Search

Orange peel oil is used extensively as an approved flavour enhancer in fruit drinks, carbonated beverages and as a scenting agent in soaps and cosmetics. Limonene, which is a monocyclic monoterpene is present in orange peel oil from 90 to 95% (w/w). Monoterpenes have been shown to be very effective chemopreventive agents against several rodent tumors and are currently in clinical trials. However, not much information is available regarding the ultrastructural changes associated with the chemopreventive effects of the monoterpenes. The effect of orange oil on the suppression of preneoplastic hepatic lesions during N-nitrosodiethylamine (DEN) induced hepatocarcinogenesis was studied electron microscopically. Rats were administered 200 ppm DEN through drinking water for a period of 1 month. After an interval of 2 weeks, the animals were administered orange oil by gavage for a period of 5 1/2 months. The chemopreventive effect of orange oil was monitored on the basis of liver weight profile, histological pattern by light microscopy and ultrastructural alterations by electronmicroscopy. Orange oil administration following DEN treatment showed decreased liver weights, increased intercellular gap junctional complexes, cell density and polarity when compared with only the DEN treated rats. In the present study chemopreventive effect of orange oil on DEN-induced hepatic preneoplasia in rats which is associated with the restoration of the normal phenotype and upregulation of junctional complexes has been demonstrated.

Laboratory studies conducted on Ma. annulifera collected from Cherthala region, Kerala, endemic for Brugian filariasis indicated that this species is highly susceptible to B. malayi parasites. The experimental infection index of this species was relatively higher (2.74). No significant loss of larvae during development was recorded. The extrinsic incubation period was estimated to be 8 days.

Oviposition response of gravid P. papatasi females to conspecific eggs was studied in laboratory colonized sandflies. It was observed that significantly higher number of eggs were laid in the vicinity of conspecific eggs. However, a certain minimum number of eggs were required to be placed on the substratum to influence the rate of oviposition. The fecundity of females (mean = 56.5 +/- 4.9 eggs) exposed to conspecific eggs was significantly higher (P < 0.05) than that of blank control group. Perhaps, the chemical substances/pheromone of egg origin stimulated the oviposition rate. In an attempt to isolate the active ingredient, solvent washing of the conspecific eggs were tested. No increase in the rate of oviposition was noticed when the test site was treated with distilled water extract, whereas, significantly larger number of eggs were laid at the site treated with di-ethyl ether extract. This indicated that the oviposition attractant associated with the eggs dissolved in the organic solvent, but not in water. The possible application of this attractant for wild sandflies in nature and for regulating the site of oviposition on the substratum in the laboratory colonized sandflies needs to be explored.

A cyclic colony of P. papatasi was successfully established, using wild caught females. The major obstacle in the colonization was infestation of fungus, which was solved when bentonite, a dehydrant was mixed in the larval diet i.e., powdered and sterilized faecal pellets of rabbit. The average duration of development from egg to adult was 46.41 +/- 3.26 days. Females readily engorged on mouse, which was kept immobilized inside restrainer cages Majority of the fed females laid viable eggs, when confined in improvised styro-foam humidity chambers and survived after oviposition. In this process a stable, cyclic colony was established and it is now in F39 generation.