Browsing by Author "Udukala, D.N."

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Antimicrobial Compounds Isolated from Endolichenic Fungi: A Review
(Molecules 2021, 2021) Wethalawe, A.N.; Alwis, Y.V.; Udukala, D.N.; Paranagama, P.A.
A lichen is a symbiotic relationship between a fungus and a photosynthetic organism, which is algae or cyanobacteria. Endolichenic fungi are a group of microfungi that resides asymptomatically within the thalli of lichens. Endolichenic fungi can be recognized as luxuriant metabolic artists that produce propitious bioactive secondary metabolites. More than any other time, there is a worldwide search for new antibiotics due to the alarming increase in microbial resistance against the currently available therapeutics. Even though a few antimicrobial compounds have been isolated from endolichenic fungi, most of them have moderate activities, implying the need for further structural optimizations. Recognizing this timely need and the significance of endolichenic fungi as a promising source of antimicrobial compounds, the activity, sources and the structures of 31 antibacterial compounds, 58 antifungal compounds, two antiviral compounds and one antiplasmodial (antimalarial) compound are summarized in this review. In addition, an overview of the common scaffolds and structural features leading to the corresponding antimicrobial properties is provided as an aid for future studies. The current challenges and major drawbacks of research related to endolichenic fungi and the remedies for them have been suggested.
Evaluation of anti-tyrosinase activity and antioxidant activity in the leaf extract of Senna auriculata (L.) Roxb. and the flower petal extract of Couroupita guianensis Aubl
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Senadeera, M. N.; Udukala, D.N.
Discovering natural products with the ability to inhibit melanogenesis has become a major area of interest in both cosmetic and pharmaceutical research. The demand for such products stems from the drawbacks associated with commercially available synthetic tyrosinase inhibitors, which often exhibit high toxicity and are known to cause adverse side effects. As a result, researchers have turned their attention towards exploring natural sources for safer and more effective alternatives. This study focuses on the anti-tyrosinase activity of the ethanolic extract of leaves of Senna auriculata and the ethanolic extract of flower petals of Couroupita guianensis. The skin whitening potential of the extracts was measured by conducting an in-vitro anti-tyrosinase assay. In addition, DPPH assay was used to measure the antioxidant activity of the extracts. A topical formulation was developed using the ethanolic extract of the flower petals of Couroupita guianensis and its tyrosinase inhibitory potential was further investigated. The ethanolic extract of Couroupita guianensis was found to have a tyrosinase inhibitory activity with an IC50 of 1296 mg/L compared to kojic acid (standard), which had an IC50 value of 79 mg/L. However, the ethanolic extract of Senna auriculata leaves did not show any tyrosinase inhibitory or activating properties. In addition, in the DPPH assay, ascorbic acid (standard) had an EC50 value of 41 mg/L, while the ethanolic extract of Senna auriculata showed more potent antioxidant activity with an EC50 value of 85 mg/L, in comparison to the ethanolic extract of Couroupita guianensis which had an EC50 of 623 mg/L. The formulation prepared with the flower petal extract of Couroupita guianensis showed moderate tyrosinase inhibition with an IC50 value of 6250 mg/L, in contrast the positive control showed an IC50 value of 1541 mg/L. The findings of this study reveal that there is a tyrosinase inhibitory potential in the flower petal extract of Couroupita guianensis and it offers a promising avenue for the development of a potential skin lightening agent in the cosmetic industry.
Identification of Volatile Compounds in Different Parts of the Brinjal Plant (Solanum melongena)
(19th Conference on Postgraduate Research, International Postgraduate Research Conference 2018, Faculty of Graduate Studies,University of Kelaniya, Sri Lanka, 2018) Nusra, M.S.F.; Paranagama, P.A.; Amarasinghe, L.D.; Udukala, D.N.
Plants synthesize and emit a large variety of volatile compounds, which produce a wide range of behavioral responses in insects. In some plants, these volatile organic compounds are the key compounds that are involved in attraction of insect pests. In addition, the synergism between insect pheromones and plant volatiles can increase the attraction of insect pest, offering new strategies for the development of more effective and reliable pest control programs. Volatile mediated foraging behavior is important in insect pests when they target host plants. The volatiles of brinjal may be functionally more important in host-finding behavior of their insect pest. Samples of brinjal plant leaves, fruits, shoots and flowers were collected from the unsprayed brinjal field. Steam distillation method was used to extract the volatiles from shade dried brinjal leaves, shoots, flowers and fresh fruits. The small pieces of the plant material were subjected to steam distillation for 4 hours at a distillation rate of 50 ml/hour. In this study, gas chromatography coupled with mass spectrometry technique was used for the identification of volatiles extracted from host plant brinjal. The GC oven was programmed at an initial oven temperature of 40 0C increased at a rate of 1 0C/min to 50 0C, then increased at a rate of 4 0C/min to 210 0C, and then raised at a rate of 8 0C/min to a final temperature of 230 0C. The MS data of eluted compounds were acquired and identified by the comparison of their retention times to those of authentic standards and with mass spectra from NIST library. Results indicated that brinjal plant produces 1-Methyl-5,8-dimethoxy-1,2,3,4-tetrahydro-1,4-iminonaphthalene, Benzyl alcohol, Phenylethyl Alcohol, Benzeneacetaldehyde, Butylated hydroxytoluene and Methyl salicylate from leaves; Butylated hydroxytoluene, n-Octyl formate, Butyl phthalate and 1,3-Dioxolane, 2-(methoxymethyl)-2-phenyl from fruits; Benzyl alcohol, 1,6-Octadien-3-ol, 3,7-dimethyl, Butylated hydroxytoluene, Hydroquinone and Methyl salicylate from shoots; and 1,6-Octadien-3-ol, 3,7-dimethyl, Methyl salicylate, Butylated hydroxytoluene, Hydroquinone and Benzyl alcohol from flowers as major compounds
Pheromone baited biopesticide for control of Leucinodes orbonalis Guenee in brinjal plant
(Frontiers in Bioscience, Elite, 2020) Nusra, M.S.F.; Paranagama, P.A.; Amarasinghe, L.D.; Udukala, D.N.
Leucinodes orbonalis Guenee, Brinjal fruit and shoot borer (BFSB), is the major pest on brinjal world wide. Larvae of this pest cause the damage; which at initial stages adversely affect the shoot growth, and in later stages diminish fruit quality. Spraying of insecticides is the main pest control method. This has been absolutely ineffective due to concealed habit of the larvae. Such a phenomenon apprehends to the development of insecticides resistance which demands continuously increasing doses. Manipulating the insect behavior using semiochemicals could be an opportunity for better management of insect pest. Application of BFSB sex pheromone components (E)-11-hexadecenyl acetate (E11-16: Ac) alone or in combination with (E)-11-hexadecen-1-ol (E11-16: OH) in traps can be used to suppress the populating growth. Goal-oriented interdisciplinary research on semiochemicals for sound administration of BFSB will depend on a better understanding of the key chemical ecology stimuli of relevance to the pest.
Synthesis, In Silico Studies, and Evaluation of Syn and Anti Isomers of N-Substituted Indole-3-carbaldehyde Oxime Derivatives as Urease Inhibitors against Helicobacter pylori
(molecules, 2021, 2021) Kalatuwawege, I.P.; Gunaratna, M.J.; Udukala, D.N.
• Gastrointestinal tract infection caused by Helicobacter pylori is a common virulent disease found worldwide, and the infection rate is much higher in developing countries than in developed ones. In the pathogenesis of H. pylori in the gastrointestinal tract, the secretion of the urease enzyme plays a major role. Therefore, inhibition of urease is a better approach against H. pylori infection. In the present study, a series of syn and anti isomers of N-substituted indole-3-carbaldehyde oxime derivatives was synthesized via Schiff base reaction of appropriate carbaldehyde derivatives with hydroxylamine hydrochloride. The in vitro urease inhibitory activities of those derivatives were evaluated against that of Macrotyloma uniflorum urease using the modified Berthelot reaction. Out of the tested compounds, compound 8 (IC50 = 0.0516 0.0035 mM) and compound 9 (IC50 = 0.0345 0.0008 mM) were identified as the derivatives with potent urease inhibitory activity with compared to thiourea (IC50 = 0.2387 0.0048 mM). Additionally, in silico studies for all oxime compounds were performed to investigate the binding interactions with the active site of the urease enzyme compared to thiourea. Furthermore, the drug-likeness of the synthesized oxime compounds was also predicted.