Thilahgavani Nagappan - Academia.edu (original) (raw)

Papers by Thilahgavani Nagappan

Rice paddy herb, Limnophila aromatica Lam. Merr, is a tropical flowering plant in the plantain fa... more Rice paddy herb, Limnophila aromatica Lam. Merr, is a tropical flowering plant in the plantain family, Plantaginaceae, and flourishes in a hot, watery environment, particularly rice fields. It is known to have a distinct flavour and aroma reminiscent of lemon/cumin, and used as salad in diet by Southeast Asian communities. The essential oil from L. aromatica from Tuaran (Sabah) was extracted and analysed, a total of 36 volatile organic constituents were identified. Detailed analysis revealed the presence of only seven major volatile compounds (amyl vinyl carbinol, terpinolene, β-linalool, sabinene, terpinen-4-ol, α-humulene, aromadendrene) in the range of 3.02 % to 30.06 %. These volatiles could be grouped into monoterpene (44.10 %), oxygenated monoterpene (32.15 %), sesquiterpene (20.87 %), oxygenated sesquiterpene (1.2 %) and oxygenated diterpene (2.27 %-1.5 1%). Interestingly, the presence of sabinene, terpinen-4-ol and α-humulene were found in a high percentage and could be suggested as chemotaxonomical markers of this herb.

Applied phycology, Feb 24, 2020

The depletion of fossil fuel reserves, concerns over global warming and the high demand for natur... more The depletion of fossil fuel reserves, concerns over global warming and the high demand for natural functional foods and products have valorized microalgae as an alternative renewable feedstock. Over the past few decades, extensive research has focussed on microalgae, driven by their increasing applications and future potential. Thus, this review reports on one of the most significant pioneer microalgae, Chlorella vulgaris Beyerinck. The value of and prospects for this microalga for various applications are presented in relation to its biochemical components. Since metabolic changes occur when microalgae are cultivated under different environmental conditions, an overview of the effects of some environmental parameters on C. vulgaris is presented with respect to biomass production enhancement along with the accumulation of molecules of interest while maintaining feasible production costs.

Journal of Tropical Biology & Conservation (JTBC)

Volatile chemical constituents of four species of local bamboo (Schizostachyum blumei Nees., Schi... more Volatile chemical constituents of four species of local bamboo (Schizostachyum blumei Nees., Schizostachyum brachycladum Nees., Schizostachyum lima (Blanco) Merrill and Schizostachyum pilosum S.Dransf.) were investigated. The oils were obtained from bamboo culm through steam distillation and profiled using Gas Chromatography-Mass Spectrometry (GCMS). A total of 59 volatile constituents were identified, and these contained oxygenated sesquiterpene, Î±-elemol (8.2~21.1 %), coumaran (6.7~32.3 %), guaiacol-4-vinyl (0.6~0.9 %), palmitic acid (1.5~25.6 %), pentacosane (0.1~0.2 %), phytol (1.0~12.6 %), phytol acetate (0.5~1.7 %) and trans-squalene (0.2~1.6 %) consistently in the specimens studied. Based on the observation, S. pilosum exhibited wider diameter of inhibition against Escherchia coli and Staphylococcus aureus compared to the other species of Schizostachyum essential oil.

The volatile chemicals from species of wild Cinnamomum spp. (C. racemosum, C. cuspidatum, C. poli... more The volatile chemicals from species of wild Cinnamomum spp. (C. racemosum, C. cuspidatum, C. politum, C. javanicum), Etlingera spp. (E. pyramidosphaera, E. megalocheilos, E. coccinea, E. elatior) and Schizostachyum spp. (S. blumei, S. brachycladum, S. lima, S. pilosum) found in Sabah were investigated. The oils were obtained from the bark, rhizome and culm of respective specimens by hydrodistillation and the profile of volatile chemicals was obtained using Gas Chromatography- Mass Spectrometry (GCMS). Dominance of eucalyptol, terpinen-4-ol and eugenol were consistent among the species from genus Cinnamomum. Aromadendrane oxide, lauryl aldehyde, elemicin, borneol and 1-dodecanol were predominant among the species from genus Etlingera. α-elemol, coumaran, guiacol-4-vinyl, palmitic acid and phytol acetate predominate the species from genus Schizostachyum. Strong inhibition against Staphylococcus aureus (MIC: 5.62 ± 0.5 μg mL-1) were exhibited by essential oils of C. cuspidatum and E. c...

Zingiberaceae is one of the largest ginger families of the plant kingdom and are often regarded a... more Zingiberaceae is one of the largest ginger families of the plant kingdom and are often regarded as an important herbaceous species.

Rice paddy herb, Limnophila aromatica Lam. Merr, is a tropical flowering plant in the plantain fa... more Rice paddy herb, Limnophila aromatica Lam. Merr, is a tropical flowering plant in the plantain family, Plantaginaceae, and flourishes in a hot, watery environment, particularly rice fields. It is known to have a distinct flavour and aroma reminiscent of lemon/cumin, and used as salad in diet by Southeast Asian communities. The essential oil from L. aromatica from Tuaran (Sabah) was extracted and analysed, a total of 36 volatile organic constituents were identified. Detailed analysis revealed the presence of only seven major volatile compounds (amyl vinyl carbinol, terpinolene, I²-linalool, sabinene, terpinen-4-ol, I±-humulene, aromadendrene) in the range of 3.02 % to 30.06 %. These volatiles could be grouped into monoterpene (44.10 %), oxygenated monoterpene (32.15 %), sesquiterpene (20.87 %), oxygenated sesquiterpene (1.2 %)and oxygenated diterpene (2.27 %-1.5 1%). Interestingly, the presence of sabinene, terpinen-4-ol and I±-humulene were found in a high percentage and could be su...

Aquaculture Reports, 2020

Oxidative stress caused by chemicals brings about mass mortalities in aquatic organisms and in th... more Oxidative stress caused by chemicals brings about mass mortalities in aquatic organisms and in this context, antioxidants and heat shock protein 70 (Hsp70) stimulating compounds represent potential alternatives to alleviate this problem during aquaculture. The antioxidant capacity and efficacies of five Malaysian indigenous microalgae, namely Auxenochlorella pyrenoidosa, Chlorella vulgaris, Messastrum gracile, Desmodesmus subspicatus and Parachlorella kessleri to regulate Hsp70 expression in the brine shrimp Artemia, an important live food species, were examined. A. pyrenoidosa contained the highest total phenol and flavonoid content (48.3 mg GAE/g extract and 34.7 mg QE/g) across all the microalgae examined in this study, whereas the lowest occurred with C. vulgaris (24.4 mg GAE/g extract and 14.0 mg QE/g). The ferric reducing antioxidant power of A. pyrenoidosa, C. vulgaris, M. gracile, D. subspicatus and P. kessleri respectively stood at 0.78, 0.62, 1.01, 0.77 and 0.68 ferrous equivalents (mM), with trolox equivalent antioxidant capacity assay revealed that A. pyrenoidosa possessed the highest scavenging activity at 1 mg/mL concentration. Interestingly, application of 1.0-2.0 × 10 6 cells/mL C. vulgaris, M. gracile, D. subspicatus, and P. kessleri as feed enhanced Hsp70 accumulation in Artemia, indicating that these microalgae consist stimulating compound(s) which potentially promote the synthesis of the 70-kDa stress protein in this crustacean species. Taken together, results from this study revealed that microalgae possess various antioxidant properties and coupled with their abilities to induce Hsp70, they are potential oxidative stress control alternatives in Artemia and perhaps other aquatic organisms used in aquaculture. In this context, natural antioxidants, such as those exist in plants and microalgae, are more superior than synthetic ones to suppress oxidative stress as the latter, such as hydroxyl anisole (BHA) and butylated hydroxyl toluene (BHT), are carcinogenic and toxic to animals (Li et al., 2007; Munir et al., 2013). Microalgae are microscopic algae typically found in marine and freshwater environments, and they occur ubiquitously in sediments and water column. Microalgae tolerate harsh environments and like other higher plants, they perform photosynthesis, utilizing carbon source, light and water to produce food. Apart from carotenoids, fatty acids, enzymes, polymers, peptides and sterols, some microalgae species are rich in natural antioxidants and they serve as valuable alternatives to

Applied Phycology, 2020

Molecules, 2011

A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutac... more A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutaceae) were obtained and examined for their effects on the growth of five antibiotic resistant pathogenic bacteria and three tumor cell lines (MCF-7, P 388 and Hela). The structures of these carbazoles were elucidated based on spectroscopy data and compared with literature data, hence, were identified as mahanine (1), mahanimbicine (2) and mahanimbine (3). The chemical constituents of the essential oil were identified using Gas Chromatography-Mass Spectroscopy (GCMS). These compounds exhibited potent inhibition against antibiotic resistant bacteria such as Staphylococcus aureus (210P JTU), Psedomonas aeruginosa (ATCC 25619), Klebsiella pneumonia (SR1-TU), Escherchia coli (NI23 JTU) and Streptococcus pneumoniae (SR16677-PRSP) with significant minimum inhibition concentration (MIC) values (25.0-175.0 mg/mL) and minimum bacteriacidal concentrations (MBC) (100.0-500.0 g/mL). The isolated compounds showed significant antitumor activity against MCF-7, Hela and P388 cell lines. Mahanimbine (3) and essential oil in particular showed potent antibacteria and cytotoxic effect with dose dependent trends (≤5.0 μg/mL). The findings from this investigation are the first report of carbazole alkaloids' potential against antibiotic resistant clinical bacteria, MCF-7 and P388 cell lines.

Journal of Tropical Biology & Conservation (JTBC)

Secondary metabolites, derivatives of primary metabolites, are known for their biological activit... more Secondary metabolites, derivatives of primary metabolites, are known for their biological activities. Marine organisms, especially marine invertebrates such as sponges, tunicates, soft corals, bryozoans, and nudibranchs are important source of secondary metabolites with diverse biological properties. Approximately 40,000 marine natural products have been identified from various marine resources. Soft corals are a group of invertebrates known for their production of a vast range of metabolites with great structural diversity. Among 39 genera of soft coral Alcyonacean, a total of eighteen different species of Lobophytum soft corals have been identified. Isolation of secondary metabolites from the genus Lobophytum is tremendously explored by researchers worldwide. This review compiles several secondary metabolites that have been isolated and published on the soft coral L. pauciflorum, including the compound structures and some notable bioactivity.

Molecules, 2012

The traditional use of Murraya koenigii as Asian folk medicine prompted us to investigate its wou... more The traditional use of Murraya koenigii as Asian folk medicine prompted us to investigate its wound healing ability. Three carbazole alkaloids (mahanine (1), mahanimbicine (2), mahanimbine (3)), essential oil and ethanol extract of Murraya koenigii were investigated for their efficacy in healing subcutaneous wounds. Topical application of the three alkaloids, essential oil and crude extract on 8 mm wounds created on the dorsal skin of rats was monitored for 18 days. Wound contraction rate and epithelialization duration were calculated, while wound granulation and collagen deposition were evaluated via histological method. Wound contraction rates were obvious by day 4 for the group treated with extract (19.25%) and the group treated with mahanimbicine (2) (12.60%), while complete epithelialization was achieved on day 18 for all treatment groups. Wounds treated with mahanimbicine (2) (88.54%) and extract of M. koenigii (91.78%) showed the highest rate of collagen deposition with well-organized collagen bands, formation of fibroblasts, hair follicle buds and with reduced inflammatory cells compared to wounds treated with mahanine (1), mahanimbine (3) and essential oil. The study revealed the

Natural product communications, 2014

The essential oil composition of six species of wild Cinnamomum found in Borneo was investigated.... more The essential oil composition of six species of wild Cinnamomum found in Borneo was investigated. The oils were obtained from bark by hydrodistillation and the volatile chemical profile was obtained via Gas Chromatography-Mass Spectrometry (GCMS). A total of 65 volatile constituents were identified, where the essential oils of the studied specimens contained high contents of oxygenated monoterpenes. Eucalyptol (1.2-31.1%), terpinen-4-ol (7.9-22.1%), eugenol (0.4-37.9%) and α-cadinol (0.4-1.8%) were detected consistently in the specimens studied. The oils of C. cuspidatum and C. crassinervium exhibited significant inhibition against Listeria monocytogenes, specifically the latter, which displayed a lower minimum bactericidal concentration (MBC) value against Staphylococcus aereus and L. monocytogenes. This result had highlighted the possible usage of the essential oil derived from wild cinnamom species against food borne pathogens.

Natural Product Communications, Feb 1, 2012

Essential oils obtained by hydrodistillation from the rhizomes of Etlingera pyramidosphaera (K. S... more Essential oils obtained by hydrodistillation from the rhizomes of Etlingera pyramidosphaera (K. Schum.) R. M. Sm, E. megalocheilos (Griff.) A.D. Poulsen, comb. nov., E. coccinea (Blume) S. Sakai & Nagam, E. elatior (Jack) R. M. Sm, and E. brevilabrum (Valeton) R. M. Sm were analyzed by GCMS. The highest oil yield was obtained from E. pyramidosphaera (0.45%), followed by E. elatior (0.38%), E. coccinea (0.30%), E. brevilabrum (0.28%) and E. megalocheilos (0.25%). The major constituents of the essential oils were oxygenated monoterpenes, followed by sesquiterpenes, oxygenated sesquiterpenes, oxygenated diterpenes and diterpenes. The essential oils from E. pyramidosphaera and E. brevilabrum exhibited the best cytotoxicity against MCF 7 (LC50: 7.5 +/- 0.5 mg mL(-1)) and HL 60 (LC50: 5.0 mg mL(-1)), respectively. Strong inhibition was also observed for the essential oils of E. coccinea and E. megalocheilos against Staphylococcus aureus (MIC: 8.0 +/- 0.5 mg mL(-1), and 5.0 +/- 0.5 mg mL(-1)) and Streptococcus pyrogenes (MIC: 6.0 +/- 0.5 mg mL(-1) and 8.0 +/- 0.5 mg mL(-1)).

Essential oils obtained by hydrodistillation from the rhizomes of Etlingera pyramidosphaera (K. S... more Essential oils obtained by hydrodistillation from the rhizomes of Etlingera pyramidosphaera (K. Schum.) R. M. Sm, E. megalocheilos (Griff.) A.D. Poulsen, comb. nov., E. coccinea (Blume) S. Sakai & Nagam, E. elatior (Jack) R. M. Sm, and E. brevilabrum (Valeton) R. M. Sm were analyzed by GCMS. The highest oil yield was obtained from E. pyramidosphaera (0.45%), followed by E. elatior (0.38%), E. coccinea (0.30%), E. brevilabrum (0.28%) and E. megalocheilos (0.25%). The major constituents of the essential oils were oxygenated monoterpenes, followed by sesquiterpenes, oxygenated sesquiterpenes, oxygenated diterpenes and diterpenes. The essential oils from E. pyramidosphaera and E. brevilabrum exhibited the best cytotoxicity against MCF 7 (LC 50 : 7.50.5 mg mL -1 ) and HL 60 (LC 50 : 5.0 mg mL -1 ), respectively. Strong inhibition was also observed for the essential oils of E. coccinea and E. megalocheilos against Staphylococcus aureus (MIC: 8.00.5 mg mL -1 , and 5.00.5 mg mL -1 ) and Streptococcus pyrogenes (MIC: 6.00.5 mg mL -1 and 8.00.5 mg mL -1 ).

Natural product communications, 2012

The composition of the essential oils of Murraya koenigii (L.) Spreng, cultivated at six location... more The composition of the essential oils of Murraya koenigii (L.) Spreng, cultivated at six locations in Peninsula Malaysia and Borneo are presented. The oils were obtained from fresh leaves by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS); 61 compounds were identified, of which eleven were present in all the specimens analyzed. The two major volatile metabolites were identified as beta-caryophyllene (16.6-26.6%) and alpha-humulene (15.2-26.7%) along with nine minor compounds identified as beta-elemene (0.3-1.3%), aromadendrene (0.5-1.5%), beta-selinene (3.8-6.5%), spathulenol (0.6-2.7%), caryophyllene oxide (0.7-3.6%), viridiflorol (1.5-5.5%), 2-naphthalenemethanol (0.7-4.8%), trivertal (0.1-1.0%) and juniper camphor (2.6-8.3%). The results suggest that beta-caryophyllene and alpha-humulene could be used as chemotaxonomical markers for Malaysian M. koenigii, hence these specimens could be of the same stock and different from the ones in India, Thailand...

Natural product communications, 2012

Molecules, 2012

Journal of Applied Phycology, 2014

ABSTRACT The green algae genus Caulerpa is coenocytic, and the thallus consists of only one cell ... more ABSTRACT The green algae genus Caulerpa is coenocytic, and the thallus consists of only one cell with many nuclei. It is widely distributed in the tropical seas. In the Southeast Asian waters, there are at least ten known species. Three species, particularly Caulerpa racemosa var. clavifera f. macrophysa (Kützing) Weber-van Bosse, C. racemosa var. laetevirens (Montagne) Weber-van Bosse, and Caulerpa lentillifera J. Agardh are widely consumed. The proximate analysis and secondary metabolite composition of these three species were determined to describe their lipid and nutritional values. Glycolipids and phospholipids were the major lipid classes, with significant levels of triacylglycerol. Polyunsaturated fatty acids (PUFA) were the major fatty acids of all the three species. Typical n-3 and n-6 PUFA such as 18:3n-3, 18:4n-3, 20:5n-3, 18;2n-6, and 20:4n-6 were found in significant amount in all these three species. All three species contained a red-pigmented secondary metabolite determined as caulerpin. All three extracts exhibited potent antimicrobial activity against human food pathogenic bacteria and anti-inflammatory activity against the murine macrophage cell line, RAW 264.7.

Molecules, 2011

A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutac... more A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutaceae) were obtained and examined for their effects on the growth of five antibiotic resistant pathogenic bacteria and three tumor cell lines (MCF-7, P 388 and Hela). The structures of these carbazoles were elucidated based on spectroscopy data and compared with literature data, hence, were identified as mahanine , mahanimbicine (2) and mahanimbine (3). The chemical constituents of the essential oil were identified using Gas Chromatography-Mass Spectroscopy (GCMS). These compounds exhibited potent inhibition against antibiotic resistant bacteria such as Staphylococcus aureus (210P JTU), Psedomonas aeruginosa (ATCC 25619), Klebsiella pneumonia (SR1-TU), Escherchia coli (NI23 JTU) and Streptococcus pneumoniae (SR16677-PRSP) with significant minimum inhibition concentration (MIC) values (25.0-175.0 mg/mL) and minimum bacteriacidal concentrations (MBC) (100.0-500.0 g/mL). The isolated compounds showed significant antitumor activity against MCF-7, Hela and P388 cell lines. Mahanimbine (3) and essential oil in particular showed potent antibacteria and cytotoxic effect with dose dependent trends (≤5.0 μg/mL). The findings from this investigation are the first report of carbazole alkaloids' potential against antibiotic resistant clinical bacteria, MCF-7 and P388 cell lines. OPEN ACCESS Molecules 2011, 16 9652

Applied phycology, Feb 24, 2020

Journal of Tropical Biology & Conservation (JTBC)

Rice paddy herb, Limnophila aromatica Lam. Merr, is a tropical flowering plant in the plantain fa... more Rice paddy herb, Limnophila aromatica Lam. Merr, is a tropical flowering plant in the plantain family, Plantaginaceae, and flourishes in a hot, watery environment, particularly rice fields. It is known to have a distinct flavour and aroma reminiscent of lemon/cumin, and used as salad in diet by Southeast Asian communities. The essential oil from L. aromatica from Tuaran (Sabah) was extracted and analysed, a total of 36 volatile organic constituents were identified. Detailed analysis revealed the presence of only seven major volatile compounds (amyl vinyl carbinol, terpinolene, I²-linalool, sabinene, terpinen-4-ol, I±-humulene, aromadendrene) in the range of 3.02 % to 30.06 %. These volatiles could be grouped into monoterpene (44.10 %), oxygenated monoterpene (32.15 %), sesquiterpene (20.87 %), oxygenated sesquiterpene (1.2 %)and oxygenated diterpene (2.27 %-1.5 1%). Interestingly, the presence of sabinene, terpinen-4-ol and I±-humulene were found in a high percentage and could be su...

Aquaculture Reports, 2020

Applied Phycology, 2020

Molecules, 2011

Journal of Tropical Biology & Conservation (JTBC)

Molecules, 2012

Natural product communications, 2014

Natural Product Communications, Feb 1, 2012

Essential oils obtained by hydrodistillation from the rhizomes of Etlingera pyramidosphaera (K. S... more Essential oils obtained by hydrodistillation from the rhizomes of Etlingera pyramidosphaera (K. Schum.) R. M. Sm, E. megalocheilos (Griff.) A.D. Poulsen, comb. nov., E. coccinea (Blume) S. Sakai & Nagam, E. elatior (Jack) R. M. Sm, and E. brevilabrum (Valeton) R. M. Sm were analyzed by GCMS. The highest oil yield was obtained from E. pyramidosphaera (0.45%), followed by E. elatior (0.38%), E. coccinea (0.30%), E. brevilabrum (0.28%) and E. megalocheilos (0.25%). The major constituents of the essential oils were oxygenated monoterpenes, followed by sesquiterpenes, oxygenated sesquiterpenes, oxygenated diterpenes and diterpenes. The essential oils from E. pyramidosphaera and E. brevilabrum exhibited the best cytotoxicity against MCF 7 (LC 50 : 7.50.5 mg mL -1 ) and HL 60 (LC 50 : 5.0 mg mL -1 ), respectively. Strong inhibition was also observed for the essential oils of E. coccinea and E. megalocheilos against Staphylococcus aureus (MIC: 8.00.5 mg mL -1 , and 5.00.5 mg mL -1 ) and Streptococcus pyrogenes (MIC: 6.00.5 mg mL -1 and 8.00.5 mg mL -1 ).

Natural product communications, 2012

Molecules, 2012

Journal of Applied Phycology, 2014

Molecules, 2011

A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutac... more A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutaceae) were obtained and examined for their effects on the growth of five antibiotic resistant pathogenic bacteria and three tumor cell lines (MCF-7, P 388 and Hela). The structures of these carbazoles were elucidated based on spectroscopy data and compared with literature data, hence, were identified as mahanine , mahanimbicine (2) and mahanimbine (3). The chemical constituents of the essential oil were identified using Gas Chromatography-Mass Spectroscopy (GCMS). These compounds exhibited potent inhibition against antibiotic resistant bacteria such as Staphylococcus aureus (210P JTU), Psedomonas aeruginosa (ATCC 25619), Klebsiella pneumonia (SR1-TU), Escherchia coli (NI23 JTU) and Streptococcus pneumoniae (SR16677-PRSP) with significant minimum inhibition concentration (MIC) values (25.0-175.0 mg/mL) and minimum bacteriacidal concentrations (MBC) (100.0-500.0 g/mL). The isolated compounds showed significant antitumor activity against MCF-7, Hela and P388 cell lines. Mahanimbine (3) and essential oil in particular showed potent antibacteria and cytotoxic effect with dose dependent trends (≤5.0 μg/mL). The findings from this investigation are the first report of carbazole alkaloids' potential against antibiotic resistant clinical bacteria, MCF-7 and P388 cell lines. OPEN ACCESS Molecules 2011, 16 9652