Bactericidal Potentiality of Purified Terpenoid Extracts from the Selected Sea Weeds and its Mode of Action

Terpenoids are hydrocarbons involved in a variety of basic functions in plants such as growth, developmentand other physiological events. Terpenes and their associ-ated molecules safe guard the organisms from pest, pathogen and herbivores.Simi-larly, therapeutically terpenoids function as antimicrobial agents against bacteria, fungi and viruses. The mechanism of bactericidal activities may be via inhibiting the synthesis of essential molecules like proteins, nucleic acids, cell-wall compo-nents, cell membrane derailment, bacterial DNA replication or inhibition of meta-bolic pathways.The crude methanolic extracts of the seaweedswere subjected to silica gel column chromatographic purification and eluted with different combina-tions of ethyl acetate: petroleum ether solvent systems. The eluted fractions were further subjected to thin layer chromatography and fractionated by GC-MS. The fractions obtained from Hypnea musciformisrevealed the terpenoids such as eico-sane, heneicosane, 2-pentadecnone,hexadecanoic acid methyl ester, n-hexadeca-noic acid, hexadecanoic acid ethyl ester, heptadecanoic acid methyl ester, 11-octadecanoic acidmetyl ester, whereas Kappapycus alvarezii displayed hexade-cane, eicosane, heptadecane, octadecane, heneicosane, tricosane, hexadecanoic acid, methyl ester and beta amyrin. Similarly, Gracillaria durarevealed hexadeca-noic acid methyl ester, n-hexadecanoic acid, 11-octadecanoic acid and phytol.Subsequently, the bactericidal activities of the purified terpenoid extracts from the sea weeds were carried. Initially, the extracts were tested for their in vitro antibac-terial activity against six bacterial strains such as three Gram-positive (Staphylo-coccus aureus, Streptococcus mutans, Enterococcus faecalis) and three Gram-negative bacteria (Klebsiella pneumoniae,Escherichia coli, Pseudomonas aeru-ginosa) by disc diffusion method. The results revealed that the purified terpenoid extracts of G. duraexhibited significant bactericidal potentiality against S. mutansas compared to other strains. The zone of inhibition, MIC and MBC values narrate the efficacy of the purified terpenoid extract of the species. Remarkable leaching of metabolites like protein and DNA further substantiates the MIC and MBC results. Scanning electron microscopic observations such as clumping, irregularity of cells and ballooned walls reflect the possible membrane damage accounted in the cells by the terpenoid extracts. Further studies are planned to validate the above data by using molecular tool

Reactive oxygen species and ascorbate–glutathione interplay in signaling and stress responses in Sesamum orientale L. against Alternaria sesami (Kawamura) Mohanty and Behera

Sesamum orientale wild and cultivar Thilarani exposed to Alternaria sesami infection triggered the signal cascade H2O2 content that was positively correlated with lipid peroxidation. The data were also supported by H2O2 localization as observed by scanning electron microscopy. Parallely, infection altered chloroplasts marginally and mitochondria effectively in susceptible cultivar than wild sesame. Deformities in the structure of these organelles were accompanied by changes in antioxidant machinery. H2O2 can be effectively detoxified via the ascorbate–glutathione cycle. Increases in ascorbate peroxidase, and glutathione reductase activities concomitant with ascorbate (AsA) and glutathione interplay, as well as AsA regeneration ability, function to keep the balance of cellular H2O2 under pathogenicity. Dehydroascorbate reductase and monodehydroascorbate reductase are responsible for AsA regeneration. Oxidative damage in Thilarani cultivar compared to wild sesame is attributed by a lower induction of the ascorbate–glutathione cycle as an antioxidant defense system and was not sufficient to protect mitochondria but prevent ultrastructural damage of chloroplasts. Overall, the availability of antioxidants and the induction of antioxidant enzyme activities for detoxifying reactive oxygen species (ROS) are regulated effectively in wild sesame against A. sesami induced oxidative stress. The experiments using ROS scavengers demonstrate that the antioxidant defense system is modulated by O2−·− or H2O2 signals

Hepatoprotective action of various partitions of methanol extract of Bauhinia purpurea leaves against paracetamol-induced liver toxicity: involvement of the antioxidant mechanisms

Background: Methanol extract of Bauhinia purpurea L. (family Fabaceae) (MEBP) possesses high antioxidant and anti-inflammatory activities and recently reported to exert hepatoprotection against paracetamol (PCM)-induced liver injury in rats. In an attempt to identify the hepatoprotective bioactive compounds in MEBP, the extract was prepared in different partitions and subjected to the PCM-induced liver injury model in rats. Methods: Dried MEBP was partitioned successively to obtain petroleum ether (PEBP), ethylacetate (EABP) and aqueous (AQBP) partitions, respectively. All partitions were subjected to in vitro antioxidant (i.e. total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH)- and superoxide-radicals scavenging assay, and oxygen radical absorbance capacity (ORAC) assay) and anti-inflammatory (i.e. lipooxygenase (LOX) and xanthine oxidase (XO) assay) analysis. The partitions, prepared in the dose range of 50, 250 and 500 mg/kg, together with a vehicle (10 % DMSO) and standard drug (200 mg/kg silymarin) were administered orally for 7 consecutive days prior to subjection to the 3 mg/kg PCM-induced liver injury model in rats. Following the hepatic injury induction, blood samples and liver were collected for the respective biochemical parameter and histopathological studies. Body weight changes and liver weight were also recorded. The partitions were also subjected to the phytochemical screening and HPLC analysis. Results: Of all partitions, EABP possessed high TPC value and demonstrated remarkable antioxidant activity when assessed using the DPPH- and superoxide-radical scavenging assay, as well as ORAC assay, which was followed by AQBP and PEBP. All partitions also showed low anti-inflammatory activity via the LOX and XO pathways. In the hepatoprotective study, the effectiveness of the partitions is in the order of EABP>AQBP>PEBP, which is supported by the microscopic analysis and histopathological scoring. In the biochemical analysis, EABP also exerted the most effective effect by reducing the serum level of alanine transaminase (ALT) and aspartate transaminase (AST) at all doses tested in comparison to the other partitions. Phytochemical screening and HPLC analysis suggested the presence of: flavonoids, condensed tannins and triterpenes in EABP; flavonoids, condensed tannins and saponins in PEBP and; only saponins in AQBP. Conclusion: EABP demonstrates the most effective hepatoprotection against PCM-induced liver injury in rats. This observation could be attributed to its remarkable antioxidant activity and the presence of flavonoids that might probably act synergistically with other biocompounds to cause the hepatoprotection