Abha Chaudhary

Nanoencapsulation and characterization of Albizia chinensis isolated antioxidant quercitrin on PLA nanoparticles

The plant isolated antioxidant quercitrin has been encapsulated on poly-d,l-lactide (PLA) nanoparticles by solvent evaporation method to improve the solubility, permeability and stability of this molecule. The size of quercitrin-PLA nanoparticles is 250±68nm whereas that PLA nanoparticles is 195 ± 55nm. The encapsulation efficiency of nanoencapsulated quercitrin evaluated by HPLC and antioxidant assay is 40%. The in vitro release kinetics of quercitrin under physiological condition reveals initial burst release followed by sustained release. Less fluorescence quenching is observed with equimolar concentration of PLA encapsulated quercitrin than free quercitrin. The presence of quercitrin specific peaks on FTIR of five times washed quercitrin loaded PLA nanoparticles provides an extra evidence for the encapsulation of quercitrin into PLA nanoparticles. These properties of quercitrin nanomedicine provide a new potential for the use of such less useful highly active antioxidant molecule towards the development of better therapeutic for intestinal anti-inflammatory effect and nutraceutical compounds.

Optimization of extraction technique and validation of developed RP-HPLC-ELSD method for determination of terpene trilactones in Ginkgo biloba leaves

Terpene trilactones are potent and selective antagonists of platelet activating factor. The present study deals with standardization of efficient extraction method and validation of newly developed simple, sensitive and rapid reversed phase high performance liquid chromatographic method with evaporative light scattering detection (RP-HPLC-ELSD) method for the quantitative determination of ginkgolide A (GA), ginkgolide B (GB), ginkgolide C (GC), ginkgolide J (GJ) and bilobalide (BB) within 8 min in Ginkgo biloba leaf extract. The analysis was conducted on a Zorbax RP-C18 column with gradient elution of methanol-water-tetrahydrofuran. The method was validated for accuracy, precession, limit of detection and quantification. The drift tube temperature of evaporative light scattering detector was set to 90 degrees C and nitrogen flow rate was 1.5 standard liter/min (SLM).

Chemical composition and larvicidal activities of the Himalayan cedar, Cedrus deodara essential oil and its fractions against the diamondback moth, Plutella xylostella

Abstract Plants and plant-derived materials play an extremely important role in pest management programs. Essential oil from wood chips of Himalayan Cedar, Cedrus deodara (Roxburgh) Don (Pinales: Pinaceae), was obtained by hydrodistillation and fractionated to pentane and acetonitrile from which himachalenes and atlantones enriched fractions were isolated. A total of forty compounds were identified from these fractions using GC and GC-MS analyses. Essential oils and fractions were evaluated for insecticidal activities against second instars of the diamondback moth, Plutella xylostella L. (Lepidoptera: Yponomeutidae), using a leaf dip method. All samples showed promising larvicidal activity against larvae of P. xylostella. The pentane fraction was the most toxic with a LC50 value of 287 µg/ml. The himachalenes enriched fraction was more toxic (LC50 = 362 µg/ml) than the atlantones enriched fraction (LC50 = 365 µg/ml). LC50 of crude oil was 425 µg/ml and acetonitrile fraction was LC50 = 815 µg/ml. The major constituents, himachalenes and atlantones, likely accounted for the insecticidal action. Present bioassay results revealed the potential for essential oil and different constituents of C. deodara as botanical larvicides for their use in pest management.

Naturally occurring himachalenes to benzocycloheptene amino vinyl bromide derivatives: as antidepressant molecules.

A new series of benzocycloheptene amino vinyl bromide derivatives (9a–9m) were synthesized from isomeric mixture of himachalenes through two-step synthesis. The unusual structure of benzocycloheptene amino vinyl bromide derivative (9a) was confirmed by NMR and X-ray crystallography analyses. The newly synthesized amino vinyl bromide derivatives of benzocycloheptene were further evaluated for their antidepressant activities. The compound 9c had shown significant reduction in the immobility period.Graphical Abstract

Spatial and Temporal Variation of Secondary Metabolite Profiles in Ginkgo biloba Leaves

Terpene trilactones (TTLs) are the main bioactive constituents of Ginkgo biloba used for the preparation of drugs for several ailments. Flavonoid glycosides (FGs) are the significant group of compounds found in Ginkgo leaves used in food and healthcare products. The variation in the content of bioactive constituents, as well as antioxidant activity, with respect to change in altitude and the time of sample collection was investigated. The amount of TTLs varied from 0.218–0.709% w/w, whereas FGs were observed in the range of 0.130–0.209% w/w. Ginkgolides J and A showed significant variation (p≤0.05) with the change in altitude, while other components remained more or less unaffected. The amount of TTLs and FGs were not affected significantly by the time of sample collection. The antioxidant capacity (by using DPPH, ABTS, and FRAP assays) of ginkgo extracts was highly dependent on the altitude, and was at maximum in the samples collected from 1000–2000 m, followed by the samples collected from altitudes lower than 1000 m and higher than 2000 m. Thus, Ginkgo harvested from 1000–2000 m of altitudinal range irrespective of the season could provide better nutraceutical formulations, whereas that from below 1000 m may yield a terpene trilactone‐enriched fraction.

Polystyrene resin supported palladium(0) (Pd@PR) nanocomposite mediated regioselective synthesis of 4-aryl-1-alkyl/(2-haloalkyl)-1H-1,2,3-triazoles and their N-vinyl triazole derivatives from terminal alkynes

An efficient general methodology has been developed for sequential one-pot synthesis of 4-aryl-1-alkyl-1H-1,2,3-triazoles influenced by polystyrene resin supported palladium(0) (Pd@PR) nanocomposite as a heterogeneous catalyst. The present work particularly emphasizes the synthesis of 4-aryl-1-(2-haloalkyl)-1H-1,2,3-triazoles through the selective mono-azidation of 1,2-dihaloethane and subsequent Pd@PR mediated 1,3-dipolar cycloaddition with terminal aryl alkynes. Potassium carbonate promoted dehydrohalogenation of synthesized 4-aryl-1-(2-haloalkyl)-1H-1,2,3-triazoles gave the corresponding N-vinyl derivatives (often used as building blocks for polymers) which are further utilized in the synthesis of 4-aryl-1-(2-arylalkenyl)-1H-1,2,3-triazoles following a Pd@PR catalyzed Heck coupling approach. Furthermore, microwave assisted one pot dehydrochlorination and Heck strategy was adopted to afford 4-phenyl-1-styryl-1H-1,2,3-triazole under Pd@PR catalyzed conditions using iodobenzene as a phenylating agent.

Simultaneous Quantification of Flavonoids and Biflavonoids in Ginkgo biloba Using RP-HPTLC Densitometry Method

A reversed-phase high-performance thin-layer chromatography (RP-HPTLC) method was developed for the determination of flavonoids (quercetin and kaempferol) and biflavonoids (sciadopitysin, ginkgetin, and bilobetin) in the aqueous methanolic extract of Ginkgo biloba. There have been a number of reports on the quantification of flavonoids in G. biloba using different analytical techniques, but the reported methods are not suitable for routine analysis and also for the simultaneous quantification of flavonoids and biflavonoids in G. biloba. The method employed here used precoated plates of silica gel 60F254 as the stationary phase with dual-run acetonitrile-water-methanol-formic acid (20:20:1:0.005, v/v/v/v) and acetonitrile-water-methanol-formic acid (20:17:1:0.005, v/v/v/v) as mobile phases with densitometric determination of flavonoids and biflavonoids at 254 nm in reflection/absorption mode. The linear regression analysis data for the calibration plots showed a linear relationship (r2 from 0.9706 to 0.9990). The method was validated for accuracy, precision, and robustness. The limits of detection (LOD) and quantification (LOQ) were in the range of 0.12–0.37 µg and 0.60–1.85 µg, respectively, for the analytes. The method is reproducible and convenient for quantitative analysis of these compounds in the leaves of G. biloba. This is the first report of simultaneous densitometry quantification of major flavonoids and biflavonoids in G. biloba using the newly developed and validated RP-HPTLC method.

Antifungal sesquiterpenes from Cedrus deodara.

Two new sesquiterpenes, (E)-(2S,3S,6R)-atlantone-2,3-diol (1) and (E)-(2S,3S,6S)-atlantone-2,3,6-triol (2), along with two known sesquiterpenes, atlantolone (3) and (E)-α-atlantone (4), were isolated from Cedrus deodara Loud. The structures of the new compounds were elucidated on the basis of UV, IR, NMR, HR‑ESI-QTOF‑MS, and EI mass spectral studies. The n-hexane and chloroformextracts of sawdust and compounds 3 and 4 from the plant exhibited antifungal activity against Aspergillus flavus, A. niger, A. ochracoeus, A. parasiticus, and A. sydowii. A weak activity was also recorded against A. parasiticus and A. sydowii for compound 1, while Trichophyton rubrum was inhibited by compound 2 and the extracts.

Supported palladium nanoparticles as switchable catalyst for aldehyde conjugate/s and acetate ester syntheses from alcohols

Polymer-supported Pd(0) (Pd@PS) nanoparticles (NPs) were explored as a switchable catalyst for oxidative aldehyde conjugate/s (AC/s) and acetate esters (AEs) syntheses from alcohols. Using the same substrates, the catalyst in the presence of oxygen and K2CO3 participated in AC/s synthesis, and in the presence of traces of air and NaOtBu, unusual AEs products were obtained.

HPTLC-densitometry method for simultaneous determination of major lignans and flavonoids in Podophyllum hexandrum

A new quantitative method using thin-layer chromatography silica gel 60F254 plates as the stationary phase and the mobile phase consisting of toluene-ethyl acetate-acetic acid (15.0:7.5:0.5, v/v) was employed for simultaneous determination of lignans and flavonoid in Podophyllum hexandrum. Densitometric determination of the constituents was performed at 254 nm in reflectance/absorbance mode. The method was validated for precision, accuracy, specificity, robustness, and recovery. The linear regression analysis data for the calibration plots showed a good linear relationship (r2 = 0.9903–0.9976) in the calibration range of 1–8 µg per band for 4′-O-demethylpodophyllotoxin (1), podophyllotoxin (2), and podophyllotoxone (4), and 2–10 µg per band for kaempferol (3) and deoxypodophyllotoxin (5) with respect to peak area. Limits of detection and quantitation were in the range of 250–617 ng per band and 856–1974 ng per band. The average recovery for 4′-O-demethylpodophyllotoxin, podophyllotoxin, kaempferol, podophyllotoxone, and deoxypodophyllotoxin was 96.38 ± 1.92 to 101.84 ± 1.05%, indicating the excellent reproducibility. Podophyllotoxin was found in highest content (9.92 µg mg−1) and podophyllotoxone in the lowest content (0.94 µg mg−1). The proposed method is rapid, simple, precise, specific, sensitive, accurate, and robust.