Abstract Algal polysaccharides exhibit a wide range of biological activities and potential applications. Many of these bioactivities correlate positively with the presence of sulfate groups on the polysaccharides. The most common method used for sulfate quantification in algal samples is the turbidimetric method using the barium chloride-gelatin reagent. However, the original procedure is difficult to adapt for routine analysis since it is laborious and time-consuming. An optimized method was established using 96-well microplates, with the advantage of reducing waste and discrimination between organic and inorganic sulfates. This proposed method produced the same accuracy as the original.

Clorofila a e carotenoides são importantes pigmentos da fotossíntese. Na literatura são encontrados vários protocolos de extração e análise desses pigmentos utilizando, principalmente, plantas vasculares. O objetivo deste estudo foi padronizar uma metodologia de extração e análise dessas substâncias em uma macroalga vermelha, Gracilaria tenuistipitata var. liui. Amostras de talos gametofíticos cultivados in vitro foram trituradas em nitrogênio líquido, extraídas em 1,5 mL de solvente, centrifugadas e os pigmentos analisados quantitativamente e qualitativamente através de espectrofotometria de UV/visível, cromatografia liquida de alta eficiência (CLAE) e CLAE-acoplada a espectrometria de massas (CLAE-EM). Foram testados os parâmetros massa mínima, solvente para extração e número de extrações. Dentre os solventes testados, o metanol foi o mais eficiente, sendo 50mg de material fresco a massa mínima indicada para ser submetida a somente uma extração. Não foram encontradas diferenças significativas na quantificação desses pigmentos comparando-se os dados obtidos em espectrofotometria de UV/visível com os de CLAE. No entanto, para a identificação dos diferentes carotenoides e suas quantificações são necessárias CLAE ou CLAE-EM.

Chlorophyll a and carotenoids are important pigments in photosynthesis. Several studies have been published describing extraction and analysis protocols of these pigments, mainly in vascular plant species. This study standardizes an extraction and analysis protocol of these substances in Gracilaria tenuistipitata var. liui, a red seaweed. Apical portions grown in vitro were triturated in liquid nitrogen. Extracts were prepared in 1.5 mL solvent and centrifuged. Quantitative and qualitative analyses of pigments were performed by UV/visible light spectrophotometry and high performance liquid chromatography (HPLC) and HPLC coupled to mass spectrometry (HPLC-MS). The parameters assessed were: minimum biomass, best extraction solvent, and number of extraction steps. Methanol was the most efficient solvent, and 50 mg fresh biomass was the amount of sample indicated, submitted to one single extraction step. No significant differences were observed in levels of these pigments by UV-visible light spectrophotometry and HPLC. However, HPLC or HPLC-MS are required to identify the different carotenoids present in this seaweed species.