Phytochemical And Antimicrobial Activity Investigation Of Nicandra Physaloides Gaertn (solanaceae)

Abstract

An enormous variety of medicinal plants are used worldwide by about 80 % of the world population, although in most cases no scientific studies have been done to prove the efficacy of these medicinal plants. Considering that most present-day western medicines are based on the traditional medicinal plants of European, Mediterranean and Arabic origin, the variety of plants in use around the world may very well represent an enormous treasure for drug development. The objectives of this study were to investigate the phytochemical properties of Nicandra physaloides, to isolate and characterize its components and to screen the crude extracts and isolated compounds for antimicrobial activity. This plant is used in traditional medicine as an analgesic, anti-inflammatory, anthelmintic, wound healing and as an insecticide. The plant was collected from gardens surrounding Kenyatta National Hospital, Nairobi county, in Kenya in August 2009. It was air dried in the laboratory and the whole aerial parts which included the stems, fruits, leaves and flowers milled into powder for use. The extraction was done by cold maceration. The crude extract was evaporated to dryness en vacuo. Alkaloids were extracted from the extract and the remaining extract was subjected to column chromatography on normal silica gel. Thin layer chromatography using precoated aluminium plates was used to monitor the fractions. Two crystalline compounds were isolated and analyzed using spectroscopic methods. One of the compounds was identified as withanicandrin. The second compound was a mixture of phytosterols, two of which were identified as stigmasterol and psitosterol.

Some extracts of the plant and the isolated compound were prepared and screened for both antibacterial and antifungal activities using agar diffusion method. Petroleum ether extract, ethyl acetate, methanol extract and the alkaloid mixture, at a concentration of 50 mg/ml, showed activity against all the bacteria tested namely; Staphylococcus aureus, Escherichia coli and Bacillus pumilus. Withanicandrin lacked activity against any of the bacterial micro-organisms. Petroleum ether extract, alkaloid mixture and withanicandrin, showed activity against the S. cerevisiae and C. albicans. Withanicandrin had the highest activity against these fungal microorganisms. From this study, Nicandra physaloides extracts showed both antibacterial and antifungal activities thus confirming scientific basis of the use in the folklore in management of wounds. The isolated compound, withanicandrin, showed antifungal activity. Further work should be done to improve on this activity.