The effect of Kraussianone-2 (Kr2), a natural pyrano-isoflavone from Eriosema kraussianum, in an L-NAME- induced pre-eclamptic rat model.

This study aimed to investigate the effects of Kraussianone-2 (Kr2), a pyrano-isoflavone isolated from the roots of Eriosema kraussianum N. E. Br. (Fabaceae) on various fetal and physiological parameters in pregnant, L-NAME treated Sprague-Dawley rats. Twenty-four pregnant Sprague-Dawley dams were divided into three groups (n = 8), i.e. the control group (CON), the experimental control group (PRE), where the pre-eclampsia-like symptoms were induced using L-NAME, and the experimental group (EK2), where the pre-eclampsia-like symptoms were once again induced using L-NAME, however, these animals were treated with Kr2. On gestation day 20 the animals were sacrificed, at which time a laparotomy was performed and the number of live pups were counted and their corresponding birth and placental weights were recorded. Blood was also collected in heparin-coated tubes and the plasma samples were then analysed for specific variables using commercially available kits for rats. Kraussianone-2 administration decreased fetal mortality and demonstrated a trend toward increasing birth and placental weights in this model. Furthermore, Kr2 administration also reduced blood pressure amplification and decreased the plasma concentrations of two antiangiogenic factors, soluble fms-like tyrosine kinase1 (sFlt-1) and soluble endoglin (sEng). We speculate that Kr2, by improving uterine artery blood flow, results in improved fetal outcomes and decreased antiangiogenic factors in pregnant, L-NAME treated, Sprague-Dawley rats.

Hypoxis hemerocallidea--not merely a cure for benign prostate hyperplasia.

The use of Hypoxis hemerocallidea Fisch. and C.A. Mey. (Hypoxidaceae) extracts for ailments other than benign prostate hyperplasia (BPH) is now a reality. The whole extract, the phytosterols, as well as the major constituents it contains (hypoxoside, and its active derivative rooperol) are now finding new applications in the area of anti-oxidants, anti-inflammatories, anti-diabetics, anti-convulsants, inhibitors of drug marker substances and new evidence is presented of activity against cancerous and premalignant cancer cells. In addition, the over-the-counter (OTC) trade has undergone enormous expansion.

Transformation of naturally-occurring 1,9-trans-9,5-cis sweroside to all trans sweroside during acetylation of sweroside aglycone.

From the rootstock of Scabiosa columbria L. loganin and sweroside were isolated. Sweroside showed moderate antibacterial activity. Pure sweroside was converted to the sweroside aglycone 1-acetoxy derivative (DABCO/Ac2O) after hydrolysis of the glucose unit. X-ray crystallography of the monoacetate showed unambiguously that it had been transformed to a new seco-iridoid having the novel trans diaxial configuration for the protons on C-1, C-9 and C-5. The mechanism for the rearrangement is discussed.

Alkaloids from Crinum moorei.

Thirteen alkaloids were isolated from Crinum moorei two of which are new. These are 3-[4'-(8'-aminoethyl)phenoxy] bulbispermine and mooreine. The structures of the new alkaloids were determined by spectroscopic methods.

Stereostructure and anti-inflammatory activity of three diastereomers of ocobullenone from Ocotea bullata.

A novel diastereomer of ocobullenone. designated as sibyllenone, was isolated from the stem bark of mature Ocotea bullata in the course of a search for anti-inflammatory compounds from this plant. The stereostructure was established by X-ray crystallography and corroborated by NOESY analysis. Ocobullenone, obtained previously, was re-isolated and crystallised successfully for X-ray analysis, thus making possible an accurate spatial comparison of ocobullenone, iso-ocobullenone and the new stereoisomer. Tested pharmacologically for cyclooxygenase-1 and 2, and 5-lipoxygenase inhibition, sibyllenone was the only compound from O. bullata which showed good inhibitory activity towards 5-lipoxygenase.

Analytical and pharmacological investigation of Ocotea bullata (black stinkwood) bark and leaves.

Ocotea bullata (Lauraceae), one of the top-ten traditional medicinal plants used in KwaZulu-Natal, is close to extinction through high demand and destructive harvesting methods. The stem bark is traditionally used to cure headaches, urinary disorders and stomach problems. Substitution of leaves for bark provides a possible resource management solution for this threatened medicinal plant. One aim of this study was to compare the chemical composition of O. bullata leaves and bark using TLC, HPLC and GC-MS analysis. The characteristic analytical fingerprints of leaf and bark extracts showed great similarities. A second aim was to investigate the pharmacological properties of O. bullata as a remedy against headaches. Leaf and bark extracts were tested in terms of cyclooxygenase-1 and 5-lipoxygenase inhibition. Extracts from the bark exhibited moderate inhibitory activity in both test systems. Extracts from fresh leaves were superior to bark extracts in terms of their in vitro inhibitory activity against cyclooxygenase-1 and 5-lipoxygenase. Volatiles obtained from n-hexane extracts of leaves and bark showed better inhibitory activity towards cyclooxygenase-1 and especially towards 5-lipoxygenase than the original n-hexane extracts. Volatiles were therefore recognized as one of the main active principles in O. bullata with regards to the anti-inflammatory properties of this medicinal plant. This lends support to the traditional usage of O. bullata bark as an inhalant or snuff.

An acylated phloroglucinol with antimicrobial properties from Helichrysum caespititium.

A new acylated form of a phloroglucinol with significant antimicrobial properties was isolated by bioactivity guided fractionation from Helichrysum caespititium (Asteraceae). The structure elucidation, and conformation of the new phloroglucinol, 2-methyl-4-[2',4',6'-trihydroxy-3'-(2-methylpropanoyl) phenyl]but-2-enyl acetate, was established by high field NMR spectroscopic and MS data. The compound inhibited growth of Bacillus cereus, B. pumilus, B. subtilis and Micrococcus kristinae at the very low concentration of 0.5 microg/ml and Staphylococcus aureus at 5.0 microg/ml. Six fungi tested were similarly inhibited at low MICs, Aspergillus flavus and A. niger (1.0 microg/ml), Cladosporium chladosporioides (5 microg/ml), C. cucumerinum and C. sphaerospermum (0.5 microg/ml) and Phylophthora capsici at 1.0 microg/ml.

Enolic iridolactone and other iridoids from Alberta magna.

From fresh leaves of Alberta magna two new iridoids and a known cyclopentene dialdehyde have been identified. One of the new compounds has the less-common irido-lactone structure and has an enolic hydrogen on C-4. Two of the compounds show short term mosquito-repellent effects.

A semi-quantitative approach to the selection of appropriate candidate plant molluscicides--a South African application.

The high cost of synthetic molluscicides, used in the control of the intermediate snail hosts of schistosomiasis (bilharzia), has resulted in renewed interest in plant molluscicides. The history of the use of plant molluscicides is reviewed. Although screening programmes have been conducted in other African countries, no efforts have been made to identify South African plants which would be suitable for use locally, using appropriate technology. The prohibitive costs (time and financial) of random surveys for activity necessitated the development of an objective selection procedure. A simple scoring system derived for this purpose is described. Of 600 plant species with potential, or recorded activity, 150 occurred in South Africa. Twenty-six taxa were active according to standards set by WHO. A further 37 species, although untested, warrant further investigation. Species were ranked on cumulative scores for: (a) coincidence of the endemic areas of the plant, snail host and disease; (b) ethnomedicinal value which would provide greater incentive for cultivation; (c) molluscicidal activity (if known, a minimum LD90 of < or = 100 ppm). Two lists resulted, those with recorded and those with potential activity. Both are important in prioritizing research on molluscicidal plants in South Africa. Problems inherent to the scoring system and to the development of plant molluscicides are discussed.

Methylated A-type proanthocyanidins and related metabolites from Cassipourea gummiflua.

The range of natural dimeric A-type proanthocyanidins is extended by identification of two new dimeric afzelechins in the form of 7-OMe-epiafzelechin-(4 beta-->8,2 beta-->0-->7)- epiafzelechin and 7-OMe-epiafzelechin-(4 beta-->8, 2 beta-->0-->7)-ent-afzelechin. These are accompanied in the stem bark of Cassipourea gummiflua by the related metabolites afzelechin, kaempferol-3-0-alpha-L-rhamnopyranoside, afzelechin-3-0- alpha-L-rhamnopyranoside, epiafzelechin (4 beta-->8,2 beta-->0-->7)-epiafzelechin and epiafzelechin-(4 beta-->8, 2 beta-->0-->7)-ent-afzelechin, the latter three compounds being reported from a natural source for the second time.

Structural changes of zeatin during Acid hydrolysis.

Acid hydrolysis of zeatin under reflux at 100°C for 3.5 hours resulted in the formation of two compounds which were active in the soybean callus bioassay. One of these compounds was identified as 6-(3,4-dihydroxy-3-methyl-butylamino)purine. Available evidence suggests that this compound is not likely to be formed when endogenous cytokinins are fractionated with a cation exchange resin such as Dowex 50 at ambient temperatures.

Cytokinins in the Leaves of Ginkgo biloba: I. The Complex in Mature Leaves.

Cytokinin conjugates of zeatin, ribosylzeatin, and their respective dihydro derivatives tentatively have been identified as the major cytokinins present in mature Ginkgo biloba L. leaves. Ribosylzeatin was present in higher levels than zeatin and dihydrozeatin. No evidence could be found that 6-(2,3,4-trihydroxy-3-methylbutylamino)purine occurs as a metabolite in the mature leaves. From the available evidence, it is concluded that cytokinin conjugates are probably the major metabolites formed in the leaves of this deciduous gymnosperm.

(N-methylpyridinium)insulins. Modification at the A19- and B16-tyrosines.

Reaction of 2-iodo-N-methylpyridinium iodide with insulin gave, amongst others, A19- and B16-(N-methylpyridinium)insulin derivatives in which the phenolic groups of the respective tyrosines had been modified. Under carefully controlled conditions the A19 derivative gave small rhombohedral crystals, whereas the B16 derivative failed to crystallize. Both these derivatives had low biological activities.

NA1, NA1, NA1-trimethylinsulin--an insulin analogue with a quaternary amino group at the A1 terminus.

By utilizing the differing reactivity of the amino groups in aqueous organic solvents, des-GlyA1-NB1,N epsilon B29-(Msc)2-insulin was prepared. Its reaction with the phenyl ester of N,N,N-trimethylglycine in the presence of N-hydroxysuccinimide afforded the crystalline NA1,NA1,NA1-trimethylinsulin analogue. In the fat cell assay this analogue has an activity of 49% and, in the mouse convulsion assay, it is 70%.

A crystalline A14-(2-nitro-4-trimethylammoniophenyl) derivative of bovine insulin.

[O-(2-Nitro-4-trimethylammoniophenyl)-TyrA 14]insulin (bovine) is a product formed on reaction of bovine insulin with the hydrophilic reagent 1-fluoro-2-nitro-4-trimethyl-ammoniobenzene iodide (TAN-F) in an aqueous buffer at pH 8.00. The derivative was isolated and its purity established by standard procedures. The identity of the derivative was determined by degrative studies with alpha-chymotrypsin. The addition of zinc to the above reaction decreases the yield of the title derivative, but increases the yield of the [N alpha-TAN-GlyA1] derivative. [N alpha-Boc-GlyA1]insulin was also reacted with the above mentioned reagent in an attempt to improve the yield of the A14-tyrosine derivative. The biological activity of this microcrystalline derivative was found to be 12.4 units/mg as measured by the mouse convulsion assay.

Isolation of a crystalline A14-(N-methylpyridinium) derivative of bovine insulin.

Reaction of insulin with 2-chloro- or 2-iodo-N-methylpyridinium iodide affords, amongst others, an insulin analogue modified at tha A14-tyrosine residue. Degradative procedures which pinpoint the exact position of modification are described. Highest yields of the derivative are obtained using the 2-iodo-N-methylpyridinium iodide as reagent. In the mouse convulsion assay this derivative retains 72% of its activity.

Receptor binding studies on A1-(2-nitro-4-trimethylammoniophenyl)insulin.

The results are presented from receptor binding studies and isolated fat cell assays on A1-(2-nitro-4-trimethylammoniophenyl)insulin. In the former tests, the derivative is shown to have properties similar to native insulin and the fat cell assays afford a value of 76 +/- 4%. The importance of a charged, hydrophilic moiety attached at A1-glycine is discussed in the light of the above findings.

Crystalline [A21-desamido]bovine insulin.

[A21-Desamido]insulin is the major product formed during mild acid hydrolysis of bovine insulin at low insulin concentration. The derivative was isolated by standard procedures and its purity established by isoelectric focusing, disc electrophoresis and electrophoresis on cellulose acetate strips. The identity of the acid-transformed derivative was determined as [A21-desamido]insulin by the action of carboxypeptidase A, using conditions under which a C-terminal aspartic acid residue would not be removed. The biological activity of this crystalline derivative was found to be 15.9 units/mg as measured by the mouse convulsion assay.

Preparation of a crystalline tris-(N-methylpyridinium)-derivative of bovine insulin.

The reaction between 2-chloro-N-methylpyridinium iodide and bovine insulin at pH 8.5 afforded a trisubstituted derivative as main product. Following purification on DEAE-Sephadex A-25, this derivative crystallized from a citrate buffer in the form of large rhombohedra very similar to native insulin. This observation was confirmed by zero-layer X-ray precession photography. Amino acid analysis indicated substitution at the B1-terminus and on two of the four tyrosine residues. In the mouse convulsion assay the derivative showed no biological activity.