Modulatory effect of Coccinia indica on aortic collagen in streptozotocin-induced diabetic rats.

1. The effects of Coccinia indica, an indigenous plant used in Ayurvedic medicine in India, on aortic collagen content and its characteristics were assessed in streptozotocin (STZ) diabetic rats. 2. Rats were made diabetic with a single intraperitoneal injection of STZ (45 mg/kg). Blood glucose, hydroxyproline, collagen, extent of glycation, collagen-linked fluorescence, soluble pattern of pepsin-soluble collagen, shrinkage temperature, alpha/beta ratio of type I collagen and type I/type III collagen ratio were determined in rats treated with C. indica leaf extract (CLEt; 200 mg/kg for 45 days using an oral intragastric tube). 3. In diabetic rats, the collagen content, as well as the degree of cross-linking, was increased, as evidenced by increased shrinkage temperature and decreased pepsin solubility. The alpha/beta ratio of type I collagen and the type I/type III collagen ratio of pepsin-soluble collagen were significantly decreased in STZ diabetic rats. 4. In conclusion, administration of CLEt for 45 days to STZ diabetic rats significantly reduced the accumulation and cross-linking of collagen. The effects of C. indica (collagen content 23.87 +/- 1.52 mg/100 mg tissue (t value = 6.80), extent of cross-linking 0.893 +/- 0.072 mg hydroxyproline/100 mg tissue (t value = 9.0)) were comparable with those of glibenclamide (collagen content 26.18 +/- 1.65 mg/100 mg tissue (t value = 4.58), extent of cross-linking 0.787 +/- 0.057 mg hydroxyproline/100 mg tissue (t value = 7.1)), a reference drug.

Similarity between the major collagens of cuttlefish cranial cartilage and cornea.

Invertebrates possess unique collagen-containing connective tissue elements, the biochemistry of which is not clearly understood. We previously reported the occurrence of a novel heterotrimeric type V/XI like collagen in the cranial cartilage of the cuttlefish Sepia officinalis. We report here the purification of the three chains by ion exchange chromatography and the physicochemical characteristics of this collagen. This collagen shared substantial similarity to the collagen purified from the cornea of S. officinalis, with respect to chain composition, cyanogen bromide peptide profile and amino acid composition. The mobility of the C3 chain was retarded in the corneal collagen, which also had an increased glycine content and a smaller ratio of hydroxylysine to lysine, together with a reduction in bound carbohydrates. The cartilage collagen had a higher denaturation temperature than corneal collagen. As observed by transmission electron microscopy of reconstituted fibrils, the heterotrimeric invertebrate collagen formed fibrils of no apparent periodicities as opposed to the regular 64-nm banding pattern of milk shark (Rhizoprionodon acutus) cartilage collagen. This is also the first report on the molecular species of collagen in an invertebrate cornea. Our results strongly support the functioning of minor vertebrate collagens as major collagens in some invertebrates, close similarity of collagens in two tissues with different functions and would hold significance to our understanding of collagen polymorphism and the evolution of the extracellular matrix.

Inhibition of collagen glycation and crosslinking in vitro by methanolic extracts of Finger millet (Eleusine coracana) and Kodo millet (Paspalum scrobiculatum).

The present investigation was carried out to study the effects of methanolic extracts of Finger millet (Eleusine coracana) and Kodo millet (Paspalum scrobiculatum) on glycation and crosslinking of collagen. Tail tendons obtained from rats weighing 200-225 g were incubated with glucose (50 mM) and 3 mg of extracts of the above millets in methanol under physiological conditions of temperature and pH for 10 days. Early glycation was estimated by phenol-sulfuric acid method and the crosslinking was assessed by pepsin digestion, cyanogen bromide peptide map and viscosity measurements. Tendon collagen incubated with glucose (50 mM) showed 65% solubility on pepsin treatment; poor resolution of bands in the cyanogen bromide peptide map, and intrinsic viscosity of 0.84 dl/g. The collagen incubated with Finger millet and Kodo millet extracts inhibited glycation; 89% and 92% solubility in pepsin; good resolution of bands in the cyanogen bromide peptide map and intrinsic viscosity of 0.46 and 0.58 dl/g respectively. The study implicates the potential usefulness of the above millets in protection against glycation and crosslinking of collagen.

Influence of Terminalia chebula on dermal wound healing in rats.

The effects of topical administration of an alcohol extract of the leaves of an evergreen plant, Terminalia chebula, on the healing of rat dermal wounds, in vivo, was assessed. T. chebula treated wounds healed much faster as indicated by improved rates of contraction and a decreased period of epithelialization. Biochemical studies revealed a significant increase in total protein, DNA and collagen contents in the granulation tissues of treated wounds. The levels of hexosamine and uronic acid in these tissues, also increased upto day 8 post-wounding. Reduced lipid peroxide levels in treated wounds, as well as ESR measurement of antioxidant activity by DPPH radical quenching, suggested that T. chebula possessed antioxidant activities. The tensile strength of tissues from extract-treated incision wounds increased by about 40%. In addition, T. chebula possessed antimicrobial activity and was active largely against Staphylococcus aureus and Klebsiella. These results strongly document the beneficial effects of T. chebula in the acceleration of the healing process.