Biological Insights and NMR Metabolic Profiling of Different Extracts of Spermacoce verticillata (L.) G. Mey.

Spermacoce verticillata (L.) G. Mey. is commonly used in the folk medicine by various cultures to manage common diseases. Herein, the chemical and biological profiles of S. verticillata were studied in order to provide a comprehensive characterization of bioactive compounds and also to highlight the therapeutic properties. The in vitro antioxidant activity using free-radical scavenging, phosphomolybdenum, ferrous-ion chelating and reducing power assays, and the inhibitory activity against key enzymes such as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), tyrosinase, α-amylase and α-glucosidase of S. verticillata extracts (dichloromethane, ethyl acetate, methanol and water) were investigated. The highest total phenolic and flavonoid content were observed in the methanolic and aqueous extracts. Exhaustive 2DNMR investigation has revealed the presence of rutin, ursolic and oleanoic acids. The methanolic extract, followed by aqueous extract have showed remarkable free radical quenching and reducing ability, while the dichloromethane extract was the best source of metal chelators. The tested extracts showed notable inhibitory activity against cholinesterases (AChE: 1.63-4.99 mg GALAE/g extract and BChE: 12.40-15.48 mg GALAE/g extract) and tyrosinase (60.85-159.64 mg KAE/g extract). No inhibitory activity was displayed by ethyl acetate and aqueous extracts against BChE and tyrosinase, respectively. All the tested extracts showed modest α-amylase inhibitory activity, while only the ethyl acetate and aqueous extracts were potent against α-glycosidase. This study further validates the use of S. verticillata in the traditional medicine, while advocating for further investigation for phytomedicine development.

In vitro anti-glycation and anti-oxidant properties of synthesized Schiff bases.

A series of mono, bis and mixed Schiff bases (1-7) were synthesised and evaluated for potential anti-glycation and anti-oxidant activities using the bovine serum albumin-glucose assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay respectively. All compounds showed significant (p<0.05) antiglycating activities with IC50 values (4.02x10(-24)±0.1-2.88x10(-1)±1.35 mM) which were lower than the standard positive control aminoguanidine (IC50: 1.51x10(-3)±2.11 mM). Moreover, compounds 1-7 were found to possess significant (p<0.05) DPPH radical scavenging properties with SC50 values (1.31x10(-19)±0.05 to 2.25x10(-1)±1.24 mM) lower than the standard ascorbic acid (SC50: 5.50x10(-3)±2.11 mM). Compound 6 was found to be the most potent anti-glycating molecule (IC50 value: 4.02x10(-24)±0.1 mM) while compound 5 was the most potent anti-oxidant molecule (SC50: 1.31x10(-19)±0.05 mM); both being significantly lower (p<0.05) than the respective positive controls used. The present data showed that the number of phenolic OH together with structural changes influence both the anti-glycation and anti-oxidant observed herein. This study provides for the first time a series of potential template molecules for possible pharmaceutical applications that warrant further investigation as potential anti-glycation and anti-oxidant agents which could be of importance in metabolic diseases including diabetes mellitus.

Screening for anti-infective properties of several medicinal plants of the Mauritians flora.

Several plants of the Mauritian flora alleged to possess anti-infective properties were studied against different strains of pathogenic bacteria and fungi. The grounded dried plant materials were extracted with different extractants and screened for anti-microbial activity using the disk diffusion and the micro-dilution techniques. Preliminary screening revealed that the methanol extracts were most active. Salmonella enteritidis, Enterobacter cloacae and Bacillus subtilis were the three test organisms, which were found to be susceptible to all the crude methanolic extracts of the different plants investigated (100% susceptibility), followed by Escherichia coli (57.1%) and Pseudomonas aeruginosa (57.1%), and Staphylococcus aureus (28.6%). The lowest minimum inhibitory concentration recorded for the different crude methanol extracts against Staphylococcus aureus, Escherichia coli, Salmonella enteritidis, Enterobacter cloacae, Bacillus subtilis and the mould fungus Candida albicans were 500, 1000, 125, 250, 1000 and 125 micro g/ml, respectively. Bioautography using Cladosporium cucumerinum revealed that dichloromethane (DCM) extracts had the highest activity against the phytopathogenic fungus. It was also noted that the DCM extracts of Michelia champaca and Antidesma madagascariense yielded the maximum number of growth inhibiting compounds against Cladosporium cucumerinum. Activity of the different crude extracts was also investigated against several phytopathogenic filamentous fungi, Colletotrichum glocosporoides, Rhizoctonia solani, Sclerotinia sclerotium, Guignardia sp. and Fusarium oxysporum. It was found that crude hexane extracts as well as crude DCM extracts exhibited marked activity against several strains of fungi, especially Colletotrichum glocosporoides, Sclerotinia sclerotium and Guignardia sp.

Experimental evidence for in vitro fluid transport in the presence of a traditional medicinal fruit extract across rat everted intestinal sacs.

The present study was designed to investigate the effects of aqueous fruit extract of Momordica charantia (MC), a traditional medicinal plant, on the transport of fluid in vitro. Everted intestinal sacs from rats were mounted in an organ bath containing Krebs solution. We compared the effect of MC extract on water transport with increasing inorganic phosphate concentration with or without D-glucose in the buffer. In the control experiments, fluid uptake was enhanced significantly (P < 0.05) at high inorganic phosphate concentration (8-10 mM) in the presence of 5.5 mM D-glucose. Addition of 3.0 mg/mL MC extract to the serosal side inhibits the uptake of fluid significantly (P < 0.05). At high inorganic phosphate concentration (8-10 mM), fluid uptake was not inhibited (P > 0.05) when incubated with 3.0 mg/mL MC fruit extract. It is hypothesized that an increase in inorganic phosphate enhances oxidative phosphorylation thereby increasing the fluid uptake across everted intestinal sacs of rat. These findings seem to indicate that the MC-induced reduction on intestinal fluid absorption capacity could be mainly the result of an interference with the carrier-mediated coupled entrance of glucose and Na(+) across the brush-border membrane.

Aprotinin suppresses ACE-inhibitor cough triggered by TAME-esterase.

N-alpha-Tosyl l-arginine methyl ester [TAME]-esterase appears to be an important biochemical marker, which displays potent contractile properties on bronchial tissues and aorta in vitro. TAME-esterase induced contractions have been shown to be mediated via a nitric oxide-cyclic GMP pathway. TAME-esterase has also been described to be a possible new cardiovascular risk factor among smokers. TAME-esterase has been reported to be an enzyme, which is involved during the sequence of events leading to the activation of the kinin-kallikrein system. Use of aprotinin (a kallikrein inhibitor) as well as aspirin and indomethacin (prostaglandin inhibitors) have shown that there is an inter-dependent relationship between the kinin-kallikrein system and the cyclo-oxygenase pathway involved during the sequence of reactions leading to TAME-esterase induced contractions. Our findings also lend support to the concept of calcium antagonism whereby verapamil, and nifedipine, mimicked in reversible fashion the effects of Ca2+ withdrawal on muscle excitability during TAME-esterase induced contractions on rat aorta in vitro. We concluded that the effects of captopril, an ACE inhibitor, on TAME-esterase induced contractions could thus be due to the degradation of bradykinin by the enzyme kininase being blocked. This paper proposes an integrated model of possible biochemical-pharmacological pathways, which involve events leading to TAME-esterase induced contractions. We hypothesize that TAME-esterase induced cough through sensitization of airway sensor nerves in hypertensive patients taking angiotensin-converting enzyme inhibitors can be inhibited by aprotinin.

Momordica charantia extracts inhibit uptake of monosaccharide and amino acid across rat everted gut sacs in-vitro.

The inhibitory effects of Momordica charantia extracts were studied on the uptake of glucose and tyrosine across rat everted gut sacs in vitro. The aqueous extract of the plant was found to inhibit primarily the uptake of glucose in a dose-dependent manner. Uptake of tyrosine was affected at high substrate concentrations only. The extract was also found to decrease the absorptive capacity of fluid across the small intestine and sodium ions. It is hypothesized that the effects of Momordica could involve a washout of glucose from the blood stream.

Effects of aspirin on N-alpha-tosyl L-arginine methyl ester [TAME]-esterase induced contractions on rat aorta in vitro.

The present study was designed to investigate whether N-alpha-tosyl L-arginine methyl ester [TAME]-esterase activation could be the result of endothelial dysfunction. Thoracic aorta from rats was mounted in an organ bath containing Krebs solution. Intact and endothelium denuded aortic strips were challenged with different concentrations of TAME (10(-15)-10(-1) m). The effects of aspirin, a cyclo-oxygenase pathway inhibitor, were also studied on [TAME]-esterase induced contraction on rat aorta strips. Our results showed that aspirin definitely blocked TAME-esterase induced contractions on rat aortic strips. In conclusion, the present work supported the hypothesis that [TAME]-esterase induced contraction in rat aorta in vitro was mediated through release of prostaglandin(s) as a result of endothelial dysfunction.