P. Rayan - Academia.edu (original) (raw)
Papers by P. Rayan
Parasitology research, Jan 16, 2015
Giardisis is a debilitating disease caused by gastrointestinal parasites of the genus Giardia. Hi... more Giardisis is a debilitating disease caused by gastrointestinal parasites of the genus Giardia. High-antioxidant T. ferdinandiana fruit extracts were investigated for the ability to block Giardia duodenalis growth. Methanolic and aqueous extracts had the most potent growth inhibitory activity (IC50 values of approximately 700 and 140 μg/ml, respectively). Ethyl acetate and chloroform extracts also inhibited G. duodenalis growth, albeit with lower potency. The hexane extract was completely devoid of G. duodenalis growth inhibitory activity. All extracts were nontoxic in the Artemia fransiscana bioassay. Nontargeted HPLC-quadrupole time-of-flight (QTOF) mass spectroscopy (with screening against three compound databases) putatively identified 17 compounds in all of the inhibitory extracts but not in the inactive hexane extract. The low toxicity of the Terminalia ferdinandiana fruit extracts and their potent G. duodenalis growth inhibitory bioactivity indicate their potential as medicina...
Introduction: Tasmannia stipitata (Dorrigo pepper) is an endemic Australian plant with a history ... more Introduction: Tasmannia stipitata (Dorrigo pepper) is an endemic Australian plant with a history of use by indigenous Australians as a food. It is taxonomically related to Tasmania lanceolata which has documented therapeutic properties as well as uses for food flavouring. Methods: T. stipitata solvent extracts were investigated by disc diffusion assay against a panel of bacteria and fungi. Their MIC values were determined to quantify and compare their efficacies. The ability to inhibit the proliferation of Giardia duodenalis was determined by direct cell counts and by using an MTS based cell proliferation assay. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: Methanolic, aqueous and ethyl acetate T. stipitata leaf and berry extracts displayed antibacterial activity in the disc diffusion assay. The berry methanolic extract had the broadest antibacterial range, inhibiting the growth of all 22 of the 23 bacteria tested (95.7%) and 2 of the 4 fungal species (50%) tested. In comparison, 18 of the bacterial species (81.8%) and 2 of the fungal species (50%) were inhibited by at least 1 of the leaf extracts. The methanol, water and ethyl acetate extracts of both berries and leaves all had similar efficacies and ranges of microbes inhibited. Whilst broad spectrum activity was seen for these extracts, they displayed only moderate to low efficacy (as determined by the zones of inhibition and MIC analyses). All extracts were more effective at inhibiting the growth Gram-negative bacteria than Gram-positive bacteria or fungi. Furthermore, the methanol, water and ethyl acetate extracts of both berry and leaf were potent inhibitors of Giardial proliferation. All T. stipitata extracts were non-toxic in the Artemia fransiscana bioassay with LC 50 values greatly in excess of 1000 µg/ml. Conclusion: The lack of toxicity of the T. stipitata extracts and their moderate broad spectrum inhibitory bioactivity against bacteria, fungi and Giardia indicates their potential as natural food preservatives and as medicinal agents in the treatment and prevention of microbial diseases.
Introduction Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has b... more Introduction Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has been used for thousands of years as a food. It is known to contain high levels of medium chain saturated fatty acids, raising the possibility that they may be useful in the treatment of Giardiasis Methods. Macadamia nuts were extracted with various solvents and tested for inhibitory activity against the gastrointestinal protozoal parasite Giardia duodenalis using colorimetric cell proliferation assays. Toxicity was evaluated using an Artemia franciscana nauplii bioassay. Results. Methanol, water and ethyl acetate extracts of macadamia nuts significantly inhibited G. duodenalis proliferation. The water extract was particularly potent, with an IC50 of 13.7 µg/ml. The methanol and ethyl acetate extracts, whilst less potent, also displayed good anti-Giardial activity (with IC50 values of approximately 125.2 and 143.5 µg/ml respectively). The chloroform and hexane extracts were ineffective as proliferation inhibitors, with no significant difference to the untreated control levels. With the exception of the water extract, all extracts were nontoxic or of low toxicity in the Artemia nauplii assay. Discussion. The antiproliferative activity and low toxicity of these extracts indicate that macadamia nut may be useful in the treatment of Giardiasis.
Pharmacognosy Communication, 2014
Parasitology Research, 2005
Giardia duodenalis is a protozoal, intestinal parasite that is a common aetiological agent of inf... more Giardia duodenalis is a protozoal, intestinal parasite that is a common aetiological agent of infectious diarrhoea in humans worldwide. Chemotherapeutic intervention presently offers a limited range of drugs and these are usually only employed after clinical diagnosis. Moreover, these drugs are ineffective against the infectious cysts, can produce unpleasant side effects, and are expensive with limited availability in developing countries. Frequent reports of drug toxicity, treatment failure and parasite drug resistance have, in some instances, also resulted in the increasing reluctance to over-prescribe synthetic anti-microbials. Alternatively, there is now mounting evidence to suggest that some of the naturally derived, medium-chain, saturated fatty acids (MCSFAs) possess anti-microbial and anti-parasitic properties. We have therefore examined the effects of four different fatty acids on G. duodenalis trophozoites in vitro. Cytotoxicity was determined using fluorescence, scanning and transmission electron microscopic techniques and standard cytotoxicity assays. Our studies have confirmed that the MCSFA, dodecanoic acid (C: 12) (common name: lauric acid), is anti-giardial, with an LD50 concentration comparable to that of metronidazole, the drug of choice in the treatment of giardiasis. Dodecanoic acid appeared to induce trophozoite death by accumulating within the parasite cytoplasm resulting in rupture of the cell membrane. This study has opened fresh avenues for development of natural drug therapy in which food supplementation may augment, or even replace, some of the standard chemotherapeutic agents presently employed in the treatment of giardiasis and possibly other infectious intestinal diseases.
Indian Journal of Pathology and Microbiology, 2010
Environmental factors affect the dissemination and distribution of intestinal parasites in human ... more Environmental factors affect the dissemination and distribution of intestinal parasites in human communities. To comprehend the prevalence of parasitic infestation and to examine whether geographical location and age also infl uence the prevalence of infection, fecal samples from 195 school children (rural = 95; male = 39; female = 56) (urban = 100; male = 60; female = 40) of fi ve age groups ranging from 5 to 11 years in two different socio-economic zones (rural and urban) were screened for specifi c intestinal parasites using standard histological techniques. Percentage incidences of parasitic species found in fecal wet mounts and concentrates in rural children were Entamoeba coli (25.3%), Giardia lamblia (17.9%), Blastocystis hominis (14.7%
Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has been used for ... more Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has been used for thousands of years as a food. Its nuts are known to keep well, raising the possibility that they may contain antimicrobial compounds and therefore may have value as a functional food to retard food spoilage and prevent food poisoning and other food-borne diseases. M. integriflora extracts were investigated for their ability to inhibit the growth of a panel of bacteria and fungi of importance to food spoilage and food poisoning, as well as the gastro-intestinal protozoal parasite Giardia duodenalis. All extracts displayed broad spectrum antimicrobial activity, each inhibiting the growth of 7 of the 18 bacterial species tested (39%). In contrast, none of the fungal species were inhibited by the macadamia nut extracts. Strong inhibitory activity was detected with MIC values as low as 0.80 µg/ml against some bacteria, although most measured MIC's were generally several orders of magnitude higher than this. All extracts were more effective against Gram-negative than Gram-positive bacteria. Indeed, all extracts inhibited 54 % of the Gram-negative bacteria tested and none of the Gram-positive bacteria. All extracts were also effective in inhibiting the gastro-intestinal protozoan parasite G. duodenalis, yet were nontoxic in the Artemia franciscana bioassay with LC50 values greatly in excess of 1 mg/ml. The inhibitory bioactivity against a range of microbes, as well as the lack of toxicity, indicates the potential of macadamia nuts in the discovery and development of new natural food preservatives and pharmaceuticals.
Parasitology research, Jan 16, 2015
Giardisis is a debilitating disease caused by gastrointestinal parasites of the genus Giardia. Hi... more Giardisis is a debilitating disease caused by gastrointestinal parasites of the genus Giardia. High-antioxidant T. ferdinandiana fruit extracts were investigated for the ability to block Giardia duodenalis growth. Methanolic and aqueous extracts had the most potent growth inhibitory activity (IC50 values of approximately 700 and 140 μg/ml, respectively). Ethyl acetate and chloroform extracts also inhibited G. duodenalis growth, albeit with lower potency. The hexane extract was completely devoid of G. duodenalis growth inhibitory activity. All extracts were nontoxic in the Artemia fransiscana bioassay. Nontargeted HPLC-quadrupole time-of-flight (QTOF) mass spectroscopy (with screening against three compound databases) putatively identified 17 compounds in all of the inhibitory extracts but not in the inactive hexane extract. The low toxicity of the Terminalia ferdinandiana fruit extracts and their potent G. duodenalis growth inhibitory bioactivity indicate their potential as medicina...
Introduction: Tasmannia stipitata (Dorrigo pepper) is an endemic Australian plant with a history ... more Introduction: Tasmannia stipitata (Dorrigo pepper) is an endemic Australian plant with a history of use by indigenous Australians as a food. It is taxonomically related to Tasmania lanceolata which has documented therapeutic properties as well as uses for food flavouring. Methods: T. stipitata solvent extracts were investigated by disc diffusion assay against a panel of bacteria and fungi. Their MIC values were determined to quantify and compare their efficacies. The ability to inhibit the proliferation of Giardia duodenalis was determined by direct cell counts and by using an MTS based cell proliferation assay. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: Methanolic, aqueous and ethyl acetate T. stipitata leaf and berry extracts displayed antibacterial activity in the disc diffusion assay. The berry methanolic extract had the broadest antibacterial range, inhibiting the growth of all 22 of the 23 bacteria tested (95.7%) and 2 of the 4 fungal species (50%) tested. In comparison, 18 of the bacterial species (81.8%) and 2 of the fungal species (50%) were inhibited by at least 1 of the leaf extracts. The methanol, water and ethyl acetate extracts of both berries and leaves all had similar efficacies and ranges of microbes inhibited. Whilst broad spectrum activity was seen for these extracts, they displayed only moderate to low efficacy (as determined by the zones of inhibition and MIC analyses). All extracts were more effective at inhibiting the growth Gram-negative bacteria than Gram-positive bacteria or fungi. Furthermore, the methanol, water and ethyl acetate extracts of both berry and leaf were potent inhibitors of Giardial proliferation. All T. stipitata extracts were non-toxic in the Artemia fransiscana bioassay with LC 50 values greatly in excess of 1000 µg/ml. Conclusion: The lack of toxicity of the T. stipitata extracts and their moderate broad spectrum inhibitory bioactivity against bacteria, fungi and Giardia indicates their potential as natural food preservatives and as medicinal agents in the treatment and prevention of microbial diseases.
Introduction Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has b... more Introduction Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has been used for thousands of years as a food. It is known to contain high levels of medium chain saturated fatty acids, raising the possibility that they may be useful in the treatment of Giardiasis Methods. Macadamia nuts were extracted with various solvents and tested for inhibitory activity against the gastrointestinal protozoal parasite Giardia duodenalis using colorimetric cell proliferation assays. Toxicity was evaluated using an Artemia franciscana nauplii bioassay. Results. Methanol, water and ethyl acetate extracts of macadamia nuts significantly inhibited G. duodenalis proliferation. The water extract was particularly potent, with an IC50 of 13.7 µg/ml. The methanol and ethyl acetate extracts, whilst less potent, also displayed good anti-Giardial activity (with IC50 values of approximately 125.2 and 143.5 µg/ml respectively). The chloroform and hexane extracts were ineffective as proliferation inhibitors, with no significant difference to the untreated control levels. With the exception of the water extract, all extracts were nontoxic or of low toxicity in the Artemia nauplii assay. Discussion. The antiproliferative activity and low toxicity of these extracts indicate that macadamia nut may be useful in the treatment of Giardiasis.
Pharmacognosy Communication, 2014
Parasitology Research, 2005
Giardia duodenalis is a protozoal, intestinal parasite that is a common aetiological agent of inf... more Giardia duodenalis is a protozoal, intestinal parasite that is a common aetiological agent of infectious diarrhoea in humans worldwide. Chemotherapeutic intervention presently offers a limited range of drugs and these are usually only employed after clinical diagnosis. Moreover, these drugs are ineffective against the infectious cysts, can produce unpleasant side effects, and are expensive with limited availability in developing countries. Frequent reports of drug toxicity, treatment failure and parasite drug resistance have, in some instances, also resulted in the increasing reluctance to over-prescribe synthetic anti-microbials. Alternatively, there is now mounting evidence to suggest that some of the naturally derived, medium-chain, saturated fatty acids (MCSFAs) possess anti-microbial and anti-parasitic properties. We have therefore examined the effects of four different fatty acids on G. duodenalis trophozoites in vitro. Cytotoxicity was determined using fluorescence, scanning and transmission electron microscopic techniques and standard cytotoxicity assays. Our studies have confirmed that the MCSFA, dodecanoic acid (C: 12) (common name: lauric acid), is anti-giardial, with an LD50 concentration comparable to that of metronidazole, the drug of choice in the treatment of giardiasis. Dodecanoic acid appeared to induce trophozoite death by accumulating within the parasite cytoplasm resulting in rupture of the cell membrane. This study has opened fresh avenues for development of natural drug therapy in which food supplementation may augment, or even replace, some of the standard chemotherapeutic agents presently employed in the treatment of giardiasis and possibly other infectious intestinal diseases.
Indian Journal of Pathology and Microbiology, 2010
Environmental factors affect the dissemination and distribution of intestinal parasites in human ... more Environmental factors affect the dissemination and distribution of intestinal parasites in human communities. To comprehend the prevalence of parasitic infestation and to examine whether geographical location and age also infl uence the prevalence of infection, fecal samples from 195 school children (rural = 95; male = 39; female = 56) (urban = 100; male = 60; female = 40) of fi ve age groups ranging from 5 to 11 years in two different socio-economic zones (rural and urban) were screened for specifi c intestinal parasites using standard histological techniques. Percentage incidences of parasitic species found in fecal wet mounts and concentrates in rural children were Entamoeba coli (25.3%), Giardia lamblia (17.9%), Blastocystis hominis (14.7%
Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has been used for ... more Macadamia integriflora (family Proteaceae) is an endemic Australian plant that has been used for thousands of years as a food. Its nuts are known to keep well, raising the possibility that they may contain antimicrobial compounds and therefore may have value as a functional food to retard food spoilage and prevent food poisoning and other food-borne diseases. M. integriflora extracts were investigated for their ability to inhibit the growth of a panel of bacteria and fungi of importance to food spoilage and food poisoning, as well as the gastro-intestinal protozoal parasite Giardia duodenalis. All extracts displayed broad spectrum antimicrobial activity, each inhibiting the growth of 7 of the 18 bacterial species tested (39%). In contrast, none of the fungal species were inhibited by the macadamia nut extracts. Strong inhibitory activity was detected with MIC values as low as 0.80 µg/ml against some bacteria, although most measured MIC's were generally several orders of magnitude higher than this. All extracts were more effective against Gram-negative than Gram-positive bacteria. Indeed, all extracts inhibited 54 % of the Gram-negative bacteria tested and none of the Gram-positive bacteria. All extracts were also effective in inhibiting the gastro-intestinal protozoan parasite G. duodenalis, yet were nontoxic in the Artemia franciscana bioassay with LC50 values greatly in excess of 1 mg/ml. The inhibitory bioactivity against a range of microbes, as well as the lack of toxicity, indicates the potential of macadamia nuts in the discovery and development of new natural food preservatives and pharmaceuticals.