In silico approaches illustrate the evolutionary pattern and protein-small molecule interactions of quinolone synthase from Aegle marmelos Correa

Quinolone synthase from Aegle marmelos (AmQNS) is a Rutacean-specific plant type III polyketide synthase that synthesizes quinolone, acridone, and benzalacetone with therapeutic potential. Simple architecture and broad substrate affinity of AmQNS make it as one of the target enzymes to produce novel structural scaffolds. Another unique feature of AmQNS despite its high similarity to acridone forming type III polyketide synthase from Citrus microcarpa is the variation in the product formation. Hence, to explore the characteristic features of AmQNS, an in-depth sequence and structure-based bioinformatics analyses were performed. Our studies indicated that AmQNS and its nearest homologs have evolved by a series of gene duplication events and strong purifying selection pressure constrains them in the evolutionary process. Additionally, some amino acid alterations were identified in the functionally important region(s), which can contribute to the functional divergence of the enzyme. Prediction of favorable amino acid substitutions will be advantageous in the metabolic engineering of AmQNS for the production of novel compounds. Furthermore, comparative modeling and docking studies were utilized to investigate the structural behavior and small molecule interaction pattern of AmQNS. The observations and results reported here are crucial for advancing our understanding of AmQNS’s phylogenetic position, selection pressure, evolvability, interaction pattern and thus providing the foundation for further studies on the structural and reaction mechanism.     

Trivalent rare‐earth activated hexagonal lanthanum fluoride (LaF3:RE3+, where RE = Tb,Sm, Dy and Tm) nanocrystals: Synthesis and optical properties

The LaF₃ nanocrystals through a facile hydrothermal route with hexagonal structures have been synthesized via doping of trivalent rare earth (RE³⁺) ions – RE = Tb, Sm, Dy and Tm – with rod‐like and perforated morphologies using NH₄F as fluorine precursor. Hexagonal phase formation was confirmed by powder X‐ray diffraction. The crystalline sizes were calculated by the Scherrer equation where found to have an average crystalline size of 12 to 35 nm. The morphological studies of the nanocrystals were carried out by means of transmission electron microscopy (TEM). The LaF₃:Tm³⁺,Sm³⁺ ions show the characteristic emission of Tb³⁺ and Tm³⁺ respectively. In Sm³⁺‐doped LaF₃, three prominent emission peaks at 561, 597 and 641 nm were found, which belong to ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2 (magnetic dipole) and ⁴G_5/2 → ⁶H_9/2 (electric dipole) transitions, respectively. The Dy³⁺ activated LaF₃ shows blue and yellow emission and the corresponding CIE color coordinate show white light emission (CCT value 10650 K).     

Plant-based corosolic acid: Future anti-diabetic drug?

Diabetes is one of the nation's most prevalent, debilitating and costly diseases. For diabetes, frequent insulin treatment is very expensive and may increase anti-insulin antibody production, which may cause unwanted side effects. Corosolic acid may also have some efficacy in the treatment of diabetes, but without induction of anti-insulin antibodies. Recently, corosolic acid from Lagerstroemia speciosa L. leaf extracts has been reported to act via an indirect mechanism (unlike insulin) in animal experiments. The insulin-complementary anti-diabetic therapeutic value observed in these Japanese preliminary clinical trials has led to renewed interest in the biosynthesis of this compound. So far, there has been no clear evidence for a corosolic acid biosynthetic pathway in plants. This article provides possible roles of corosolic acid and hypothetical information on the biosynthetic pathway in plants.     

Highly selective and sensitive ‘on–off’ fluorescent chemosensor for Fe3+ ions crafted by benzofuran moiety in both experimental and theoretical methods

A benzofuran glycinamide-based chemosensor, 3-(2-([4-fluorobenzyl]amino)acetamido)benzofuran-2-carboxamide ( BGA ) was developed and synthesized for the selective and sensitive detection of Fe³⁺ ions. The photophysical properties of the probe BGA were studied using UV–visible light absorption and fluorescence spectrophotometers. The chemosensor BGA showed a marked ‘on–off’ fluorescence response towards Fe³⁺ ions in the presence of other metal ions in DMSO/H₂O solution (9/1, v/v). The very low limits of detection (LOD) were calculated to be 10 nM and 43 nM using UV–visible light absorption and fluorescence spectrophotometers, respectively. Job's plot analysis revealed the formation of a BGA -Fe³⁺ complex with a 1:1 binding stoichiometry ratio using UV–visible light spectroscopy. The sensing mechanism was also demonstrated using density functional theory calculation.     

Demethyloleuropein and beta-glucosidase activity in olive fruits

Demethyloleuropein plays a major role in the defense mechanism of olive fruits. To understand how this molecule is metabolized during different stages of maturation of olive fruits, a biomolecular approach to identify the demethyloleuropein chemistry was employed. The beta-glucosidase activity in crude extracts was assayed spectrophotometrically using the chromogenic substrate p-nitrophenyl-beta-D-glucopyranoside. Demethyloleuropein was extracted and identified by HPLC-MS from both infected and uninfected olive fruits at different physiological stages. The release of more functionally relevant dialdehydes in uninfected fruits was investigated using ESIMS/ MS. In fruits harvested in October, the activity of beta-glucosidase was significantly enhanced in uninfected fruits when compared to the infected fruits. Quantitative differences in the demethyloleuropein content from uninfected fruits showed the highest values (5.09 mg/g) in October, whereas lower levels (4.44 mg/g) were found in infected fruits. The results demonstrated that demethyloleuropein derivatives could be influenced by beta-glucosidase activity to improve the quality of the olive products with the best dialdehyde nutraceutical content.     

Freshwater fish biodiversity in the River Ganga (India): changing pattern, threats and conservation perspectives

The river Ganges is the largest river in India and the fifth longest in the world. Although, many studies on fish ecology and systematic have been conducted largely to improve fisheries but fish diversity and their distribution pattern from conservation point of view have never been adequately addressed in the Ganges. In this connection, current distribution and abundance of freshwater fishes of river Ganges was studied and assessed from April 2007 to March 2009. We documented and described 143 freshwater fish species in the all stretches of the river which is higher than what was reported earlier. Some species were observed with shift in their distribution ranges. First time, a total of 10 exotic fishes, including Pterygoplichthys anisitsi, which has never been reported from India found in the Ganges. Alterations of the hydrological pattern due to various types of hydro projects was seems to be the largest threat to fishes of Ganges. Indiscriminate and illegal fishing, pollution, water abstraction, siltation and invasion of exotic species are also threatening the fish diversity in the Ganges and as many as 29 species are listed under threatened category. The study advocates a need to identify critical fish habitats in the Ganga basin to declare them as conservation reserves to mitigate the loss of fish diversity from this mighty large river.     

Impact of d-pinitol on the attenuation of proinflammatory cytokines,hyperglycemia-mediated oxidative stress and protection of kidney tissue ultrastructure in streptozotocin-induced diabetic rats

Oxidative stress plays a crucial role in the progression and development of diabetes and its complications due to chronic hyperglycemia. The present study was aimed to investigate the kidney tissue protective nature of d-pinitol, a cyclitol present in soybean, by assessing the key markers of hyperglycemia-mediated oxidative stress, proinflammatory cytokines and ultrastructural alterations in streptozotocin-induced diabetic rats. Oral administration of d-pinitol (50 mg/kg body weight/day) for 30 days to diabetic group of rats showed a significant elevation in the level of total protein and significant decline in the levels of blood urea, serum uric acid, creatinine and advanced glycation endproducts (AGEs) and kidney proinflammatory cytokines such as TNF-α, IL-1β, IL-6, NF-κB p65 subunit and nitrite. Further, d-pinitol administration elicited a significant attenuation in the activities of kidney enzymatic antioxidants such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) and the levels of kidney non-enzymatic antioxidants such as vitamin E, vitamin C and reduced glutathione (GSH) in the diabetic group of rats, with a concomitant decline in the levels of kidney lipid peroxides, hydroperoxides and protein carbonyls. The histological and ultrastructural observations on the kidney tissues also confirmed the renoprotective nature of d-pinitol. Thus the present study demonstrated the renoprotective nature of d-pinitol by attenuating the hyperglycemia-mediated proinflammatory cytokines and antioxidant competence in kidney tissues of streptozotocin-induced diabetic rats.