Abhay K. Pandey

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.

Efficiency of Artemisia nilagirica (Clarke) Pamp. essential oil as a mycotoxicant against postharvest mycobiota of table grapes

BACKGROUND In order to get a potent botanical fungicide for the management of fungal decay of table grapes, an experiment was conducted in which 20 essential oils of higher plants were screened at 0.33 µL mL(-1) against dominant fungi causing decay of table grapes, including Aspergillus flavus, A. niger and A. ochraceus. Furthermore, the minimum inhibitory/fungicidal concentration, fungitoxic spectrum and mycotoxin inhibition activity of the most potent oil were determined. The efficacy of the most potent oil in preservation of table grapes, along with organoleptic evaluation, was also carried out by storing 1 kg of grapes in the oil vapour. RESULTS Artemisia nilagirica oil was found to be most toxic, exhibiting 100% mycelia inhibition of all test fungi. Moreover, 0.29 µL mL(-1) A. nilagirica oil was fungistatic and 0.58 µL mL(-1) was fungicidal for all tested species of Aspergillus. The oil exhibited a broad range of fungitoxicity against other grape berry-rotting fungi. Artemisia nilagirica oil completely suppressed the growth and mycotoxin (AFB1 and OTA) secretion of aflatoxigenic and ochratoxigenic strains of Aspergillus at 1.6 µL mL(-1) . During the in vivo experiment, fumigation of 1 kg of table grapes with 200 and 300 µL dosage of A. nilagirica oil enhanced the shelf life for up to 9 days. The oil did not show any phytotoxic effect. Besides, oil application did not substantively change the sensory properties of the fruits. CONCLUSION Artemisia nilagirica oil can be used as an alternative botanical fungicide for the control of fruit-rotting fungi of stored grapes.

The Genus Artemisia: a 2012–2017 Literature Review on Chemical Composition, Antimicrobial, Insecticidal and Antioxidant Activities of Essential Oils

Essential oils of aromatic and medicinal plants generally have a diverse range of activities because they possess several active constituents that work through several modes of action. The genus Artemisia includes the largest genus of family Asteraceae has several medicinal uses in human and plant diseases aliments. Extensive investigations on essential oil composition, antimicrobial, insecticidal and antioxidant studies have been conducted for various species of this genus. In this review, we have compiled data of recent literature (2012–2017) on essential oil composition, antimicrobial, insecticidal and antioxidant activities of different species of the genus Artemisia. Regarding the antimicrobial and insecticidal properties we have only described here efficacy of essential oils against plant pathogens and insect pests. The literature revealed that 1, 8-cineole, beta-pinene, thujone, artemisia ketone, camphor, caryophyllene, camphene and germacrene D are the major components in most of the essential oils of this plant species. Oils from different species of genus Artemisia exhibited strong antimicrobial activity against plant pathogens and insecticidal activity against insect pests. However, only few species have been explored for antioxidant activity.

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.

Efficacy of Some Essential Oils Against Aspergillus flavus with Special Reference to Lippia alba Oil an Inhibitor of Fungal Proliferation and Aflatoxin B1 Production in Green Gram Seeds during Storage

During mycofloral analysis of green gram (Vigna radiata (L.) R. Wilczek) seed samples taken from different grocery stores by agar and standard blotter paper methods, 5 fungal species were identified, of which Aspergillus flavus exhibited higher relative frequency (75.20% to 80.60%) and was found to produce aflatoxin B1 . On screening of 11 plant essential oils against this mycotoxigenic fungi, Lippia alba essential oil was found to be most effective and showed absolute inhibition of mycelia growth at 0.28 μL/mL. The oil of L. alba was fungistatic and fungicidal at 0.14 and 0.28 μL/mL, respectively. Oil had broad range of fungitoxicity at its MIC value and was absolutely inhibited the AFB1 production level at 2.0 μL/mL. Chemical analysis of this oil revealed geranial (36.9%) and neral (29.3%) as major components followed by myrcene (18.6%). Application of a dose of 80 μL/0.25 L air of Lippia oil in the storage system significantly inhibited the fungal proliferation and aflatoxin production without affecting the seed germination rate. By the virtue of fungicidal, antiaflatoxigenic nature and potent efficacy in storage food system, L. alba oil can be commercialized as botanical fungicide for the protection of green gram seeds during storage.

Biological spectrum of Trichoderma harzianum Rifai isolates to control fungal diseases of tomato (Solanum lycopersicon L.)

Abstract Three Trichoderma harzianum isolates viz., Th-Sks, Th-Ke and Th-Ar collected from respective states of India viz., Rajasthan, Kerala and Andhra Pradesh were evaluated for the management of six fungal diseases namely damping off, Fusarium wilt, Rhizoctonia wilt, early leaf spot, late blight and Septoria leaf spot in tomato. During in vitro analysis, T. harzianum isolates inhibited the pathogens’ growth. Isolate Th-Sks was the most virulent antagonist against all the test pathogens and exhibited maximum of 79.47% growth inhibition of Phytophthora infestans. Isolate Th-Sks proved most effective at suppression efficacy in the range of 95–100% and 91–100% against all diseases under glasshouse and in the field conditions, respectively. Tomato seeds treatment with isolate Th-Sks also promoted plant height (78.23 cm) and fruits yield (290 g/plant) during field trial and data were found to be not-significantly different from other isolates. Thus, it is concluded that isolate Th-Sks can be utilised as a biocontrol agent for management of fungal diseases in tomato.