Aripiprazole (ARP) is one of antipsychotics and binds to human serum albumin (HSA) with a high affinity. In this study, we investigated the binding characteristics of ARP to oxidized HSA as observed in chronic disease conditions. Oxidized HSAs were prepared using chloramine-T (CT-HSA) or metal-catalyzed oxidation system (MCO-HSA) in vitro, respectively. An increase in the carbonyl content was confirmed in oxidized HSAs. From the results of circular dichroism (CD) and tryptophan fluorescence spectra, no significant structural change of oxidized HSAs was observed. These results indicate that prepared HSAs are mildly oxidized and well reflects the status of HSA during chronic diseases. However, oxidized HSAs were observed to have a significant decrease in binding to ARP. The results of the induced CD spectrum suggested that ARP bound to oxidized HSAs with a similar orientation. These results suggest that oxidation of HSA during chronic disease state significantly affected the microenvironment of the binding site for ARP and binding capacity of HSA to ARP.
A possible anti-anesthetic effect of idazoxan using the depth versus latency of cortical cellular response and somatosensory evoked potentials as indices of anesthesia was studied. With the administration of 10 mg/kg (i.p.) idazoxan, a potent and selective alpha 2-adrenoceptor antagonist, to an anesthetized rat with 1.25-1.5 g/kg (i.p.) urethane, the modal latency of somatosensory cortical responses to electrical stimulation of the forepaw (0-90 V, 1 Hz) was shortened to 87 +/- 3.6% (mean +/- S.D.; n = 3) of the baseline value. The number of units firing increased by 259 +/- 98.5% (n = 3). The combined parameter (1/L x Pi; L, latency; Pi, initial positive wave) of the somatosensory evoked potentials was enhanced to 125.0 +/- 16.2% (n = 19) versus saline (98.9 +/- 25.6%; n = 18) during the desynchronized electroencephalogram (EEG). The initial negative component (Ni) of the somatosensory cortical response was increased to 192.0 +/- 83.1% (n = 19) and 134.8 +/- 36.9% (n = 19) during the synchronized and desynchronized EEG, respectively. Thus idazoxan appears to produce effects resembling a "lightening of anesthesia." This may provide the impetus for further studies on the possibility of using alpha 2-adrenoceptor antagonists in the recovery from certain types of anesthetic agents.
Enzyme inhibitory activities of 14 iridoids previously obtained from two Malaysian medicinal plants, Saprosma scortechinii and Rothmannia macrophylla, were evaluated in vitro using soybean lipoxygenase and bovine testis hyaluronidase. Most of the iridoids, including asperulosidic acid, paederosidic acid, and an epimeric mixture of gardenogenins A and B, did not show any effect on the enzyme activities, except for the bis-iridoids, which inhibited the lipoxygenase activity with their IC(50) values of approximately 1.3 times that of a known inhibitor, fisetin. Structural modification of asperulosidic acid and paederosidic acid through enzymatic hydrolysis by beta-glucosidase resulted in their inhibition towards the enzyme activities, and these activities were enhanced by the presence of some amino acids (lysine, leucine or glutamic acid) or ammonium acetate. Mixtures of gardenogenins A and B; isomers of non-glucosidic iridoids, incubated with amino acid or ammonium acetate did not show any inhibitory effect on the enzyme activities during the 6 h incubation period, except for lysine where spontaneous reaction between the iridoids and amino acid resulted in the inhibition of lipoxygenase activity. The results from these biomimetic reactions suggested that the iridoid aglycons and the intermediates formed by these reactive species could inhibit the enzyme activities, and thus substantiate previous reports that the formation of iridoidal aglycons is a prerequisite for the iridoid glycosides to demonstrate some of the biological activities. In addition, the results also indicated that it is worthwhile to further explore these intermediates as potential anti-inflammatory agents.
Breast cancer is the most common cancer in women, and it can metastasize very rapidly. Tumor metastasis is the primary cause of cancer deaths. In the present study, we investigated the capability of koetjapic acid, a natural triterpene, in the induction of apoptosis and the inhibition of metastasis in the breast cancer cell line (MCF 7). The effects of koetjapic acid against 4 steps of metastasis have been assessed, including cell survival, clonogenicity, migration and invasion. Koetjapic acid exhibited cytotoxic activity against MCF 7 cells with an IC(50) of 68.88±6.075 μg/mL. The mechanism of cell death was confirmed due to the induction of apoptosis machineries; early and late apoptosis-related changes were detected, including the stimulation of caspase 3/7 activities, apoptosis-related morphological changes such as membrane blebbing, chromatin condensation and DNA fragmentation. A mitochondrial apoptosis pathway was found to be involved in koetjapic acid-induced cell death induction. Moreover, at a sub-toxic dose (15 μg/mL), Koetjapic acid inhibited cell migration and invasion significantly. Finally, koetjapic acid inhibited the colony formation properties of MCF 7 significantly. These results indicate that koetjapic acid possesses significant antitumor and antimetastatic effects, and warrants further investigation.
The leaf, stem and root extracts of Chromolaena odorata were evaluated for their effect on platelet-activating factor (PAF) receptor binding on rabbit platelets using 3H-PAF as a ligand. The leaf extract demonstrated high PAF receptor binding inhibitory activity of 79.2+/-2.1% at 18.2 microg/ml. A total of eleven flavonoids were subsequently isolated from the active leaf extract and evaluated for their effects on PAF receptor binding. Eight of the flavonoids exhibited >50% inhibition on the binding activity at 18.2 microg/ml. These flavonoids were identified as eriodictyol 7,4'-dimethyl ether, quercetin 7,4'-methyl ether, naringenin 4'-methyl ether, kaempferol 4'-methyl ether, kaempferol 3-O-rutinoside, taxifolin 4'-methyl ether, taxifolin 7-methyl ether and quercetin 4'-methyl ether. Their IC50 values ranged from 19.5 to 62.1 microM.
The effects of Eurycoma longifolia JACK were studied on the orientation activities of sexually experienced male rats towards receptive females (mounting, licking, anogenital sniffing), environment (exploration, raring, climbing), themselves (genital grooming, non-genital grooming) and mobility (unrestricted, restricted) after dosing them with 200, 400 and 800 mg/kg body weight twice daily for 10 d prior to the test. The results showed that E. longifolia JACK modified the orientation activities of the treated male rats in that they significantly displayed more frequent and vigorous mounting, licking and anogenital sniffing towards the receptive females, and it further intensified self orientation as indicated by the increased grooming of the genitals compared to the controls (p<0.05). In addition, rats treated with 800 mg/kg of methanol, water and butanol extracts of E. longifolia JACK continued to show confinement to a particular area of the cage (around the female), thus showing restriction in movement as compared to the controls (p<0.05). However, the treated males possessed a lack of interest in the external environment as indicated by a reduction in exploration, raring and climbing on the cage wall. Hence, the present study further supports the folk use of E. longifolia JACK as an aphrodisiac.