Inhibitory effects on phospholipase A2 and antivenin activity of melanin extracted from Thea sinensis Linn

Hung, Yao Ching; Sava, Vasyl; Hong, Meng-Yen; Huang, G. S.

doi:10.1016/j.lfs.2003.09.048

Cited by 51 publications

(23 citation statements)

References 19 publications

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“…Intraperitoneal injection of 3 mg of a "melanin" extracted from black tea substantially reduced the toxic effects of several snake venom toxins [103]. The antivenin activity appears to be due to the chelation of the tea melanin to calcium ions and to nonspecific binding to phospholipase A2 present in the snake venom.…”

Section: Snake Venom Toxinsmentioning

confidence: 98%

Overview of antibacterial, antitoxin, antiviral, and antifungal activities of tea flavonoids and teas

Friedman¹

2006

Molecular Nutrition Food Res

548

367

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Tea leaves produce organic compounds that may be involved in the defense of the plants against invading pathogens including insects, bacteria, fungi, and viruses. These metabolites include polyphenolic compounds, the six so-called catechins, and the methyl-xanthine alkaloids caffeine, theobromine, and theophylline. Postharvest inactivation of phenol oxidases in green tea leaves prevents oxidation of the catechins, whereas postharvest enzyme-catalyzed oxidation (fermentation) of catechins in tea leaves results in the formation of four theaflavins as well as polymeric thearubigins. These substances impart the black color to black teas. Black and partly fermented oolong teas contain both classes of phenolic compounds. A need exists to develop a better understanding of the roles of polyphenolic tea compounds in food and medical microbiology. This overview surveys and interprets our present knowledge of activities of tea flavonoids and teas against foodborne and other pathogenic bacteria, virulent protein toxins produced by some of the bacteria, virulent bacteriophages, pathogenic viruses and fungi. Also covered are synergistic, mechanistic, and bioavailability aspects of the antimicrobial effects. Further research is suggested for each of these categories. The herein described findings are not only of fundamental interest, but also have practical implications for nutrition, food safety, and animal and human health.

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Section: Snake Venom Toxinsmentioning

confidence: 98%

Overview of antibacterial, antitoxin, antiviral, and antifungal activities of tea flavonoids and teas

Friedman¹

2006

Molecular Nutrition Food Res

548

367

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“…Melanin also plays an important role in microorganisms against damages from high temperatures, chemical stress, and biochemical threats [19]. The role of biologically active melanin includes being cytotoxic, antitumor [20], antivenin [21], antiviral [22], and radio protective [23]. Sun-screens containing water soluble melanin protect against harmful UV radiations.…”

Section: Introductionmentioning

confidence: 99%

Production and Cytotoxicity of Extracellular Insoluble and Droplets of Soluble Melanin byStreptomyces lusitanusDMZ-3

Madhusudhan

Mazhari

Dastager

et al. 2014

BioMed Research International

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A Streptomyces lusitanus DMZ-3 strain with potential to synthesize both insoluble and soluble melanins was detected. Melanins are quite distinguished based on their solubility for varied biotechnological applications. The present investigation reveals the enhanced production of insoluble and soluble melanins in tyrosine medium by a single culture. Streptomyces lusitanus DMZ-3 was characterized by 16S rRNA gene analysis. An enhanced production of 5.29 g/L insoluble melanin was achieved in a submerged bioprocess following response surface methodology. Combined interactive effect of temperature (50°C), pH (8.5), tyrosine (2.0 g/L), and beef extract (0.5 g/L) were found to be critical variables for enhanced production in central composite design analysis. An optimized indigenous slant culture system was an innovative approach for the successful production (264 mg/L) of pure soluble melanin from the droplets formed on the surface of the culture. Both insoluble and soluble melanins were confirmed and characterized by Chemical, reactions, UV, FTIR, and TLC analysis. First time, cytotoxic study of melanin using brine shrimps was reported. Maximum cytotoxic activity of soluble melanin was Lc50-0.40 µg/mL and insoluble melanin was Lc50-0.80 µg/mL.

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“…It is shown that Sepia melanin can be nanonized and dispersed in pure water or biological medium by processing of melanin powder in suspension with a magnetic stirrer running for 48 h. It is also shown that irradiation of Sepia melanin in suspension with femtosecond laser pulses can result in photo-fragmentation, which leads to nanonization and dispersibilization at a rate higher than that with mechanical stir. In this report and our previous work [9] we have demonstrated that both Sepia melanin (natural melanin) and synthetic melanin can be nanonized and dispersed in pure water or biological medium by processing of melanin powder in suspension with a magnetic stirrer running for 48 h. Although water-dispersible melanin processed with the techniques reported herein would not be practical photosensitizer for PDI, we expect it could be utilized in other applications such as adjuvant in radiation therapy [38], antioxidant [4,5,9,39], metal-ion scavenger [40], antidote for acute radiation syndrome [38], antitumor drug [41,42], antivenin drug [43], antivirus [44] and contrast-enhancing agent in magnetic resonance imaging (MRI) [45,46].…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the Practicality of Melanin as a Photodynamic-Inactivation Photosensitizer by Its Nanonization

Liu

Lin

2015

J. Photopol. Sci. Technol.

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It has been proposed that melanin may play a role in the antimicrobial defense system of a human body. Furthermore, it has been found that melanin has efficacy against oxidative stress, tumor, venin, virus, and heavy metal ions. In view of the great potential of melanin in medical applications revealed by its photodynamic actions, we develop techniques based on mechanical stir and photo-fragmentation with femtosecond laser pulses respectively for nanonization of melanin to produce nanometer-sized and water-dispersible melanin, in order to more reliably study melanin as a photodynamic-inactivation photosensitizer. In vitro experiments on the antimicrobial efficacy of nanonized melanin were conducted. It was found that both Sepia melanin and synthetic melanin do not have a significant effect on lowering the survival rate of Gram-positive bacteria Streptococcus mutans with or without light irradiation. Therefore, it is concluded that melanin, though capable of generating melanin radicals and reactive oxygen species, is not a practical agent for photodynamic inactivation.

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Inhibitory effects on phospholipase A2 and antivenin activity of melanin extracted from Thea sinensis Linn

Cited by 51 publications

References 19 publications

Overview of antibacterial, antitoxin, antiviral, and antifungal activities of tea flavonoids and teas

Overview of antibacterial, antitoxin, antiviral, and antifungal activities of tea flavonoids and teas

Production and Cytotoxicity of Extracellular Insoluble and Droplets of Soluble Melanin byStreptomyces lusitanusDMZ-3

Evaluation of the Practicality of Melanin as a Photodynamic-Inactivation Photosensitizer by Its Nanonization

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