Chemistry

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A study of synergistic effects of some Sri Lankan essential oils against cowpea bruchids
(Callosobruchusmaculatus,Proceedings of eleventh Asian symposium on Medicinal plants, Spices and Other Natural Products, Kunming, China, 2003) Paranagama, P.A.; Adhikari, A.A.C.K.; Abeywickrama, K.P.; Bandara, K.A.N.P.
Aflatoxigenic Aspergillus flavus and aflatoxin formation in selected spices during storage
(2009) Rajasinghe, M.; Abeywickrama, K.P.; Jayasekera, R.
Proliferation of aflatoxigenic fungi and accumulation of aflatoxins take place during storage of spices at various environmental conditions. The objective of this research was to identify the aflatoxigenic fungal species and their aflatoxin forming potential in selected spices during storage in the laboratory and refrigerator. Dilution series of spice samples namely chilli (Capsicum annum) powder, curry powder, turmeric (Curcurma longa) powder and pepper (Piper nigrum) powder (purchased from two producers) were prepared separately and the frequency of occurrence of aflatoxigenic and other fungi were assessed after plating each on Potato Dextrose Agar and incubating at ambient temperature. Aflatoxin formation of A. flavus was confirmed by growing a pure culture on a SMKY medium and identifying toxins on thin layer chromatographic plates. The presence of aflatoxins in spice samples stored at 30 ± 20C and 40C was also confirmed. Long storage of spices leads to aflatoxin production irrespective of storage temperature hence, it is advisable to consume spices such as chilli powerder, tumeric etc. within a relatively short period to avoid build up of aflatoxins.
An integrated strategy to control post-harvest decay of Embul banana by combining essential oils with modified atmosphere packaging
(International Journal of Food science & Technology, 2007) Jayawardena, B.M.; Abeywickrama, K.P.
Mature Embul (Musa, AAB) bananas were treated with emulsions of either cinnamon bark or leaf (Cinnamomum zeylanicum) or clove (Syzygium aromaticum) oils to control post-harvest diseases, packed under modified atmosphere (MA) using low-density polyethylene (0.075 mm, LDPE) bags, and stored in a cold room (14 � 1 �C, 90% RH) or at ambient temperature (28 � 2 �C). The effects of the essential oils on post-harvest diseases; physico-chemical properties and organoleptic properties were determined and compared with controls and bananas treated with benomyl. Treatments with cinnamon bark and leaf oils controlled crown rot, whereas clove oil treatment did not affect crown rot development. Treatment with emulsions of cinnamon oils combined with MA packaging can be recommended as a safe, cost-effective method for extending the storage life of Embul bananas up to 21 days in a cold room and 14 days at 28 � 2 �C without affecting the organoleptic and physico-chemical properties.
Behavioural Studies of Cowpea Seed Bruchid, Callosobruchus maculatus (F.) Against Volatile Leaf Extracts of Lemongrass, Neem and Curry Leaf
(Tropical Agricultural Research, 2002) Adhikari, A.A.C.K.; Paranagama, P.A.; Abeywickrama, K.P.; Bandara, K.A.N.P.
Bioactivity of leaf volatiles of Azadirachta indica A. and Murraya koenigii (spreng) against Sitophilus orysae (L.) (Coleoptera: Curculionidae)
(Tropical Agricultural Research and Extension, 2002) Paranagama, P.A.; Abeysekera, K.H.T.; Nugeliyadde, L.; Abeywickrama, K.P.
Bioactivity of the essential oil of Cymbopogon citratus (Lemongrass) on Sitophllus oryzae(L) (Coleoptera : Curcuolionidae) [Rice Weewil]
(Sri Lanka Association for the Advancement of Science (SLAAS), 2001) Paranagama, P.A.; Jayaratne, K.H.T.; Nugeliyadde, L.; Abeywickrama, K.P.
Bioactivity of the essential oil of lemongrass, (Cymbopogon citratus) against rice weevil-Sitophilus oryzae(L.) and grain moth-Sitorroga cerealella (Olivier)
(Annual Research Symposium, Faculty of Graduate Studies, University of Kelaniya, 2001) Jayaratne, K.H.T.; Paranagama, P.A.; Nugeliyadde, L.; Abeywickrama, K.P.
Bioactivity of volatile constitutents of Sri Lankan plants against cowpea bruchids, Callosobruchus maculatus
(Proceedings of AFASSA Regional Symposium on Natural Products, 2004) Paranagama, P.A.; Abeywickrama, K.P.; Bandara, K.A.N.P.; Adhikari, A.A.C.K.
Cymbopogon citratus (lemongrass) and citral a+ b spray treatments alone or in combination with sodium bicarbonate in controlling crown rot in Embul banana (Musa acuminata AAB)
(2004) Abeywickrama, K.P.; Kularathna, L.; Sarananda, K.; Abeygunawardena, D.
The mounting pressure against synthetic fungicidal dips and sprays, restrict their use in controlling crown rot, a major post-harvest disease in banana. Generally regarded as safe (GRAS) compounds have a great potential to be used as alternatives to fungicides. Identification of chemical constituents of Cymbopogon citratus oil revealed the presence of citral as the main component. Cymbopogon citratus and citral with sodium bicarbonate (SBC) was fungicidal against the 3 banana fungal pathogens at 0.10-0.20 % v/v and 0.07-0.08 % v/v respectively. Embul banana sprayed with C. citratus alone or in combination with SBC after induced ripening, indicated a crown rot severity of 25 - 5 0% whereas, citral treatment resulted in a slightly lower disease severity. The physico-chemical parameters tested were not affected by the treatments. Oil/citral, SBC treated bananas and control were ranked good to excellent with respect to odour, flavour, taste and overall acceptability. The low disease severity of crown rot due to spray treatment of citral and SBC highlights the importance in adapting this simple, alternate treatment strategy for quality maintenance.
Deterrent effects of some Sri Lankan essential oils on oviposition and progeny production of the cowpea bruchid, Callosobruchus maculatus (F.)(Coleoptera; Bruchidae)
(2003) Paranagama, P.; Adhikari, C.; Abeywickrama, K.P.; Bandara, P.
Essential oils extracted from five plant materials were tested on oviposition and progeny production of F1 adult of cowpea bruchid, Callosobruchus maculatus on cowpea seeds. All oils tested showed a significant inhibition of oviposition and F1 adult emergence compared to the control during no-choice tests. Cymbopogon citratus and C. nardus showed higher effect on oviposition and F1 adult emergence than the essential oils of Alpinia calcarata, Cinnamomum zeylanicum and Murraya koinigii. In the choice test, the percentage ovipositions in all oils treated samples (except 10 mg of M. koinigii) were significantly lower than that of the control and ethanol treated samples. The percentage eggs deposited decreased with increasing doses of the oils ranging from 10 to 160 mg. The percentage of eggs laid was zero in samples treated with 40 mg of C. nardus or A. calcarata, 80 mg of C. citratus and 160 mg of C. zeylanicum. The essential oils of M. koinigii showed the lowest effect on oviposition when compared to other four essential oils.
Effect of Chemical Pretreatments on the Quality of Minimally Processed Pineapple Stored in Polystyrene Packages
(2012) Ediriweera, S.; Abeywickrama, K.P.; Latifah, M.
Minimally processed pineapple (Ananas comosus L.) cv. Mauritius stored at cold temperature for seven days were evaluated for physicochemical, sensory and microbiological qualities. Pineapple pieces were treated with 1% sodium chloride, 1% calcium chloride, a combination of 1% sodium chloride and calcium chloride, 1% ascorbic acid, 1% citric acid, 0.1% chitosan and distilled water (control) and packed in polystyrene packages before storage. Pretreatments did not significantly affect the physicochemical properties studied. Many sensory attributes in minimally processed pineapple decreased after seven days of storage. However, sodium chloride (1%) and a combination of 1% sodium chloride and calcium chloride pretreatments resulted in maintaining a better flavour in pineapple after a seven day storage period than the rest of the treatments. Microbial counts for all treatments and the control were within safe-to-consume limits while Salmonella was not detected in any sample.
Effect of coconut (Cocos nucifera) water extract on the development of adventitious roots in Polyscias fillicifolia stem cuttings
(The Journal of Agricultural Sciences - Sri Lanka, 2021) Jayawardena, B.M.; Agampodi, V.A.; Abeywickrama, K.P.
Purpose Vegetative propagation continues to be a popular method to propagate ornamental plant species. Coconut water (CW) can be considered as an abundant source of hormones and other plant growth regulators (PGRs). In this study, vegetative propagation of Polyscias fillicifolia was attempted using PGRs isolated from CW. Research method Stem cuttings were treated with varying concentrations (5, 10, 25, 50,100 μg mL-1) of PGR isolated from CW. The results were compared with a control set (treated with distilled water) and with those treated with solutions of pure synthetic indole acetic acid (IAA). Findings P. fillicifolia canes treated with a 25 μg mL-1 concentration of IAA, isolated from CW, showed the highest levels of root induction and development. Root development was more rapid (5 weeks) in the samples treated with PGRs isolated from CW compared to the canes propagated in the field by placing the canes on coir beds in plant nurseries. (6 weeks). Originality This is the first study to use PGRs isolated from CW extracts to improve lateral root proliferation, induce shoot development and leaf emergence in P. fillicifolia.
Effect of the essential oil of Cymbopogon nardus on Aspergillus flavus Link isolated from Sri Lankan paddy and rice
(University of Kelaniya, 2002) Paranagama, P.A.; Abeysekera, K.H.T.; Nugeliyadde, L.; Abeywickrama, K.P.
Effect of the essential oils of Cymbopogon citratus, C. nardus and Cinnamomum zeylanicum on pest incidence and grain quality of rough rice (paddy) stored in an enclosed seed box
(WFL Publisher, 2003) Paranagama, P.A.; Abeysekera, T.; Nugaliyadde, L.; Abeywickrama, K.P.
The protective effect of the essential oils of Cymbopogon citratus, C. nardus and Cinnamomum zeylanicum leaf on paddy stored in wooden boxes lined with aluminium foil were evaluated. After 168 days of storage in oil treated boxes Sitotroga cerealella population was significantly lower in oil treated paddy than the control. The 1000 grain weight was higher in all three treatments (21.1 - 22.9 g) compared to the control (19.8 g). Percentage grain damage was lower in C. citratus and C. nardus treated paddy than the control. The percentage seed germination was not significantly different from that of the control in oil treated paddy though, in C. citratus treatment the seed germination was reduced. The milling quality of paddy was not affected by the essential oil treatment however; the flavour and stickiness of cooked rice was enhanced when treated with C. zeylanicum and C. citratus oils.
Effect of volatile constituents of Curry leaf, Murraya koenigii on cowpea seed bruchid, Callosobruchu smaculatus (F.) in stored cowpea
(University of Kelaniya, 2001) Adhikari, A.A.C.K.; Paranagama, P.A.; Bandara, K.A.N.P.; Abeywickrama, K.P.
The efficacy of methanol extracts of leaves of lemongrass- Cymbopogon citratus (DC) Stapf and Curry leaf – Murraya koinigii Spreng on Callosobruchus maculatus
(Proceedings of Sri Lanka Association of Advancement of Science, 2002) Paranagama, P.A.; Adhikari, A.A.C.K.; Abeywickrama, K.P.; Bandara, K.A.N.P.
Electroantennograme and behavioral responses of male and female Callosobruchus maculatus (F.) to essential oil of lemongrass Cymbopogon citratus (Stapf)
(Annual Research Symposium, 2002) Paranagama, P.A.; Adhikari, A.A.C.K.; Abeywickrama, K.P.; Bandara, K.A.N.P.
Foliage preservatives for vase life extension of two dieffenbachia species
(2010) Thambugala, S.; Abeywickrama, K.P.; Karunarathna, S.
Cut foliage of Dieffenbachia maculata and Dieffenbachia amoena were subjected to continuous treatment with several foliage preservatives and export simulation. The preservatives used were 1.75% of sodium hypochlorite, 5% vinegar and VimTM dish washing detergent. Tap water without any added chemicals was used as the control. The highest vase life of 45.1 days was observed in D. maculata cut foliage when subjected to continuous treatment with tap water. Cut foliage of D. maculata subjected to continuous treatment with 0.016% (v/v) dish washing detergent (Vim™) solution and 0.016% (v/v) sodium hypochlorite (NaOCl) and subjected to export simulation for two days at 12-140 C and 85-90% relative humidity (RH), had relatively longer vase life of 38.9 days and 37 days respectively. Cut foliage of D. amoena had the longest vase life of 21 days when subjected to 0.016% NaOCl treatment and export simulation. NaOCl which is considered as a biocide and mild vinegar solution which is acidic inhibited the bacterial growth in vase solutions increasing the vase life of cut foliage. A Bacillus sp. and a Staphylococcus sp. were associated with vase solutions of D. maculata and D. amoena cut foliage. Treatment with NaOCl and VimTM satisfactorily extended the vase life of cut foliage of D. amoena and D. maculata respectively and could be recommended as preservatives for use during export.
Fungicidal activity of essential oils of Cinnamomum zeylanicum (L.) and Syzygium aromaticum (L.) Merr et L.M.Perry against crown rot and anthracnose pathogens isolated from banana
(Letters in Applied microbiology, 2002) Ranasinghe, L.S.; Jayawardena, B.M.; Abeywickrama, K.P.
Aims: To develop a post-harvest treatment system against post-harvest fungal pathogens of banana using natural products. Methods and Results:Colletotrichum musae was isolated and identified as the causative agent responsible for anthracnose peel blemishes while three fungi, namely Lasiodiplodia theobromae, C. musae and Fusarium proliferatum, were identified as causative agents responsible for crown rot. During the liquid bioassay, cinnamon [Cinnamomum zeylanicum (L.)] leaf, bark and clove [Syzygium aromaticum (L.)] oils were tested against the anthracnose and crown rot pathogens. The test oils were fungistatic and fungicidal against the test pathogens within a range of 0�03?0�11% (v/v). Conclusions:?Cinnamon and clove essential oils could be used as antifungal agents to manage post harvest fungal diseases of banana. Significance and Impact of the Study: Cinnamon and clove essential oil could be used as alternative post-harvest treatments on banana. Banana treated with essential oil is chemically safe and acceptable to consumers. Benomyl (Benlate), which is currently used to manage fungal pathogens, can cause adverse health effects and could be replaced with volatile essential oils.
Fungicidal and anti-aflatoxigenic effects of the essential oil of Cymbopogon citratus (DC.) Stapf. (lemongrass) against Aspergillus flavus Link. isolated from stored rice
(The Society for Applied Microbiology, 2003) Paranagama, P.A.; Abeysekera, K.H.T.; Abeywickrama, K.P.; Nugaliyadde, L.
Aims: To develop a natural fungicide against aflatoxigenic fungi, to protect stored rice, using the essential oil of lemongrass. Methods and Results: Aspergillus flavus Link. was isolated from stored rice and identified as an aflatoxigenic strain. Lemongrass oil was tested against A. flavus and the test oil was fungistatic and fungicidal against the test pathogen at 0Æ6 and 1Æ0 mg ml)1, respectively. Aflatoxin production was completely inhibited at 0Æ1 mg ml)1. The results obtained from the thin layer chromatographic bioassay and gas chromatography indicated citral a and b as the fungicidal constituents in lemongrass oil. During the fumigant toxicity assay of lemongrass oil, the sporulation and the mycelial growth of the test pathogen were inhibited at the concentrations of 2Æ80 and 3Æ46 mg ml)1, respectively. Conclusion: Lemongrass oil could be used to manage aflatoxin formation and fungal growth of A. flavus in stored rice. Significance and Impact of the Study: Currently, fungicides are not used to control fungal pests or mycotoxin production on stored rice. Rice treated with the essential oil of lemongrass could be used to manage fungal pests as well as the insect pests in stored rice. The essential oil is chemically safe and acceptable to consumers, as synthetic chemical fungicides can cause adverse health effects to consumers.