Punctaria Latifolia As A New Source Of Alginate: Optimization Of Culture Conditions And Alginate Characterization

Abstract

Alginate production is estimated to be around 30,000 metric tonnes per year, sourced mainly from seaweeds collected from a natural habitat. To generate a sustainable market over time, it is important to find new alginate-producing species that can be cultivated. We evaluated the physical-chemical characteristics of Punctaria latifolia alginate (APL) and the best culture conditions for gametophytes and sporophytes. An alginate yield of 17 % (w/w) with a weight-average molecular mass of ≈ 303 x 103 g mol-1, a polydispersity index of 1.6, and a M/G ratio by 1H NMR spectroscopy of 1.09 was obtained. FT-IR spectra confirmed that the extracted polysaccharide had the characteristic of alginates. Rheological properties of 0.1 N NaCl aqueous solutions of APL showed that viscous modulus is higher than elastic one. Also, APL had an antioxidant capacity of 1.24 ± 0.1 mg AAEq g-1 alginate and showed an antitumor effect on tumoral MCF-7 cells at concentrations of 1000 and 2000 μg mL-1. APL had no cytotoxic effects on normal osteoblastic (hFOB) and fibroblastic (NIH3T3) cell lines. In the culture assays, P. latifolia showed the highest gametophyte density at 16 ºC, high concentrations of Provasoli medium (PES) and PES +Kelpak®, salinity of 27.5 to 20 psu and light intensities of 5-35 μmol m-1s-1. On the other hand, the highest sporophyte densities were recorded at 20 ºC, low concentrations of PES and PES + Kelpak®, salinity of 27.5 and low light intensities of 5 μmol m-1s-1.