The isolation and characterization of gamma-L-glutamyl-S-(trans-1-propenyl)-L-cysteine sulfoxide from sandal (Santalum album L). An interesting occurrence of sulfoxide diastereoisomers in nature

Amino acids in sandal (Santalum album L) with special reference to cis-4-hydroxy-l-proline and sym. homospermidine

Sandal (Santalum album L) contains several interesting amino acids and amines which are not seen in other plants. This includes cis-4-hydroxy-l-proline in free form in leaves, flowers and seeds while trans-4-hydroxy-l-proline in bound form. Traces of 3, 4 dehydroproline is also detected in sandal leaves. Biosynthesis of cis-4-hydroxy proline indicates that hydroxylation taken place at proline present in peptidyl form especially bound to glutamic acid and aspartic acid. Pyrrolizidine-2-carboxylic acid an interesting isatin positive heterocyclic compound is also present in sandal leaves. Sandal also contains sym. homospermidine which is not present in any other plants till today. Biosynthesis of sym. homospermidine goes by a unique pathway of putrescine oxidation, Schiff base formation, condensation and reduction. Moreover sandal leaves contain γ-glutamyl derivative of the lachrymatory precursor of onion, γ-glutamyl-S-propenyl cysteine superoxide. This review summarizes the studies on the amino acids in sandal.

A gamma-glutamyl peptide isolated from onion (Allium cepa L.) by bioassay-guided fractionation inhibits resorption activity of osteoclasts

One gram of onion added to the food of rats inhibits significantly (p < 0.05) bone resorption as assessed by the urinary excretion of tritium released from bone of 9-week-old rats prelabeled with tritiated tetracycline from weeks 1 to 6. To isolate and identify the bone resorption inhibiting compound from onion, onion powder was extracted and the extract fractionated by column chromatography and medium-pressure liquid chromatography. A single active peak was finally obtained by semipreparative high-performance liquid chromatography. The biological activity of the various fractions was tested in vitro on the activity of osteoclasts to form resorption pits on a mineralized substrate. Medium, containing the various fractions or the pure compound, was added to osteoclasts of new-born rats settled on ivory slices. After 24 h of incubation, the tartrate-resistant acid phosphatase positive multinucleated cells, that is, osteoclasts, were counted. Subsequently, the number of resorption pits was determined. Activity was calculated as the ratio of resorption pits/osteoclasts and was compared to a negative control, that is, medium containing 10% fetal bovine serum only and to calcitonin (10(-12) M) as a positive control. Finally, a single peak inhibited osteoclast activity significantly (p < 0.05). The structure of this compound was elucidated with high-performance liquid chromatography-electrospray ionization-mass spectrometry, time-of-flight electrospray ionization mass spectrometry, and nuclear magnetic resonance spectroscopy. The single peak was identified as gamma-L-glutamyl-trans-S-1-propenyl-L-cysteine sulfoxide (GPCS). It has a molecular mass of 306 Da and inhibits dose-dependently the resorption activity of osteoclasts, the minimal effective dose being approximately 2 mM. As no other peak displayed inhibitory activity, it likely is responsible for the effect of onion on bone resorption.

Role of sulfur chirality in the chemical processes of biology

Chiral structures profoundly influence chemical and biological processes. While chiral carbon biomolecules have received much attention, chirality is also possible in certain sulfur compounds; just as with carbon, there can be differences in the physiological behavior of chiral sulfur compounds. For instance, one drug enantiomer, Nexium (esomeprazole, a chiral sulfoxide), is used for its superior clinical properties as a proton pump inhibitor over the racemic mixture, Prilosec (Losec, omeprazole). This critical review introduces sulfur stereochemistry and nomenclature, and provides a comprehensive approach to chiral sulfur compounds and their enzymatic reactions in general and secondary metabolism. The major structural types of biological interest are sulfonium salts, sulfoxides, and sulfoximines. (103 references).

Cysteine sulfoxide derivatives in Petiveria alliacea

Two diastereomers of S-benzyl-L-cysteine sulfoxide have been isolated from fresh roots of Petiveria alliacea. Their structures and absolute configurations have been determined by NMR, MALDI-HRMS, IR and CD spectroscopy and confirmed by comparison with authentic compounds. Both the R(S) and S(S) diastereomers of the sulfoxide are present in all parts of the plant (root, stem, and leaves) with the latter diastereomer being predominant. Their total content greatly varied in different parts of the plant between 0.07 and 2.97 mg g(-1) fr. wt, being by far the highest in the root. S-Benzylcysteine has also been detected in trace amounts (<10 microg g(-1) fr. wt) in all parts of the plant. This represents the first report of the presence of S-benzylcysteine derivatives in nature.

A novel alliinase from onion roots. Biochemical characterization and cDNA cloning

We have purified a novel alliinase (EC 4.4.1.4) from roots of onion (Allium cepa L.). Two isoforms with alliinase activity (I and II) were separated by concanavalin A-Sepharose and had molecular masses of 52.7 (I) and 50.5 (II) kD on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 51 (I) and 57.5 (II) kD by gel filtration fast-protein liquid chromatography. Isoform I had an isoelectric point of 9.3, while isoform II had isoelectric points of 7.6, 7.9, 8.1, and 8.3. The isoforms differed in their glycosylation. Both contained xylose/fucose containing complex-type N-linked glycans, and isoform II also contained terminal mannose structures. Both isoforms had activity with S-alk(en)yl-L-cysteine sulfoxides. Unlike other allium alliinases, A. cepa root isoforms had cystine lyase activity. We cloned a gene from A. cepa root cDNA and show that it codes for A. cepa root alliinase protein. Homology to other reported allium alliinase genes is 50%. The gene coded for a protein of mass 51.2 kD, with two regions of deduced amino acid sequence identical to a 25- and a 40-amino acid region, as determined experimentally. The A. cepa root alliinase cDNA was expressed mainly in A. cepa roots. The structure and function of the alliinase gene family is discussed.

Chemoprotection of garlic extract toward cyclophosphamide toxicity in mice

The effect of the administration of an extract of garlic (Allium sativum) was studied in mice that were treated with a chronic lethal dose of cyclophosphamide (50 mg/kg body wt, 14 days). The intraperitoneal administration of garlic (50 mg/animal, 14 days) along with cyclophosphamide reduced the toxicity of the latter considerably with an increase in life span of more than 70%. The administration of garlic extract did not improve the lymphopenia produced by cyclophosphamide or liver alkaline phosphatase, but there was a significant reduction in liver glutamic-pyruvic transaminase. Moreover, garlic extract reduced the level of lipid peroxidation induced in the liver by cyclophosphamide administration. Administration of garlic extract did not interfere with the tumor-reducing activity of cyclophosphamide.