In vivo developmental studies of Helicoverpa armigera and in silico molecular interactions with trypsin reveal the bio-insecticidal potential of trypsin inhibitor (SSTI) isolated from Solanum surattense.

We report the impact of gut protease inhibition on the development of Helicoverpa armigera by trypsin inhibitor and the use of molecular modeling to understand the mechanism of trypsin inhibition. Larvae of H. armigera fed on an artificial diet containing 150 and 300 µg/ml SSTI showed a negative impact on the insects' development in terms of mean larval weight, larval fatality, survival rate, and nutritional indices. Prominent physical abnormalities like curled wings, malformed appendages, and small body size were observed during the development. Gene expression studies revealed down regulation in trypsin (HaTry 1, 2, 3, 4, 6, 8) and chymotrypsin (HaChy 1, 2, 3, 4) genes of the larval gut upon treatment of SSTI. Homology modeling has been used to build the three-dimensional structure of SSTI, which showed ß-sheets having a stable canonical inhibitory loop (CIL) with conserved lysine residue. Molecular docking studies showed the strong binding of SSTI at the active site of trypsin. Molecular dynamic (MD) simulation revealed the stable interactions of the rigid CIL of SSTI at the active site of trypsin, leading to its destabilization. Conserved lysine63 of the P1 site in SSTI forms a strong hydrogen bonding network with residues Asp189 and Ser190 of trypsin.

Characterization of a Bowman-Birk type trypsin inhibitor purified from seeds of Solanum surattense.

A Bowman-Birk type trypsin inhibitor protein (SSTI) from seeds of the medicinal plant Solanum surattense was isolated, purified and characterized. SSTI showed a single band on SDS-PAGE corresponding to 11.4 kDa molecular weight. It is a glycoprotein (2.8% glycosylation) that differentially interacted with trypsin and chymotrypsin in a concentration-dependent manner. Its peptide sequence is similar to other Bowman-Birk type protease inhibitors found in Glycine max and Phaseolus acutifolius. The inhibitory activity was stable over a wide range of pH (1-10) and temperatures (10-100° C). Far-UV Circular Dichroism (CD) studies showed that SSTI contains ß sheets (~ 23%) and α helix (~ 6%) and demonstrated structural stability at wide pH and high temperature. The kinetic analysis revealed a noncompetitive (mixed) type nature of SSTI and low inhibitor constant (Ki) values (16.6 × 10-8 M) suggested strong inhibitory activity. Isothermal titration calorimetric analysis revealed its high affinity towards trypsin with dissociation constant (Kd) 2.28 µM.

Chebulinic acid and Boeravinone B act as anti-aging and anti-apoptosis phyto-molecules during oxidative stress.

INTRODUCTION: Aquatic pollutant Malachite green (MG) induces oxidative stress by producing intracellular H2O2 and associated hydroxyl, hydroxymethyl or hydroperoxide radicals in Saccharomyces cerevisiae. These radicals disturb cellular functions leading to early aging. Exogenous supply of natural antioxidants may play a crucial role as anti-aging by ensuring the cellular survival. METHODS: Protective effect of Chebulinic acid (CA) and Boeravinone B (BB) was biochemically evaluated by measuring the expression levels of antioxidant enzymes. Intracellular oxidants generation, nuclear damage, necrosis, apoptosis, reduction in caspase 3/7 activity studied microscopically, spectrofluorometrically and biochemically along with growth dynamics and relative quantitation of Yap1, Sir2 and Bir1 expression using RT-PCR. RESULTS: Malachite green (MG) showed adverse effect on S. cerevisiae showing 400.83% enhancement in accumulation of intracellular H2O2 and associated hydroxyl, hydroxymethyl or hydroperoxide radicals. Independent supplementation of CA (5 µg/ml) and BB (3 µg/ml) significantly reduced the accumulation by 385.78 and 372.68%, respectively. Presence of MG extended the lag phase of growth curve and also reduced colony forming units (CFUs)/ml to 3 × 108 from 15 × 108. Whereas, CA and BB maintained the normal growth curve, CFUs and proved as anti-aging. Elevation in the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) by 241.35, 539.02 and 432.60% was observed after 2 h MG exposure. However, CA and BB significantly reduced the CAT, SOD and GPx activities. Microscopic observation of CA and BB augmented cells revealed protection from H2O2 and associated hydroxyl, hydroxymethyl or hydroperoxide radicals accumulation, nuclear disorganization, morphological distortion, apoptosis and necrosis contrary to MG exposed cells. An enhancement of 112.78% in caspase 3/7 activity was noted in MG exposed cells over control. Both CA and BB supplementation reduced the caspase 3/7 activity by 106.06 and 105.82%, respectively which was almost near normal. MG was found to induce the expression of yeast transcription factor Yap1; while presence of CA and BB restored expression of Yap1. Expression of longevity responsible gene Silent Information Regulator (Sir2) was also found to be reduced during MG exposure. However, CA and BB triggered the expression of Sir2. Similarly, MG lowered the expression of Baculoviral IAP repeat (Bir1) which is the inhibitor of apoptosis while CA and BB aided the over expression of Bir1. CONCLUSIONS: CA and BB supplementation could significantly decrease oxidative stress, enhance cell viability and ultimately protected S. cerevisiae cells form aging.

Genomic and functional characterization of coleopteran insect-specific α-amylase inhibitor gene from Amaranthus species.

The smallest 32 amino acid α-amylase inhibitor from Amaranthus hypochondriacus (AAI) is reported. The complete gene of pre-protein (AhAI) encoding a 26 amino acid (aa) signal peptide followed by the 43 aa region and the previously identified 32 aa peptide was cloned successfully. Three cysteine residues and one disulfide bond conserved within known α-amylase inhibitors were present in AhAI. Identical genomic and open reading frame was found to be present in close relatives of A. hypochondriacus namely Amaranthus paniculatus, Achyranthes aspera and Celosia argentea. Interestingly, the 3'UTR of AhAI varied in these species. The highest expression of AhAI was observed in A. hypochondriacus inflorescence; however, it was not detected in the seed. We hypothesized that the inhibitor expressed in leaves and inflorescence might be transported to the seeds. Sub-cellular localization studies clearly indicated the involvement of AhAI signal peptide in extracellular secretion. Full length rAhAI showed differential inhibition against α-amylases from human, insects, fungi and bacteria. Particularly, α-amylases from Helicoverpa armigera (Lepidoptera) were not inhibited by AhAI while Tribolium castaneum and Callosobruchus chinensis (Coleoptera) α-amylases were completely inhibited. Molecular docking of AhAI revealed tighter interactions with active site residues of T. castaneum α-amylase compared to C. chinensis α-amylase, which could be the rationale behind the disparity in their IC50. Normal growth, development and adult emergence of C. chinensis were hampered after feeding on rAhAI. Altogether, the ability of AhAI to affect the growth of C. chinensis demonstrated its potential as an efficient bio-control agent, especially against stored grain pests.

Phytoremediation of fluoride with garden ornamentals Nerium oleander, Portulaca oleracea, and Pogonatherum crinitum.

Nursery grown plants of Nerium oleander, Pogonatherum crinitum, and Portulaca oleracea were observed to remove fluoride up to 92, 80, and 73%, respectively, from NaF solution at the concentration of 10 mg L-1 within 15 days. Concentration range of 10-50 mg L-1 of fluoride revealed a constant decrease of removal from 92 to 51% within 15 days by N. oleander, while the biomass (one to five plants) showed enhancement in removal from 74 to 98% in 10 days. Translocation and bioaccumulation factors calculated after fluoride contents in roots and leaves of N. oleander, P. crinitum, and P. oleracea were 1.85, 1.19, and 1.43, and 9.8, 3.6, and 2.2, respectively. P . oleracea, P. crinitum, and N. oleander showed reductions in chlorophyll contents by 40, 57 and 25 and 8%, carbohydrates by 50, 44, and 16%, and proteins by 38, 53, and 15%, respectively. Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) in the roots of P. oleracea, P. crinitum, and N. oleander were observed to be induced by 400, 383, and 500%; 80, 105, and 424%; and 153, 77, and 71%, respectively, while the leaves showed induction in SOD, CAT, and GPX activities by 550, 315, and 165%; 196, 227, and 243%; and 280, 242, and 184%, respectively. Results endorsed the superiority of N. oleander for fluoride removal over other plant species.

A glycoprotein α-amylase inhibitor from Withania somnifera differentially inhibits various α-amylases and affects the growth and development of Tribolium castaneum.

BACKGROUND: Identification and characterisation of plant defensive molecules enrich our resources to design crop protection strategies. In particular, plant-derived proteinaceous inhibitor(s) of insect digestive enzymes appear to be a safe, sustainable and attractive option. RESULTS: A glycoprotein having non-competitive α-amylase inhibitory activity with a molecular weight of 8.3 kDa was isolated and purified from seeds of Withania somnifera α-amylase inhibitor (WSAI). Its mass spectrometry analysis revealed 59% sequence coverage with Wrightide II-type α-amylase inhibitor from Wrightia religiosa. A dose-dependent inhibition of α-amylases from Aspergillus oryzae, Bacillus subtilis, Helicoverpa armigera and Tribolium castaneum was recorded. Interestingly, WSAI did not inhibit human salivary α-amylase significantly. When adults of T. castaneum were fed with WSAI (1.6 mg g-1 ), decrease in consumption, growth and efficiency of conversion of ingested food was evident, along with over fourfold increases in feeding deterrence index. A decline in larval residual α-amylase activity after feeding of WSAI resulted in a reduction in longevity of T. castaneum. CONCLUSION: The study reflects the significance of WSAI in affecting the overall growth and development of T. castaneum. Pre- and post-harvest pest resistive capability makes WSAI a potential candidate for insect pest management. Further, the effectiveness of this inhibitor could be explored either in formulations or through a transgenic approach. © 2016 Society of Chemical Industry.

Characterization of two coleopteran α-amylases and molecular insights into their differential inhibition by synthetic α-amylase inhibitor, acarbose.

Post-harvest insect infestation of stored grains makes them unfit for human consumption and leads to severe economic loss. Here, we report functional and structural characterization of two coleopteran α-amylases viz. Callosobruchus chinensis α-amylase (CcAmy) and Tribolium castaneum α-amylase (TcAmy) along with their interactions with proteinaceous and non-proteinaceous α-amylase inhibitors. Secondary structural alignment of CcAmy and TcAmy with other coleopteran α-amylases revealed conserved motifs, active sites, di-sulfide bonds and two point mutations at spatially conserved substrate or inhibitor-binding sites. Homology modeling and molecular docking showed structural differences between these two enzymes. Both the enzymes had similar optimum pH values but differed in their optimum temperature. Overall, pattern of enzyme stabilities were similar under various temperature and pH conditions. Further, CcAmy and TcAmy differed in their substrate affinity and catalytic efficiency towards starch and amylopectin. HPLC analysis detected common amylolytic products like maltose and malto-triose while glucose and malto-tetrose were unique in CcAmy and TcAmy catalyzed reactions respectively. At very low concentrations, wheat α-amylase inhibitor was found to be superior over the acarbose as far as complete inhibition of amylolytic activities of CcAmy and TcAmy was concerned. Mechanism underlying differential amylolytic reaction inhibition by acarbose was discussed.

Phytoremediation of sulfonated Remazol Red dye and textile effluents by Alternanthera philoxeroides: An anatomical, enzymatic and pilot scale study.

Alternanthera philoxeroides Griseb. a macrophyte was found to degrade a highly sulfonated textile dye Remazol Red (RR) completely within 72 h at a concentration of 70 mg L(-1). An induction in the activities of azoreductase and riboflavin reductase was observed in root and stem tissues; while the activities of lignin peroxidase, laccase and DCIP reductase were induced in leaf tissues. Some enzymes namely tyrosinase, veratryl alcohol oxidase, catalase and superoxide dismutase displayed an increase in their activity in all the tissues in response of 72 h exposure to Remazol Red. There was a marginal reduction in contents of chlorophyll a (20%), chlorophyll b (5%) and carotenoids (16%) in the leaves when compared to control plants. A detailed anatomical study of the stem during uptake and treatment revealed a stepwise mechanism of dye degradation. UV-vis spectrophotometric and high performance thin layer chromatographic analyses confirmed the removal of parent dye from solution. Based on the enzymes activities and gas chromatography-mass spectroscopic analysis of degradation products, a possible pathway of phytotransformation of RR was proposed which revealed the formation of 4-(phenylamino)-1,3,5-triazin-2-ol, naphthalene-1-ol and 3-(ethylsulfonyl)phenol. Toxicity study on Devario aequipinnatus fishes showed that the anatomy of gills of fishes exposed to A. philoxeroides treated RR was largely protected. The plants were further explored for rhizofiltration experiments in a pilot scale reactor. A. philoxeroides could decolorize textile industry effluent of varying pH within 96 h of treatment which was evident from the significant reductions in the values of American dye manufacturers' institute color, chemical oxygen demand, biological oxygen demand, total dissolved and total suspended solids.

Evaluation of comparative free-radical quenching potential of Brahmi (Bacopa monnieri) and Mandookparni (Centella asiatica).

Ayurvedic texts describe rejuvenate measures called Rasayana to impart biological sustenance to bodily tissues. Rasayana acting specifically on brain are called Medhya Rasayana. Brahmi is one of the most commonly practiced herbs for the same. Yet there exist a controversy regarding the exact plant species among Bacopa monnieri L. Penn (BM) and Centella asiatica (L.) Urban (CA) to be used as Brahmi in the formulations. Though the current literature available has suggested a very good nootropic potential of both the drugs, none of the studies have been carried out on comparative potential of these herbs to resolve the controversy. Free-radical scavenging potential for these plants is studied to find out their comparative efficacy. The study revealed a very good in vitro free-radical scavenging properties of aqueous and ethanolic extracts of both the plants as evidenced by FRAP, DPPH, reducing power, and antilipid peroxidation assays. It can be concluded from the studies that both the plants, although taxonomically totally different at family level, showed similar type of in vitro activities. The total phenolic and flavonoid contents also revealed a significant similarity in the two plants. The in vitro study supports the Ayurvedic concept of BM and CA having a similar potential.