Rakesh Deosharan Singh

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.

Evaluating the non-destructive method for determining the chlorophyll and nitrogen content in Stevia rebaudiana (Bertoni) leaf

Leaf chlorophyll (Chl) content is an indicator of photosynthetic activity, stress condition and nutritional status of a plant. The efficacy of a hand-held Chl meter (CCM-200) for non-destructive estimation of total Chl and nitrogen content in the stevia (Stevia rebaudiana Bertoni) leaves has been evaluated.

Seasonal variation in phytochemicals of essential oil from Juniperus communis needles in western Himalaya

Essential oil from Juniperus communis needles were examined in three different seasons (spring, rainy and winter) throughout the year for the analysis of yield and chemical composition. Volatiles of the needles were obtained by hydrodistillation process using clevenger type apparatus. The essential oil yield in all the seasons was not significantly changed and was found 0.29% (rainy), 0.3% (winter) and 0.33% (spring). Chemical compositions of the oils were analyzed by GC and GC-MS techniques on DB-5 capillary column resulted in identification of twenty-eight components. Identified components accounted for 91.1–93.1% of the total oils. The major class of compounds identified in present essential oil was monoterpene hydrocarbons (51.9–63.7%) with sabinene (30.1–37.1%) as the major constituent. Other compounds characterized in all the seasons were limonene (11.3–15.7%), 4-terpineol (9.1–10.5%), α-pinene (3.6–7.9%), δ-cadinene (3.7–4.6%), cis-sabinene hydrate (3.6–4.2%), myrcene (2.5–3.1%), α-terpinene (2.3–2.8%) and manool (1.3–2.2%). In this experiment winter was found to be most suitable time for the isolation of sabinene and limonene.

Temporal and spatial variation in quality of essential oil of Hedychium spicatum and evaluation of its antioxidant activity

The essential oil of Hedychium spicatum rhizome is used in perfumery and medicines. The rhizome is reported to be stomachic, carminative, a bronchodilator stimulant and a tonic. For studying seasonal variation of the composition of its volatiles, rhizomes of H. spicatum were collected from the Council of Scientific and Industrial Research–Institute of Himalayan Bioresource Technology (CSIR-IHBT), Palampur, Himachal Pradesh, India. To study the spatial diversity in essential oil content and composition, the rhizomes were collected from five different locations of Himachal Pradesh. Essential oils obtained by hydro-distillation were evaluated for their chemical composition by gas chromatography (GC) and GC/mass spectrometry (GC/MS) analyses. Twenty-two compounds were identified from the rhizome oil with major components 1,8-cineole, β-eudesmol, β-pinene and 10-epi–γ-eudesmol. All the essential oil samples were evaluated for their antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity. The essential oil extracted from the rhizomes collected from Biling had highest antioxidant activity; hence, it was also tested for cytotoxic activity against C-6, A549 and SiHa cell lines.

Integrated Weed Management in Plantation Crops

Plantation crops are long-term crops established for commercial interest. Major plantation crops are tea (Camellia spp.), coffee (Coffea arabica L.), oil palm (Elaeis guineensis Jacq.), areca nut (Areca catechu L), cardamom (Elettaria cardamomum Maton and Amomum subulatum Roxb.), coconut (Cocos nucifera L.), cashew (Anacardium occidentale L.), cocoa (Theobroma cacao L.), and rubber (Hevea brasiliensis Mull. Arg.). Being long-term crops, and often grown as monocultures, plantation crops are severely infested with weeds. This chapter deals with the nature and effect of the weed menace in the above mentioned crops along with methods adopted for weed management. In the plantation crops, weeds are managed by physical, mechanical, and chemical methods similar to those generally adopted in arable/field crops. However, there are reports on the use of low-density polyethylene sheets for mulching interrow space and mowing between the rows to control weeds. Planting smother crops or leguminous cover crops and intercropping in the row space, and deploying grazing animals are the biological methods for weed management in some of these crops. Integrated approach involving a combination of cultural, mechanical, and biological weed control methods is also adopted for combating weeds in an effective, economical, and eco-friendly manner.

Rapid validated RP-HPTLC method for the quantification of major bioactive constituents of Crataegus oxyacantha L.

A reverse phase high-performance thin-layer chromatography (RPHPTLC) method was developed for determination of vitexin, hyperoside, vitexin-2″-O-rhamnoside, quercetin, and apigenin in the Crataegus oxyacantha extract. The method employed precoated plate of RP-18 silica gel 60F254 as the stationary phase with acetonitrile-methanol-water-formic acid (10:10:20:0.05, v/v) as mobile phase, and densitometric determination was carried out at wavelength 254 nm in reflection/absorption mode. The linear regression analysis data for the calibration plots showed linear relationship (r) from 0.9985 to 0.9992. The method was validated for accuracy, precision, and robustness. The limits of detection and quantification were in the range of 100–300 ng and 310–960 ng, respectively, for analytes. The method is reproducible and convenient for quantitative analysis of these flavonoids in the leaves of C. oxyacantha. This is the first report of simultaneous densitometry quantification of major bioactive constituents in C. oxyacantha by developed and validated RP-HPTLC method. The change in the content of bioactive constituents with growth of the plant was also examined in leaf samples collected for 2 years.