N. N. Tripathi

Chemistry and bioactivities of essential oils of some Ocimum species:an overview

ABSTRACT Essential oils of different species of the genus Ocimum are natural flavouring materials of commercial importance. The data given in current literature are pertaining to the chemical composition of essential oils of different Ocimum species viz., Ocimum basilicum Linn. (alt. Ocimum basilicum var. minimum, Ocimum basilicum var. purpurience), Ocimum campechianum Mill., Ocimum canum Sims. (Ocimum americanum), Ocimum citriodorum, Ocimum gratissimum Linn., Ocimum kilimandscharicum Linn., Ocimum micranthum Willd., Ocimum sanctum Linn., (alt. Ocimum tenuiflorum Linn.), Ocimum selloi Benth., Ocimum trichodon, Ocimum utricifolium from different geographical regions. A considerable difference in chemical composition of a particular species is found, which may be due to their occurrence in different eco-climatic zones and changes in edaphic factors. Attention is also focused on the biological properties of Ocimum oils which are related to their various interesting applications as antimicrobial, antioxidant, repellent, insecticidal, larvicidal, nematicidal and therapeutic (anti-inflammatory, antinociceptive, antipyretic, antiulcer, analgesic, anthelmintic, anticarcinogenic, skin permeation enhancer, immunomodulatory, cardio-protective, antilipidemic) agents.

Essential Oils: Sources of Antimicrobials and Food Preservatives

Aromatic and medicinal plants produce essential oils in the form of secondary metabolites. These essential oils can be used in diverse applications in food, perfume, and cosmetic industries. The use of essential oils as antimicrobials and food preservative agents is of concern because of several reported side effects of synthetic oils. Essential oils have the potential to be used as a food preservative for cereals, grains, pulses, fruits, and vegetables. In this review, we briefly describe the results in relevant literature and summarize the uses of essential oils with special emphasis on their antibacterial, bactericidal, antifungal, fungicidal, and food preservative properties. Essential oils have pronounced antimicrobial and food preservative properties because they consist of a variety of active constituents (e.g., terpenes, terpenoids, carotenoids, coumarins, curcumins) that have great significance in the food industry. Thus, the various properties of essential oils offer the possibility of using natural, safe, eco-friendly, cost-effective, renewable, and easily biodegradable antimicrobials for food commodity preservation in the near future.

Assessment of Cymbopogon citratus (DC.) stapf essential oil as herbal preservatives based on antifungal, antiaflatoxin, and antiochratoxin activities and in vivo efficacy during storage.

Thirty-five randomly collected samples of stored table grapes (Vitis vinifera L.) from different markets of Gorakhpur city, Uttar Pradesh, India, revealed occurrence of 11 types of fungi. Of which, Aspergillus flavus, Aspergillus niger, and Aspergillus ochraceus were dominant causing severe decay of grapes with 58%, 52%, and 67% incidence, respectively. On screening of 15 essential oils at 0.33 μL/mL, Cymbopogon citratus oil caused 100% mycelial inhibition against aforesaid dominant fungi. Oil was fungistatic at 0.29 μL/mL and exhibited broad fungitoxicity against other fruit rotting fungi associated with collected samples. C. citratus oil completely inhibited the growth and mycotoxin (AFB1 and OTA) secretion of the aflatoxigenic and ochratoxigenic strains of A. flavus, A. niger, and A. ochraceus at 0.8 μL/mL. E-Citral (52.9%) and Z-Citral (39.38%) were the major components of C. citratus oil during gas chromatography and gas chromatography-mass spectrometry analysis. Application of 200 and 300 μL of C. citratus oil on 1 kg of stored grapes showed enhancement of shelf life up to 10 d. The oil did not exhibit any phytotoxic effect on fruits. These results confirm that C. citratus oil could be a natural alternative to commercial fungicide for control of fruit rotting fungi of stored grapes.

Application of Chenopodium ambrosioides Linn. essential oil as botanical fungicide for the management of fungal deterioration in pulses

Essential oils isolated from 35 aromatic plants of Gorakhpur Division, India, were screened at 0.36 μl ml− 1 against four dominant fungi Aspergillus flavus Link, A. niger van Tieghem, A. ochraceus Wilhelm and A. terreus Thom found on stored pigeon pea (Cajanus cajan Linn.) seeds. Chenopodium ambrosioides Linn. and Citrus aurantium Linn. oils exhibited strong antimycotic activity (100% mycelial inhibition). The minimum inhibitory concentration of C. ambrosioides oil was less (0.07 μl ml− 1) than that of C. aurantium oil, against all the test fungi. Both the oils were fungicidal at higher doses (1.71–2.78 μl ml− 1). C. ambrosioides oil exhibited broad fungitoxic spectrum against 16 other storage fungi of pigeon pea seeds. The oil remained effective with increased inoculum load, and physical factors had no adverse effect on its toxicity. C. ambrosioides oil proved superior to aluminium phosphide and ethylene dibromide, synthetic fumigants, at 0.29 μl ml− 1 and significantly protected 1 kg of pigeon pea seeds from microbial attack for up to 6 months. Chenopodium oil can be recommended as an effective substitute of synthetic fumigants for storage of pigeon pea seeds.

Evaluation of Clausena pentaphylla (Roxb.) DC oil as a fungitoxicant against storage mycoflora of pigeon pea seeds

BACKGROUND The present study aimed to evaluate the antifungal activity of 30 essential oils against four dominant fungi Aspergillus flavus Link., A. niger van Tieghem, A. ochraceus Wilhelm and A. terreus Thom of stored pigeon pea seeds at a concentration of 0.36 µL mL(-1). Various fungitoxic properties, such as minimum inhibitory concentration, minimum fungicidal concentration and fungitoxic spectrum, of the most potent oil were determined. The efficacy of the most potent oil in preservation of pigeon pea seeds for 6 months was also carried out by storing 1 kg of seeds in the oil vapour. RESULTS Clausena pentaphylla and Citrus limon oils were more effective against all the fungi tested, which exhibited 100% per cent mycelial inhibition. The minimum inhibitory concentration of C. pentaphylla oil was determined as 0.07 µL mL(-1) against all the test fungi and was found to be more toxic than Citrus limon oil. C. pentaphylla oil exhibited a broad range of fungitoxicity against 16 other storage fungi of pigeon pea seeds. C. pentaphylla oil significantly protected 1 kg seeds of pigeon pea from fungal deterioration and was superior to synthetic fumigants. The oil did not show any phytotoxicity and the protein content of the seeds was significantly retained for up to 6 months of storage. CONCLUSION Thus, C. pentaphylla oil may be used as an effective fumigant in the ecofriendly management of storage fungi of pigeon pea seeds.

New report on the chemical composition of the essential oil from leaves of Clausena pentaphylla from India

Clausena pentaphylla DC. (Ratanjote), belonging to the family Rutaceae, is a small aromatic deciduous, perennial shrub up to 2m in height and distributed in some forests of Gorakhpur Division (Uttar Pradesh, India). Several species of the genus Clausena (C. anisata, C. heptaphylla and C. pentaphylla) are used in folk medicine for human ailments. Ethanobotanical information revealed that the bark powder of C. pentaphylla is applied to fresh wounds for quick healing [1]. Singh and Mall [2] reported that a decoction of the leaf mixed with black pepper (Piper nigrum) and barley seeds (Hordeum vulgare) is taken twice a day for dysentery. A compound, clausmarin, isolated from C. pentaphylla leaves showed spasmolytic activity and reduces blood pressure [3]. Although investigations have been carried out on the essential oil composition of other Clausena species [4], there is no report concerning the chemical composition of C. pentaphylla oil. The present investigation reports the chromatographic (GC/MS) analysis of the oil obtained by hydrodistillation from leaves of C. pentaphylla. The oil sample has a characteristic slight pale yellow color with a yield of 0.8% (v/w) on a fresh weight basis. In present study, GC and GC/MS analysis of the C. pentaphylla oil led to the identification of 17 compounds representing around 97.5% of the oil (Table 1), with 11 monoterpene hydrocarbons (57.7%), five oxygenated monoterpenes (45.7%), and one sesquiterpene hydrocarbon (0.1%). The major volatile constituents were methyl eugenol (38.1%), sabinene (24.7%), -terpinolene (13.8%), limonene (7.8%), and safrole (6.7%). In an earlier report on the other species of Clausena, e.g., C. heptaphylla, anethole (21.7%) and methyl chavicol (25.7%) were reported as major components [5]. On the contrary, a report of Lockwood [6] indicated trace amounts of methyl chavicol (0.6%), with anethole as the major component. The leaf essential oil of another species of Clausena, C. anisata, further showed anethole as the major component [7], but in current study no such compounds were detected. This compositional variation may be of chemotaxonomic value in the intraspecific differentiation of Clausena species. The current investigation is the first report on the chemical composition of C. pentaphylla oil. Fresh plant material was collected from Kusumahi Forest (Gorakhpur Division) in February, 2009. The plant collecting site was located in the eastern part of Uttar Pradesh, India between a latitude of 27 05 to 27 25 North and a longitude of 83 20 to 84 10 East. A plant specimen was duly identified and deposited at the herbarium of the Botanical Survey of India (BSI), Northern Circle, Dehradun (Acc. No. 112883). The essential oil of fresh leaves was obtained through hydrodistillation using a Clevenger-type apparatus [8] for 4 h. The oil was dried over anhydrous Na2SO4 and was stored at low temperature (4 C) in a clean sealed glass vial for GC and GC/MS analysis. About 0.1 L of pure oil sample was subjected to GC and GC/MS analyses. The GC consist of an Agilent Technology 6890 N gas chromatograph data handling system equipped with a split-splitless injector and fitted with an FID using N2 as the carrier gas. The column was an HP-5 capillary column (30 m 0.32 mm, 0.25 m film thickness) and the temperature program used was as follows: initial temperature of 60 C (hold 2 min) programmed at a rate of 3 C/min to a final temperature of 220 C (hold 5 min). The temperatures of the injector and FID were maintained at 210 C and 250 C, respectively. The GC/MS analysis was carried out on a Perkin–Elmer Clarus 500 gas chromatograph equipped with a split-splitless injector (split ratio 50:1) data handling system. The column was an Rtx®-5 capillary column (60 m 0.32 mm, 0.25 m film thickness). Helium was the carrier gas at a flow rate of 1.0 mL/min. The GC was interfaced with a Perkin–Elmer Clarus 500 mass detector operating in the EI+ mode.

Bioefficacy of plant essential oils against pulse beetles Callosobruchus spp. (Coleoptera: Bruchidae) in pigeon pea seeds with particular reference to Clausena pentaphylla (Roxb.) DC.

Thirty essential oils from higher plants of Gorakhpur Division (India) were evaluated at 0.36 μl/ml against two pulse beetles, Callosobruchus chinensis L. and C. maculatus F., causing infestation of pigeon pea seeds during storage. Clausena pentaphylla oil was more effective and exhibited absolute repellency against both the insects followed by Ocimum canum, Salvia plebeia and Zingiber zerumbet oils. Among these four oils, C. pentaphylla oil was most toxic and showed 100% mortality of both the insects at 10-μl dosage and 24-h exposure (LD50 = 2.7 μl for C. chinensis & 2.4 μl for C. maculatus). Physical factors, viz. temperature, storage and autoclaving, did not cause any adverse effect on the toxicity of Clausena oil. During in vivo investigation, the oil protected 1 kg of pigeon pea seeds completely without reducing weight loss and seed damage up to 6 months when stored in gunny bags and glass containers. The oil was standardised by determining its various physicochemical properties. Thus, C. pentaphylla oil can be judiciously exploited as herbal insecticide against pulse beetles of pigeon pea seeds during storage.

Mycotoxin Menace in Stored Agricultural Commodities and Their Management by Plant Volatiles: An Overview

Mycotoxins are toxic metabolites of fungi when they grow on food commodities. These are potent toxins having severe manifestations in humans and animals, being carcinogenic, mutagenic and teratogenic. Mycotoxin contamination is most widespread in agricultural commodities. These mycotoxins are secondary metabolite products and are produced by several fungi occurring on commercially importance agricultural produce during pre- and post-harvest and incur significant side effects on animalia. Aflatoxins, fumonisins, ochratoxins, deoxynivalenol, zearalenone, patulin are major mycotoxins, produced by Aspergillus, Fusarium, and Penicillium species. Among all, aflatoxins, fumonisins, and ochratoxins are found to have very important role in creating several side effects in human health worldwide. For control of these mycotoxins in agricultural commodities, several physical, chemical and biological management techniques and measures have been developed. However, physical and chemical methods have their own limitations. Plant volatiles isolated from higher plants certainly provide a potential mycotoxin management strategy in stored food commodities. This review describes the mycotoxins contamination in some commercially importance agricultural crops such as rice, wheat, maize, peanut, sorghum, pearl-millets, barley, oat, pulses, oil seeds, fruits and their management through plant volatiles; which may be helpful in developing proper management strategies. Information from meticulous studies of mycotoxins in food commodities throughout the world will help in providing safer food for consumption and in prioritizing future research programs.