B. R. Rajeswara Rao

Effect of seasonal climatic changes on biomass yield and terpenoid composition of rose-scented geranium (Pelargonium species)

Abstract Variations in biomass yield, essential oil yield and terpenoid composition in rose-scented geranium ( Pelargonium species) in response to seasonal climatic changes were investigated under semiarid tropical climatic conditions. A large number of essential oil samples were collected during different seasonal months (once a month) and daily during the peak summer season months of May and June. They were analysed for terpenoid composition by GC and GC-MS. The crop yielded the lowest values for biomass yield, essential oil yield and essential oil concentration in the summer months of April to June. Evaluation of terpenoid compositions showed minimum concentrations (% of essential oil) of linalool, geraniol and its esters and maximum concentrations of citronellol and its esters during summer months. The percentages of geraniol and its esters were highest during cool winter season months of December and January followed by rainy and autumn season months. Isomenthone, 10-epi-gamma-eudesmol and other minor terpenoid compounds (present in

Volatile constituents of the essential oils of the seeds and the herb of palmarosa (Cymbopogon martinii (Roxb.) Wats. var. motia Burk.)

The essential oil of palmarosa (Cymbopogon martinii (Roxb.) Wats. var. motia Burk.) seeds collected from three different geographical locations in India was analysed by capillary GC and GC–MS. The composition of the oil samples was compared with that of the oil of flowering palmarosa herb. Besides the main constituent, geraniol (74.5–81.8%), 55 other constituents, including those present in trace amounts, were identified in the seed essential oil. Although the composition of the seed oils is similar to that of the herb oil, quantitative differences in the concentration of some constituents were observed. The seed oil was found to contain lower amounts of geranyl acetate and higher amounts of (E, Z)-farnesol than the herb oil.

Volatile flower oils of three genotypes of rose‐scented geranium (Pelargonium sp.)

The volatile flower oils of three genotypes of rose-scented geranium (Pelargonium sp.) commercially cultivated at a high altitude (2200 m above MSL) location (Kodaikanal) in India were investigated by GC and GC–MS. Freshly collected flowers of genotypes 1, 2 and 3 on distillation produced oil yields of 0.32%, 0.34% and 0.50%, respectively. The flower oil of genotype 1 was richer in α-pinene (1.7%), (Z) and (E)-rose oxides (1.3% and 0.6%), isomenthone (6.8%), citronellol (43.8%), citronellyl formate (20.4%), citronellyl acetate (1.0%), β-caryophyllene (2.6%), citronellyl butyrate (2.1%) and citronellyl tiglate (1.9%). The flower oil of genotype 2 was richer in terpinen-4-ol (1.3%), geranyl formate (3.6%), β-bourbonene (1.2%), α-muurolene (1.3%), geranyl isovalerate (0.9%), 10-epi-γ-eudesmol (4.6%) and geranyl tiglate (2.9%). The flower oil of genotype 3 was richer in linalol (7.6%), geraniol (38.6%), geranyl acetate+geranic acid (5.2%), β-phenylethyl butyrate (4.6%), 6,9-guaiadiene (2.3%) and α-humulene (1.5%). Copyright

Comparative Chemical Composition of Steam- Distilled and Water-Soluble Essential Oils of South American Marigold (Tagetes minuta L.)

Abstract Flowering shoot biomass of feld-grown South American marigold (Tagetes minuta L.) was hydrodistilled in Clevenger-type apparatus, steam-distilled in a feld distillation unit and the distillation water was collected. Chemical profles of hydrodistilled, steam-distilled and water-soluble (recovered from the distillation water of feld distillation unit employing hexane as the solvent) essential oils were analyzed by GC and GC/MS. The solubility of T. minuta oil in cold water at room temperature (30° C), in hot water (80° C) and the effciencies of hydrodistillation and hexane methods for isolating dissolved oil in water were studied under laboratory conditions. The solubility of the oil ranged from 0.11% in cold water to 0.15% in hot water. Hydrodistillation recovered 33.3–36.7% of dissolved oil in hot water and 55.0–60.0% of dissolved oil in cold water. Hexane extraction recovered 82.7–83.3% of dissolved oil in hot water and 90.0–90.5% of dissolved oil in cold water. Hydrodistilled and steam-distilled oils were richer in mono-and sesquiterpene hydrocarbons, while the water-soluble oil was richer in oxygenated monoterpenes (83.1–93.5%). Hydrodistilled and steam-distilled oils contained (Z)-β-ocimene (13.6–42.2%), dihydrotagetone + (E)-β-ocimene (14.8–30.3%), (Z)-tagetone (7.1–11.9%), (Z)-ocimenone (3.7–5.9%) and (E)-ocimenone (1.8–12.7%) as their major constituents. The main components of the water-soluble oil were: dihydrotagetone + (E)-β-ocimene (3.9–6.8%), (Z)-tagetone (6.2–7.9%), (E)-ocimenone (10.7–13.0%) and geraniol + linalyl acetate (47.5–52.0%).

Volatile constituents of different parts of cornmint (Mentha arvensis L.)

The volatile constituents of the essential oils of different parts (shoot stem, shoot leaf, stolon stem, stolon leaf) of cornmint, Mentha arvensis L., grown under semi-arid tropical climatic conditions were investigated. The shoot leaf gave the highest yield of oil (0.62%), while the stems produced negligible quantities of oil (0.02%). Menthol was the major component of all the oils, with the highest percentage in shoot stem oil (78.16%) and the lowest in stolon (runner) stem oil (43.7%). β-Caryophyllene oxide was present in shoot (stem and leaf) oils, while α-phellandrene and terpinolene were identified in stolon (stem and leaf) oils, which were also richer in limonene, menthone and pulegone than the shoot oils. Significant variations were observed among these oils for other components also. The underground rhizomes of cornmint plants did not yield any essential oil. Copyright

First observation of little leaf disease and its impact on the yield and composition of the essential oil of rose‐scented geranium (Pelargonium sp.)

Rose-scented geranium (Pelargonium sp.) plants infected with little leaf disease, probably caused by mycoplasma, were firstly observed during 1996–1998. The plants exhibited symptoms of reduced leaf/petiole size (little leaf), yellowing and bunching of leaves and cessation of plant growth, resulting in plant mortality. Plant parameters, viz. plant height, plant spread, number of branches, leaf size, leaf weight, etc., were adversely affected by little leaf disease, leading to significant reductions in shoot (49–70%), root (65–84%) and oil (67–91%) yields of diseased plants in comparison to healthy plants. Healthy plants recorded higher concentrations of geraniol, while little leaf disease-affected plants had higher percentages of isomenthone, citronellol, citronellyl formate, 10-epi-γ-eudesmol, citronellyl tiglate and geranyl tiglate. Copyright

Yield and chemical composition of the essential oils of three Cymbopogon species suffering from iron chlorosis

The yield and chemical composition of the essential oils of Java citronella (Cymbopogon winterianus Jowitt.), lemongrass (Cymbopogon flexuosus (Nees ex. Steud.) Wats. var. flexuosus Hack.) and palmarosa (Cymbopogon martinii (Roxb.) Wats. var. motia Burk.) plants suffering from iron chlorosis were examined. Iron chlorosis significantly reduced biomass and essential oil yields and total chlorophyll content of the leaves of all the three species. The citronellal, citronellol and geraniol contents of Java citronella, the (E)-citral percentage of lemongrass and the geraniol concentration of palmarosa were lower in plants affected by iron chlorosis as compared to healthy plants. The minor constituents of the essential oils of these crops were also affected by iron chlorosis, but the crops differed in their response to iron deficiency.

Chemotype Categorization of Curry Leaf Plants {Murraya koenigii (L.) Spreng.}

Abstract Curry leaf plants {Murraya koenigii (L.) Spreng., family: Rutaceae} were distinguished into 14 chemotypes under 3 major categories (monoterpenoid, sesquiterpenoid and mono- and sesquiterpenoid predominant oils) based on leaf essential oil chemical profiles. The monoterpenoid plants were grouped into 7 chemotypes. The sesquiterpenoid and the mono- and sesquiterpenoid plants were divided into 3 and 4 chemotypes, respectively. The categorization points to the possibility of existence of more number of chemotypes. Common experience of differences in flavour characteristics of curry leaves originating from diverse locations can be explained in terms of the quantitative and qualitative differences in these chemotypes. Existence of several chemotypes offers opportunities for consumers and flavourists to select curry leaves and essential oils with preferential flavour/ composition and for researchers to identify genotypes for yield and quality improvement.

Effect of method of distillation on the yield and chemical composition of Artemisia annua essential oil

Flowering shoot biomass of Artemisia annua var. Jeevanraksha grown under the semi-arid tropical climate of Hyderabad, South India, and distilled by field- and hydro-distillation techniques produced 0.26% and 0.35% essential oil yields on a fresh weight basis, respectively. Gas chromatography–flame ionization detector (GC–FID) and GC/mass spectrometry (GC/MS) analyses yielded fifty-four constituents accounting for 95.8% and 92.0% of the oils in field and hydro-distillations, respectively. The major compounds of the field-distilled oil were: camphor (23.6%), β-caryophyllene (16.6%), α-humulene (5.4%) and germacrene D (17.0%). The principal components of the hydro-distilled oil were: 1,8-cineole (11.1%), camphor (36.6%), β-caryophyllene (5.7%) and germacrene D (5.9%). Aliphatic ketones (37.7%), monoterpene hydrocarbons (11.2%) and oxygenated monoterpenes (19.9%) were higher in the hydro-distilled oil. Sesquiterpene hydrocarbons (54.1%) and oxygenated sesquiterpenes (6.8%) were present in large amounts in the field-distilled oil.

Storage of Essential Oils: Influence of Presence of Water for Short Periods on the Composition of Major Constituents of the Essential Oils of Four Economically Important Aromatic Crops

Abstract Appropriate storage of essential oils is important to retain their quality until their marketing by the producers or their utilization in flavour and fragrance consumer products by the industry. Water, air, light are reported to influence the composition of essential oils during prolonged storage, if they are improperly stored. In India, aromatic crops are cultivated largely by small and marginal farmers with limited resources and traders often report that farmers bring essential oils mixed with different proportions of distillation water. A laboratory experiment was therefore, conducted to investigate the influence of presence of varying quantities of water for short storage periods, on the composition of major chemical constituents of the essential oils of four economically important aromatic crops namely, palmarosa {Cymbopogon martinii (Roxb.) Wats. var. motia Burk., Family: Poaceae}, lemongrass {Cymbopogon flexuosus (Nees ex Steud) Wats., Family: Poaceae}, citronella (Cymbopogon winterianus Jowitt., Family: Poaceae) and lemon-scented gum (Eucalyptus citriodora Hook., Family: Myrtaceae). Principal chemical constituents of the essential oils of palmarosa (geraniol: 80.1 – 84.2 %, geranyl acetate: 10.3 – 11.3 %, linalool: 3.4 – 3.5 %), lemongrass (citral: 73.3 – 75.9 %, geraniol: 5.3 – 5.6 %), citronella (citronellal: 35.1 – 37.9 %, citronellol: 18.0 – 19.0 %, geraniol: 16.8 – 17.5 %, linalool: 1.4 – 1.5 %) and lemon-scented gum (citronellal: 73.9 – 76.3 %, isopulegol: 4.9–6.8 %, citronellol: 5.0 – 5.5 %, linalool: 1.0 – 1.3 %) did not significantly differ during the short storage periods of 1 to 15 days in the presence of 10 % or 20 % (by volume of the essential oils) of water.