Aditi Kundu

Cadinene sesquiterpenes from Eupatorium adenophorum and their antifungal activity

Bioactive constituents of Eupatorium adenophorum were investigated for antifungal activity. A structure-antifungal activity relationship of cadinene sesquiterpenes was predicted by evaluating individual derivatives. Cadinene derivatives were extracted from leaves of Eupatorium adenophorum using ethyl acetate. Five cadinene sesquiterpenes were isolated by column chromatography and Preparative Thin Layer Chromatography. Bioactivity of these cadinene sesquiterpenes were evaluated in vitro against four phytopathogenic fungi using poison food technique. Purified sesquiterpenes were spectroscopically elucidated as cadinan-3-ene-2,7-dione (1), 7-hydroxycadinan-3-ene-2-one (2), 5,6-dihydroxycadinan-3-ene-2,7-dione (3), cadinan-3,6-diene-2,7-dione (4) and 2-acetyl-cadinan-3,6-diene-7-one (5). Antifungal evaluation of these compounds against pathogenic fungi was found to be selective. Compound 1 was highly inhibitory towards S. rolfsii (ED50 181.60 ± 0.58 μgmL−1) and R. solani (ED50 189.74 ± 1.03 μgmL−1). Availability of plant material and significant antifungal activity makes the plant a potential source of antifungal agent and that can be exploited for the development of a natural fungicide.

Genetic analysis of plant endophytic Pseudomonas putida BP25 and chemo-profiling of its antimicrobial volatile organic compounds.

Black pepper associated bacterium BP25 was isolated from root endosphere of apparently healthy cultivar Panniyur-5 that protected black pepper against Phytophthora capsici and Radopholus similis - the major production constraints. The bacterium was characterized and mechanisms of its antagonistic action against major pathogens are elucidated. The polyphasic phenotypic analysis revealed its identity as Pseudomonas putida. Multi locus sequence typing revealed that the bacterium shared gene sequences with several other isolates representing diverse habitats. Tissue localization assays exploiting green fluorescence protein expression clearly indicated that PpBP25 endophytically colonized not only its host plant - black pepper, but also other distantly related plants such as ginger and arabidopsis. PpBP25 colonies could be enumerated from internal tissues of plants four weeks post inoculation indicated its stable establishment and persistence in the plant system. The bacterium inhibited broad range of pathogens such as Phytophthora capsici, Pythium myriotylum, Giberella moniliformis, Rhizoctonia solani, Athelia rolfsii, Colletotrichum gloeosporioides and plant parasitic nematode, Radopholus similis by its volatile substances. GC/MS based chemical profiling revealed presence of Heneicosane; Tetratetracontane; Pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); Tetracosyl heptafluorobutyrate; 1-3-Eicosene, (E)-; 1-Heneicosanol; Octadecyl trifluoroacetate and 1-Pentadecene in PpBP25 metabolite. Dynamic head space GC/MS analysis of airborne volatiles indicated the presence of aromatic compounds such as 1-Undecene;Disulfide dimethyl; Pyrazine, methyl-Pyrazine, 2,5-dimethyl-; Isoamyl alcohol; Pyrazine, methyl-; Dimethyl trisulfide, etc. The work paved way for profiling of broad spectrum antimicrobial VOCs in endophytic PpBP25 for crop protection.

Antioxidant potential of essential oil and cadinene sesquiterpenes of Eupatorium adenophorum

Eupatorium adenophorum (E. adenophorum) was hydro-distilled and the obtained essential oil was analyzed by gas chromatography—mass spectrometry (GC–MS). Twenty six essential oil constituents comprising sesquiterpenes and monoterpenes were identified. γ-Cadinene was most abundant followed by germacrene-D and γ-elemene. E. adenophorum leaf powder was extracted with different solvents. Three pure constituents were isolated and identified by chromatographic and spectroscopic techniques. The antioxidant activities of the oil and cadinenes were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the ferric reducing ability assay (FRAP), together with three antioxidant standards, i.e. ascorbic acid, tert-butyl-4-hydroxy toluene (BHT), and gallic acid. The antioxidant activity of essential oil was comparable with the standards. The essential oil and the cadinene sesquiterpene-rich extract of E. adenophorum have exhibit potential antioxidant activities. Wide availability of the plant and the potential antioxidant activity makes it a potential natural antioxidant.

Optimal extraction and fingerprinting of carotenoids by accelerated solvent extraction and liquid chromatography with tandem mass spectrometry

Accelerated solvent extraction (ASE) is applied for the extraction of carotenoids from orange carrot and the extraction parameters were optimized. Two carotenoids, lutein and β-carotene, are selected as the validation process. Hildebrand solubility parameters and dielectric constant of solvents were taken into consideration in selecting solvent mixture. The effects of various experimental parameters, such as temperature, static time, drying agent etc., on the ASE extraction efficiency are investigated systematically. Interactions among the variables were also studied. Furthermore, two carotenoids were analyzed and characterized by LC-ESI MS. The study concluded that Hildebrand solubility parameter approach may be applicable for less polar bioactive molecules like carotenoids. The properties of solvent and extraction temperature are found to be the most important parameters affecting the ASE extraction efficiency of thermolabile natural compounds.

Microwave assisted solvent-free synthesis and biological activities of novel imines (Schiff bases)

Twelve new ortho-Hydroxyketimines were synthesized by conventional as well as microwave method and evaluated for their antinemic activity against Meloidogyne incognita [(Kofoid and White) Chitwood]. Conventional methods for synthesis of Schiff bases require refluxing at 140°C of the reactants in different solvents for at least 24 h or more, where as the microwave-assisted synthesis has brought down the reaction time from 24 h to 1 minute. The procedure reported is simple as it does not require any organic solvents and the time has been reduced to only 1 minute. Comparative yields of all compounds by different methods revealed that the yield was low in conventional method (79–87%) as compared to microwave assisted synthesis (94–97%). The bioassay revealed that all the test compounds exhibited promising nematicidal activity; N-propyl-2-hydroxypropiophenonimine being the most effective with LC50 value of 74.46 mgL−1 followed by N-hexyl-2-hydroxyacetophenonimine with LC50 value of 99.60 mgL−1 after 72 h of exposure. The results obtained from bioassay indicated that this class of compounds has not only given a lead with regard to potential of Schiff bases in pest control, but has suggested that a carbon chain length of 6 atoms in the side chain is optimum on the basis of structure activity relationship (SAR).

Capsaicinoids, Tocopherol, and Sterols Content in Chili (Capsicum sp.) by Gas Chromatographic-Mass Spectrometric Determination

A gas chromatography-mass spectrometry method was developed for the quantitative determination of capsaicinoids, vitamin E, and phytosterols in chili peppers using a simple extraction technique for rapid screening. These components were extracted with acetonitrile and were injected into gas chromatography attached with mass spectrometry. The mean recovery values for triplicate analysis were between 90.6–99.7%. Besides major capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin), four more minor capsaicinoids (nonivamide, nornordihydrocapsaicin, homodihydrocapsaicin I and II) were detected in chili samples. α-Tocopherol was also detected in the same run along with three phytosterols (campesterol, γ-sitosterol, and stigmasterol). Variations were observed across the chili sample in all of the constituents except a few minor capsaicinoids. The method was suitable for simultaneous estimation of capsaicinoids, vitamin E, and phytosterols in a single run from any types of pepper. Thus, the method is effective for rapid screening of peppers for its nutraceutical composition using single solvent extraction.

Plant growth inhibitory terpenes from Eupatorium adenophorum leaves

Eupatorium adenophorum is commonly known as Crofton weed, growing widely throughout the northern hilly terrains. Bioactive potential of E. adenophorum leaves was investigated through phytochemical study and in vitro plant growth inhibitory. Essential oil was hydrodistilled from leaves and analyzed by GCMS. Leaf material was extracted using cold extraction process followed by evaporation of solvent under reduced pressure. Five cadinene sesquiterpenes and one sterol were isolated from hexane and EtOAc concentrates and their structures were established spectroscopically. Plant growth inhibitory activity of extractives and isolated terpenes were studied against different seeds of weed and crops . Essential oil was moderate seedling growth inhibitor. Among various extracts, EtOAc extract was found to be most inhibitory to Phalaris minor seeds (EC 50 117 μg mL -1 ). Among the sesquiterpenes, 5,6-dihydroxycadinan-3-ene-2,7-dione was found to be most active and inhibited both shoot and root growth of Phalaris minor seed (EC 50 97 μg mL -1 ) and Polygonum plebejum (EC 50 117 μg mL -1 ).

Isolation, characterisation of major secondary metabolites of the Himalayan Trichoderma koningii and their antifungal activity

Ethyl acetate extracts of two strains of Trichoderma koningii were evaluated for antifungal activity against soilborne pathogenic fungi, Rhizoctonia solani, Sclerotium rolfsii, Macrophomina phaseolina and Fusarium oxysporum by poisoned food technique. Secondary metabolites, namely δ-decanolactone, 6-pentyl-α-pyranone and 6-(4-oxopentyl)-2H-pyran-2-one were isolated from T. koningii (T-8) extract while palmitic acid, 6-pentyl-α-pyranone and stigmasterol were isolated from T. koningii (T-11) extract. Secondary metabolites were identified by 1H NMR, 13C NMR and mass spectroscopic methods. These metabolites were evaluated for antifungal activity against the test pathogens 6-Pentyl-α-pyranone and 6-(4-oxopentyl)-2H-pyran-2-one exhibited excellent antifungal activity against S. rolfsii. The antifungal activity though slightly less was comparable to that of hexaconazole, a commercial fungicide.

Purity Evaluation of Curcuminoids in the Turmeric Extract Obtained by Accelerated Solvent Extraction

Curcuminoids, the active principle of Curcuma longa L, is one of the most researched subjects worldwide for its broad-spectrum biological activities. Being traditionally known for their anticancer properties and issues related to bioavailability, the curcuminoids, including diferuloylmethane (curcumin), have gained special attention. Thus, the current study focused on the purity profiling of curcuminoids when extracted by accelerated solvent extraction, which was run with turmeric rhizome powder (20 g) at 1500 psi and at 50°C, with a static time of 10 min and with three cycles. The performance of ethanol, ethyl acetate, and acetone as extraction solvents was comparatively evaluated. Once extracted, the individual curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin) were purified by column chromatography, followed by preparative TLC, and the compounds were characterized by spectroscopic and chromatographic techniques. The HPLC method was standardized by using a gradient mobile phase of water and acetonitrile containing 0.1% formic acid. The LODs were calculated as 0.27, 0.33, and 0.42 μg/mL for curcumin, demethoxycurcumin, and bisdemethoxycurcumin, respectively. Accuracy (relative percentage error) and precision RSD values of the developed HPLC method were below 5%. The intraday accuracy ranged between -0.9 and -3.63%. The physical yield was the highest in ethanol (8.4%) extraction, followed by ethyl acetate (7.4%) and acetone (6.6%). Maximum purity was recorded in acetone (46.2%), followed by ethanol (43.4%) and ethyl acetate (38.8%), with no significant differences across the individual curcuminoids. This research will be useful for future applications related to the extraction of curcuminoids at a commercial level and to their profiling in food matrixes.

Compositional and functional difference in cumin (Cuminum cyminum) essential oil extracted by hydrodistillation and SCFE

Abstract Essential oils were obtained from same raw material of cumin seed by extraction with hydrodistillation and super critical fluid extraction (SCFE). For SCFE, supercritical carbon dioxide at 45°C and 100 bar was used as variable for the extraction. The composition of the extracts was determined by gas chromatography-mass spectrometry. Yield of essential oil was more in the SCFE method. Extract obtained by supercritical fluid extraction technique using CO2 was heavier than the hydrodistilled volatile oil. Cumin oil obtained by hydrodistillation contained higher percentage of cuminaldehyde (52.6%), then did oil obtained by SCFE (37.3%), whereas cumin oil obtained by hydrodistillation had the lower percentage of cuminic alcohol (13.3%) as compared to 19.3% in SCFE method. However, cuminal (2-caren-10-al) content was almost similar in cumin oil obtained by the SCFE and hydrodistillation method (24.5–25.8%). Hydrodistilled volatile oil showed better antioxidant activity measured by DPPH and FRAP assay and more total phenol content. The results indicated that though essential oil yield was more in the SCFE method, antioxidant property was more in conventional hydrodistillation method. SCFE extracted non polar (wax materials) compounds along with volatile oil and it was recorded that enhanced aroma of signature compounds of cumin.