Present status of Catharanthus roseus monoterpenoid indole alkaloids engineering in homo- and hetero-logous systems.

Catharanthus roseus synthesizes one of the most structurally, chemically and biologically active phytomolecules monoterpenoids indole alkaloids (MIAs) with having a wide range of pharmaceutical activities. Being the sole source of antineoplastic MIAs vinblastine and vincristine C. roseus has become one of the most valued plant. The low in planta availability of these MIAs and unavailability of alternative chemical synthesis system has enhanced their demand and equally let to the exorbitant market cost. To bridge this gap alternative production systems have been investigated using MIAs metabolic engineering (ME) in the homologous and heterologous systems. The availability of improved recombinant technologies along with genomics and metabolomics tools has opened the door of tremendous new potentials of ME. To encash these potentials of ME for MIAs pathway, efforts were made by expressing constitutive structure biosynthesis enzymes, transporters, and transcription factors of C. roseus MIAs biosynthesis in both homologous and heterologous systems. Here we review the knowledge of C. roseus MIAs pathway metabolic engineering in homologous and heterologous systems, gained in the past 35 years of C. roseus research.

Recent advancements in supporting materials for immobilised photocatalytic applications in waste water treatment.

The aim of this paper is to provide a review on the usage of different anchoring media (supports) for immobilising commonly employed photocatalysts for degradation of organic pollutants. The immobilisation of nano-sized photocatalysts can eliminate costly and impractical post-treatment recovery of spent photocatalysts in largescale operations. Some commonly employed immobilisation aids such as glass, carbonaceous substances, zeolites, clay and ceramics, polymers, cellulosic materials and metallic agents that have been previously discussed by various research groups have been reviewed. The study revealed that factors such as high durability, ease of availability, low density, chemical inertness and mechanical stability are primary factors responsible for the selection of suitable supports for catalysts. Common techniques for immobilisation namely, dip coating, cold plasma discharge, polymer assisted hydrothermal decomposition, RF magnetron sputtering, photoetching, solvent casting, electrophoretic deposition and spray pyrolysis have been discussed in detail. Finally, some common techniques adopted for the characterisation of the catalyst particles and their uses are also discussed.

Scientific evaluation of Ayurvedic drugs - the use of N-of-1 clinical trials.

Despite its ancient roots and prominence in India as an accepted alternative to modern medicine, Ayurveda's growth has been hampered by an inability to carry out clinical studies of its effectiveness and safety using modern scientific methods - while preserving the core of Ayurveda, which is personalised medicine. In this comment, we propose that the N-of-1 trial be used as a practical method to evaluate Ayurvedic treatments, which is simultaneously consistent with the canons of modern medicine and of Ayurveda. We emphasise the importance of doing this as a practical alternative that will benefit patients. We need not wait to resolve the epistemic inconsistency between Ayurveda and modern medicine to take steps in this direction.

Pharmacokinetics, toxicity, and functional studies of the selective Kv1.3 channel blocker 5-(4-phenoxybutoxy)psoralen in rhesus macaques.

The small molecule 5-(4-phenoxybutoxy)psoralen (PAP-1) is a selective blocker of the voltage-gated potassium channel Kv1.3 that is highly expressed in cell membranes of activated effector memory T cells (TEMs). The blockade of Kv1.3 results in membrane depolarization and inhibition of TEM proliferation and function. In this study, the in vitro effects of PAP-1 on T cells and the in vivo toxicity and pharmacokinetics (PK) were examined in rhesus macaques (RM) with the ultimate aim of utilizing PAP-1 to define the role of TEMs in RM infected with simian immunodeficiency virus (SIV). Electrophysiologic studies on T cells in RM revealed a Kv1.3 expression pattern similar to that in human T cells. Thus, PAP-1 effectively suppressed TEM proliferation in RM. When administered intravenously, PAP-1 showed a half-life of 6.4 hrs; the volume of distribution suggested extensive distribution into extravascular compartments. When orally administered, PAP-1 was efficiently absorbed. Plasma concentrations in RM undergoing a 30-day, chronic dosing study indicated that PAP-1 levels suppressive to TEMs in vitro can be achieved and maintained in vivo at a non-toxic dose. PAP-1 selectively inhibited the TEM function in vivo, as indicated by a modest reactivation of cytomegalovirus (CMV) replication. Immunization of these chronically treated RM with the live influenza A/PR8 (flu) virus suggested that the development of an in vivo, flu-specific, central memory response was unaffected by PAP-1. These RM remained disease-free during the entire course of the PAP-1 study. Collectively, these data provide a rational basis for future studies with PAP-1 in SIV-infected RM.

Allium sativum constituents: effect on free radical generation from rat neutrophils.

Reactive oxygen species formation or respiratory burst by the neutrophils helps to remove the invaded pathogens and thus constitute a major defense against pathogenic microorganisms. Production of these radicals by activated neutrophils at the site of inflammation however inflicts damage to the host tissue. Modulation of the neutrophil respiratory burst is therefore important in determining the balance between immune defense and host tissue injury during inflammatory conditions. Garlic extracts and various compounds isolated from garlic have been found to possess various activities, however no report is available on their effect on neutrophil free radical generation. The present study was therefore undertaken to evaluate the effect of garlic aqueous extract, alcoholic extract and various fractions on the free radical generation from neutrophils. Among the tested fractions, chloroform fraction of garlic seems to be very potent in attenuating the free radical generation from rat neutrophils, which could be beneficial in the inflammation associated pathological conditions.

Effect of peripheral administration of cinnarizine and verapamil on the abstinence syndrome in diazepam-dependent rats.

The effects of two calcium channel blockers (verapamil and cinnarizine) were evaluated on diazepam withdrawal symptoms. Rats were made diazepam dependent by chronic treatment with daily injections of the drug, 20 mg/kg IP for 3 weeks. On abrupt termination of the drug, animals showed withdrawal hyperactivity that was assessed by autonomic, behavioural and motor signs. The peak effect was seen 3 days after the withdrawal of diazepam. On IP administration, verapamil and cinnarizine (10, 20 and 40 mg/kg) given on eight occasions at an interval of 12 h reversed the withdrawal-induced increase in spontaneous motor activity. Cinnarizine in higher doses (20 and 40 mg/kg) was found to be effective in suppressing the behavioural signs but verapamil did not show any protective effect against startle response and irritability. These results suggest that modulation of the calcium influx in the CNS might influence withdrawal.

Memory enhancing effects of granisetron (BRL 43694) in a passive avoidance task.

Recent evidence suggests that serotonin plays an important role in learning and memory processes in animals. The present study examined the effect of the 5-HT3 receptor antagonist, granisetron (BRL 43694), on acquisition, retention and retrieval of a passive avoidance response in mice. Granisetron (1 and 10 micrograms/kg) administered 30 min before presentation of footshock increased the step-down latency when tested 24 h after footshock. The acquisition process was not affected by a dose of 100 micrograms/kg. Granisetron (10 and 100 micrograms/kg) produced a significant increase in latency to step out of the safety zone, when administered immediately after or 23.5 h after footshock. However, at 1 microgram/kg, granisetron had no effect. These results confirm the important role played by 5-HT in the process of learning and memory, and also suggest that memory enhancement may be possible with non-cholinergic treatments.

Effect of subacute insecticide exposure on body weight, drug responses & electrical convulsions in mice.

Effect of subacute insecticide exposure was studied in male albino mice treated with phosphamidon, propoxur or aldrin at 1/40 LD50 dose intraperitoneally daily for 8 wk. The parameters studies included body weight, pentobarbitone (50 mg/kg) sleeping time, chlorpromazine (6 mg/kg) induced motor incoordination and convulsions induced by leptazol (100 mg/kg) and electrical stimulation (18 mA for 0.2 msec). While body weight and electrically induced convulsions were not affected, the effect of various drugs was significantly decreased. The observed changes may be due to the induction of hepatic drug metabolising enzymes by the insecticides. The study suggests that certain dose adjustment of drugs may be necessary in those exposed to insecticides over long periods.

MK-801 antagonizes the lethal action of centrally and peripherally administered cypermethrin in mice and rats.

The present study investigated the effect of MK-801, an N-methyl-D-aspartate antagonist, on the convulsant lethal action of cypermethrin administered centrally or peripherally. Cypermethrin produced severe convulsions and death in a dose-dependent manner. MK-801 (0.5, 1 and 2 mg kg-1, intraperitoneally) significantly increased the onset time of convulsions and decreased the mortality in the peripherally treated cypermethrin group. MK-801 (1.0 and 2.0 mg kg-1) attenuated the convulsant action of cypermethrin (50 micrograms, intracerebroventricularly) significantly. Survival rate was also increased significantly. However, MK-801 (0.5 mg kg-1) did not produce any significant protective effect against centrally administered cypermethrin. These results suggest excitatory amino acids to be a target for pyrethroid-induced neurotoxicity.

Post-coital antifertility action of Ruta graveolens in female rats and hamsters.

Different preparations of Ruta graveolens were administered orally to female rats (Days 1-10 post coition) and female hamsters (Days 1-6 post coition). The powdered root (CDR), aerial parts (CDA) and the aerial parts aqueous extract (AEA) all showed potential anticonceptive activity in rats. Limited administration on selected days of CDA showed uniformly lesser activity than with 10-day treatment. Sequentially prepared petroleum ether and methanol extracts of CDA were as active as CDA itself. The benzene and chloroform extracts were toxic and inactive. Rutin, a known chemical constituent of the plant, was found to be inactive. None of the above preparations showed activity in hamsters.

Acute toxicity study of the oil from Azadirachta indica seed (neem oil).

The seed oil of Azadirachta indica (neem oil) is well known for its medicinal properties in the indigenous Indian system of medicine. Its acute toxicity was documented in rats and rabbits by the oral route. Dose-related pharmacotoxic symptoms were noted along with a number of biochemical and histopathological indices of toxicity. The 24-h LD50 was established as 14 ml/kg in rats and 24 ml/kg in rabbits. Prior to death, animals of both species exhibited comparable pharmacotoxic symptoms in order and severity, with lungs and central nervous system as the target organs of toxicity. Edible mustard seed oil (80 ml/kg) was tested in the same manner to document the degree to which the physical characteristics of an oil could contribute to the oral toxicity of neem oil.

Interactions of verapamil and diltiazem with ketamine: effects on memory and sleeping time in mice.

The effects of ketamine (3, 10 and 30 mg/kg) alone and in combination with verapamil (10 mg/kg) or diltiazem (30 mg/kg) on the acquisition, consolidation and retrieval of memory using a passive avoidance task in mice were studied. Ketamine significantly inhibited the acquisition and consolidation of memory at 10 and 30 mg/kg dose levels and these effects were antagonized by diltiazem 30 mg/kg but not by verapamil 10 mg/kg. Studies of sleeping time demonstrated that pretreatment with verapamil 10 mg/kg increased the duration of sleeping time. Diltiazem, however, did not potentiate the effects of ketamine on sleeping time. The present findings indicate that diltiazem can counter the effects of ketamine on memory. The data also indicates that pretreatment of surgical patients with verapamil may reduce the dose of ketamine required for anesthesia.

Possible mechanism of haloperidol-induced enhancement of memory retrieval.

The effects of pretest administration of haloperidol on retention of a step-through passive avoidance task was studied with a 3-day training and retention test interval. Haloperidol at doses of 0.3 mg/kg and 0.5 mg/kg i.p. enhanced memory retrieval. This effect of haloperidol is possibly mediated by interaction with alpha 2-adrenergic receptors, that results in increasing the noradrenergic transmission, or it could be due to direct interaction with dopamine receptors. Yohimbine (2.5 mg/kg) also enhanced memory retrieval, as shown by haloperidol. Clonidine (0.05 mg/kg) significantly antagonized the effect of haloperidol on memory retrieval. Scopolamine (0.5 mg/kg) did not have any effect on enhancement of memory produced by haloperidol.

Control of persistent vesical bleeding due to radiation cystitis by intravesical application of 15 (S) 15-methyl prostaglandin F2-alpha.

A 45 year old female who received radiotherapy for stage II-B uterine cervical cancer four and half years ago, presented with persistent hematuria due to radiation cystitis. 15 (S)-15-methyl prostaglandin F2-alpha (1 mg in 100 ml of normal saline) was instilled into the bladder daily for two days. The severity of bleeding decreased considerably. However, significant hematuria recurred 19 days later which continued despite bladder irrigation with normal saline. 1 mg of 15 (S) 15-Me PGF2 alpha mixed with hydroxyethyl cellulose gel to a volume of 10 ml was then instilled into the urinary bladder daily for three days and macroscopic hematuria ceased. Urinary frequency and urgency were the side effects which lasted for ten days. There has been no recurrence of macroscopic hematuria during the five months follow-up. In conclusion, 15 (S) 15-Me PGF2-alpha may be administered intravesically to control moderate hematuria due to radiation cystitis.

Effect of subacute DDT on pharmacokinetics of isoniazid and liver function in rabbits.

DDT administration (30 mg/kg per day, po, for 21 consecutive days) to rabbits showed an increase in peak plasma concentration and a decrease in time to reach peak plasma concentration of isoniazid whereas no change was observed in elimination rate constant and area under the plasma concentration-time curve. DDT treatment caused increased absorption of isoniazid. Early signs of hepatic damage were also observed. Since there was no change in the levels of serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase, it can be concluded that DDT does not significantly affect liver function at the dosage used. The observed elevated levels of alkaline phosphatase could be due to direct activation of the enzyme. Leukopaenia and neutropaenia with relative lymphocytosis indicated that DDT might have suppressant effect on granulocyte cell line of WBCs.

Conjunctival impression cytology in children with persistent diarrhea as indicator of pre-clinical vitamin A deficiency.

Children with persistent diarrhea may be at a higher risk of developing vitamin A deficiency. Impression cytology of the conjunctiva has been shown to be a simple and objective diagnostic test for detection of early, physiologically significant vitamin A deficiency. We studied, changes in conjunctival impression cytology using millipore HAWG filter paper in 25 children aged less than 5 years suffering from persistent diarrhea, who had no ocular manifestations of vitamin A deficiency (Group I). Twenty five age matched healthy children constituted the control group (Group II). Seventeen of the 25 children with persistent diarrhea (68%), showed the following abnormalities: (i) the shape of the epithelial cells were abnormal, and (ii) goblet cells were absent. The study could be repeated after 2 weeks of administration of vitamin A in 7 children. Reappearance of PAS-positive mucous glycoproteins and presence of normal epithelial cells was demonstrated in all 7 children retested. This test can prove to be of significant value in assessment of response to vitamin A therapy. This study shows that children with persistent diarrhea appear to be at high risk for developing vitamin A deficiency, which can be detected by the technique of conjunctival impression cytology. This is a cheap and reliable method of detecting preclinical vitamin A deficiency which can be performed by a pediatrician in the office laboratory.

Possible mechanism of endosulfan-induced enhancement of memory acquisition and retention in mice.

The effects of pre-training and post-training administration of endosulfan on retention of a step-down passive avoidance task was studied in mice. Endosulfan at doses of 1.0 mg/kg(ip) and 2.0 mg/kg(ip) enhanced memory acquisition and retention. This effect of endosulfan was possibly mediated by interaction with cholinergic neurotransmission, as scopolamine (0.5 mg/kg, ip) significantly antagonized the memory enhancing effects of endosulfan. Clonidine (0.05 mg/kg, ip) did not have any effect on enhancement of memory produced by endosulfan, thus indicating possibly no role of noradrenergic system.

Acute neurobehavioural toxicity of phosphamindon and its drug-induced alteration.

Phosphamidon, a systemic organophosphate insecticide, (1.4 mg/kg - dose 1/4th of LD50 given ip), produced several autonomic, neurological and behavioral effects in mice with peak effects being at 15 min. Similar dose in rats also abolished conditioned avoidance response. Pre-treatment with atropine, iproniazid, alpha-methyl-p-tyrosine, p-chlorophenylalanine or thiosemicarbazide reduce many of these effects. This suggests that phosphamidon toxicity involves the central cholinergic, adrenergic, serotonergic and GABAergic systems in addition to peripheral cholinergic effects.

Effects of ranitidine alone and in combination with chlorpheniramine on histamine-induced wheal and flare and psychomotor performance.

Some reports suggest that addition of an H2 antagonist increases the efficacy of H1 antagonist but the influence on the side effect profile of antihistamines are largely unknown. The effects of ranitidine, chlorpheniramine, their combination and placebo on histamine induced wheal and flare, psychomotor performance and subjective symptoms were studied in 6 healthy male volunteers in a double blind randomized and cross-over (Latin square) study. Ranitidine significantly reduced the histamine induced wheal at 4 hrs (P < 0.05). Chlorpheniramine and the combination significantly reduced both histamine induced wheal and flare at 2 hrs and at 4 hrs (P < 0.05). Addition of ranitidine reduced the feeling of sleepiness produced by chlorpheniramine, though other subjective symptoms were not affected. None of the treatment schedules produced any consistent change in the psychomotor performance of the volunteers.

Evaluation of antimuscarinic activity in human volunteers: a teaching aid in clinical pharmacology.

The antimuscarinic activity of oxyphenonium bromide, diphenhydramine hydrochloride and astemizole were evaluated in six volunteers. The parameters used were salivary secretion, heart rate and pupillary size. The results indicated that the changes in heart rate and pupillary size and measurements were not convenient parameters for class room demonstration. However, salivary secretion and dryness of mouth were found to be reliable parameters for measurement. It was concluded that simple procedures like evaluation of antimuscarinic activity could be introduced as teaching aids in clinical pharmacology for undergraduate students.