Phytochemical Screening, Acute Toxicity and Anti-Rabies Activities of Extracts of Selected Ethiopian Traditional Medicinal Plants

Abstract

Background: Croton macrostachyus, Justicia schimperiana, and Ricinus communis have been widely used for the traditional treatment of rabies in Ethiopia. The objective of this study was to investigate the phytochemical constituents, acute toxicity, and antirabies activity of crude extracts of the leaves of Justicia schimperiana and Ricinus communis and the stem bark of Croton macrostachyus. Methods: In studying the presence of phytochemicals within each plant extract, standard procedures were used. The Organization for Economic Corporation and Development (OECD) Guideline No.423 was used for the determination of acute toxicity and antirabies activities of extracts towards Swiss albino mice. Different concentrations of extracts were tested for their cytotoxic effect on Vero cells through 3-(4, 5-Dimethylthiazol-2-yl)-2, 5Diphenyltetrazolium Bromide (MTT) assay. The antirabies assay was carried out based on the minimal toxic concentration of extracts. Results: The phytochemical constituents identified were alkaloids, flavonoids, phenols, steroids, tannins, and terpenoids. All the extracts were slightly toxic in the Swiss albino mice model but noncytotoxic in Vero cell lines. The antirabies assay result showed that all plant extracts had a moderate to good antirabies potential. The methanol extracts exhibited an appreciable antirabies activity compared to the other extracts under investigation. Conclusion: The present study concluded that the studied plant extracts have possessed different phytochemicals and have shown appreciable antirabies activities. Hence these plants could be a potential source of the novel antirabies compound and also may be effective against other viruses.

Acute and Sub-Acute Toxicity Evaluation of the Crude Methanolic Extract of Justicia schimperiana Leaf in Wistar Albino Rats

“…36,37 Prior acute oral toxicity tests of the crude 80% methanolic extract of J. schimperiana leaf (JSLM80) showed inconsistent levels of LD 50 . 13,16,23,25,26,28,29,31 The discrepancy in the LD 50 level reported among the previous studies could be due to the variation in toxicity experimental protocol followed and animal characteristics (age, sex, weight, and genetic background). Moreover, the composition of the plant material (geographical location, climate, harvesting time, and storage conditions) and extraction methods can also impact the LD 50 level of plant extracts.…”

“…6 In several parts of Ethiopia, the plant J. schimperiana is used traditionally for a variety of illnesses like jaundice, rabies, anthrax, asthma, common cold, stomachache, diarrhea, tapeworm infestation, wound, external parasite, and skin irritation. [8][9][10][11] Phytochemical analysis of various parts of J. schimperiana showed the presence of major secondary metabolites such as Terpenoids, 12,13 Phenols, [13][14][15] Tannins, [12][13][14]16,17 Steroids, 12,18 Flavonoids 13-15,18 7), Saponins, [13][14][15]18,19 and Alkaloids. 15,18,19 Methyl elaidate, methyl oleate, methyl hexadecanoate, and many other chemical compounds were isolated from J. schimperiana.…”

“…20 Several biologically active chemical compounds, such as apigenin, naringenin, phytol, etc., were also identified in the plant of the same genus, Justicia gendarussa Burm. 21 J. schimperiana demonstrated antibacterial, 18,22 antidiarrheal, 13 antimalarial, 15,23,24 anti-diabetic, 25 hepatoprotective, 26 anti-asthmatic, [27][28][29] wound healing, 17 antifungal, 14,22,30 and anti-rabies 16,31 activities.…”