Collagen treated with (+)-catechin becomes resistant to the action of mammalian collagenase

Summary Treatment of radioactively labeled guinea-pig skin soluble collagen or calf skin collagen with the flavonoid (+)-catechin makes the collagen resistant to the action of mammalian collagenase but not to the action of bacterial collagenase. Complete resistance to the action of the mammalian enzyme may be achieved by incubating 0.6 mg of collagen (dry weight) with 0.1 mM (+)-catechin, followed by dialysis to remove the unbound flavonoid. Since incubation of the mammalian enzyme with (+)-catechin does not inhibit its activity, it is postulated that (+)-catechin binds tightly to collagen and modifies its structure sufficiently to make it resistant to enzyme degradation.Acknowledgments. This work was supported by grants from the Easter Seal Research Foundation of the National Easter Seal Society for Crippled Children and Adults (R-7821), and the National Institutes of Health (HL-20447). (+)-Catechin was a generous gift from Zyma SA, CH-1260 Nyon, Switzerland.     

Abnormally soluble collagen produced in fibroblasts cultures

Summary Abnormally soluble collagen is synthesized in vitro not only by skin fibroblasts of Marfan patients but also by those of patients with Ehlers-Danlos type V and cutis laxa. The excessive solubility of collagen is corrected by the addition to the culture medium of a synthetic flavonoid, (+)-catechin.Supported by grants from the National Institutes of Health (Nos. AM-10811, HL-05435, GM-19513 and GM-00081), the National Fondation-March of Dimes, and Zyma, S.A., Nyon, Switzerland.     

Effect of (+)-catechin on renal and intestinal transport.

The ability of dog renal cortex slices to accumulate beta-methyl-glucoside or glycine is enhanced by the flavonoid (+)-catechin at a concentration of 3.5 mM. This stimulatory effect is apparently due to a decreased rate of efflux of either substrate. On the other hand, the uptake of p-amino-hippuric acid and N1-methyl-nicotinamide is inhibited by (+)-catechin. The drug at the same concentration is without action on amino-acid transport by guinea-pig intestine in vitro.     

Inhibitory effects of phenolic compounds on CCl4-induced microsomal lipid peroxidation

The antiperoxidative effects of 35 phenolic compounds, most of them belonging to the flavonoid class, were investigated using CCl4-induced peroxidation of rat liver microsomes. This system was rather insensitive to gallic acid, methyl gallate and ellagic acid. Nevertheless it was inhibited by flavonoids and structure/activity relationships were established. The most potent compounds were gardenin D, luteolin, apigenin (flavones), datiscetin, morin, galangin (flavonols), eriodictyol (flavanone), amentoflavone (biflavone) and the reference compound, (+)-catechin. The natural polymethoxyflavone gardenin D has shown a potency comparable to that of (+)-catechin and higher than that of silybin. Thus, it may be considered as a new type of natural antioxidant with potential therapeutical applications.     

Inhibitory effects of phenolic compounds on CCl4-induced microsomal lipid peroxidation

Summary The antiperoxidative effects of 35 phenolic compounds, most of them belonging to the flavonoid class, were investigated using CCl₄-induced peroxidation of rat liver microsomes. This system was rather insensitive to gallic acid, methyl gallate and ellagic acid. Nevertheless it was inhibited by flavonoids and structure/activity relationships were established. The most potent compounds were gardenin D, luteolin, apigenin (flavones), datiscetin, morin, galangin (flavonols), eriodictyol (flavanone), amentoflavone (biflavone) and the reference compound, (+)-catechin. The natural polymethoxyflavone gardenin D has shown a potency comparable to that of (+)-catechin and higher than that of silybin. Thus, it may be considered as a new type of natural antioxidant with potential therapeutical applications.     

Effect of (+)-catechin on renal and intestinal transport

Summary The ability of dog renal cortex slices to accumulate -methyl-glucoside or glycine is enhanced by the flavonoid (+)-catechin at a concentration of 3.5 mM. This stimulatory effect is apparently due to a decreased rate of efflux of either substrate. On the other hand, the uptake of p-amino-hippuric acid and N¹-methyl-nicotinamide is inhibited by (+)-catechin. The drug at the same concentration is without action on amino-acid transport by guineapig intestine in vitro.This study was supported by grants from Zyma S.A., Nyon. We are grateful to MmesH. Capt andP. Ganguillet and MlleD. Mettraux for their skilful technical assistance.     

Stabilisation of collagen by betel nut polyphenols as a mechanism in oral submucous fibrosis

Treatment of reconstituted collagen fibrils and pieces of rat dermis with the crude extract, purified tannins or (+)-catechin from betel nut (Areca catechu) increases their resistance to both human and bacterial collagenases in a concentration-dependent manner. These tanning agents may stabilise collagen in vivo following damage to the oral epithelium, and promote the sub-epithelial fibrosis which occurs in betel nut chewers.     

Stabilisation of collagen by betel nut polyphenols as a mechanism in oral submucous fibrosis

Summary Treatment of reconstituted collagen fibrils and pieces of rat dermis with the crude extract, purified tannins or (+)-catechin from betel nut (Areca catechu) increases their resistance to both human and bacterial collagenases in a concentration-dependent manner. These tanning agents may stabilise collagen in vivo following damage to the oral epithelium and promote the sub-epithelial fibrosis which occurs in betel nut chewers.     

3′-O-Methyl-(+)-catechin glucuronide and 3′-O-methyl-(+)-catechin sulphate: new urinary metabolites of (+)-catechin in the rat and the marmoset

Summary The major urinary metabolites of (+)-catechin (cyanidanol-3) in the rat were (+)-catechin glucuronide, 3′-O-methyl-(+)-catechin glucuronide and 3′-O-methyl-(+)-catechin sulphate. The latter conjugate was the major metabolite in marmoset urine. To whom reprint requests should be addressed. Acknowledgment. The authors wish to thank Miss Rosemary Dring and Mr P.B. Wood for skilled technical assistance, Zyma S.A., Nyon, Switzerland, for financial support, and the Medical Research Council for a research studentship (to I.C.S.).     

Degradation of collagen by the cariogenic bacteria, Streptococcus mutans

The behaviour of cariogenic Bacteria (Streptococcus mutans) is studied with regard to collagen, which represents 90% of the dentine organic matrix. Collagenase activity of cariogenic Bacteria is measured with radioactive precursors and gel electrophoresis and compared to reference bacterial collagenase (Clostridium histolyticum). Labelled collagen substrate has been prepared with two different methods: extraction by 0,5 M acetic acid from young Rat skin, previously labelled with L-proline 14C, or reduction by Na B3H4. Both collagen sutstrates have been incubated for 2 h in Terleckyj medium in which the Streptococcus mutans have been inoculated. The experiments show a proteolytic activity of Streptococcus Mutans on the collagen substrate.     

Suppressed collagenolytic activity in polymorphonuclear leucocytes from diabetic humans

Summary Extracts of polymorphonuclear leucocytes (PMNL) from diabetic human exhibited less collagenolytic activity than extracts from normoglycemic control subjects. Partially purified control extracts produced ^A and ^B collagen breakdown products of the type generated by mammalian collagenase; the diabetic preparation produced decreased amounts of the same products. The diabetic PMNLs may synthesize abnormally low levels of collagenase or contain inactive forms of this enzyme.Supported by a grant (No. DE-03987) from the National Institute of Dental Research (N.I.H.), USA. This study forms part of the Ph.D. thesis of G.A. Nicoll.Acknowledgments. The authors wish to thank Ms Salema Karim and Mr F.R. Singh for excellent technical assistance.     

Debriding ability of a novel multi-enzyme preparation isolated from Antarctic krill (Euphausia superba)

Summary The wound-debriding activity of various types of proteolytic enzymes and proteases from Antarctic krill (multi-enzyme system consisting of both endo- and exopeptidases) was evaluated. The results, based on the enzymatically acieved weight reduction of a necrotic animal material (excised rat skin) in vitro, clearly showed that the multi-enzyme system (krill) had a higher degrading activity than the single enzyme preparation, or that with only a few enzymes. The debriding effect of the krill enzymes was markedly related to the enzyme concentration, resulting in 70–100% substrate degradation after 24 h. The digesting capacity of trypsin reached about 50%, but an increase in concentration of this enzyme did not substantially influence its overall activity. The effect of streptokinase-streptodornase, collagenase and plasmin-desoxyribonuclease was weak (10–20% digested).     

Anti-phalloidine and anti-α-amanitine action of silybin in comparison with compounds similar to structural parts of silybin

Summary Silybin significantly antagonises the lethal poisoning of mice with -amanitine or phalloidine. In the same test, taxifolin, coniferyl alcohol, fisetin and (+)-catechin were not effective.     

Action de la (+)-catéchine surPseudomonas fluorescens

Summary The (+)-catechin stimulates the multiplication and the protidic biosynthesis ofP. fluorescens. Its effect seems related to a modification of the terminal respiratory pathway.     

Tyrosinase inhibitors from natural and synthetic sources: structure, inhibition mechanism and perspective for the future

Tyrosinase is known to be a key enzyme in melanin biosynthesis, involved in determining the color of mammalian skin and hair. Various dermatological disorders, such as melasma, age spots and sites of actinic damage, arise from the accumulation of an excessive level of epidermal pigmentation. In addition, unfavorable enzymatic browning of plant-derived foods by tyrosinase causes a decrease in nutritional quality and economic loss of food products. The inadequacy of current conventional techniques to prevent tyrosinase action encourages us to seek new potent tyrosinase inhibitors. This article overviews the various inhibitors obtained from natural and synthetic sources with their industrial importance.Received 9 February 2005; received after revision 4 April 2005; accepted 14 April 2005     

Reinterpretation of the ultrastructure of cartilage matrix.

The epiphyseal cartilage from new-born mouse was treated with collagenase in two ways: either before fixation or after glutaraldehyde fixation. The electron dense granules of the matrix were not seen in the micrographs of cartilage treated with collagenase before fixation. It is concluded that collagen plays a definite role in the formation of the granules at the time of tissue fixation and that the granules are fixation artifacts.     

Reinterpretation of the ultrastructure of cartilage matrix

Summary The epiphyseal cartilage from new-born mouse was treated with collagenase in two ways: either before fixation or after glutaraldehyde fixation. The electron dense granules of the matrix were not seen in the micrographs of cartilage treated with collagenase before fixation. It is concluded that collagen plays a definite role in the formation of the granules at the time of tissue fixation and that the granules are fixation artifacts.Commonwealth Academic Staff Fellow. Permanent address: Department of Zoology, University of Poona, Poona 411007, India.     

Elastase, collagenase and the radial elastic properties of arteries

Studies were performed on 203 pairs of dog carotid arteries subjected to unidirectional radial compression. Treatment with 80 U/ml purified elastase for 90 min decreased radial stress, but treatment with 640 U/ml collagenase for 90 min did not. These data suggest that elastin, but not collagen, contributes to wall resistance to radial compression.     

Elastase,collagenase and the radial elastic properties of arteries

Summary Studies were performed on 203 pairs of dog carotid arteries subjected to unidirectional radial compression. Treatment with 80 U/ml purified elastase for 90 min decreased radial stress, but treatment with 640 U/ml collagenase for 90 min did not. These data suggest that elastin, but not collagen, contributes to wall resistance to radial compression.     

Annexin V interactions with collagen

Annexin V was originally identified as a collagen-binding protein called anchorin CII and was isolated from chondrocyte membranes by affinity chromatography on native type II collagen. The binding of annexin V to native collagen type II is stable at physiological ionic strength when annexin V is reconstituted in liposomes. The binding to native collagen types II and X, and to some extent to type I as well, was confirmed using recombinant annexin V. A physiological role for annexin V interactions with extracellular collagen is consistent with the localization of annexin V on the outer cell surface of chondrocytes, microvilli of hypertrophic chondrocytes, fibroblasts and osteoblasts. A breakthrough in our understanding of the function of annexin V was made with the discovery of its calcium channel activity. At least one of several putative functions of annexin V became obvious from studies on matrix vesicles derived from calcifying cartilage. It was found that calcium uptake by matrix vesicles depend on collagen type II and type X binding to annexin V in the vesicles and was lost when collagens were digested with collagenase; calcium influx was reconstituted after adding back native collagen II or V. These findings indicate that annexin V plays a major role in matrix vesicle-initiated cartilage calcification as a collagen-regulated calcium channel.