Browsing by Author "DINESH KUMAR YADAV"

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    ThesisItemOpen Access
    Impact of turmeric terpenoids on bioavailability of curcumin
    (DIVISION OF AGRICULTURAL CHEMICALS ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI –, 2016) DINESH KUMAR YADAV; Supradip Saha
    Rhizome of turmeric (Curcuma longa) is one of the richest sources of bioactive compounds. Curcuminoids, the active constituent are one of the most researched topic worldwide for its broad spectrum of biological activities. Efforts have been made to incorporate the molecules into commercial food products as a pharmaceutical and nutraceutical agent but the low bioavailability limits its application. The present study aimed at utilization of bioactive terpenoid constituents present in turmeric fixed oil for the improvement of bioavailability of curcuminoids. Turmeric fixed oil (yield 5.7% w/v) from rhizome powder was extracted with hexane and purified by column chromatography for separation of terpenoids. Purified oil mixture was analyzed by GC-MS and found three major peaks in the chromatogram. α, β- turmerone was separated together and their structure was confirmed by GC- EI-MS. ar- turmerone was separated as pure peak and characterized by mass, IR and 1H-NMR. For the separation of curcuminoids, defatted turmeric powder was extracted with ethyl acetate and the extract was purified using column chromatography, followed by prep-TLC to get individual compounds (Rf 0.78, 0.53, 0.25). Purified curcuminoids were analyzed by HPLC using RP-18 column with PDA detector (max 425 nm) under isocratic conditions using mobile phase of acetonitrile 0.1% formic acid (60:40, v/v). Three purified curcuminoids were characterized by FT-IR,1H-NMR and HRMS data. Based on spectroscopic data, the purified compounds were confirmed as 1,7-bis(4-hydroxy-3-methoxyphenyl)- 1,6-heptadiene-3,5-dione or curcumin-I (C); 1-(4-hydroxyphenyl)-7-(4-hydroxy-3- methoxyphenyl)-1,6-heptadiene-3,5-dione or curcumin-II (DC); and 1,7-bis(4- hydroxyphenyl)-1,6-heptadiene-3,5-dione or curcumin-III (BDC). The HPLC method was validated; LOD and LOQ values were calculated as 0.27, 0.33 & 0.42 µg mL-1 and 0.80, 1.00 & 1.25 µg mL-1 for C, Dc and BDC, respectively. Accelerated solvent extraction experiment was conducted using ethanol, ethyl acetate and acetone as extraction solvent, keeping homogenization technique as a control. Ethanol provided maximum physical yield (9.2 %) by ASE experiment followed by acetone (6.1 %) and ethyl acetate (5.8 %), although there is significant differences between ethyl acetate and acetone. Similarly, ethanol yielded maximum extract upon extraction by homogenization. But, opposite trend was recorded in case of acetone and ethyl acetate. No significant differences were observed in ASE as well as homogenization in terms of purity of individual curcuminoids. Antioxidant assay evaluated using DPPH and ABTS assay found that IC50 value of curcuminoids mixture were 78.8 and 145.7 µg mL-1 respectively. The antioxidant activity of three curcuminoids, followed the order C > DC > BDC in both assays. The bioavailability study was carried out individually with each curcuminoids and along with turmerones to observe their effect on bioavailability of curcumin. In-vitro study revealed that in the presence of turmerone and turmerone mixture the bioavailability of curcumin has increased 2 fold and more. The information might be useful for the development of improved bioavailable curcumin formulation.
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    ThesisItemOpen Access
    SYNTHESIS OF FERROCENYL CHALCONES AND THEIR EVALUATION AGAINST PLANT PATHOGENIC FUNGI AND ROOT KNOT NEMATODE
    (DIVISION OF AGRICULTURAL CHEMICALS ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI, 2020) DINESH KUMAR YADAV; N. A. Shakil
    Chalcones and their derivatives are conventionally known to possess biological activity due to their highly reactive unsaturated carbonyl group. Chalcone nucleus containing compounds have been a subject of interest for the scientists all over the world and research is directed towards the development of potent crop protection chemicals based on this nucleus. However, poor solubility is a major concern and prevents their use in crop protection. In order to overcome this, thirty four substituted ferrocenyl chalcones have been synthesized by microwave method (MM) and compared the reaction time and yield of products with that of conventional method (CM). Microwave Assisted Organic Synthesis (MAOS) has provided a great impetus to organic synthesis during the last few decades and has become most useful for functional group inter conversions. The use of microwave has several advantages such as shorter reaction times, higher yields, ease of manipulation and lower costs. Furthermore, reactions under microwave have great advantage of not using organic solvents (solvent-free) and thus such reactions are environment friendly and generate less waste. Environmentally benign character of the microwave method is desirable for large scale industrial applications. A series of ferrocenyl chalcones was synthesized by base-catalyzed condensation of acetylferrocene with different benzaldehydes and ferrocenecarboxyaldehyde with different acetophenones. All the products were obtained in appreciable amounts and the yields for different compounds were higher in microwave method (77-92%) as compared to conventional method (71-87%). The synthesized compounds were characterized by various spectroscopic techniques viz. IR, 1H-NMR, 13C-NMR and LC-HRMS. All synthesised compounds were tested against root knot nematode, Meloidogyne incognita. Although all the compounds possessed activity against M. incognita, but compounds 3b, 3f, 3h, 3m, 3o, 6g, 6h, 6j, 6k and 6p were found to be more potent. However, all the synthesized compounds were found to be less active than commercially available carbofuran and velum prime. Pot study revealed that, all plant growth parameters (shoot length, shoot weight, root length, root weight, average no. of galls/plant and yield (g)) were positively influenced by these compounds. As the nematicial activity of test compounds increased, plant growth parameters were also increased. The activity was highest in compounds 3f, 3h, 6g, and 6h @ 80 ppm at 30 DAI and 60 DAI. The activity was higher in soil drenching method compared to root dipping method. All the synthesized compounds showed antifungal activity. Among (3a-3p) series compounds, 3o i.e. (2E)-1-Ferrocenyl-3-(2,6-dichlorophenyl)-prop-2-en-1-one showed highest fungicidal activity against Sclerotium rolfsii with ED50 of 23.24 ppm. But in case of Alternaria solani, among (3a-3p) series compounds, 3c i.e. (2E)-1- Ferrocenyl-3-(4-fluorophenyl)-prop-2-en-1-one, having value ED50 = 29.9 ppm showed highest activity. Among (6a-6r) series compounds, 6o i.e. (2E)-1-(5-Chloro-2-hydroxyphenyl)- 3-ferrocenyl-prop-2-en-1-one showed highest fungicidal activity against S. rolfsii with ED50 of 21.50 ppm. In case of A. solani, among (6a-6r) series compounds, 6b i.e. (2E)- 1-(4-Bromophenyl)-3-ferrocenyl-prop-2-en-1-one showed highest fungicidal activity with ED50 of 31.14 ppm. Based on in vitro results, three most effective compounds 3b, 3o and 6o were chosen for pot experiment against S. rolfsii. The study revealed that shoot length was significantly increased as compared to control. The shoot length wasfound to be highest (24.50 cm) in plants treated with 3b followed by 3o and 6o @ 1000 ppm at 60 DAI. 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 @ 1000 ppm. The disease incidence was minimum in soil drenching method compared to root dipping method. In conclusion, this is the first attempt to synthesise a series of ferrocenyl chalcones by Microwave Synthesis Reactor. Study revealed that microwave method was quick and green method as compared to conventional method. All the synthesized compounds were found to have good to moderate nematicidal and fungicidal activity. Keywords: