In vitro and in vivo efficacy of partially purified herbal extracts against bacterial fish pathogens

The effect of partially purified extracts of sea grass (Cymodocea serrulata), turmeric (Curcuma longa), Spirulina (Spirulina platensis), and beet root (Beta vulgaris) on the antimicrobial, antioxidant, and hemato-biochemical changes in ornamental dotty back, Pseudochromis dilectus against isolated fish bacterial pathogens (Proteus mirabilis, Bacillus pumilus, and Staphylococcus sciuri) under in vitro and in vivo conditions is reported. Among the extracts turmeric extract exhibited significant antibacterial activity. The extract possesses the highest antioxidant property and phenol content; the GC-MS analysis revealed the highest presence of Ar-turmerone (42.85%) and Curlone (18.80%). The potential fractions possess reducing power and free radical scavenging activity. The mortality against P. mirabilis at doses of 2.5 x 10(8) and 2.5 x 10(8) CFU was 100% whereas against S. sciuri (2.5 x 10(7) and 2.5 x 10(8)) it was 70 and 80%. The highest bacterial load was observed in kidney (3.1 x 10(7) CFU/g) and liver (2.6 x 10(8) CFU/g) against P. mirabilis. The LD50 study suggested that all the fish die at doses of 2.5 x 10(7) (CFU/fish) and 2.5 x 10(8) (CFU/fish) after 15 days of challenge with P. mirabilis. Among the purified sub fractions, the sub-fraction II (F-II) at 5 and 10 mg/ml resulted in elevated levels of WBC and RBC, lymphocytes, and neutrophils; further the percentage of monocytes and granulocytes, total protein, total lipid, and glucose also increased significantly. At 1 mg/ml the relative percent survival (RPS) was 100% in sub-fraction II (F-I) group as in control. With 5 mg/ml in F-I and 1 mg/ml in F-II group the RPS was 94%; however, in 10 mg/ml of F-I and 5 mg/ml of F-II groups the RPS declined to 89%. The lowest mortality of RPS (79%) was observed in 10mg/ml in F-II group. The present results suggest that the partially purified turmeric extract elevated antimicrobial and antioxidant activities by improving the hemato-biochemical profiles and survival rate in P. dilectus against P. mirabilis. (C) 2016 Elsevier B.V. All rights reserved.