Acute and subchronic safety assessment of Porphyridium purpureum biomass in the rat model

Porphyridium purpureum biomass was assessed for its acute and subchronic safety in albino Wistar rats and for its use as animal feed/human food application. P. purpureum contained 29.9 % protein, 7.99 % lipid, and 2.98 % phycoerythrin on dry basis. Polyunsaturated fatty acids constituted >50 % of the total fatty acids (53.9 % w/w), with eicosapentaenoic acid as the predominant ω3 (21.9 %) and arachidonic acid as the predominant ω6 fatty acid (15.7 %) with an overall ω6/ω3 ratio of 0.42. The essential amino acids (EAAs) constituted 37.97 % (w/w) of proteins with leucine as the predominant amino acid (10.99 %). The EAA index was similar to casein and soybean proteins. Water absorption capacity (WAC; 3.86 ± 0.01 g water g−1 biomass) and oil absorption capacity (OAC; 3.57 ± 0.04 g oil g−1 biomass) were six times higher compared to the basal diet (WAC 0.66 ± 0.007 g water g−1 feed and OAC 0.57 ± 0.02 g oil g−1feed). The acute toxicity study showed that the biomass was safe at acute doses and LD50 exceeded 5.0 g kg−1 body weight, the highest dose used in the study. In a subchronic study, rats were fed a diet containing 0, 2.5, 5.0, 7.5, and 10.0 % levels (w/w) for a period of 13 weeks. The biomass fortification did not induce any untoward changes in physiology such as body weight gain, relative organ weights, histopathology, and hematological and serum biochemical indices. However, supplementation of P. purpureum biomass resulted in decreased serum cholesterol and triglyceride levels compared to control groups indicating its high nutritional value.