaB-dependent reporter gene transcription, and these effects were inhibited by bortezomib ( P < or = .01). Combined treatment with suberoylanilide hydroxamic acid and bortezomib induced greater reactive oxygen species generation, more apoptosis ( P < or = .02), and more cell death ( P < or = .001) than either drug alone. N-acetyl cysteine diminished the induction of apoptosis and enhanced cell survival ( P < or = .04). CONCLUSIONS: Suberoylanilide hydroxamic acid and bortezomib synergistically induce reactive oxygen species generation in non-small cell lung cancer, and this plays a critical role in the induction of apoptosis after treatment. Combined treatment with suberoylanilide hydroxamic acid and bortezomib might be an effective treatment strategy for non-small cell lung cancer.

Apoptosis↗
PubMed2004

Use of a novel histone deacetylase inhibitor to induce apoptosis in cell lines of acute lymphoblastic leukemia.

BACKGROUND AND OBJECTIVES: Chromatin structure and thereby transcription is controlled by the level of acetylation of histones, which is determined by the balance between histone acetyl transferase (HAT) activity and histone deacetylase (HDAC) activity. HDAC inhibitors are a class of compounds able to regulate gene expression by modulating chromatin structure. There are two major classes of HDAC inhibitors: the hydroxamic acid derivatives such as trichostatin A (TSA) or SAHA, and the butyrates such as phenyl-butyrate. HDAC inhibitors interfere with differentiation, proliferation and apoptosis in tumor cells. Here, we investigated the activity of a new hydroxamic acid derivative, LAQ824, on lymphoblastic cells. DESIGN AND METHODS: Four different pre-B lymphoblastic cell lines: Sup-B15 and TMD-5, both t(9;22) positive, SEM, t(4;11) positive, and NALM-6 cells were exposed to the hydroxamic acid derivatives, LAQ824 and TSA. Histone hyperacetylation, apoptosis, cell cycle and related pathways were assessed by flow cytometry and Western blotting. RESULTS: LAQ824 significantly inhibited the proliferation of leukemic lymphoblastic cell lines. The effect of LAQ824 was due to increased apoptosis accompanied by activation of caspase-3 and caspase-9, cleavage of poly(ADP-ribose)-polymerase (PARP) as well as by down-regulation of Bcl-2 and disruption of the mitochondrial membrane potential. Surprisingly, LAQ824-induced apoptosis was at least partially independent of caspase activation as indicated by the fact that LAQ824-induced apoptosis was inhibited only partially in both t(9;22) positive Sup-B15 and TMD-5 cells, whereas no inhibition was observed in t(4;11) positive SEM cells upon exposure to the polycaspase inhibitor zVAD-fmk. INTERPRETATION AND CONCLUSIONS: Our study establishes that LAQ824 is a promising agent for the therapy of acute lymphoblastic leukemia.

Apoptosis↗
PubMed2005

Conformational variability of matrix metalloproteinases: beyond a single 3D structure.

The structures of the catalytic domain of matrix metalloproteinase 12 in the presence of acetohydroxamic acid and N-isobutyl-N-[4-methoxyphenylsulfonyl]glycyl hydroxamic acid have been solved by x-ray diffraction in the crystalline state at 1.0 and 1.3-A resolution, respectively, and compared with the previously published x-ray structure at 1.2-A resolution of the adduct with batimastat. The structure of the N-isobutyl-N-[4-methoxyphenylsulfonyl]glycyl hydroxamic acid adduct has been solved by NMR in solution. The three x-ray structures and the solution structure are similar but not identical to one another, the differences being sizably higher in the loops. We propose that many of the loops show a dynamical behavior in solution on a variety of time scales. Different conformations of some flexible regions of the protein can be observed as "frozen" in different crystalline environments. The mobility in solution studied by NMR reveals conformational equilibria in accessible time scales, i.e., from 10(-5) s to ms and more. Averaging of some residual dipolar couplings is consistent with further motions down to 10(-9) s. Finally, local thermal motions of each frozen conformation in the crystalline state at 100 K correlate well with local motions on the picosecond time scale. Flexibility/conformational heterogeneity in crucial parts of the catalytic domain is a rule rather than an exception in matrix metalloproteinases, and its extent may be underestimated by inspection of one x-ray structure. Backbone flexibility may play a role in the difficulties encountered in the design of selective inhibitors, whereas it may be a requisite for substrate binding and broad substrate specificity.

Catalytic Domain↗
PubMed2005

N-hydroxy-2-(naphthalene-2-ylsulfanyl)-acetamide, a novel hydroxamic acid-based inhibitor of aminopeptidase N and its anti-angiogenic activity.

In the course of our screening, N-hydroxy-2-(naphthalene-2-ylsulfanyl)-acetamide (1), which contains a metal-chelating hydroxamate group, has been identified as a potent inhibitor of aminopeptidase N (APN, EC 3.4.11.2). Compound 1 potently inhibited APN activity with a K(i) value of 3.5 microM. It also inhibited the basic fibroblast growth-factor-induced invasion of bovine aortic endothelial cells at low micromolar concentrations.

Acetamides↗
PubMed1999

Photoaffinity labeling and mass spectrometry identify ribosomal protein S3 as a potential target for hybrid polar cytodifferentiation agents.

The ability of a novel class of hybrid polar compounds (HPCs) to induce differentiation and consequent cessation of proliferation of transformed cells has led to their development as potential chemotherapeutic agents in the treatment of cancer. Suberoylanilide hydroxamic acid (SAHA) is a prototype of a family of hydroxamic acid based compounds (SAHA-like HPCs) that can, at micromolar concentrations, induce a variety of transformed cell lines to differentiate. The mechanism of action of the HPCs is not entirely understood. Searching for a cellular target of the SAHA-like HPCs, we synthesized a photoaffinity labeling reagent structurally based on SAHA, and probed for SAHA-binding proteins in murine erythroleukemia (MEL) cells. Photoaffinity labeling in cell free extracts identified a 32-kDa protein (p32) that was specifically labeled by the photoaffinity reagent. Cell fractionation assays localized p32 to the P100 fraction. p32 was partially purified and identified by mass spectrometry as the 40 S ribosomal protein S3. Expression of epitope-tagged S3 in bacterial lysates followed by photoaffinity labeling confirmed its specific labeling. Identification of a cytodifferentiation agent target may shed light on the mechanism by which the SAHA-like HPCs exert their antitumor effects.

Affinity Labels↗
PubMed2003

Histone deacetylase inhibitors induce growth suppression and cell death in human rhabdomyosarcoma in vitro.

PURPOSE: A group of histone deacetylase inhibitors has been shown to be effective in suppressing the growth of a variety of transformed cell lines in vitro and in vivo. The effects of two of these agents, suberoylanilide hydroxamic acid (SAHA) and suberoyl-3-aminopyridineamide hydroxamic acid (pyroxamide), were investigated for their growth-suppressive effects on rhabdomyosarcoma (RMS) cells. EXPERIMENTAL DESIGN AND RESULTS: Dose-response experiments of two RMS cell lines, RD (embryonal) and RH30B (alveolar), were performed with SAHA (0.25-3.0 micro M) and pyroxamide (1.25-20.0 micro M). Both agents caused a dose-dependent decrease in viable cell number and an increase in percentage of dead cells over time. Exposure of the RMS cells to SAHA and pyroxamide resulted in an accumulation of acetylated histones with increasing doses by Western blot analysis. Additionally, there was an induction of p21/WAF1 at 15 and 24 h when the cells were cultured with SAHA (2.0 micro M) or pyroxamide (20.0 micro M), concentrations that were tested because they successfully induced inhibition of cell growth and initiated cell death in both RMS cell lines. An increase in nuclei with hypodiploid or sub-G(1) fraction was found by flow cytometry with increasing doses of both SAHA (0.25-3.0 micro M) and pyroxamide (1.25-20.0 micro M) over time. This finding is consistent with DNA fragmentation and cell death by apoptosis. CONCLUSIONS: SAHA and pyroxamide induce growth suppression and cell death in human RMS in vitro. Accumulation of acetylated histones and induction of p21/WAF1 expression are observed in cells exposed to either agent.

Acetylation↗
PubMed2006

Optimization of the catalytic asymmetric addition of nitroalkanes to cyclic enones with trans-4,5-methano-L-proline.

[reaction: see text] The conjugate addition of symmetrical 2-nitroalkanes to 2-cycloalkenones catalyzed by trans-4,5-methano-l-proline proceeds with >99% ee and excellent chemical yields. 1-Nitroalkanes afford diastereomeric syn/anti products that can be separated with good individual enantioselectivities. Proline hydroxamic acid and its trans-4,5-methano -l-proline hydroxamic acid are also effective organocatalysts in the addition of 2-nitropropane to 2-cyclohexenone (75% and 81% ee, respectively).

Alkanes↗
PubMed1994

Peroxidative metabolism of carcinogenic N-arylhydroxamic acids: implications for tumorigenesis.

Peroxidative oxidations of chemical carcinogens including N-substituted aryl compounds could result in their metabolic activation because the products react with cellular molecules and lead to cytotoxicity, mutagenicity, and carcinogenicity. In vivo, peroxidative activities are chiefly of neutrophilic leukocyte origin. Neutrophils may be attracted to the site(s) of exposure to carcinogen and, via phagocytosis and respiratory burst, release oxidants that catalyze carcinogen activation and/or cause DNA damage. Our studies, presented herein, concern oxidations of carcinogenic N-arylhydroxamic acids, N-hydroxy-N-2-fluorenylacetamide (N-OH-2-FAA), and N-hydroxy-N-2-fluorenylbenzamide (N-OH-2-FBA), by enzymatic and chemical systems simulating those of neutrophils, myeloperoxidase and hydrogen peroxide (H2O2) +/- halide, and hypohalous acid and halide at the physiologic concentrations (0.1 M Cl- and/or 0.1 mM Br-) and the pH (4-6.5) of phagocytosis. Studies also concern oxidations of the hydroxamic acids by rat peritoneal neutrophils stimulated to undergo respiratory burst and release myeloperoxidase in medium-containing 0.14 M Cl- +/- 0.1 mM Br-. The metabolites formed in the presence of exogenous H2O2 are consistent with two peroxidative mechanisms: one electron-oxidation to a radical that dismutates to equimolar 2-nitrosofluorene (2-NOF) and the ester of the respective hydroxamic acid and halide-dependent oxidative cleavage, especially efficient in the presence of Br-, to equimolar 2-NOF and the respective acyl moiety. 2-NOF and the esters undergo further enzymatic and nonenzymatic conversions to unreactive products and/or may bind to cellular macromolecules. The results suggest that peroxidative metabolism of N-arylhydroxamic acids by neutrophils, yielding the potent direct mutagen 2-NOF and the electrophilic esters, occurs in vivo and is involved in the activation and thus local tumorigenicities of the hydroxamic acids at the site(s) of application.

Amines↗
PubMed2000

Purification and characterization of a beta-glucosidase from rye (Secale cereale L.) seedlings.

Cyclic hydroxamic acids and a glucosidase that occur in rye seedlings were investigated. The concentration of the glucoside of 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA-Glc) in shoots increased soon after germination and decreased to a lower, constant level as the plants started autotrophic growth. Cyclic hydroxamic acid glucoside beta-glucosidase activity also occurred transiently, and the timing of the increase and decrease was concurrent with that of cyclic hydroxamic acid glucosides. The glucosidase was isolated from 48-h-old rye shoots and purified to apparent homogeneity by using isoelectric precipitation, anion exchange chromatography, and gel filtration. The isoelectric point and the optimum reaction temperature were 4.9-5.1 and 25-30 degrees C, respectively. The N-terminal amino acid sequence was almost identical to that of the wheat glucosidases, but did not show any similarity to the sequences of other glucosidases of plant origin. SDS- and native-PAGE analyses showed that rye had several isozymes of glucosidase, and each isozyme was an oligomer of 60-kDa monomers with a molecular mass of approximately 300 kDa. The enzyme was highly active not only for DIMBOA-Glc but also for its 7-demethoxy analogue, DIBOA-Glc, which was different from the specificities of maize and wheat glucosidases.

Journal Article↗
PubMed1979

Identification of 1,4-Benzoxazin-3-ones in Maize Extracts by Gas-Liquid Chromatography and Mass Spectrometry.

Gas-liquid chromatography-mass spectrometry (GLC-MS) has been used for the separation, detection, and identification of 1,4-benzoxazin-3-ones (hydroxamic acids and lactams) and benzoxazolinones found in maize (Zea mays L.) extracts. Compounds of interest were partitioned into ethyl acetate from aqueous maize seedling extracts. For analysis by GLC-MS, trimethylsilyl derivatives were prepared, chromatographed on a column of 3% OV-1, and detected in the mass spectrometer. Mass spectra were obtained for all peaks present in extracts of four maize lines. A data comparison system was developed for relating unidentified spectra to the spectra of the reference compounds. Based on spectral comparisons, three hydroxamic acids (2,4-dihydroxy-2H-1, 4-benzoxazin-3(4H)-one; 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one; and 2,4-dihydroxy-7,8-dimethoxy-2H-1,4-benzoxazin-3(4H)-one), three lactams (2-hydroxy-2H-1,4-benzoxazin-3(4H)-one; 2,7-dihydroxy-2H-1,4-benzoxazin-3(4H)-one; and 2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one), one benzoxazolinone (6-methoxybenzoxazolinone), and two organic acids (malic and aconitic) were identified in the extracts. In addition, one other hydroxamic acid and one other related compound were tentatively identified based on mass spectral evidence.

Journal Article↗