Efficacy of indigenous plant extracts on the malaria vector Anopheles subpictus Grassi (Diptera: Culicidae).

Background & objectives: Mosquito control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of plant origin may serve as suitable alternative biocontrol techniques in the future. The purpose of the present study was to assess the ethyl acetate, acetone and methanol extracts of Andrographis paniculata, Eclipta prostrata and Tagetes erecta leaves tested for oviposition-deterrent, ovicidal and repellent activities against malaria vector, Anopheles subpictus Grassi (Diptera: Culicidae). Methods: The dried leaves of the three plants were powdered mechanically and extracted with ethyl acetate, acetone and methanol. One gram of crude extract was first dissolved in 100 ml of acetone (stock solution). From the stock solution, test solution concentrations of 31.21- 499.42 mg/l for oviposition- deterrence assay and repellency and 15.60 - 998.85 mg/l were used in ovicidal assay. The percentage oviposition- deterrence, hatching rate of eggs and protection time were calculated. One-way analysis of variance was used for the multiple concentration tests and for per cent mortality to determine significant treatment differences. Results: The percentage of effective oviposition repellency was highest at 499.42 mg/l and the lowest at 31.21 mg/l in ethyl acetate, acetone and methanol extracts of A. paniculata, E. prostrata and T. erecta. The oviposition activity index (OAI) value of ethyl acetate, acetone and methanol extracts of A. paniculata, E. prostrata and T. erecta at 499.42 mg/l were -0.91, -0.93, -0.84, -0.84, -0.87, -0.82, -0.87, -0.89 and -0.87, respectively. Mortality (no egg hatchability) was 100 per cent with ethyl acetate and methanol extracts of A. paniculata, E. prostrata and T. erecta at 998.85 mg/l. The maximum adult repellent activity was observed at 499.42 mg/l in ethyl acetate extracts of A. paniculata, E. prostrata and methanol extracts of T. erecta, and the mean complete protection time ranged from 120 to 150 min with the different extracts tested. Interpretation & conclusions: The acetone extract of A. paniculata, methanol extract of E. prostrata and T. erecta showed good oviposition-deterrent, ovicidal and repellent activities respectively. These results suggest that the leaf extracts of A. paniculata, E. prostrata and T. erecta may have the potential to be used as an ideal eco-friendly approach for the control of the An. subpictus.

Evaluation of antioxidant potential of Clitoria ternata L. and Eclipta prostrata L.

Free radical-mediated oxidative stress is believed to be the primary cause of many disorders, such as cardiovascular diseases, brain dysfunction, cataract, diabetes mellitus, arthritis, cancer, ageing etc. In treatment of these diseases, antioxidant therapy has gained an utmost importance in the recent years. Current research is now directed towards finding naturally occurring antioxidants of plant origin. In Indian system of medicine, Clitoria ternata L. and Eclipta prostrata L. are the important medicinal plants, which have a wide range of applications. In the present study, the antioxidant potential of aqueous extracts of C. ternata and E. prostrata was evaluated by determining the levels of enzymatic and non-enzymatic antioxidants. In vitro antioxidant capacity was also determined using different assays and the results were compared with standard antioxidants such as butylated hydroxy toluene (BHT), ascorbic acid and rutin. Our results showed that both plant extracts possessed significant levels of enzymatic and non-enzymatic antioxidants and also exhibited antioxidant capacity. However, C. ternata showed higher levels of enzymatic and non-enzymatic antioxidants, as compared to E. prostrata. In addition, the antioxidant capacity of C. ternata was observed to be significant as compared to E. prostrata.

Investigation on the effect of eclipta alba on animal models of learning and memory.

Short and long term memory loss may result from deteriorating cerebral mechanisms due to varied causes which could have a tremendous impact on the quality of life. Herbs are being constantly explored to resolve cognitive deficits. Eclipta alba (Ea) commonly called as the trailing Eclipta is being examined for its memory enhancing quality as it is traditionally used for this purpose. The shade dried leaves of Eclipta alba was extracted with distilled water. The suspension of Ea containing 100 and 200 mg/kg was administered to rats to evaluate Transfer Latency (TL) on an elevated plus maze. TL was a measure of acquisition and retrieval learning. Mice were placed at the center of open field apparatus to assess spatial habitual learning, observed for 20 minutes for rearing and time spent during rearing using varied doses for 30 minutes, 24 hours and 96 hours and 144 hrs. The results revealed significant improvement of retrieval memory.

Anti-malarial activity of Eclipta alba against Plasmodium berghei infection in mice.

The anti-malarial activity of Eclipta alba leaves extract was evaluated against Plasmodium'berghei ANKA strain in mice. A standard inoculum of 1 x 10(6) infected erythrocytes was used. The methanolic leaf extract (250-750 mg/kg) produced a dose-dependant chemosupression or schizontocidal effect during early and established infection and high mean survival time (m.s.t.) values particularly in the group administered 750 mg/kg/day of extract. The plant extract also exhibited repository activity. The results of the preliminary studies carried out with E. alba are encouraging, which can be exploited in malaria therapy.