Identification of a new phytotoxic compound from culture filtrates of an aggressive Rhizoctonia solani AG 1A isolate inducing sheath blight of rice.

Phytotoxins produced by Rhizoctonia solani AG1-1A (Anastomosis Group 1 Subgroup 1A) play a significant role in developing sheath blight disease in rice. A phytotoxin in the partially purified ethyl acetate fraction from the culture filtrate of a highly aggressive R. solani (RIRS-K) isolate, with Indian Type Culture Collection (ITCC) number 7479, infecting rice that could incite necrotic symptoms characteristic of the fungus was identified. The role of the crude toxin in the pathogenicity and virulence of the fungal pathogen on rice was first established by artificial inoculation assay under controlled conditions. The crude ethyl acetate extract obtained from the culture filtrate of RIRS-K was first fractionated by column chromatography. Further purification of the bioactive fraction was carried out by using bioassay-guided fractionation, and a toxic fraction was obtained. The most bioactive fraction was analyzed by GC-MS analysis, and 3-butylpyridine (3-BP) was identified as a major compound in the active fraction by comparing its mass spectrum with NIST library and its standard. The purified bioactive fraction and standard (3-BP) toxicity was further validated and compared at 1000 ppm. The result showed that both the bioactive fraction and the 3-BP have caused necrosis, similar to the one incited by R. solani. This study showed that 3-BP is one of the major compounds responsible for the necrosis development in the rice plant during ShB disease and is a hitherto unexplored toxin of R. solani in rice.

Bioefficacy evaluation of ferrocenyl chalcones against Meloidogyne incognita and Sclerotium rolfsii infestation in tomato.

The present study reports, bioefficacy evaluation of effective compounds against Meloidogyne incognita and Sclerotium rolfsii in pot cultured tomato. The identified five most effective compounds, i.e. (2E)-1-(4-Methylphenyl)-3-ferrocenyl-prop-2-en-1-one (6g), (2E)-1-(4-Methoxyphenyl)-3-ferrocenyl-prop-2-en-1-one (6h), (2E)-1-(3-Bromophenyl)-3-ferrocenyl-prop-2-en-1-one (6j), (2E)-1-(2,4-Dichlorophenyl)-3-ferrocenyl-prop-2-en-1-one (6k) and (2E)-1-(3,5-Dichloro-2-hydroxyphenyl)-3-ferrocenyl-prop-2-en-1-one (6p) along with Carbofuran 3G as positive control were tested at 20, 40 and 80 ppm by soil drenching and root dipping methods. The study revealed that all plant growth parameters were positively influenced by these compounds. The presence of an electron releasing group positively influenced the efficacy, and the activity was highest in compounds 6g and 6h at 80 ppm. Based on in vitro results against S. rolfsii, (2E)-1-Ferrocenyl-3-(4-bromophenyl)-prop-2-en-1-one (3b), (2E)-1-Ferrocenyl-3-(2,6-dichlorophenyl)-prop-2-en-1-one (3o) and (2E)-1-(5-Chloro-2-hydroxyphenyl)-3-ferrocenyl-prop-2-en-1-one (6o) along with Tebuconazole 25.9% EC and Hexaconazole 5% SC as positive control were evaluated. The shoot length was found to be highest (24.50 cm) in plants treated with 3b followed by 3o and 6o at 1000 ppm. The percent disease incidence was significantly decreased as compared to control. The percent disease incidence was found to be minimum in plants treated with 3b at 1000 ppm. However, root dipping was not as effective as soil drenching. Therefore, ferrocenyl chalcone derivatives proved to be of great fungicidal and nematicidal potential opening new opportunities for expanding their effectiveness as new pest control agents.

Microwave assisted synthesis, characterization and biological activities of ferrocenyl chalcones and their QSAR analysis: Part II.

A series of ferrocenyl chalcones using acetylferrocene, with ferrocenyl group at the keto carbonyl group, and different aldehydes were synthesized and their bioefficacy evaluation was done against Sclerotium rolfsii, Alternaria solani and Meloidogyne incognita. In continuation of our quest for potent crop protection products, in the present study, a series of 18 substituted ferrocenyl chalcones were synthesized in which ferrocenyl group was attached to the aldehyde moiety, using ferrocenecarboxyaldehyde and different acetophenones by microwave method (MM) and conventional method (CM) [cf: MM 1 to 5 min; CM 12-40 h] and characterized by various techniques viz. IR, LC-HRMS, 1H-NMR and 13C-NMR. In vitro fungicidal activity showed that compound, (2E)-1-(5-Chloro-2-hydroxyphenyl)-3-ferrocenyl-prop-2-en-1-one (34) (ED50 = 21.50 mg L-1) was found to be most active against S. rolfsii and compound, (2E)-1-(4-Bromophenyl)-3-ferrocenyl-prop-2-en-1-one (21) (ED50 = 31.14 mg L-1) showed highest activity against A. solani. As regards nematicidal activity, compound (2E)-1-(3-Bromophenyl)-3-ferrocenyl-prop-2-en-1-one (29) was more potent with LC50 values of 11.95, 8.07 and 4.34 mg L-1 at 24, 48 and 72 h, respectively. QSAR study revealed that MLR for S. rolfsii (r 2 = 0.9834, q 2= 0.8975) and A. solani (r 2 = 0.9807, q 2= 0.8713) and PLS for M. incognita (r 2 = 0.9023, q 2= 0.7818) were the best models.

Amphiphilic polymer based nanoformulations of mancozeb for management of early blight in tomato.

Controlled release (CR) nanoformulations of Mancozeb (Manganese-zinc double salt of N, N-bisdithiocarbamic acid), a protective fungicide, have been developed using poly (ethylene glycols) (PEGs) based functionalized amphiphilic copolymers and evaluated for the management of early blight in tomato. During the field experiment, it was observed that number of infected leaflets/plants were less in developed formulation treated plants as compared to commercial products. Number of infected leaflets per plant was 2.40-4.60 and the number of fruits per plant were 6.40-9.00 at 50 mg L-1, whereas at 100 mg L-1, the corresponding numbers were 2.10-4.10 and 6.30-9.10 respectively. These formulations can be used to optimize the release of Mancozeb to achieve disease control for the desired period depending upon the matrix of the polymer used. Importantly, sufficient amount of active ingredient remains available for a reasonable period of time after application leading to reduced number of applications of pesticide.

Delivery of phytochemicals by liposome cargos: recent progress, challenges and opportunities.

Bio-availability is a major concern in delivery of dietary phytochemicals for better bio-efficacy. The reduced bio-availability of food bioactive compounds is evident due to degradation during human digestion process which involves liberation, absorption, distribution, metabolism and elimination. The bio-efficacy of any nutrient can be increased by increasing bio-availability. Different technologies are available for engineered efficient delivery systems; still many challenges remain with advancement of delivery systems. The ease of preparedness and adaptability of liposomes has resulted in wide-range of applicability and acceptability in scientific field, especially as delivery vehicles. In view, of properties like biocompatibility and biodegradability, liposomes have been modified with different usable methodologies for delivery of phytochemicals. The aim of this review is to abridge liposomes, methods of preparation, their application as delivery cargo in dietary phytochemicals, result of using different preparation techniques on properties.

Insecticidal activity of phenolic acid amides against brown planthopper (BPH), Nilaparvata lugens (Stål) and their QSAR analysis.

A series of 42 phenolic acid amides, synthesized using different phenolic acids (salicylic acid, 3-hydroxy cinnamic acid, p-coumaric acid, caffeic acid, ferulic acid, o-coumaric acid, cinnamic acid and amines (propyl amine, hexyl amine, heptyl amine, undecyl amine, hexadecyl amine, octadecyl amine) were screened for their insecticidal activities against Brown Planthopper (BPH), Nilaparvata lugens. These phenolic acid amides showed moderate to good insecticidal activity with the lowest LC50 value of 63.84 ppm from N-propyl-2-hydroxycinnamamide. 2D-Quantitative structural activity relationship (2D-QSAR) analysis of these phenolic acid amides was carried out by developing three different models namely multiple linear regression (MLR), principal component regression (PCR) and partial least squares (PLS). Statistical significance and predictive ability of these models were assessed by internal and external validation and verified by leave one-out cross-validation. PLS (model 3) was found best for QSAR study with correlation coefficient (r2) 0.8388, cross-validated correlation coefficient (q2) 0.7797 and r2 pred 0.7347. It was found that + vePotentialSurfaceArea, XAMostHydrophobic, SaasCE-index, T_O_O_3 and T_O_O_6 are the major descriptors which influence the insecticidal activities of these phenolic acid amides. The QSAR study could help in structural optimization of phenolic acid amides in developing potential compounds to get better bioefficacy against N. lugens.

Microwave synthesis, characterization, and bio-efficacy of novel halogenated Schiff bases.

A new series of halogenated Schiff bases was synthesized by the condensation of 5-fluoro-2-hydroxy acetophenone and 3,5-dichloro-2-hydroxy acetophenone with different alkyl amines, namely propyl, pentyl, hexyl, heptyl, octyl, nonyl, dodecyl, tetradecyl, hexadecyl, and octadecyl amines, under microwave irradiation. Newly formed molecules were characterized by Infrared and nuclear magnetic resonance ((1)H NMR and (13)C NMR) spectroscopic techniques. Further, the Schiff bases were screened for antifungal bioassay, and the results showed potential fungicidal activity against two very important plant infecting fungi, viz. Rhizoctonia solani and Sclerotium rolfsii. Among the screened compounds, 2,4-dichloro-2-[1-(propylimino)ethyl]phenol was found to be the most active compound against both R. solani (ED50 8.02 mg L(-1)) and S. rolfsii (ED50 21.51 mg L(-1)) followed by 2,4-dichloro-2-[1-(pentylimino) ethyl]phenol (ED50 13.02 and 29.57 mg L(-1), respectively). The synthesized compounds were also screened for antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging technique. All the compounds showed very low to moderate activity as compared with Gallic acid.

Synthesis, Biological Evaluation, and QSAR Studies of 3-Iodochromone Derivatives as Potential Fungicides.

Despite the emergence of novel biotechnological and biological solutions, agrochemicals continue to play an important role in crop protection. Fungicide resistance is becoming a major problem; numerous cases of fungicide resistance have occurred worldwide in the last decade, resulting in the loss of several fungicides. The discovery of new molecules has therefore assumed critical importance in crop protection. In our quest for biologically active molecules, we herein report the synthesis of a series of twenty-one 3-Iodochromone derivatives (4a-4u), in a two-step process by condensation of 2-hydroxyacetophenone derivatives (2a-2u) with N,N-dimethylformamidedimethylacetal yielding enaminones (3a-3u), followed by cyclization with iodine to corresponding 3-iodochromones. Characterization of these compounds was done by IR, 1H NMR, 13C NMR, and LC-HRMS techniques. All synthesized compounds were screened for their fungicidal activity against Sclerotium rolfsii. Among these 6,8-Dichloro-3-iodochromone 4r was found to be most active (ED50 = 8.43 mg L-1). 2D-Quantitative Structural Activity Relationship (2D-QSAR) analysis was also performed by generating three different models viz., Multiple Linear Regression (MLR, Model 1), Principal Component Regression (PCR, Model 2), and Partial Least Squares (PLS, Model 3). Predictive power and statistical significance of these models were assessed with external and internal validation and leave one-out cross-validation was used for verification. In QSAR study, MLR (Model 1) was found to be best having correlation coefficient (r2) 0.943, cross-validated correlation coefficient (q2) 0.911 and r2pred 0.837. It was observed that DeltaEpsilonC, T_2_Cl_6, T_2_F_6, T_T_F_3, and ZCompDipole are the major descriptors which influence the fungicidal activity of 3-Iodochromone derivatives. The physicochemical parameters were estimated by the VLifeMDS 4.6 software. The QSAR study results will be helpful for structure optimization to improve the activity.

Microwave Assisted Synthesis, Characterization and Biological Activities of Ferrocenyl Chalcones and Their QSAR Analysis.

A new microwave method (MM) has been developed for the synthesis of a series of 16 substituted ferrocenyl chalcones using acetylferrocene (1) with different aldehydes (2a-2p) and comparing it with conventional method (CM). The synthesized compounds were characterized by various spectroscopic techniques viz IR, HR-MS, 1H NMR, and 13C NMR. The time required for completion of reaction in MM varied from 1 to 5 min as compared to CM which required 10-40 h. All the synthesized compounds were screened for antifungal activity against Sclerotium rolfsii and Alternaria solani. In vitro fungicidal activity revealed that compound 3o (ED50 = 23.24 mg L-1) was found to be most active against S. rolfsii. But in case of A. solani, compound 3c (ED50 = 29.9 mg L-1) showed highest activity. The nematicidal activity revealed that the compound 3b was more potent with LC50 values of 10.67, 7.30, and 4.55 ppm at 24, 48, and 72 h, respectively. 2D-Quantitative Structural Activity Relationship (2D-QSAR) analysis of these ferrocenyl chalcones was carried out by developing three different models namely Partial Least Squares (PLS, Model 1), Multiple Linear Regression (MLR, Model 2) and Principal Component Regression (PCR, Model 3). Statistical significance and predictive ability of these models were assessed by internal and external validation and also verified by leave one-out cross-validation. QSAR study revealed that MLR for S. rolfsii (r 2 = 0.999, q 2 = 0.996), PLS for A. solani (r 2 = 0.934, q 2 = 0.749) and PCR for M. incognita (r 2 = 0.878, q 2 = 0.772) were the best model. The physico-chemical parameters were calculated using VLife MDS 4.6 software. QSAR study could be employed for structure optimization to achieve better activity.

A new xanthone glycoside and antioxidant constituents from the rhizomes of Swertia speciosa.

From the rhizomes of Swertia speciosa, a traditional medicinal plant from the Himalayan region of Uttaranchal (North India), a new constituent, 6-hydroxy-3,5-dimethoxy-1-[(6-O-beta-D-xylopyranosyl-beta-D-glucopyranosyl)oxy]-9H-xanthen-9-one (8), was isolated, together with nine known compounds. Their structures were elucidated on the basis of chemical, physical, and spectroscopic evidence. Both the acetone and MeOH extracts, as well as the known constituents ursolic acid (5) and 1,5,8-trihydroxy-3-methoxy-9H-xanthen-9-one (6) exhibited potent antioxidant activities in different biological assays (Table 2).

Chemical constituents and antioxidant activity of Mallotus roxburghianus leaves.

Mallotus roxburghianus is used in the traditional medicine in North-Eastern India, but previously no work has been done on the identification of bioactive compounds. Two new compounds, 3-(1-C-beta-D-glucopyranosyl)-2,6-dihydroxy-5-methoxybenzoic acid (6) and 2,4,8,9,10-pentahydroxy-3,7-dimethoxyanthracene-6-O-beta-D-rhamnopyranoside (7) together with beta-sitosterol (1), stigmasterol (2), betulinic acid (3), 4-hydroxybenzoic acid (4), beta-sitosterol-beta-D-glucoside (5), and bergenin (8) were isolated and identified from the leaves of M. roxburghianus. The chloroform soluble portion of the alcoholic extract of leaf, and compounds 3, 6, 7, and 8 exhibited encouraging antioxidant activities.

Comparative evaluation of two Trichoderma harzianum strains for major secondary metabolite production and antifungal activity.

This investigation was undertaken to identify the major secondary metabolite, produced by two Trichoderma harzianum strains (T-4 and T-5) with their antifungal activity against phytopathogenic fungi using poison food technique. The ethyl acetate extract was subjected to column chromatography using n-hexane, ethyl acetate and methanol gradually. Chromatographic separation of ethyl acetate extract of T. harzianum (T-4) resulted in the isolation and identification of palmitic acid (1), 1,8-dihydroxy-3-methylanthraquinone (2), 6-pentyl-2H-pyran-2-one (3), 2(5H)-furanone (4), stigmasterol (5) and ß-sitosterol (6), while T. harzianum (T-5) gave palmitic acid (1), 1-hydroxy-3-methylanthraquinone (7), δ-decanolactone (8), 6-pentyl-2H-pyran-2-one (3), ergosterol (9), harzianopyridone (10) and 6-methyl-1,3,8-trihydroxyanthraquinone (11) as major metabolites. Among compounds screened for antifungal activity, compound 10 was found to be most active (EC50 35.9-50.2 µg mL(-1)). In conclusion, the present investigation provided significant information about antifungal activity and compounds isolated from two different strains of T. harzianum obtained from two different Himalayan locations.

Compositions of the volatile oils of Citrus macroptera and C. maxima.

The essential oils obtained by hydrodistillation from the fresh peels of Citrus macroptera Montr. and C. maxima (Burm.) Merr. were analyzed by GC and GC/MS. The yields of oil ranged from 0.53% in C. macroptera to 0.13% in C. maxima cultivar (white). Forty-seven compounds were identified in the oils with limonene (55.3-80.0%), dodecyl acrylate (2.2-8.0%), geranial (0.4-3.5%), trans-linalool oxide (1.0-2.8%), alpha-terpineol (0.7-2.3%), linalool (0.7-1.5%) and cis-linalool oxide (0.5-1.4%) identified as major compounds. The oil ofC. macroptera contained limonene (55.3%), beta-caryophyllene (4.7%) and geranial (3.5%) as main compounds. Similarly, oils from two C. maxima (pink and white) cultivars were rich in limonene (72.0-80.0%), dodecyl acrylate (8.0-7.2%) and nootkatone (1.6-2.5%). C. maxima (pink and white) cultivars were found to contain higher amount of limonene (72.0 and 80.0%) as compared with C. macroptera (55.3%). The chemical compositions of the oils were found to be similar, but nootkatone (1.6-2.5%) was identified only in C. maxima cultivars.

Chemical composition of the essential oil of Zingiber zerumbet var. darcyi.

The chemical composition of essential oil obtained by hydrodistillation method from the rhizomes of Z. zerumbet var. darcyi was determined by GC and GC-MS. Thirty-three compounds, accounting for 93.6% of the oil were identified including twenty compounds in minor (0.1-0.6%) and eight in trace (<0.05%) amounts. The main compounds were zerumbone (69.9%) alpha-humulene (12.9%), humulene epoxide II (2.5%), caryophyllene oxide (1.1%) and camphene (1.9%). In this analysis, it has been found that the variety could be used as an additional new source of natural zerumbone besides Zingiber zerumbet. This is a first report on the analysis of Z. zerumbet var. darcyi oil.

Chemical variability in the essential oil of Cinnamomum tamala L. leaves from India.

The chemical composition of the essential oils obtained from the fresh leaves of Cinnamomum tamala Nees et Eberm. was determined by GC and GC-MS. The yield of the oil on a dry weight basis ranged from 1.2% to 3.9% (w/w). Phenyl propanoids constitute the major portion (88.9-95.0%) of the oils. Fifty-four compounds were identified from the oils. Eugenol (91.4-41.8%) was the main compound, followed by eugenyl acetate (0.0-47.1%) and α-phellandrene (0.6-2.5%) in the analysed oils.