Synthesis, antifungal evaluation, 2D-Quantitative structure activity relationship and molecular docking studies of isoxazole derivatives as potential fungicides

BACKGROUND

Sheath blight and bakanae disease, prominent among emerging rice ailments, exert a profound impact on rice productivity, causing severe impediments to crop yield. Excessive use of older fungicides may lead to the development of resistance in the pathogen. Indeed, a pressing and immediate need exists for novel, low-toxicity and highly selective fungicides that can effectively combat resistant fungal strains RESULTS: A series of 20 isoxazole derivatives were synthesized using alkoxy/halo acetophenones and N,N-dimethylformamidedimethylacetal. These compounds were characterized by various spectroscopic techniques viz. 1H NMR, 13C NMR and LC-HRMS and were evaluated for their fungicidal activity against Rhizoctonia solani and Fusarium fujikuroi. Compound 5n (5-(2-chlorophenyl) isoxazole) exhibited highest activity (ED50 = 4.43 μg mL-1) against R. solani, while 5p (5-(2,4-dichloro-2-hydroxylphenyl) isoxazole) exhibited highest activity (ED50 = 6.7 μg mL-1) against F. fujikuroi. 2D-Quantitative Structural Activity Relationship (2D-QSAR) analysis, particularly MLR (Model 1), highlighted chi6chain and DistTopo as the key descriptors influencing fungicidal activity. Molecular docking studies revealed the potential of these isoxazole derivatives as novel fungicides targeting sterol 14α-demethylase enzyme, suggesting their importance as crucial intermediates for the development of novel and effective fungicides.

CONCLUSION

All test compounds were effective in inhibiting both fungi, according to the QSAR model, various descriptors such as structural, molecular shape analysis, electronic, and thermodynamic play an important role. Molecular docking studies confirmed that these compounds can potentially replace commercially available fungicides and help control fungal pathogens in rice crops effectively. This article is protected by copyright. All rights reserved.

Unleashing the bioactive potential of Capsicum chinense cv Bhut Jolokia: a comparison of microwave- and ultrasound-mediated extraction techniques for lipophilic capsaicin

This study investigated the extraction of capsaicin from Capsicum chinense cv Bhut Jolokia using rice bran oil (RBO) as a 'green solvent' via microwave- and ultrasound-mediated techniques (MME and UME) as an alternative to hazardous organic solvents. Extraction conditions were optimised using MME at 180 and 300 W for 2 and 8 min and UME at 300 and 400 W for 10 and 30 min. The maximum capsaicin yield obtained was 12.47 mg/mL, with a corresponding gamma oryzanol content of 8.46 mg/mL. The peroxide value of the extract (capsaicin-infused RBO) was found to be within permissible limits as per Codex Alimentarius specifications. Results strongly suggest the potential of RBO as a novel solvent for extraction of capsaicin. The capsaicin-enriched oil can be used as a functional food ingredient due to its health-promoting properties.

Potential use of barks of woody vascular plants in bone mending: A review

The use of synthetic drugs to overcome bone ailments causes severe side effects, but the application of herbals is helpful in maintaining bone health and accelerating bone mending. Currently, there is no oral allopathic medicine to hasten bone healing, though folk and traditional practices have adopted herbal to fasten the recovery from bone ailments. Earliest recovery is a universally desired phenomenon, especially for elderly people where many more cases of traumatic injuries are common along the compromised body immunity. The computerized database search engines, such as Google Scholar, PubMed, ScienceDirect, Springer Link, etc., and textbooks were used to collect all relevant information about barks for bone mending activity published from 1990 onwards using certain keywords such as bark, folklore/ traditional bone healing practices, and phytopharmacology. The results obtained were compiled to make this review and related information is tabulated herewith. Traditional herbal bone healing exists in every society in the world. The plant barks of a few species (e.g., Ficus religiosa, Prunus cerasoides, Terminalia arjuna, etc.) have outstanding significance for bone healing because of their special chemical composition and novel properties to reduce swelling, pain, soreness, and speedy recovery of functions. Mostly bark extracts are rich in polyphenols, and minerals, represented with antioxidant, immunostimulatory, antibacterial properties, etc. There is a diversity of bark utilization for bone healing from different plant species, globally, of which only a few have been phytopharmacologically deciphered. Validated bark ingredients as medicine or food supplements are more useful due to the least side effects. Entrepreneurs have a scope to use bioactive obtained from plant barks that have not been scientifically screened till now. The research focused on the commercial application of plant barks as green medicine needs fingerprints of bioactive and clinically validated data including the concentration of biomarkers in the blood (IC50) for reducing the healing period. Phytopharmacological screening of barks used in folk medicine and synthesizing the therapeutics at mega quantities in industries is an array of hopes for sustainable utilization of natural resources. The bio-stimulating knowledge of certain herbal ingredients will be helpful in the development of synergistic formulations for rapid bone mending.

Boosting the Biocontrol Efficacy of Bacillus amyloliquefaciens DSBA-11 through Physical and Chemical Mutagens to Control Bacterial Wilt Disease of Tomato Caused by Ralstonia solanacearum

Bacterial wilt disease of tomato (Solanum lycopersicum L.), incited by Ralstonia solanacearum (Smith), is a serious agricultural problem in India. In this investigation, chemical mutagenic agents (NTG and HNO₂ treatment) and ultraviolet (UV) irradiation have been used to enhance the antagonistic property of Bacillus amyloliquefaciens DSBA-11 against R. solanacearum UTT-25 towards an effective management of tomato wilt disease. The investigation established the fact that maximum inhibition to R. solanacearum UTT-25 was exerted by the derivative strain MHNO₂-20 treated with nitrous acid (HNO₂) and then by the derivative strain MNTG-21 treated with NTG. The exertion was significantly higher than that of the parent B. amyloliquefaciens DSBA-11. These two potential derivatives viz. MNTG-21, MHNO₂-20 along with MUV-19, and a wild derivative strain of B. amyloliquefaciens i.e.,DSBA-11 were selected for GC/MS analysis. Through this analysis 18 major compounds were detected. Among the compounds thus detected, the compound 3-isobutyl hexahydropyrrolo (1,2), pyrazine-1,4-dione (4.67%) was at maximum proportion in the variant MHNO₂-20 at higher retention time (RT) of 43.19 s. Bio-efficacy assessment observed a record of minimum intensity (9.28%) in wilt disease and the highest bio-control (88.75%) in derivative strain MHNO₂-20-treated plants after 30 days of inoculation. The derivative strain MHNO₂-20, developed by treating B. amyloliquefaciens with nitrous acid (HNO₂), was therefore found to have a higher bio-efficacy to control bacterial wilt disease of tomato under glasshouse conditions than a wild-type strain.

Bio-Intensive Tactics for the Management of Invasive Fall Armyworm for Organic Maize Production

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is an invasive pest native to the American continent. The present study focused on bio-intensive tactics like intercropping, using natural enemies, botanical insecticides and biopesticides for managing S. frugiperda for the organic production of maize in Indian conditions. A total of eight different parasitoids attacking the different stages of S. frugiperda viz., eggs and larvae were found in the study area. The total parasitism rate due to all the parasitoids ranged from 28.37 to 42.44%. The egg-larval parasitoid, Chelonus formosanus Sonan (Hymenoptera: Braconidae) was the dominant parasitoid (12.55%), followed by Chelonus nr. blackburni (Hymenoptera: Braconidae) (10.98%) and Coccygydium sp. (4.85%). About 36.58 percent of the egg masses collected was parasitized by egg parasitoids, among which Telenomus remus (Nixon) (Hymenoptera: Scelionidae) was the dominant parasitoid. The botanicals insecticides such as citronella and annona extract were most effective, resulting in 100% mortality of FAW larvae (168 h after treatment). The essential oil of garlic (100%) was found highly effective in inhibiting egg hatching, followed by geraniol (90.76%). The maize intercropped with lady's finger (okra) recorded significantly the lowest pest infestation and recorded higher grain yield (6.17 q/ha) than other intercropping systems and control (5.10 q/ha). The overall bioefficacy of commercial biopesticides against the larvae of S. frugiperda was in the following order azadirachtin > Metarhizium anisopliae (Metch.) Sorokin (Hypocreales: Clavicipitaceae) > Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae) at 168 h after treatment.

Differential effects of rhizobacteria from uninfected and infected tomato on Meloidogyne incognita under protected cultivation

Intermingled uninfected and root-knot nematode-infected tomato plants are commonly observed under protected cultivation. To understand the role of rhizobacteria underlying the susceptibility to nematode infectivity in these tomato plants, 36 rhizobacteria (18 from each type) with morphologically distinct colony characteristics were isolated from the rhizosphere of uninfected and root-knot nematode-infected tomato plants. The in vitro nematicidal potential of rhizobacteria from the uninfected rhizosphere was significantly higher than that from the infested rhizosphere. The three most effective antagonists were identified as Microbacterium laevaniformans, Staphylococcus kloosii, Priestia aryabhattai from root-knot-nematode-infected tomato rhizosphere and Staphylococcus sciuri, Bacillus pumilus, and Priestia megaterium from the rhizosphere of uninfected tomato. Volatile organic compounds from these rhizobacteria were characterized. Except for S. kloosi, the soil drenching with other rhizobacteria significantly reduced juvenile penetration (>60%) in tomato roots. Furthermore, the application of a single or consortium of these rhizobacteria affected nematode reproduction in tomato. Four consortia of rhizobacteria (S. sciuri + B. pumilus + P. megaterium), (B. pumilus + P. megaterium), (S. sciuri + B. pumilus), and (S. sciuri + P. megaterium) from uninfested rhizosphere and two consortia (M. laevaniformans + P. aryabhattai), (M. laevaniformans + S. kloosii + P. aryabhattai) from infested rhizosphere (IRh) effectively reduced M. incognita reproduction and considerably enhanced plant growth and yield in tomato. The nematicidal efficacy, however, decreased when S. kloosii was applied in the consortium. These distinctive effects illustrate how the plant susceptibility to nematode infectivity is modulated under natural conditions.

Metabolomic profiling and its association with the bio-efficacy of Aspergillus niger strain against Fusarium wilt of guava

Bio-control agents are the best alternative to chemicals for the successful management of plant diseases. The fungus Aspergillus niger is known to produce diverse metabolites with antifungal activity, attracting researchers to exploit it as a bio-control agent for plant disease control. In the present study, 11 A. niger strains were isolated and screened for their antagonism against the guava wilt pathogen under in vitro and in planta conditions. Strains were identified morphologically and molecularly by sequencing the internal transcribed spacer (ITS), β-tubulin, and calmodulin genes. The strains were evaluated through dual culture, volatile, and non-volatile methods under an in vitro study. AN-11, AN-6, and AN-2 inhibited the test pathogen Fusarium oxysporum f. sp. psidii (FOP) at 67.16%, 64.01%, and 60.48%, respectively. An in planta study was conducted under greenhouse conditions with 6 months old air-layered guava plants (var. Allahabad Safeda) by pre- and post-inoculation of FOP. The AN-11 strain was found to be effective under both pre- and post-inoculation trials. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis was carried out to characterize the volatile compounds of the most potential strain, A. niger. The hexane soluble fraction showed the appearance of characteristic peaks of hexadecenoic acid methyl ester (4.41%), 10-octadecanoic acid methyl ester (3.79%), dodecane (3.21%), undecane (3.19%), gibepyrone A (0.15%), 3-methylundecane (0.36%), and citroflex A (0.38%). The ethyl acetate fraction of the bio-control fungi revealed the occurrence of major antifungal compounds, such as acetic acid ethyl ester (17.32%), benzopyron-4-ol (12.17%), 1,2,6-hexanetriol (7.16%), 2-propenoic acid ethanediyl ester (2.95%), 1-(3-ethyloxiranyl)-ethenone (0.98%), 6-acetyl-8-methoxy dimethyl chromene (0.96%), 4-hexyl-2,5-dihydro dioxo furan acetic acid (0.19%), and octadecanoic acid (1.11%). Furthermore, bio-control abilities could be due to hyper-parasitism, the production of secondary metabolites, and competition for sites and nutrients. Indeed, the results will enrich the existing knowledge of metabolomic information and support perspectives on the bio-control mechanism of A. niger.

Metabolomic analysis of sheath blight disease of rice (Oryza sativa L.) induced by Rhizoctonia solani phytotoxin

AIM

To understand the mechanism of necrosis incited by a host-selective phytotoxin designated as Rhizoctonia solani toxin (RST) identified to be a potential pathogenic factor of Rhizoctonia solani AG1 IA, causing sheath blight (ShB) of rice.

METHODS AND RESULTS

The metabolomic changes induced by the phytotoxic metabolite in a ShB susceptible rice cultivar were elucidated by Gas Chromatography-Mass Spectrometry (GC-MS) analysis and compared with that of the pathogen to identify rice metabolites targeted by the phytotoxin. The profiles of about 29 metabolites with various physiological roles in rice plants have been identified worldwide. Unsupervised and supervised multivariate chemometrics (Principal Component Analysis, PCA and Partial Least Squares-Discriminant Analysis, PLS-DA) and cluster (Heat maps) analyses were used to compare the metabolites obtained from chemical profiles of the treatments with sterile distilled water (SDW) control. The results indicated that the rice plant expressed more metabolites in response to the pathogen than the phytotoxin and was lowest in SDW control. The key metabolites expressed in rice in response to the treatments were investigated by the Variable Importance in Projection (VIP) analysis using P< 0.05 VIP >15. The analysis identified 7 and 11 upregulating metabolites in the phytotoxin and the pathogen treatments, respectively, compared to the untreated control. Among the phytotoxin-treated and the pathogen inoculated samples, the phytotoxin treated sample recorded upregulation of 6 metabolites, whereas 9 metabolites were upregulated in the pathogen inoculated samples. These upregulating metabolites are speculated for the necrotic symptoms characteristic to both the phytotoxin and pathogen. In this analysis, hexadecanoic acid and dotriacontane were highly expressed metabolites specific to the phytotoxin and pathogen-treated samples, respectively. Besides upregulation, the metabolites also have a VIP score of >1.5 and hence fulfilled the criteria of classifying them as reliable potential biomarkers. In the pathway analysis, hexadecanoic acid and dotriacontane were identified to be involved in several important biosynthetic pathways of rice, such as the biosynthesis of saturated fatty acid and unsaturated fatty acids cutin, suberin, and wax.

CONCLUSIONS

The study concludes that though certain metabolites induced by the phytotoxin in the susceptible variety during necrosis shares with that of the pathogen, the identification of metabolites specific to the phytotoxin in comparison to the pathogenic and SDW controls indicated that the phytotoxin modulates the host metabolism differently and hence can be a potential pathogenicity factor of the ShB fungus.

SIGNIFICANCE AND IMPACT OF THE STUDY

Due to lack of knowledge on the pathway genes of RST and in the absence of an ShB resistant variety, understanding differentially expressed metabolic changes induced in the susceptible variety by the phytotoxin in comparison to that of the pathogenic and uninoculated controls enables us to identify the key metabolite changes during the ShB infection. Such metabolomic changes can further be used to infer gene functions for exploitation in ShB control.

Current Research Trends and Prospects for Yield and Quality Improvement in Sesame, an Important Oilseed Crop

Climate change is shifting agricultural production, which could impact the economic and cultural contexts of the oilseed industry, including sesame. Environmental threats (biotic and abiotic stresses) affect sesame production and thus yield (especially oil content). However, few studies have investigated the genetic enhancement, quality improvement, or the underlying mechanisms of stress tolerance in sesame. This study reveals the challenges faced by farmers/researchers growing sesame crops and the potential genetic and genomic resources for addressing the threats, including: (1) developing sesame varieties that tolerate phyllody, root rot disease, and waterlogging; (2) investigating beneficial agro-morphological traits, such as determinate growth, prostrate habit, and delayed response to seed shattering; (3) using wild relatives of sesame for wide hybridization; and (4) advancing existing strategies to maintain sesame production under changing climatic conditions. Future research programs need to add technologies and develop the best research strategies for economic and sustainable development.

Bioefficacy evaluation of chalcone derivatives against Meloidogyne graminicola infecting rice, Oryza sativa L

A series of chalcones (1-14) were synthesized, characterized (using IR and 1H NMR techniques), and evaluated with an objective to manage rice root-knot nematode (RRKN) (Meloidogyne graminicola) both under pluronic gel and field conditions. Out of these fourteen compounds, 1-(4-fluoro-phenyl)-3-phenyl-propenone (13) and 1,3-diphenyl-propenone (14) showed promising and dose dependent activity at 10, 20, and 40 mg L^-1. A significant reduction in penetration of second stage juveniles (J₂s) in rice roots was observed in compounds 13 (9.5-12.0 J₂s/plant) and 14 (10.5-13.4 J₂s/plant) compared to control plants (PB1121) (13.5-23.6 J₂s/plant) in pluronic gel study. The results of field trials indicated that 14, showed significantly (P ≤ 0.05) better plant growth on 28 days after sowing (DAS) compared to 13. Both 13 and 14 reduced gall formation significantly than carbofuran 3 G @1 kg a.i./ha. However, lower concentrations were less effective in field in reducing the gall formation. Also, a significant reduction in the number of galls was observed when soil was drenched with 14 @ 40 mg L^-1. However, root dipping was not as effective as soil drenching. The study revealed that both the chalcones have the potential for effective management of RRKN in fields, and can be a better alternative to carbofuran.

Massive lower intestinal bleeding--a decade of experience

BACKGROUND

Lower gastrointestinal bleeding is defined as hemorrhage orginating distal to the ligament of Treitz. Its diagnosis is difficult, often requiring endoscopy, angiography and isotope scans.

METHODS

All patients with massive lower gastrointestinal bleeding seen in three gastroenterology centers of Armed Forces during an 11 year period between 1988 and 1999 were retrospectively analysed.

RESULTS

A total of 91 patients with massive lower gastro intestinal bleeding were seen during 11 years. The mean age of the patients was 38.9 years and 64 were males. Aetiological diagnosis was: Non-specific ulcers--11, Ileal tuberculosis--8, NSAID enteropathy--8, Enteric fever--7, Meckel's diverticulum--7, Polyps--6, Ulcerative colitis--5, Carcinoma colon--5, Colonic diverticulosis--5, No cause found--5, Polyposis coli--5, Jejunal diverticulae--3, Angiodysplasia colon--3, Radiation colitis--3, Ischaemic colitis--3, Ileal tumor--2, Ileal angiodysplasia--2, Intestinal Lymphoma--2, Bechet's syndrome--1. Bleeding stopped on conservative therapy in 18 patients (including 5 where no diagnosis could be made). Diagnosis was made in 36 patients on fiber-optic colonoscopy done during active bleeding. Remaining patients were subjected to emergency laparotomy and diagnosis was obvious on inspection of abdominal contents in 25 cases. The diagnosis was finally made in remaining 12 cases by intraoperative endoscopic examination through an ileotomy. Four patients died, only one of them due to rebleed after surgery from an additional lesion.

CONCLUSIONS

Compared with experience in Western countries, massive lower gastro-intestinal hemorrhage in India affects younger patients, has different causes and carries a lower mortality. Colonoscopy is useful in making diagnosis during active lower intestinal bleeding in about one-third cases. Exploratory laparotomy and Intra-operative endoscopy are complimentary to above examination and can make the diagnosis in most of the remaining cases.

Thiophosphorylation of histidine

The preparation of a novel phosphorus species, thiophosphoramidate, has enabled the specific thiophosphorylation of histidine at its 3-position. The rates of phosphorylation and thiophosphorylation of histidine are reported, as well as the spectroscopic properties of both thiophosphoramidate and 3-thiophosphohistidine. Structural assignment of the latter was made by analogy to the NMR properties of the known 3-phosphohistidine. The alkylation of 3-thiophosphohistidine by phenacyl bromide serves as a model for the introduction of labeling or probe reagents into histidine phosphorothioate-containing proteins.

Recognition of 5-aminouracil (U(#)) in the central strand of a DNA triplex: orientation selective binding of different third strand bases

A necessary feature of the natural base triads for triplex formation is the requirement of a purine (A or G) in the central position, since only these provide sets of two hydrogen bond donors/acceptors in the major groove of the double helix. Pyrimidine bases devoid of this feature have incompatible complementarity and lead to triplexes with lower stability. This paper demonstrates that 5-aminouracil (U#) (I), a pyrimidine nucleobase analogue of T in which 5-methyl is replaced by 5-amino group, with hydrogen bonding sites on both sides, is compatible in the central position of triplex triad X*U# x A, where X = A/G/C/T/2-aminopurine (AP), and * and x represent Hoogsteen and Watson-Crick hydrogen bonding patterns respectively. A novel recognition selectivity based on the orientation (parallel/antiparallel) of the third strand purines A, G or AP with A in the parallel motif (A(p)*U# x A), and G/AP in the antiparallel motif (G(ap)/AP(ap)*U# x A) is observed. Similarly for pyrimidines in the third strand, C is accepted only in a parallel mode (C(p)*U(#) x A). Significantly, T is recognised in both parallel and antiparallel modes (T(p)/T(ap)*U(#) x A), with the antiparallel mode being stable compared to the parallel one. The 'U(#)' triplexes are also more stable than the corresponding control 'T' triplexes. The results expand the lexicon of triplex triads with a recognition motif consisting of pyrimidine in the central strand.

5-Amino-dU: a nucleoside analogue in the central strand of DNA triplex for orientation selective binding of A/G/C/T in the third strand

[formula: see text] 5-Amino-dU, a designed nucleoside analogue, when placed in the central strand of DNA triple helix, recognizes all four bases A, G, C, and T in the third strand, with a selectivity based on the orientation (parallel/antiparallel) of the third strand.

Massive lower gastrointestinal bleeding as a presenting feature of Behcet's disease

This reports a 27 yr old female Patient with seronegative polyarthritis who presented with lower GI bleeding and subsequently developed evidence of cutaneous vasculitis (palpable purpura) and orogenital ulcers. The cause of the GI bleeding was multiple ulcerations in the terminal ileum, cecum ascending colon and transverse colon. Continued and massive bleeding necessitated surgical resection of the involved segment of gut which on histopathological examination confirmed the presence of vasculities. This patient was thus diagnosed as having Behcet's disease. Although major GI bleeding is a rare manifestation of Behcet's disease with vasculitis of the gut, one must consider this possibility if the patient has multi-system involvement with evidence of vasculitis involving the skin in the form of palpable purpura.