Evaluation of pharmacognostic profile, phytochemical, and antimicrobial properties of Psychotria vogeliana Benth. (Rubiaceae), Leaf

Abstract

The use of plants for the treatment of human diseases is as old as mankind on earth.. While there are reports on some Psychotria species there is virtually none on the plant Psychotria vogeliana Benth, (Rubiaceae). This research aims to evaluate the pharmacognostic, phytochemical and antimicrobial activities of the leaves of the plant. Macroscopic and microscopic characters of the plant material were evaluated and recorded. The plant material was sequentially extracted with n-hexane, ethyl acetate and methanol using a soxhlet extractor. The methanol extract was evaluated for acute toxicity using Lorke’s method. Phytochemical analysis was carried out using standard methods while antimicrobial screening was done to test for antibacterial and antifungal activities following methods Clinical and Laboratory Standards Institute (CLSI) document M07-A9 2012). The phytochemical analysis was carried out using standard methods. Extraction yield; Methanol Extract = 9.73 %, ethyl acetate extract= 6.35 %, n-hexane extract = 7.22 %. The bitterness value (expressed as Mean ± SEM) was 0.65±0.04 IU/g, swelling index was insignificant. Results for Foaming Index indicated an insignificant foaming index. Ethanol soluble extractive (%) was 5.2±0.00, Water soluble extractive (%) was 5±0.012 Total ash (%) was 6.67±0.003, Moisture content (Loss-on-drying) (%) was 7.50±0.00. The leaf is hypostomatic with the paracytic type of stomata, with stomatal number 30.6 ±0.27, stomatal size 293.56 ±9.95 stomatal index 27.7 ±0.17%, vein islet number 3.82. The methanol extract was found to be non-toxic at doses below 400 mg kg-1. The qualitative phytochemical analysis revealed the presence of alkaloids, reducing sugars, tannins, glycosides, saponins, terpenoids, steroids, flavonoids, phenols, cyanogenic compounds. The methanol extract has activity against all the tested organisms, but the n-hexane extract has no activity against Pseudomonas aeruginosa, while the ethyl acetate extract had no activity against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. The methanol and n-hexane fractions showed activity against C.albicans. The qualitative phytochemical analysis revealed the presence of alkaloids, reducing sugars, tannins, glycosides, saponins, terpenoids, steroids, flavonoids, phenols, cyanogenic compounds. The plant Psychotria vogeliana Benth (Rubiaceae), leaf contains many major phytochemicals and methanol extract possesses antimicrobial activity. Further work should be carried out to investigate other activities of the plant.