Naringenin isolated from Citrus reticulata blanco fruit peel inhibits the toxicity of snake venom proteins - An in vitro and in vivo study.

Snake envenomation is a serious hazard in tropical countries. In the current study, the bioactive compound from the methanolic extract of Citrus reticulata was purified using polarity gradient chromatography and structurally characterized by UV-spectroscopy, NMR, and LC-MS. The purified metabolite, naringenin, inhibited PLA2 (51%) and hemolytic (59.8%) activity of the Naja naja venom. Histopathological examination and edema studies carried out using mice confirmed the inhibitory effects of naringenin. This is the first report on the inhibitory potential of naringenin isolated from Citrus reticulata. The study thus unravels the possibility for the use of Citrus reticulata metabolites as a supplement during the snake bite treatment.

Synergistic effect of flavonoids combined with antivenom on neutralisation of Naja naja venom

Objective: To evaluate the neutralizing effects of flavonoids on snake venom toxicity by stand-alone and combinatorial approaches. Methods: Synthetic flavonoids were assessed, either individually or in combination with antivenom, for their neutralization of phospholipase A

Synergistic effect of flavonoids combined with antivenom on neutralisation of Naja naja venom

Objective: To evaluate the neutralizing effects of flavonoids on snake venom toxicity by stand-alone and combinatorial approaches. Methods: Synthetic flavonoids were assessed, either individually or in combination with antivenom, for their neutralization of phospholipase A

Metabolites from the citrus extracts inhibit the activity of selected proteins in Indian Cobra (Naja naja) venom.

ETHNOPHARMACOLOGICAL RELEVANCE: Snakebite is a severe problem in many parts of the world, specifically in tropical and subtropical regions. A range of medicinal plant extracts are administered for treating snake bite. Of the many common plants, extracts of Citrus species have been documented to be used for treating snake bite and have been shown to decrease the snake venom toxicity. AIM: The aim of the current work is to evaluate the utility of citrus peel extracts (Citrus aurantium L. and Citrus reticulate Blanco) in the management of Indian cobra envenomation. MATERIALS AND METHODS: Peels of citrus species were evaluated for their phospholipase A2, protease and haemolytic inhibition properties. The phytochemicals present in the extract were inferred using GC-MS. In-vivo studies, using mice model, were done to confirm the inhibitory effect of the extracts. Molecular docking was used to understand the possible binding modes of selected phytochemicals to snake venom phospholipase. RESULTS: Citrus peel extracts are rich in polyphenols, flavonoids and tannins. The methanolic extract of Citrus aurantium L. and Citrus reticulate Blanco inhibits phospholipase (75%), protease (71%) and hemolysis (80%) activity of the venom. GC-MS analyses indicate the presence of ß-sitosterol, n-hexadecanoic acid, eicosanoic acid, and flavone in both the extracts. In addition, C. reticulate extract contains α-tocopherol and squalene. Molecular docking revealed that α-tocopherol, spiro [androst-5-ene-17,1'-cyclobutan]-2'-one,3-hydroxy-(3ß,17ß)- and ß-sitosterol acetate bind with moderate affinity to the catalytic site of phospholipase A2. CONCLUSION: The present study provides new molecular insight and scientific evidence on the utility of the methanolic extracts of citrus peels to neutralize the venom toxins of Naja naja.

Differential Production of Pigments by Halophilic Bacteria Under the Effect of Salt and Evaluation of Their Antioxidant Activity.

Microorganisms that survive in the high salt environment have been shown to be a potential source for metabolites with pharmaceutical importance. In the present study, we have investigated the effect of 5 and 10% (w/v) NaCl on growth, biochemical changes, and metabolite production in seven moderately halophilic bacteria isolated from the salterns/mangrove area of South India. Metabolite production by Bacillus VITPS3 increased by 3.18-fold in the presence of 10% (w/v) NaCl concentration. Total phenolic and flavonoid content increased in Bacillus VITPS5 (11.3-fold) and Planococcus maritimus VITP21 (5.99-fold) whereas ß-carotene content was less at higher NaCl concentrations. VITP21 and VITPS5, in response to NaCl, produced metabolites with higher (6.72- and 4.91-fold) DPPH and ABTS radical scavenging activity. UV/visible spectrophotometry of the extracts confirmed the presence of flavonoids, phenolics, and related compounds. 1H-NMR spectra indicated substantial changes in the metabolite production in response to salt concentration. Principal component analysis (PCA) revealed that VITP21 extracts exhibited the highest antioxidant activity compared with other extracts. The present study presents the first report on the comparative analysis of pigment production by moderate halophilic bacteria, in response to the effect of salt and their relation to radical scavenging property.

Lauric acid and myristic acid from Allium sativum inhibit the growth of Mycobacterium tuberculosis H37Ra: in silico analysis reveals possible binding to protein kinase B.

CONTEXT: The bulb of Allium sativum Linn (Alliaceae) has numerous medicinal values. Though the petroleum ether extract of the bulb has shown to exhibit antimycobacterial activity, the phytochemical(s) responsible for this inhibitory activity is not known. OBJECTIVE: To characterize the bioactive compounds in the petroleum ether extract of Allium sativum (garlic) that inhibit the growth of Mycobacterium tuberculosis H37Ra. MATERIALS AND METHODS: Bioactivity-guided fractionation was employed to isolate the bioactive compounds. Antimycobacterial activity was evaluated by well-diffusion method and microplate alamar blue assay (MABA). Infrared spectroscopy, mass spectrometry and nuclear magnetic resonance spectroscopy were used to characterize the bioactive compounds. Autodock was used to obtain information on molecular recognition, and molecular dynamics simulation was performed using GROMACS. RESULTS: The bioactive compounds that inhibited the growth of M. tuberculosis H37Ra were found to be lauric acid (LA) and myristic acid (MA). The minimal inhibitory concentration of LA and MA was found to be 22.2 and 66.7 µg/mL, respectively. In silico analysis revealed that these fatty acids could bind at the cleft between the N-terminal and C-terminal lobes of the cytosolic domain of serine/threonine protein kinase B (PknB). DISCUSSION AND CONCLUSION: The inhibition activity was dependent on the alkyl chain length of the fatty acid, and the amino acid residues involved in binding to fatty acid was found to be conserved across the Pkn family of proteins. The study indicates the possibility of using fatty acid derivatives, involving Pkn family of proteins, to inhibit the signal transduction processes in M. tuberculosis.

Pre-clinical assessment of the effectiveness of modified polyvalent antivenom in the neutralization of Naja naja venom toxicity.

The potency of conventional antivenom (AV) conjugated to soy protein nanoparticles (NPs) (C-AV) was compared with the free AV in neutralizing the systemic toxicity of Naja naja venom. The effective dose (ED50 ) of AV and C-AV to neutralize the venom-induced toxicity in mice was found to be 19.89 and 9.50 mg, respectively. The histopathological examination of heart, liver, and kidney indicated that the systemic toxicity induced by the venom was effectively neutralized by lower concentrations of C-AV than compared with AV. In addition, C-AV was found to be more effective in neutralizing the edema forming activity of N. naja venom compared with the AV. Thus, the results of this study indicate that the potency of commercially available AV could be improved by conjugating it to soy protein NPs.

Planococcus maritimus VITP21 synthesizes (2-acetamido-2-deoxy-α-d-glucopyranosyl)-(1→2)-ß-d-fructofuranose under osmotic stress: a novel protein stabilizing sugar osmolyte.

A halotolerant bacterium, Planococcus maritimus VITP21 isolated from a saltern region in Kumta along the Arabian Sea Coast of India was found to have increased cellular levels of sugars (up to 2.3-fold) under osmotic stress when grown in minimal medium with glucose as the sole carbon and energy source supplemented with 10% w/v NaCl. The major sugar osmolyte which increased with the concentration of NaCl in the growth medium was purified and characterized using various nuclear magnetic resonance spectroscopy techniques. The sugar was found to be similar to sucrose but with the C-2 hydroxyl group of the glucose ring substituted with acetamido group, which is not previously reported for its natural synthesis by any other organism. This novel sugar, (2-acetamido-2-deoxy-α-d-glucopyranosyl)-(1→2)-ß-d-fructofuranose, exhibited stabilizing effect on a model protein α-amylase by increasing the apparent midpoint transition, onset temperature of denaturation, and free energy of thermal unfolding.