Anti–white spot syndrome virus activity of Ceriops tagal aqueous extract in giant tiger shrimp Penaeus monodon

Bioassay Directed Fractionation of Petroleum Ether Extract of Aerial Parts of Ceriops tagal: Isolation of Lupeol as the Nematicidal Agent against Cyst Nematode Heterodera zeae

Plant parasitic cyst nematode  Heterodera zeae  is a pest, causing substantial economic losses in agriculture. Organic pesticides, based on plant products have emerged as eco-benign nematicidal agents.  Ceriops tagal  is a well-known marine medicinal plant which has not been evaluated against any nematode. Petroleum ether extract of the aerial parts of the plant (CTP), exhibited promising activity against infective stage larvae of  H. zeae . On subjecting to classical solvent-solvent separation, it afforded petroleum ether soluble (CTP-S), methanol soluble ( CTPMS-1 , CTPMS-2) and insoluble (CTPM-IN-2) fractions, which exhibited activity against the cyst nematode within 24 h exposure. GC, GCMS and ESI-HRMS analyses of CTPMS-1 and CTPMS-2 fractions resulted in the identification of a number of compounds, including pentacyclic triterpenoids, lupeol ( 1 ), betunal ( 2 ), betulin ( 3 ), lupenone ( 4 ), betulonaldehyde ( 5 ), betulonic acid ( 7 ), methyl-3-acetoxy-27- O -(3,4-dihydroxy- E -cinnamoyl)-20(29)-lupen-28-oate ( 8 ) and  β -amyrin, along with phenylpropanoid esters, fatty acids and their derivatives, benzamide, and indole derivatives. CTPM-IN-2 which mainly contained lupeol ( 1 ) exhibited maximum nematicidal activity, with 91% and 93% mortality of the larvae of  H. zeae , after exposure for 72 h at the concentration of 0.5% and 1%, respectively. Its fractionation and purification through column chromatography resulted in the isolation and identification of four lupane-type triterpenoids  1 ,  3 ,  4  and betulinic acid ( 6 ). One of its most abundant column fractions CC-9-18 (145 mg) which exhibited substantial activity, with 81% mortality at the lowest concentration of 0.125% after 48 h of incubation mainly contained lupeol. It seems lupeol, a wide spread bio-privileged triterpenoid is the nematicidal principle of the plant as its authentic sample showed LC 50 value of 0.061 after 72 h exposure. It is for the first time that nematicidal activity is reported for any part of  C. tagal  and that of lupeol against  H. zeae.  Pentacyclic triterpenoids  1 - 8  are biosynthetically related. Of the twenty-four compounds isolated or identified in the present investigation only five constituents  1 ,  3 ,  6 ,  7  and palmitic acid have been isolated previously from  C. tagal .

Functional Characterization of a c-type Lysozyme from Indian Shrimp Fenneropenaeus indicus

Lysozyme gene from Fenneropenaeus indicus was cloned, expressed in Escherichia coli and characterized. The cDNA consists of 477 base pairs and encodes amino acid sequence of 159 residues. F. indicus lysozyme had high identity (98%) with Fenneropenaeus merguiensis and Fenneropenaeus chinensis and exhibits low to moderate identities with lysozymes of other invertebrates and vertebrates. This lysozyme is presumed to be chicken types as it possesses two catalytic and eight cysteine residues that are conserved across c-type lysozymes and a c-terminal extension, which is a characteristic of lysozymes from marine invertebrates. Further, the antimicrobial properties of the recombinant lysozyme from F. indicus were determined in comparison with recombinant hen egg white lysozyme. This exhibited high activity against a Gram-negative pathogenic bacterium Salmonella typhimurium and two fungal strains Pichia pastoris and Saccharomyces cerevisiae in turbidimetric assay. Distribution of lysozyme gene and protein in tissues of shrimps infected with white spot syndrome virus revealed that the high levels of lysozyme are correlated with low and high viral load in abdominal muscle and tail, respectively. In conclusion, lysozyme from F. indicus has a broad spectrum of antimicrobial properties, which once again emphasizes its role in shrimp innate immune response.

Sulfated galactans isolated from the red seaweed Gracilaria fisheri target the envelope proteins of white spot syndrome virus and protect against viral infection in shrimp haemocytes

The present study was aimed at evaluating an underlying mechanism of the antiviral activity of the sulfated galactans (SG) isolated from the red seaweed Gracilaria fisheri against white spot syndrome virus (WSSV) infection in haemocytes of the black tiger shrimp Penaeus monodon. Primary culture of haemocytes from Penaeus monodon was performed and inoculated with WSSV, after which the cytopathic effect (CPE), cell viability and viral load were determined. Haemocytes treated with WSSV-SG pre-mix showed decreased CPE, viral load and cell mortality from the viral infection. Solid-phase virus-binding assays revealed that SG bound to WSSV in a dose-related manner. Far Western blotting analysis indicated that SG bound to VP 26 and VP 28 proteins of WSSV. In contrast to the native SG, desulfated SG did not reduce CPE and cell mortality, and showed low binding activity with WSSV. The current study suggests that SG from Gracilaria fisheri elicits its anti-WSSV activity by binding to viral proteins that are important for the process of viral attachment to the host cells. It is anticipated that the sulfate groups of SG are important for viral binding.