Antioxidant activity of two phloroglucinol derivatives from Dryopteris crassirhizoma

The rhizome of Dryopteris crassirhizoma NAKAI exhibited significant antioxidant activity, as assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity in vitro. Two phloroglucinol derivatives, flavaspidic acids PB (1) and AB (2), were isolated from the rhizome of D. crassirhizoma by a bioassay-guided fractionation. 1H-, 13C-NMR, and UV analysis were used to determine the structures. Furthermore, the two compounds were tested for their antioxidant activities, such as their DPPH radical scavenging, superoxide radical scavenging, and lipid peroxidation (LPO) inhibitory activities. Compounds 1 and 2 exhibited potent antioxidant activity against the LPO inhibitory test with IC(50) values of 12.9 and 13.1 microM, respectively, compared with alpha-tocopherol (IC(50); 15.6 microM) and butylated hydroxy anisole (BHA, IC(50); 10.8 microM), while the two compounds had a moderated effect on the DPPH radical scavenging activity (IC(50); 71.7, 76.3 microM) as well as superoxide radical scavenging activity (IC(50); 58.6, 64.4 microM). The potent activity of the flavaspidic acids (1, 2) on inhibiting LPO might be due to possible stabilization as a result of chelating with iron.     

Alkyl phloroglucinol derivatives from Syzygium levinei and their differentiation-inducing activity

Eleven compounds have been identified from the whole plants of Syzygium levinei (Myrtaceae) on the basis of spectroscopic analysis and chemical methods. Among these compounds, (Z)-1-(2,6-dihydroxy-4-methoxyphenyl)-oct-5-en-1-one (1), (3 E,7 Z)-1-(2,6-dihydroxy-4-methoxyphenyl)-deca-3,7-dien-1-one (2), and 1-(2-O-beta-D-glucopyranosyl-5,6-dihydroxy-4-methoxyphenyl)-octan-1-one (3) were characterized as new alkyl phloroglucinol derivatives, and 1-(2,6-dihydroxy-4-methoxyphenyl)-hexan-1-one (4) was identified as a new natural product. Compounds 1, 2, and 4 were found to inhibit the proliferation of leukemia K562 and HL-60 cells and also to induce the differentiation of K562 cells as determined by the appearance of matured morphology and the increase in the intracellular hemoglobin level.     

In vitro acetylcholinesterase activity of peptide derivatives isolated from two species of Leguminosae

Abstract

Context: Cratylia mollis Martius ex Benth. and Cenostigma macrophyllum Tul. (Leguminosae) are both endemic Brazilian plants and they are used by the natives as medicinal plants, and the leaves of C. mollis are also employed as forage for cattle during the dry season of region.

Objective: Isolation of the compounds responsible for the acetylcholinesterase (AChE) inhibition from the CHCl₃ active extract.

Materials and methods: Two peptidic compounds were isolated by chromatographic techniques from the CHCl₃ extract of the leaves of C. mollis and C. macrophyllum. They were identified by spectrometric data analysis (MS and NMR) and they were subjected to AChE inhibition employing Ellman’s test.

Results: The peptides were identified as N-benzoylphenylalaninoyl-phenlyalaninolacetate (aurentiamide acetate) (1) and N-benzoylphenylalaninyl-N-benzoylphenylalaninate (2). Both peptides 1 and 2 exhibit AChE inhibition, with IC₅₀ values equal to 111.34?µM and 137.6?µM, respectively.

Discussion and conclusion: Compound 1 (aurentiamide acetate) has rarely been isolated from the Leguminosae family, and N-benzoylphenylalaninyl-N-benzoylphenylalaninate (2) is a compound that has never previously been isolated from this family. Compound 1 is shown to be a potent inhibitor of AChE, with IC₅₀ values similar to the physostigmine control (141.51?µM).     

Three new phloroglucinol derivatives from Hypericum scabrum

A chemical investigation on the aerial parts of Hypericum scabrum L. resulted in the isolation of three new phloroglucinol derivatives, hyperscabrins A (1), B (2), and C (3), together with one known compound, (2R,3R,4S,6R)-3-methyl-4,6-di(3-methyl-2-butenyl)-2-(2-methyl-1-oxopropyl)-3-(4-methyl-3-pentenyl)-cyclohexanone (4). The structures were elucidated by means of spectroscopic methods, including MS, IR, 1D NMR, and 2D NMR, and the absolute configurations of chiral centers in these phloroglucinol derivatives were determined for the first time by studying their circular dichroism spectra.     

Three new phloroglucinol derivatives from Hypericum scabrum

A chemical investigation on the aerial parts of Hypericum scabrum L. resulted in the isolation of three new phloroglucinol derivatives, hyperscabrins A (1), B (2), and C (3), together with one known compound, (2R,3R,4S,6R)-3-methyl-4,6-di(3-methyl-2-butenyl)-2-(2-methyl-1-oxopropyl)-3-(4-methyl-3-pentenyl)-cyclohexanone (4). The structures were elucidated by means of spectroscopic methods, including MS, IR, 1D NMR, and 2D NMR, and the absolute configurations of chiral centers in these phloroglucinol derivatives were determined for the first time by studying their circular dichroism spectra.     

Studies on antioxidative activity of some C-glycosylflavones.

Ten flavonoid C-glycosyl derivatives: orientin (1), isoorientin (2), vitexin (3), isovitexin (4), isovitexin 7,2"-di-O-glucoside (5), isovitexin 7-O-galactoside-2"-O-glucoside (6), two different 6,8-di-C-hexosylapigenins (7, 8), and two different 6-C-hexosyl-8-C-pentosylapigenins (9, 10) have been either produced from flavonoid fractions from Adonis vernalis L. (1, 2) and Crataegus species (3, 4), or isolated from Stellaria media (L.) Vill. (5-10) to study their antioxidative properties. These were found only for two compounds: orientin (1) and isoorientin (2).     

Two novel phloroglucinol derivatives from Euphorbia ebracteolata hayata

Two new phloroglucinol derivatives, named ebracteolatain A and ebracteolatain B, along with three known phloroglucinol derivatives were isolated from Euphorbia ebracteolata Hayata., and their structures were elucidated as 3,3′-diacetyl-2,4′-dimethoxy-2′,4,6,6′-tetrahydroxy-5′-methyl diphenylmethane (1) and 1-[3,5-bis-(3-acetyl-2,6-dihydroxy-4-methoxy-benzyl)-2,4,6-trihydroxy-phenyl]-ethanone (2) on the basis of spectroscopic techniques and chemical methods.     

Two novel phloroglucinol derivatives from Euphorbia ebracteolata hayata

Two new phloroglucinol derivatives, named ebracteolatain A and ebracteolatain B, along with three known phloroglucinol derivatives were isolated from Euphorbia ebracteolata Hayata., and their structures were elucidated as 3,3'-diacetyl-2,4'-dimethoxy-2',4,6,6'-tetrahydroxy-5'-methyl diphenylmethane (1) and 1-[3,5-bis-(3-acetyl-2,6-dihydroxy-4-methoxy-benzyl)-2,4,6-trihydroxy-phenyl]-ethanone (2) on the basis of spectroscopic techniques and chemical methods.     

Two new prenylated phloroglucinol derivatives from Hypericum scabrum

Two new prenylated phloroglucinol derivatives (1–2), and a known compound furohyperforim isomer 2 (3), were isolated from the aerial parts of Hypericum scabrum. Their structures were elucidated by various spectroscopic methods, including MS, IR, UV, and NMR.     

Antimicrobial activity of seven hypericum entities from central Italy

Methanol-acetone extracts from aerial parts of seven entities of the genus Hypericum [H. perforatum L. subsp. perforatum, H. perforatum L. subsp. veronense (Schrank) Ces., H. montanum L., H. hyssopifolium Chaix, H. hirsutum L., H. hircinum L. subsp. majus (Aiton) N. Robson, H. tetrapterum Fr.] growing in the Appennino Umbro-Marchigiano (central Italy) were tested in vitro for their antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis), two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and the yeast Candida albicans, by the Kirby-Bauer agar diffusion method. The two H. perforatum subspecies were particularly active against Gram-positive and Gram-negative bacteria, supporting the use of these plants in the traditional medicine of central Italy to treat wounds, skin and infectious diseases. However significant values of inhibition were given also by H. hirsutum against S. aureus and P. aeruginosa, and by H. hyssopifolium, H. hircinum subsp. majus and H. tetrapterum against C. albicans. These results suggest that hypericin and hyperforin are the main components responsible for antimicrobial activity, but not the only ones, as other extracts, showing a low level of these compounds, possess evident activity. Isolation of pure compounds from the most active extracts is in progress.     

Free radical scavenging and antioxidative activity of melatonin derivatives

This article describes the synthesis and antioxidative properties of melatonin derivatives. Tryptamines and cysteinyl or mercaptopropionyl derivatives were deliberately condensed with coupling reagents to give melatonin derivatives 4a-d and 5a, b. The preliminary evaluation indicated that compound 4c showed improved scavenging activity compared with vitamin C (IC50 43 microM vs 65 microM, where IC50 is the concentration of the test compound that induced a change of 50% in absorbance during the 30 min observation) on diphenyl-p-picrylhydrazyl (DPPH) tests. Derivative 5b, which possesses the thiolactyl moiety, showed moderate potency compared with melatonin (IC50 235 microM vs 690 microM) in the H(2)O(2) scavenging test. Intriguingly, 4c displayed 2-fold more potency than melatonin (IC50 51 microM vs 125 microM) in scavenging NO in the macrophage model. These results suggested that the cysteinyl-conjugated derivative 4c may be a suitable lead to further optimize potent antioxidants for certain oxidative stress conditions.     

太子参水提物的抗氧化活性

目的:研究太子参水提物的抗氧化活性及其机制。方法:用D-半乳糖造衰老小鼠模型,受试药组衰老小鼠分别灌胃生药量1.44,2.88,5.76g.kg-1.d-1的太子参水提物,qd,共7周,观察其对衰老模型小鼠抗氧化系统的影响。结果:太子参水提物能使心、肝、肾组织中丙二醛(MDA)不同程度下降;超氧化物歧化酶(SOD)及谷胱甘肽过氧化物酶(GSH-Px)活力不同程度提高;脑组织中脂褐质(LF)不同程度下降。结论:太子参水提物通过清除.OH,提高SOD及GSH-Px活力而发挥抗氧化活性。     

NMR spectroscopy of naturally occurring phloroglucinol derivatives

Carbon-13 NMR spectra of eight 2-acyl- and -6-methyl-substituted filicinic acid (4,4-dimethyl-1,3,5-cyclohexantrione) derivatives were recorded in hexadeuterioacetone and in deuteriochloroform and the signals assigned on basis of chemical shifts and J (CH) coupling considerations. The data prove that the prevailing tautomeric structure of these derivatives is the monoketonic one with the carbonyl function in position 3 and hydroxyl groups in positions 1 and 5, the former being hydrogen bonded to the acyl side chain carbonyl. The 2-acyl-6,6-dimethyl compounds have the diketonic structure and a hydrogen-bonded hydroxyl group in position 3. The skeletal structure of 2-butyryl-4-hydroxy-4,6-dimethyl-1,3,5-cyclohexantrione is identical with that of humulone. This compound and its homologues also exist in the monoketonic tautomeric form, where C-3 carries the carbonyl function. In the solvents used the 6-methyl-2,3-dihydropyrane-2,4-dione exists predominantly as a single tautomer having two ring double bonds; the remaining carbonyl group is a part of an alpha, beta-unsaturated lactone grouping.     

Methylated 2-aryl-1,4-naphtoquinone derivatives with diminished antioxidative activity

Methylated 2-aryl-1,4-naphtoquinone derivatives with diminished antioxidative activity 2-(3,5-Di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthoquinone (1) is a selective 5-lipoxygenase (5-LOX) inhibitor possessing high antioxidative activity (AOA). In order to study the question if this activity corresponds to the mechanism of the 5-LOX inhibition (redox type 5-LOX inhibitor) the analogues 57-66 and their 3-methoxy derivatives 47-56 of the reference compound 1 were synthezised. These compounds are mono- and dimethylated within the benzoid molecular moiety which were tested for their 5-LOX inhibiting activity using human granulocytes and for their AOA by a chemiluminometric method. The synthesis of the test compounds runs in the following manner: Diels-Alder reaction of 1,4-benzoquinone (2) with the buta-1,3-dienes 3-8, bromination of the 1,4-naphthoquinones 9-14, arylation with 2,6-di-tert-butylphenol and substitution of bromine of the aryl-bromonaphthoquinones 33-46 by methoxy and hydroxy functions. A key step is the cc separation of the regioisomeric mixtures 25/26-31/32. The most potent 5-LOX inhibitors (IC50 = 1-3 microM) possess methylfunctions in 5-/8-position and show markedly diminished AOA compared with 1. 5-LOX inhibition and AOA in this class of compounds hence are not positively correlated.     

Spiranthenones A and B, tetraprenylated phloroglucinol derivatives from the leaves of Spiranthera odoratissima

Two new polyprenylated acylphloroglucinols, spiranthenones A (1) and B (2), a sesquiterpenoid, 6 α-acetoxy,1 β-hydroxyeudesm-4(15)-ene (3), along with sesamin and β-sitosterol, were isolated from the EtOAc extract of the leaves of Spiranthera odoratissima, and shown to display antiprotozoal activity. Their structures and relative stereochemistry were elucidated by NMR and mass spectrometry. These compounds exhibited moderate antiprotozoal activity, but without significant cytotoxicity against fibroblasts cell line NIH-3T3. Compound 3 was the most selective towards parasites.     

Studies on the anticomplementary activity of Jozann. Anticomplementary activity of steroid derivatives

Methanol extracts of 53 crude drugs were tested on the anticomplementary activity. Of these, 12 samples showed the potent activity. Of these 12 samples, the extract of Jozann (Dichrome Radix) was studied on the isolation and structural elucidation of the anticomplementary constituents. As active constituents, 3 beta-hydroxystigmast-5-en-7-one was isolated and its structure was confirmed by deriving this compound from beta-sitosterol. The activity of such steroid derivatives as stigmastane, cholestane, androstane and pregnane type steroids were further studied. Of these, several kinds of steroids showed the potent activity. From these experiments, the structure and activity relationship was discussed.