Pyrrolizidine alkaloids from Anchusa strigosa and their antifeedant activity

The pyrrolizidine alkaloid (PA) content of flowers, leaves, and roots of Anchusa strigosa (Boraginaceae) was analysed by ESI-LC-MS. Six PAs, including two new natural compounds, were detected, characterized by NMR spectroscopy, and quantified in each plant organ. The results indicated that the highest total concentration of PAs was in the leaves (23.63 mg/g of dried part), followed by the flowers (19.77 mg/g), and finally by the roots (1.80 mg/g). All PAs isolated were subjected to Spodoptera exigua and Pieris brassicae larvae. Feeding activity by both herbivore species using a bioassay was inhibited up to circa 75% depending on PA and applied concentration.     

Minor diterpenes from Persea indica: their antifeedant activity

The new diterpenes anhydrocinnzeylanone, garajonone and 2,3-didehydrocinnzeylanone, and the known anhydrocinnzeylanine, have been isolated from Persea indica. The antifeedant activity of these compounds has been evaluated showing the importance of the 11-hemiketal group for the antifeedant effects of ryanodane diterpenes.     

New pregnane glycosides from Brucea javanica and their antifeedant activity

Three new pregnane glycosides, 3-O-β-D-glucopyranosyl-(1→2)-α-L-arabinopyranosyl-(20R)-pregn-5-ene-3β,20-diol (1), 3-O-α-L-arabinopyranosyl-(20R)-pregn-5-ene-3β,20-diol-20-O-β-D-glucopyranoside (2), 3-O-α-L-arabinopyranosyl-(20R)-pregn-5-ene-3β,20-diol-20-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside (3) were isolated along with four known compounds, 4-7, from the leaves and stems of Brucea javanica. Their structures were determined by detailed analyses of 1D- and 2D-NMR spectroscopic data. All of the compounds isolated from Brucea javanica were tested for the antifeedant activities against the larva of Pieris rapae. Compounds 1, 3, and 5 showed significant antifeedant activities after 72 h incubation.     

Biological activity and pharmacological prospects of lupane terpenoids: II. Semisynthetic lupane derivatives

The discussion of lupane triterpenoids as prospective medicinal preparations is continued, and semisynthetic triterpenoids are being discussed. Acyl derivatives that mainly exhibit high anti-HIV, antitumor, and organo-protective activities are described. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru.     

Biological activity and pharmacological prospects of lupane terpenoids: II. Semisynthetic lupane derivatives

The discussion of lupane triterpenoids as prospective medicinal preparations is continued, and semisynthetic triterpenoids are being discussed. Acyl derivatives that mainly exhibit high anti-HIV, antitumor, and organoprotective activities are described.     

Semisynthetic derivatives of glucagon. The contribution of histidine-1 to hormone conformation and activity

Semisynthetic N epsilon- acetimidoglucagon was prepared from the [des- His1 ]analogue by coupling the N-hydroxysuccinimide ester of N alpha- tBoc - Nimidazole -DNP-L-histidine to the peptide in dimethylformamide in the presence of 1-hydroxybenzotriazole. The deprotected, purified product was chemically identical to N epsilon- acetimidoglucagon and equipotent to N epsilon- acetimidoglucagon and native glucagon in its ability to activate adenylate cyclase and displace [125I] iodoglucagon from rat liver plasma membranes. Semisynthetic [ Phe1 ]-, [ Ala1 ]-, and [des- His1 ] glucagons prepared similarly achieved 85, 55, and 35% of the maximal activity and 22, 2, and 6% of the binding potency of N epsilon- acetimidoglucagon . The biological assays indicate that the amino group is involved to a greater extent in transduction than in binding, but the aromatic nature and hydrogen bonding capability of the imidazole ring of histidine-1 are important for both binding and transduction. In circular dichroism studies, all derivatives exhibited increased helicity in 2-chloroethanol. The [ Phe1 ] analogue although less soluble behaved similarly to native glucagon, while the [ Ala1 ] and [des- His1 ] derivatives exhibited an increased helical content in 0.01 N HCl as a result of an increased propensity of these derivatives to self-associate in the absence of 2-chloroethanol. The unexpected conformational changes throughout the molecule may have relevance for the functional activity.     

Semisynthetic neoboutomellerone derivatives as ubiquitin-proteasome pathway inhibitors

The interesting pharmacological properties of neoboutomellerones 1 and 2 were the basis for the assembly of a small library of analogues consisting of natural products isolated from the plant Neoboutonia melleri and of semisynthetic derivatives. As the two enone systems (C23-C24a and C1-C3) and the two hydroxyls groups (C22 and C26) of neoboutomellerones are required for activity, modifications were focused on these functional groups. Biological evaluation by using a cellular assay for proteasome activity provided clues regarding the mechanism of action of these natural products and synthetic derivatives. Certain neoboutomellerone derivatives inhibited the proliferation of human WM-266-4 melanoma tumor cells at submicromolar concentration and warrant evaluation as anticancer agents.     

Biological activity of phytosterols and their derivatives

This review is devoted to contemporary status of investigation of C-29 and C-28 plant sterols (phytosterols) in relation to their biological activity in mammals and mammalian cells. On the basis of experimental studies published during the last decade the following questions are discussed: phytosterols and nutrition; phytosterols and body cholesterol level; phytosterols and intestinal absorption of lipids, the role of phytosterols in lipid metabolism regulation; phytosterols and cultured mammalian cells; products of phytosterols oxidation; phytoecdysteroids and induced gene expression.     

Novel oxindole derivatives and their biological activity

The antifungal activity of fourteen novel derivatives of oxindole with side chain was studied using representatives of toxinogenic, phytopathogenic and dermatophytic filamentous fungi. Derivatives with exocyclic C=C bond in position C-3 exhibited a higher antifungal activity compared with derivatives with an exocyclic C−C bond in the same position. The strongest antifungal effects were shown by 3-(-2-thienoylmethylidene)-indol-2(3H)-ones.     

Semisynthetic epsilon-isorhodomycins: their synthesis using glycals and their structure-activity relationship

Syntheses and structure-activity relationships of 7-O-(3-amino-2,3,6-trideoxy-a-L-lyxo- (18), -L-arabino- (20) and -L-ribo- hexopyranosyl)-epsilon-isorhodomycins (25) and their 3'-dimethylamino derivatives 22, 23 and 26 are described. Condensation (trimethylsilyl triflate, molecular sieves 4 A, 10:1 dichloromethane-acetone, -15 degrees) of epsilon-isorhodomycinone (epsilon-isoRMN, 6) with 1,5-anhydro-4-O-p-nitrobenzoyl-3-trifluoroacetamido-L-lyxo- (5) -L-arabino- (9) or -L-ribo-hex-l-enitols (10) afforded mainly the 7-O-a-glycosyl-epsilon-isoRMNs 7, 11, and 12. Similar glycosylation of 6 with 1,5-anhydro-3-azido-4-O-p-nitrobenzoyl-2,3,6-trideoxy-L-arabino-hex-1-++ +enitol (15) yielded a-glycoside 16. Removal (M NaOH) of the p-nitrobenzoyl and trifluoroacetyl groups from 7, 11, and 12 gave the 7-O-(3-amino-2,3,6-trideoxy-a-L-hexopyranosyl)-epsilon-isoRMNs 18, 20, and 25. Reductive alkylation (CH2O, NaCNBH3) of these products afforded the 3'-N,N-dimethyl analogues 22, 23, and 26. The cytotoxic effect (IC50) of the semisynthetic epsilon-isorhodomycins was tested in vitro in leukemia cell line L1210.     

Betuligenol derivative with growth inhibition and antifeedant activity

The title chiral amine, 3-(4-methoxyphenyl)-1-methylpropylamine 5 has been synthesized from naturally abundant betuligenol 1 in three steps and also in good yield. Furthermore, the versatile intermediate 3 could be manipulated for the preparation of chiral disulphide 7. The amine derivative 5 prepared from (-)-betuligenol showed significant growth inhibition and antifeedant activity.     

Parallel synthesis of DAPT derivatives and their gamma-secretase-inhibitory activity

Parallel synthesis of the C-terminal-modified DAPT (1) derivatives was accomplished utilizing our novel resin 7. Condensation reaction of the N-acylamino acid 10 with the amines 11a-o proceeded smoothly to give the corresponding amides 6a-o without any epimerization. Among the analogues, the benzophenonemethyl amide derivative 6o showed 30 times more potent activity than the original DAPT (1).     

昆虫拒食剂蓼二醛的合成及其对害虫的拒食活性

以 β-环柠檬醛为原料 ,经 6步合成了蓼二醛 ( ( -) -polygodial)的消旋体 ,总收率为 1 9 8% ;并合成了其甲胺衍生物。经生物活性测定 ,辣蓼的粗提物和合成的蓼二醛及其甲胺的衍生物对蚜虫和菜青虫有很好的拒食活性     

Insect antifeedant activity of clerodane diterpenes and related model compounds

A comprehensive compilation of all test results on the insect antifeedant activity of clerodane diterpenes and related model compounds is reported. To increase the compatibility of data from different sources, some of the results reported in the literature have been converted into a standardized form. The compounds were sorted into groups according to the different types of sidechain attached to C-9. Despite the wealth of information, collected in 15 tables, it remains difficult to assign importance to separate structural elements in relation to the observed antifeedant activity. A detailed analysis of the structure-activity relationships could not be presented, but some interesting trends can be distinguished based on the structures of the strongest antifeedants. The compilation covers the literature up to December 2001.     

Oxidised derivatives of silybin and their antiradical and antioxidant activity

Carboxylic acids derived from silybin (1) and 2,3-dehydrosilybin (2) with improved water solubility were prepared by selective oxidation of parent compounds and a new inexpensive method for preparation of 2,3-dehydrosilybin from silybin was developed and optimised. The antioxidative properties of the above-mentioned compounds and of side product 3a from oxidation of compound 1 were determined by cyclic voltammetry, free radical scavenging (DPPH, superoxide) assays, and by inhibition of in vitro generated liver microsomal lipid peroxidation. Dehydrogenation at C((2))-C((3)) in flavonolignans (silybin vs 2,3-dehydrosilybin; silybinic acid vs 2,3-dehydrosilybinic acid) strongly improved antioxidative properties (analogously as in flavonoids taxifolin vs quercetin). Thus, in antioxidative properties, dehydrosilybin was superior to silybin by one order, but its water solubility is too low for application in aqueous milieu. On the other hand, 2,3-dehydrosilybinic acid is a fairly soluble derivative with antilipoperoxidation and antiradical activities better than that of silybin.     

Antibacterial activity of oleanolic and ursolic acids and their derivatives

Bacterial resistance to antibiotics is increasing at an alarming rate and many commonly used antibiotics are no longer effective. Thus, there is considerable interest in investigating novel antibacterial compounds, such as the plant-derived pentacyclic triterpenoids, including oleanolic acid (OA), ursolic acid (UA) and their derivatives. These compounds can be isolated from many medicinal and crop plants and their antibacterial, antiviral, antiulcer and anti-inflammatory effects are well documented. OA and UA are active against many bacterial species, particularly Gram-positive species, including mycobacteria. They inhibit bacterial growth and survival, and the spectrum of minimal inhibitory concentration (MIC) values is very broad. In addition, OA, UA and their derivatives display potent antimutagenic activity. Studies to identify the cellular targets and molecular mechanisms of OA and UA action were initiated a few years ago and it has already been demonstrated that both acids influence bacterial gene expression, the formation and maintenance of biofilms, cell autolysis and peptidoglycan turnover. Before these compounds can be used clinically as antimicrobial agents, further extensive studies are required to determine their cytotoxicity and the optimum mode of their application.     

Synthesis of sulfated derivatives of curdlan and their anti-HIV activity

Sulfopropyl curdlan was synthesized, its structure was determined, and the anti-HIV activity was compared with that of standard curdlan sulfates obtained with piperidine N-sulfonic acid in dimethyl sulfoxide. It was shown that sulfopropyl curdlan exhibits weaker anti-HIV activity than curdlan sulfate. Curdlan sulfates were synthesized with a SO₃-pyridine complex in a heterogeneous phase. It was shown from ¹³C-NMR spectra of acetylated curdlan sulfates that they had a different substituent distribution from standard curdlan sulfate. The cytotoxicity of the curdlan sulfates was attributed to their heterogeneous structure.     

Synthesis of some new bistriazolidine derivatives and their biological activity

Aromatic aldazines with thiocyanates in glacial acetic acid produce corresponding bistriazolidine derivatives via criss-cross cycloaddition reaction. The chemical structure was confirmed by elemental and spectral analysis. Biological activity against some microorganisms was tested.