Chemistry
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Item Evaluation of phytochemical composition and biological activities of ethanol extract of bark of Dialium ovoideum Thwaites(Chathurangani,D. A. Upeka and Udukala,Dinusha N. and Gunaratna,Medha J., 20240352316, English, Journal article, India, doi:10.5958/0975-6892.2024.00037.8, 0975-4261 0975-6892, 16, (2), New Delhi, Medicinal Plants - International Journal of Phytomedicines and Related Industries, (350–358), Society for Conservation and Resource Development of Medicinal Plants, Evaluation of phytochemical composition and biological activities of ethanol extract of bark of Dialium ovoideum thwaites., (2024), 2024) Chathurangani, D.A. Upeka; Udukala, Dinusha N.; Gunaratna, Medha J.The present study aimed to investigate the biological activities of the ethanol extract of the bark of Dialium ovoideum Thwaites (DOEB), which is an endemic plant of Sri Lanka with various medicinal values. A powdered bark sample was subjected to soxhlet extraction using ethanol followed by solvent evaporation to obtain the bark extract. The phytochemical screening performed on DOEB revealed the presence of phenols, flavonoids, tannins, saponins, terpenoids and steroids. The total phenolic and flavonoid contents of the DOEB were measured as 233.4±22.7 mg GAE/g and 198.1±24.5 mg QE/g, respectively. The antioxidant activity of DOEB showed an EC 50 of 68.5±6.3 μg/mL for the DPPH free radical scavenging assay and a significant (p<0.05) reductive potential compared to the ascorbic acid for the FRAP assay with a percentage reductive potential ranging from 5.7±0.8 to 79.2±2.2% across concentrations of 12.5 to 400 μg/mL. The modified L-DOPA method revealed the anti-tyrosinase activity of DOEB which is expressed as the IC50 of 1298.3±36.2 μg/mL. The human red blood cell stabilization assay by heat hemolysis resulted in an IC 50 of 425.7±9.3 μg/mL. The agar-well diffusion assay was conducted to assess the anti-microbial activities against the Staphylococus aureus, Escherichia coli, Klebsiella pneumoniae bacterial strains and the fungus, Candida albicans. The results exhibited that DOEB inhibited the growth of all three bacteria and fungi in different concentrations. Functional groups analysis of DOEB by FT-IR spectroscopy revealed the presence of alcohols, carboxylic acids, alkanes, alkenes, aliphatic esters, carbonyl and aromatic compounds. This study showed that DOEB has promising bioactivities based on the assays conducted which has a high potential to isolate bioactive compounds. Hence, DOEB may be employed as a prospective candidate in the food and pharmaceutical industries.Item Evaluation of phytochemical composition and biological activities of ethanol extract of bark of Dialium ovoideum Thwaites(Journal of Environmental Accounting and Management, 2023) Chathurangani, D.A. Upeka; Udukala, Dinusha N.; Gunaratna, Medha J.Antioxidants have been discovered to play an important unction in protecting the body rom damage caused by reactive ree radicals via interacting with ree radicals, chelating, and serving as oxygen scavengers. Dialium ovoideum thwaites, an endemic plant in Sri Lanka, which is locally identified as Gal Siyambala. Leaves o D. ovoideum thwaites have been reported to possess antioxidant properties. Hence, this study aimed to investigate the phytochemical profile and evaluate the antioxidant properties o the ethanol extract o the bark o D. ovoideum thwaites. The extract was prepared using the Soxhlet extraction method and it was subjected to phytochemical screening using standard procedures. The gravimetric method was utilized to conduct the quantitative analysis o flavonoids, tannins, and saponins. Folin-Ciocalteau assay was used to determine the total phenolic content. DPPH radical scavenging and erric-reducing power assays were used to determine the antioxidant properties. The results o qualitative phytochemical screening showed the presence o phenols, flavonoids, saponins, steroids and tannins. In quantitative analysis, the phytochemical constituents indicated 10.7% (w/w) o flavonoids, 1.1% (w/w) o tannins and 0.9% (w/w) o saponins. The total phenolic content was 233.4±22.7 mg gallic acid equivalent/g extract while the IC50 value or the DPPH assaywas 68.5±6.3 µg/mL which is comparable to ascorbic acid (32.0±2.1 µg/mL). The reducing potential o the extract showed that it possesses a significant (p<0.05) reductive potential as compared with the ascorbic acid standard. Results revealed that the ethanol extract o the bark o D. ovoideum thwaites exhibits antioxidant properties which are positively correlated with its total phenolic content.Item Synthesis, evaluation and structure activity relationship study of 2-phenyl-3H-quinazolinone derivatives as urease inhibitors against Helicobacter pylori(Institute of Chemistry Ceylon, 2020) Alwis, Y. Vindula; Gunaratna, Medha J.; Udukala, Dinusha N.Urease is a nickel containing metalloenzyme, which catalyzes the hydrolysis of urea into ammonia and carbon dioxide. It is an essential enzyme for Helicobacter pylori, which is a bacterium that has an ability to colonize upon the gastric wall, causing gastric ulcers and development of adenocarcinoma. By inhibition of urease, their growth and colonization can be ceased and therefore can be used as a pharmaceutical agent against H. pylori. This research was focused on the synthesis of the derivatives of 2-phenyl-3H-quinazolin-4-one and on the evaluation of their urease inhibitory action. Six derivatives of 2-phenyl-3H-quinazolin-4-one were synthesized in good yields (64%- 88%) by the oxidative cyclo-condensation of 2-aminobenzamide with benzaldehydes (namely 4-hydroxybenzaldehyde, 4-methoxybenzaldehyde, 4-chlorobenzaldehyde, 4-cyanobenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde and benzaldehyde) in a refluxing aqueous solution of FeCl3. The structures of synthesized analogues were confirmed using spectroscopic techniques such as 1H-NMR, 13C-NMR and FT-IR and by the determination of the melting points of compounds which were previously reported in literature. The urease inhibitory activities of synthesized compounds were quantified using an assay developed from Berthelot’s reaction. Urease required for the assay was extracted from the germinated seeds of Macrotyloma uniflorum (Horse-gram) and thiourea was used as the positive control. The synthesized derivatives of 2-phenyl-3H-quinazolin-4-one showed moderate to high potencies in the urease inhibition, as the IC50 values of all compounds except 2-(4-cyanophenyl)-3H-quinazolin-4-one and 2-(4-chlorophenyl)-3H-quinazolin-4-one, were less than that of the positive control (i.e., 0.80 mg/mL). When a Structure Activity Relationship (SAR) study was carried out by building up a linear free-energy correlation diagram, the exponential of the potencies of synthesized compounds were found to be directly proportional to the substituent constants, where the potency increased with the electron donating nature of the substituent groups. Thus, 2-phenyl-3H-quinazolin-4-one derivatives can be further optimized as “hits” in the drug discovery against H. pylori.Item Evaluation of urease inhibitory activity in the testa (seed coat) and the mesocarp of Cocos nucifera variety Aurantiaca(2020) Ranasinghe, Y. E.; Udukala, Dinusha N.; Gunaratna, Medha. J.Helicobacter pylori is an organism in the gastric mucosa of humans, which releases the enzyme urease facilitating its colonization, leading to gastritis and gastric cancer. The existing pharmacological agents against this causative bacterial urease, exhibit various side effects. Therefore, numerous studies have been focused upon the effectiveness of traditional medicinal herbs against gastritis. Certain parts of King Coconut are being used in folk medicine of Sri Lanka for the treatment of gastro-intestinal disorders. King Coconut is of the variety Aurantiaca, which is one of the varieties of Cocos nucifera. This study is focused on exploring the urease inhibitory activity in mesocarp and testa of King Coconut. The extracts of mesocarp and testa of King Coconut, were prepared by a sequential extraction method in increasing polarity order with hexane, ethyl acetate, methanol and water. The urease enzyme was extracted from Macrotyloma uniflorum (Horse-gram). The extent of urease inhibition, in known quantities of the extracts were examined, using a methodology modified from the Berthelot’s color reaction, employing the UV-Visible spectrophotometer. Urease enzyme inhibition potency of the eight extracts were investigated, where only the aqueous mesocarp extract of King Coconut showed an inhibition. The IC50 value of the aqueous mesocarp extract of King Coconut was found to be 1.12 ± 0.0393 mg/mL with respect to the standard urease inhibitor: thiourea (0.821 ± 0.00300 mg/mL). Hence, the aqueous mesocarp extract of King Coconut was subjected to phytochemical quantitative tests; polyphenolic test using gallic acid as the standard and flavonoid test using quercetin as the standard. The flavonoid and polyphenolic contents of the above extract were 0.328 mg g-1 and 0.149 mg GAE g-1 respectively. The results suggest that King Coconut has a therapeutic potential against the Helicobacter pylori infection, which could be developed as a novel drug in the future for gastrointestinal disorders.Item Urease inhibitory activity of the leaves and fruits of Trichosanthes cucumerina Linn.(Institute of Chemistry Ceylon, 2020) Dharmajeewa, H. D. O. P.; Gunaratna, Medha J.; Udukala, Dinusha N.Helicobacter pylori is a bacterium found in stomach which secretes bacterial urease, a major virulent factor to cause peptic ulcers. Hence, numerous studies have been carried out to investigate urease inhibitory activity of herbal extracts to treat peptic ulcers through the elimination of colonization of Helicobacter pylori. The plant of interest in this research was Trichosanthes cucumerina Linn. which is referred by the name ‘dummella’ in Sinhala. Leaves of this plant are currently being used to treat peptic ulcers in traditional medicinal methods and have been strongly suggested for research. This study was focused on exploring the urease inhibitory activity of leaves and fruits of Trichosanthes cucumerina Linn. Following the extractions prepared using hexane, ethyl acetate, methanol and water, urease inhibitory activity of each extract was evaluated using a colorimetric assay developed from Berthelot’s reaction. Urease enzyme was extracted from Macrotyloma uniflorum (Horse gram/“Kollu”) and thiourea was used as the standard inhibitor. Among the five samples which showed the urease inhibitory property, the lowest IC50 value of 1.134±0.008 mg/mL was obtained for the ethyl acetate extract of the fruit of Trichosanthes cucumerina Linn., thereby showed the highest urease inhibitory activity. The water extract of leaves of the plant showed the highest total phenolic content (0.104±0.003 mg GAE g-1) and total flavonoid content (0.027±0.005 mg of quercetin equivalents/g of dried weight. These results suggest a strong indication to use this plant parts in the treatment against the main causative of peptic ulcers and further research on such natural origins can be used to design and develop novel drugs with lesser toxicity.Item Design, synthesis and evaluation of 3-hydroxy quinazolinone derivatives as urease inhibitors against Helicobacter pylori(Institute of Chemistry Ceylon, 2020) Ruhunage, S. A.; Udukala, Dinusha N.; Gunaratna, Medha J.Gastritis is a common virulent disease found in the present world. The main pathogen which can cause gastritis is Helicobacter pylori and the infection from this bacterium in the upper gastrointestinal tract can lead to ulcers and gastric carcinoma. The activity and the growth of this bacteria in gastric juice of the stomach are favored by the bacterial urease enzyme. Therefore, urease enzyme inhibition plays a significant role in reducing the survival of the pathogen in the stomach. Apart from that, due to bacterial resistance and toxicity problems associated with the current drugs available against H. pylori, discovery of novel urease inhibitors is highly demanded. In this study, two 3-hydroxyquinazolinone derivatives were synthesized using anthranilic acid. Synthesized compounds were characterized using NMR spectroscopy. Urease inhibitory action of the synthesized compounds was measured by a colorimetric method called the Berthelot method. The amount of ammonia produced from urea due to urease enzyme activity was determined by this method. Inhibition of urease resulted low levels of ammonia produced and therefore low levels of absorbance. Among the two compounds, 3-hydroxy- 2-phenyl-4(3H)-quinazolinone exhibited high levels of inhibition at low concentrations with an IC50 value of 19.95 ± 1.03 μg/mL. This experiment was supported by a computational approach with the use of Gold score software for docking analysis and Chimera 1.9 for visualization of the docked molecules. The computational scores resulted in which 3-hydroxy-2-phenyl-4(3H)-quinazolinone was shown to be a better urease inhibitor compared to 3-hydroxy-2-methyl-4(3H)-quinazolinone by providing higher binding affinity and better Gold score values. Both experimental and computational results favored 3-hydroxy-2-phenyl-4(3H)-quinazolinone as a preferable urease inhibitor.Item Design, synthesis, and evaluation of 2, 3-disubstituted quinazolin-4(3H)-one derivatives as urease inhibitors against Helicobacter pylori(Institute of Chemistry Ceylon, 2020) Madujith, E. A. D. N.; Gunaratna, Medha J.; Udukala, Dinusha N.Helicobacter pylori is a pathogenic bacterium that causes ulcers and inflammations in the stomach lining. This bacterium produces urease enzyme which catalyzes the hydrolysis of urea in the stomach to carbon dioxide gas and ammonia. Resultant ammonia neutralizes stomach acid and helps H. pylori to survive and colonize in the acidic environment of the stomach. Therefore, inhibition of urease is a good strategy for controlling Helicobacter pylori. In this study, a series of 2,3-disubstituted quinazolinone derivatives was designed and their binding affinities to urease enzyme were studied using molecular docking. Auto dock GOLD 5.0.3 and Discovery studio v16.1.0.15 software were used for the computational docking study. In the synthesis, anthranilic acid was reacted with benzoyl chloride followed by dehydration to form a benzoxazinone intermediate. Subsequent addition of an amine to the benzoxazinone intermediate provided fused quinazolinone, named 3-amino-2- phenylquinazolin-4(3H)-one (NE-05). An improved method was developed for the synthesis of NE-05 in solvent-free conditions. Schiff bases (NE-06, 07, 08) were synthesized by the reaction of NE-05 with aldehydes benzaldehyde, p-hydroxybenzaldehyde and formaldehyde respectively. The structures of the synthesized derivatives were confirmed using IR and NMR spectroscopy. In vitro, urease inhibitory activity of the synthesized compounds was evaluated using modified Berthelot’s spectrophotometric method. Among the synthesized compounds, NE-05, NE-06, NE-07 and NE-08 showed an inhibitory effect of more than 50%, and among them, NE-06 and NE-07 are the two most promising compounds