Vivek Ahluwalia

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.

Chemical composition and antifungal activity of Artemisia nilagirica essential oil growing in northern hilly areas of India

Essential oil extracted from aerial parts of Artemisia nilagirica was analysed by gas chromatography–mass spectroscopy. Forty-three constituents amounting to 98.16% of the total essential oil contents were identified. The essential oil contained approximately 79.91% monoterpenoids and 18.25% sesquiterpenoids. α-Thujone (36.35%), β-thujone (9.37%), germacrene D (6.32%), 4-terpineol (6.31%), β-caryophyllene (5.43%), camphene (5.47%) and borneol (4.12%) were identified as the major constituents. The essential oil exhibited significant antifungal activity against Rhizoctonia solani (ED50, 85.75 mg L−1), Sclerotium rolfsii (ED50, 87.63 mg L−1) and Macrophomina phaseolina (ED50, 93.23 mg L−1). This study indicated that A. nilagirica essential oil can be used to control phytopathogenic fungi infesting agricultural crops and commodities.

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 β-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.

Synthesis and pesticidal activity of new N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines

A series of novel N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines were synthesized as potential new agents to control pests. Their structures were confirmed on the basis of IR, NMR and elemental analyses. Six new N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines were prepared by reduction of corresponding Schiff bases using sodium borohydride in 80–87 % yields. These compounds were tested for their antifungal activity against two pathogenic fungi viz., Rhizoctonia bataticola ITCC 0482 and Sclerotium rolfsii ITCC 5226 and for insecticidal activity against insects of stored grain pest Callosobruchus analis. Fungicidal bioassay revealed that compound N-Decyl-N-[1-(2-hydroxyphenyl)ethyl]amine, was highly effective against R. bataticola (ED50 6.86 mg L−1) which was comparable with that of commercial fungicide hexaconazole (ED50 6.35 mg L−1). Also compounds N-Heptyl-N-[1-(2-hydroxyphenyl)ethyl]amine, N-Octyl-N-[1-(2-hydroxyphenyl)ethyl]amine and N-Nonyl-N-[1-(2-hydroxyphenyl)ethyl]amine displayed promising fungitoxicity against same pathogen. However, compound N-Heptyl-N-[1-(2-hydroxyphenyl)ethyl]amine was also found to be effective against S. rolfsii (ED50 4.92 mg L−1 as against 1.27 mg L−1 for hexaconazole). Compound N-Hexyl-N-[1-(2-hydroxyphenyl)ethyl]amine was most effective as insecticide followed by compound N-Octyl-N-[1-(2-hydroxyphenyl)ethyl]amine. LC50 values for these compounds were 155.0 and 275.0 mg L−1 respectively as against 36.70 mg L−1 for commercial insecticide dichlorovos. The results obtained from bioassays indicate that this class of compounds can be utilized for the design of new substances endowed with pesticidal activities.

Synthesis and antimicrobial activity of esters of 3-ethoxy-4-hydroxybenzaldehyde oxime

ABSTRACT A series of oxime esters was synthesized by esterification of 3-ethoxy-4-benzaldehyde oxime with acid chlorides in the presence of triethylamine. They were evaluated for their in vitro antifungal activity against three pathogenic fungi, namely Rhizoctonia bataticola, Fusarium udum, and Alternaria porii, and their antibacterial activity against the three bacterial strains Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoneae. The compounds bearing medium-length alkyl chains showed greater activity than those with long alkyl chains. An electron-donating group in para position of the aryl ring confers highest activity.

Essential oil composition, antifungal, and seedling growth inhibitory effects of zerumbone from Zingiber zerumbet Smith

Abstract The composition of the essential oil isolated from the rhizomes of Zingiber zerumbet Smith was determined using GC and GC–MS. Zerumbone (74.82%), humulene (6.02%), and β-copaen-4α-ol (4.32%) were identified as major compounds. E-Bisabol-11-ol (4.32%), E-bisabol-11-ol (0.92%), β-sinensal (0.57%), and α-himachalene oxide (0.19) were reported for the first time in its oil. Zerumbone was further isolated from the crude mixture of oil and identified by FTIR, NMR (1H, 13C, DEPT, HXCO, and HMBC), and mass (EI-MS) spectral data. Zerumbone showed promising antifungal activity against three phytopathogenic fungi, namely Rhizoctonia solani (EC50, 39.6 ppm), Sclerotium rolfsii (EC50, 59.3 ppm), and Macrophomina phaseolina (EC50, 147.4 ppm) compared with hexaconazole (EC50, 18.3, 13.4, and 4.5 ppm, respectively). Zerumbone has also shown concentration-dependent affect on seedling growth of Phalaris minor Retz., compared with control and Triticum aestivum L. (wheat). Zerumbone strongly suppressed the root and shoot growth of P. minor seedling at 1000 ppm compared with control and wheat. It exhibited no or less effect on the germination of seeds of T. aestivum.

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.

Isolation of a new flavonoid and waste to wealth recovery of 6-O-Ascorbyl Esters from Seeds of Aegle marmelos (family- Rutaceae)

Abstract Aegle marmelos is a plant species native to India. Commercially available food products such as jam, jelly, candy, squash etc. are prepared from ripe fruit pulp of A. marmelos. Ripe fruit processing accounts for 60% of whole fruit mass while 40% remains unutilized and generates waste (hard shell, pomace, fiber and seeds) on a massive scale which do not have high value applications. A new flavone 3,5,7-trihydroxy-2-(4′-hydroxy-3′-isopentyloxyphenyl-4H-chromen-4-one (5) in addition to the known compounds 1–4, has been isolated from seeds of A. marmelos. Also, compound 7-(3′-methylbut-2′-enyloxy)-2H-chromen-2-one (2) has been isolated for the first time from A. marmelos. The structure of compounds 1–5 was determined by spectral analysis (UV, IR, NMR, etc.). Additionally, the non-edible oil obtained from seeds was investigated for waste to wealth recovery of 6-O-ascorbyl esters in high regioselectivity via one step semi-synthetic approach in the presence of ascorbic acid and H2SO4 at ambient temperature. Graphical Abstract