A Review of the Antimalarial, Antitrypanosomal, and Antileishmanial Activities of Natural Compounds Isolated From Nigerian Flora

Abstract

The West African country Nigeria features highly diverse vegetation and climatic conditions that range from rain forest bordering the Atlantic Ocean in the South to the Desert (Sahara) at the Northern extreme. Based on data from the World Conservation Monitoring Center of the United Nations Environmental Protection, Nigeria, with ~5,000 documented vascular plants, ranks amongst the top 50 countries in terms of biodiversity. Such a rich biodiversity implies that the country is rich in diverse secondary metabolites—natural products/unique chemicals produced by the plant kingdom to confer selective advantages to them. Like many tropical countries, Nigeria is also endemic to numerous infectious diseases particularly those caused by parasitic pathogens. These phytochemicals have been exploited for the treatment of diseases and as a result, a new branch of chemistry, natural product chemistry, has evolved, to try to reproduce and improve the therapeutic qualities of particular phytochemicals. In this review, we have compiled a compendium of natural products, isolated from Nigerian flora, that have been reported to be effective against certain protozoan parasites with the aim that it will stimulate interests for further investigations, and give impetus to the development of the natural products into registered drugs. In total 93 structurally characterized natural compounds have been identified with various levels of anti-parasite activity mainly from Nigerian plants. The synthesis protocol and molecular target for some of these natural anti-parasite agents have been established. For instance, the anti-plasmodial compound fagaronine (7), a benzophenanthridine alkaloid from Fagara zanthoxyloides has been successfully synthesized in the laboratory, and the anti-trypanosomal compound azaanthraquinone (55) elicits its effect by inhibiting mitochondrial electron transfer in trypanosomes. This review also discusses the barriers to developing approved drugs from phytochemicals, and the steps that should be taken in order to accelerate the development of new antiparasitics from the highlighted compounds.

High Antiplasmodial Activity of Golden Gamat (S.hermanni) Extract Through In Vitro Study

“…Flavonoids have been found to have antimalarial effects via reducing hemoglobin breakdown by blocking the action of the cysteine protease enzyme falcipain-2 [3]. The saponins also have an antimalarial impact by damaging the cell membranes of infected erythrocytes, causing erythrocyte cells to lyse [23], [24]. Alkaloids have been proven to reduce parasitemia levels by suppressing parasite DNA and RNA production 25 .…”

Antiviral Effects of Plant Extracts Used in the Treatment of Important Animal Viral Diseases

“…Since nearly 80% of people rely on traditional medicine, plants and plant products have been used in the treatment of diseases for many centuries before the active principles in these products could be elucidated. About 50% of prescribed drugs are either plant-produced or their derivatives (Ungogo et al, 2020). Combination therapy using medicinal plants has effectiveness against a number of viruses, including herpes and influenza viruses.…”

Plant Terpenoids as Hit Compounds against Trypanosomiasis

“…Over the last decade, several reviews have reported the bioactivity of natural products against protozoan neglected diseases [ 7 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. However, natural products described in these reviews were obtained from different sources, including microbial [ 19 ], endophytes [ 20 ] and other fungi [ 21 ], marine [ 22 ], or animal origins [ 23 , 24 ].…”

“…Some reviews also present a mix of natural compounds origins [ 7 , 17 ]. Regarding natural products from plants, since 2016, there have been some reviews focusing exclusively on compounds from higher plants [ 16 , 18 , 25 , 26 , 27 , 28 , 29 , 30 ]. Nevertheless, the information is scattered amongst the diverse antiprotozoal diseases, compound families, and sources.…”