Ved R. Singh

Chemical Composition and Allelopathic, Antibacterial, Antifungal, and Antiacetylcholinesterase Activity of Fish-mint (Houttuynia cordataThunb .) from India

Fish‐mint (Houttuynia cordataThunb.), belonging to family Saururaceae, has long been used as food and traditional herbal medicine. The present study was framed to assess the changes occurring in the essential‐oil composition of H. cordata during annual growth and to evaluate allelopathic, antibacterial, antifungal, and antiacetylcholinesterase activities. The essential‐oil content ranged from 0.06 – 0.14% and 0.08 – 0.16% in aerial parts and underground stem, respectively. The essential oils were analysed by GC‐FID, GC/MS, and NMR (1H and 13C). Major constituents of aerial‐parts oil was 2‐undecanone (19.4 – 56.3%), myrcene (2.6 – 44.3%), ethyl decanoate (0.0 – 10.6%), ethyl dodecanoate (1.1 – 8.6%), 2‐tridecanone (0.5 – 8.3%), and decanal (1.1 – 6.9%). However, major constituents of underground‐stem oil were 2‐undecanone (29.5 – 42.3%), myrcene (14.4 – 20.8%), sabinene (6.0 – 11.1%), 2‐tridecanone (1.8 – 10.5%), β‐pinene (5.3 – 10.0%), and ethyl dodecanoate (0.8 – 7.3%). Cluster analysis revealed that essential‐oil composition varied substantially due to the plant parts and season of collection. The oils exhibited significant allelopathic (inhibition: 77.8 – 88.8%; LD50: 2.45 – 3.05 μl/plate), antibacterial (MIC: 0.52 – 2.08 μl/ml; MBC: bacteriostatic) and antifungal (MIC: 2.08 – 33.33 μl/ml; MFC: 4.16 – 33.33 μl/ml) activities. The results indicate that the essential oil from H. cordata has a significant potential to allow future exploration and exploitation as a natural antimicrobial and allelopathic agent.

Characterization of the Leaf Essential Oil Composition of Annonasquamosa L. from Foothills of North India

The leaf essential oil composition of Annona squamosa L., collected from the lower region of Himalaya was investigated using gas chromatography-flame ionisation detector (GC-FID) and GC-mass spectrometry (GC-MS). A total of forty-three constituents, representing 88.6% of the total oil composition were identified. The essential oil was primarily composed of sesquiterpenoids (sesquiterpene hydrocarbons: 63.4% and oxygenated sesquiterpenes: 21.8%). Major constituents of the oil were (E)-caryophyllene (15.9%), γ-cadinene (11.2%), epi-α-cadinol (9.4%), (Z)- caryophyllene (7.3%), γ-muurolene (5.4%), α-humulene (5.2%), viridiflorene (5.0%), α-cadinol (3.9%), aromadendrene (2.9%), δ-cadinene (2.9%), α-cadinene (2.9%), (2Z,6Z)-farnesal (2.2%) and caryophyllene oxide (2.1%).

Stable variety selection over locations and recommendations for rose-scented geranium (Pelargonium graveolens L’ Herit. ex Aiton.)

Abstract Objective: In this study, productivity and essential oil quality of rose-scented geranium (Pelargonium graveolens L’ Herit. ex Aiton.) varieties, namely CIMAP Bio-G-171, CIM-Pawan and Bourbon were assessed and compared in two locations of north India. Methods: A field experiment was conducted to evaluate the productivity, while the chemical composition of the essential oils was assessed by GC-FID and GC-MS. Result: Yields of fresh leaves and essential oil from CIMAP Bio-G-171 were significantly higher (173.64–174.42 q h-1 and 69.93–79.06 l h-1) than those of CIM-Pawan (158.08–160.56 q h-1 and 55.57–64.46 l h-1) and Bourbon (133.34–139.33 q h-1 and 44.19–48.38 l h-1). Major constituents of the oils were citronellol (20.9–39.5%), geraniol (10.9–26.5%), linalool (2.9–14.2%), isomenthone (7.4–9.4%), citronellyl formate (5.5–9.1%) and 10-epi-γ-eudesmol (5.2–9.0%). Conclusion: The essential oil yields and chemical compositions were substantially influenced by variety and location of growing. The variety CIMAP Bio-G-171 showed improvement up to 58.2–63.4% and 22.6–25.8% in essential oil productivity over the existing prevalent varieties, Bourbon and CIM-Pawan, respectively.

Chemical composition and antibacterial activity of p-menthane chemotype of Cymbopogon martini (Roxb.) W. Watson (Poaceae) from India

Abstract In this study, the essential oil composition and antibacterial activity of an underexplored population of Cymbopogon martinii (Roxb.) W. Watson was investigated using GC–FID, GC–MS, disc diffusion and micro dilution broth assay. To substantiate the stability of the essential oil profile, the population was grown in the experimental field and its oil was analysed at different growth stages. Altogether, forty-eight constituents, comprising 91.5–96.8% of the total oil composition were identified. Main constituents of the oil were trans-p-mentha-2,8-dien-1-ol (16.6–22.8%), cis-p-mentha-2,8-dien-1-ol (7.2–9.7%), trans-p-mentha-1(7),8-dien-2-ol (9.8–15.8%), cis-p-mentha-1(7),8-dien-2-ol (11.3–18.0%), limonene (10.5–34.8%), isopiperitenol (3.1–5.0%), trans-carveol (3.5–4.5%) and carvone (2.6–3.6%). The oil exhibited wide spectrum, moderate to very good activity against pathogenic bacterial strains (zone of growth inhibition: 9–25 mm; minimum inhibitory concentration, MIC: 125–500 μg/mL). In conclusion, due to high percentage of monoterpene alcohols, the examined oil demonstrated potent antibacterial activity against both Gram-positive and Gram-negative strains.

p-Menthenols chemotype of Cymbopogon distans from India: composition, antibacterial and antifungal activity of the essential oil against pathogens

Abstract Cymbopogon distans (Nees. ex. Steud.) W. Watson (family: Poaceae) is a perennial aromatic grass widely distributed in tropical and subtropical zones of north-western Himalaya. The essential oil of C. distans has industrial potential for aromatherapy, fragrances and for natural aroma isolates. In view of chemotypic variations and industrial potential of the essential oil of C. distans, the present study was carried out to investigate the variability in chemical composition of p-menthenols chemotype of the C. distans harvested in different seasons during annual growth, and to evaluate the antimicrobial potential of its essential oil against pathogenic bacterial and fungal strains. The major constituents identified in essential oil of C. distans were cis-p-menth-2-en-1-ol (24.5–26.7%), δ-2-carene (19.9–28.2%), cis-piperitol (10.9–23.6%), trans-p-menth-2-en-1-ol (8.4–13.3%) and trans-piperitol (5.4–7.3%). The essential oil showed antagonist activity against nine bacterial strains (MIC: 250–1000 μg/mL) and three fungal strains (MIC: 130–530 μg/mL). Results revealed that the essential oil of C. distans possessed >50.0% of p-menthenols viz., cis-p-menth-2-en-1-ol, trans-p-menth-2-en-1-ol, cis-piperitol and trans-piperitol as major constituents, with a significant antimicrobial potential for pathogenic microbial strains.

Optimization of harvesting and post-harvest drying methods of Ocimum africanum Lour. for production of quality essential oil

ABSTRACT The influences of cropping seasons, crop maturity stages and wilting period on essential oil composition of Ocimum africanum Lour. var. CIM-Jyoti, grown at foothills agroclimatic conditions of northern India, were studied and compared using gas chromatography–flame ionization detector and gas chromatography–mass spectrometry. Altogether, 28 constituents, forming 91.8–99.1% of the total oil composition, were identified by comparing their retention indices and mass spectral data. The essential oil content was found to vary from 0.38% to 0.66% during different maturity stages with maximal in full bloom stage. Citral (55.0–75.5%), (E)-γ-bisabolene (2.6–9.5%), nerol (1.7–8.9%), geraniol (1.5–6.5%), linalool (1.1–6.0%), β-caryophyllene (0.7–3.2%), α-humulene (0.4–2.7%) and 6-methyl-5-hepten-2-one (≤0.03–2.1%) were identified as the characteristic constituents of the essential oil of O. africanum. Significant variations in the essential oil content and qualitative chemical composition were noticed in different harvesting stages of two cropping seasons.

Optimization of distillation conditions for better recovery of Acorus calamus L. essential oil

Abstract The comminution and distillation time are two important factors, which affect the essential oil yield and/or composition of aromatic plants significantly. To find out the suitable comminution process and optimum distillation time for isolation of essential oil from Acorus calamus L., an experiment was conducted. The comminuted rhizomes (sliced and powdered) were hydrodistilled for different durations and their yields and compositions were compared. Distillation of uncomminuted rhizome for 8 hours gave 2.37% of essential oil. However, in comminuted rhizomes, yield varied from 2.27 to 6.60% under different distillation durations. The resulting essential oils were analyzed using GC-FID and GC-MS. Twenty-seven constituents, representing 94.7–97.2% of the total oil compositions were identified. Major constituents of the oils were (Z)-asarone (84.8–91.2%), and (E)-asarone (2.5–5.2%). The comminution and distillation time showed noteworthy effect on the essential oil yield; however, they showed no major change on the essential oil composition of A. calamus. It was concluded that powdering of dried rhizomes and effecting distillation for 4 hours are appropriate parameters for extracting maximum essential oil from A. calamus at laboratory scale.

Natural benzaldehyde from Prunus persica (L.) Batsch

ABSTRACT Benzaldehyde is one of the most important molecules in the flavour industry. Presently, most of its industrial requirement is met through synthetic route. In this research, leaf essential oil of Prunus persica (L.) Batsch. extracted in different seasons was analysed using GC-FID, GC-MS, and NMR (1H and 13C) techniques. The oil was characterised by higher amounts of benzaldehyde (63.1%–98.3%). The yield of benzaldehyde was higher during rainy (0.45 g/100 g fresh leaves) and autumn (0.44 g/100 g fresh leaves) seasons. In conclusion, leaves of P. persica can be used as a natural source of benzaldehyde for flavour industry.