Melanins are enigmatic pigments that are produced by a wide variety of microorganisms including several species of bacteria and fungi. For more than 40 years, fungi have been known to produce pigments called melanins. Melanin pigment production by mushrooms was not intensively studied. The present study was carried out on isolation and characterization of melanin from an edible mushroom Pleurotus cystidiosus var. formosensis. The mushroom produced dark mucous mass of hyaline arthrospores on mycelium. The coremia exclusively produced dikaryotic arthrospores with the remnant of a clamp connection. Continuous cell extension and division in the coremium stipe supplied cells for arthroconidiation at the coremium apex, which is surrounded by a liquid droplet (coremioliquid). The black coloured coremea (conidia) were produced by Antromycopsis macrocarpa (anamorph of P. cystidiosus) when cultured on potato dextrose agar medium. The agar plate was incubated at continuous light illumination for high amount of pigment (coremea) production. The slimy layer of the coremea was extracted and partially purified by alkaline and acid treatment. The black pigment was confirmed as melanin based on UV, IR and EPR spectra apart from chemical analysis. This is the first report on characterization of melanin obtained from Pleurotus cystidiosus var. formosensis.

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a b s t r a c tSenecio candicans DC is an endemic sub-shrubby climber and the hot water extract of this plant is being used traditionally for the treatment of gastric ulcer. The first objective of the present study was to design a standardized protocol for in vitro regeneration of S. candicans from leaf explants and compare the antioxidant activities of aqueous extracts of in vitro calluses and in vivo leaves by three different methods. Callus was initiated on Murashige and Skoog's (MS) basal media supplemented with various concentrations (0.5 mg L −1 to 2.0 mg L −1 ) and combinations of auxins and cytokinins under dark incubation for 2 weeks. The percentage of callus induction (PCI) and the fresh weights were recorded after 28 days of culture. The fresh weights were again recorded after 4 weeks of sub-culture to determine the relative fresh weight growth (RFWG). The highest PCI of 87% and RFWG of 3.245 were obtained on an MS medium supplemented with 6-benzyl amino purine (BA) 2 mg L −1 and indole-3-acetic acid (IAA) 2 mg L −1 . The callus obtained after 28 days of culture were inoculated on MS medium supplemented with different growth regulators. The maximum average shoot length (4.28 ± 0.27 cm) and maximum percentage of shoot induction (81%) was observed on MS medium supplemented with BA (2.0 mg L −1 ) + IAA (1.0 mg L −1 ). The maximum root induction percentage (90%) from shoots was observed on half strength MS medium fortified with 3.0 mg L −1 α-naphthalene acetic acid (NAA) alone. The antioxidant activity of in vivo leaf was significantly high compared to the in vitro callus in all the three antioxidant assays. A linear correlation between antioxidant activity and the total phenolic content was observed. The current protocol for in vitro regeneration would pave the way for further research on the isolation of bioactive compounds including antioxidants by cell suspension culture.

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