Potentials of marine natural products against malaria, leishmaniasis, and trypanosomiasis parasites: a review of recent articles.

BACKGROUND: Malaria and neglected communicable protozoa parasitic diseases, such as leishmaniasis, and trypanosomiasis, are among the otherwise called diseases for neglected communities, which are habitual in underprivileged populations in developing tropical and subtropical regions of Africa, Asia, and the Americas. Some of the currently available therapeutic drugs have some limitations such as toxicity and questionable efficacy and long treatment period, which have encouraged resistance. These have prompted many researchers to focus on finding new drugs that are safe, effective, and affordable from marine environments. The aim of this review was to show the diversity, structural scaffolds, in-vitro or in-vivo efficacy, and recent progress made in the discovery/isolation of marine natural products (MNPs) with potent bioactivity against malaria, leishmaniasis, and trypanosomiasis. MAIN TEXT: We searched PubMed and Google scholar using Boolean Operators (AND, OR, and NOT) and the combination of related terms for articles on marine natural products (MNPs) discovery published only in English language from January 2016 to June 2020. Twenty nine articles reported the isolation, identification and antiparasitic activity of the isolated compounds from marine environment. A total of 125 compounds were reported to have been isolated, out of which 45 were newly isolated compounds. These compounds were all isolated from bacteria, a fungus, sponges, algae, a bryozoan, cnidarians and soft corals. In recent years, great progress is being made on anti-malarial drug discovery from marine organisms with the isolation of these potent compounds. Comparably, some of these promising antikinetoplastid MNPs have potency better or similar to conventional drugs and could be developed as both antileishmanial and antitrypanosomal drugs. However, very few of these MNPs have a pharmaceutical destiny due to lack of the following: sustainable production of the bioactive compounds, standard efficient screening methods, knowledge of the mechanism of action, partnerships between researchers and pharmaceutical industries. CONCLUSIONS: It is crystal clear that marine organisms are a rich source of antiparasitic compounds, such as alkaloids, terpenoids, peptides, polyketides, terpene, coumarins, steroids, fatty acid derivatives, and lactones. The current and future technological innovation in natural products drug discovery will bolster the drug armamentarium for malaria and neglected tropical diseases.

Antioxidant and hepatoprotective potentials of active fractions of Lannea barteri Oliv. (Anarcadiaceae) in rats.

INTRODUCTION: Lannea barteri is used in the folkloric treatment of many disease states ranging from epilepsy, diarrhoea, oedema and ulcers, etc. This study investigated the antioxidant and hepatoprotective potentials of methanol (MFLB), n-hexane (nHFLB) and ethyl acetate (EFLB) leaf fractions of L. barteri and identified the active metabolites. MATERIALS AND METHODS: The in vitro models used were 1, 1-diphenyl-1-picrylhydrazyl (DPPH), reducing power and thiobarbituric acid assays while in the in vivo model, carbon tetrachloride-induced oxidative liver damage in albino rats was used, and the biomarkers assayed were aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), malondialdehyde (MDA), serum total protein, serum direct and total bilirubin. Also, histopathological examination of the liver, high performance liquid chromatography (HPLC) profiling and liquid chromatography-mass spectroscopy-electrospray ionization (LC-MS-ESI) analysis of the fractions were done. RESULTS: In the in vitro assays, the decreasing order of DPPH free radical scavenging activity of the ascorbic acid and fractions at 400 µg/ml is as follows: ascorbic acid (86.6%), MFLB (52.8%), EFLB (36.6%), and nHFLB (28.1%). The percentage scavenging activity of the samples at 400 µg/ml in the TBA followed this pattern: ascorbic acid (117.1%), MFLB (82.2%), nHFLB (80.0%), and EFLB (46.9%). The ascorbic acid elicited highest reducing power (42.6%), followed by MFLB (22.5%), nHFLB (13.7%), and EFLB (-0.93%). The in vivo study showed significant (p < 0.0001) reduction in serum AST, ALT, and direct bilirubin with a non-significant reduction in ALP, total bilirubin and MDA, and mild elevation in total protein. Histopathological studies revealed a restorative effect on liver architecture. The phytochemical analyses revealed the presence of resins, terpenoids, flavonoids, carbohydrates, alkaloids, reducing sugar, saponins, tannins and proteins. HPLC-ESI-MS analysis revealed the presence of potentially bioactive compounds in L. barteri fractions. CONCLUSION: The fractions from L. barteri leaf possessed in vitro antioxidant and hepatoprotective potentials against CCl4-hepatic oxidative damage; therefore, proper isolation and characterization of these identified bioactive compounds responsible for the observed effects are ongoing.

Antibiotics Development and the Potentials of Marine-Derived Compounds to Stem the Tide of Multidrug-Resistant Pathogenic Bacteria, Fungi, and Protozoa.

As the search for new antibiotics continues, the resistance to known antimicrobial compounds continues to increase. Many researchers around the world, in response to antibiotics resistance, have continued to search for new antimicrobial compounds in different ecological niches such as the marine environment. Marine habitats are one of the known and promising sources for bioactive compounds with antimicrobial potentials against currently drug-resistant strains of pathogenic microorganisms. For more than a decade, numerous antimicrobial compounds have been discovered from marine environments, with many more antimicrobials still being discovered every year. So far, only very few compounds are in preclinical and clinical trials. Research in marine natural products has resulted in the isolation and identification of numerous diverse and novel chemical compounds with potency against even drug-resistant pathogens. Some of these compounds, which mainly came from marine bacteria and fungi, have been classified into alkaloids, lactones, phenols, quinones, tannins, terpenes, glycosides, halogenated, polyketides, xanthones, macrocycles, peptides, and fatty acids. All these are geared towards discovering and isolating unique compounds with therapeutic potential, especially against multidrug-resistant pathogenic microorganisms. In this review, we tried to summarize published articles from 2015 to 2019 on antimicrobial compounds isolated from marine sources, including some of their chemical structures and tests performed against drug-resistant pathogens.

Pharmacological Evaluation of the Anticancer Activity of Extracts and Fractions of Lannea barteri Oliv. (Anacardiaceae) on Adherent Human Cancer Cell Lines.

In western Africa ethnomedicine, Lannea barteri Oliv. (Anacardiaceae) is believed to have activity against gastrointestinal, neurological and endocrine diseases. Previous studies on this plant have revealed antimicrobial, anticholinestrase, anticonvulsant, antioxidant and anti-inflammatory activities. However, the anticancer potential of L. barteri has not been studied to date. The aim of this study was to evaluate the anticancer potential of hot and cold extracts and silica gel column chromatographic fractions of L. barteri leaf and stem bark. The extracts and fractions were tested for anticancer activity by using the crystal violet cell proliferation assay on four adherent human carcinoma cell lines-5637 (bladder), KYSE 70 (oesophagus), SiSo (cervical) and HepG2 (hepatic). The inhibitory concentration (IC50) of fractions IH, 1I, 2E and 2F were: 3.75 ± 1.33, 3.88 ± 2.15, 0.53 ± 0.41, and 0.42 ± 0.45 µg/mL against KYSE 70 and 1.04 ± 0.94, 2.69 ± 1.17, 2.38 ± 3.64, 2.17 ± 1.92 µg/mL against SiSo cell lines respectively. Fraction 2E showed weak apoptotic activity at double the IC50 and some sign of cell cycle arrest in the G2/M phase. Thus, phytoconstituents of L. barteri leaf and stem bark can inhibit the proliferation of cancer cell lines indicating the presence of possible anticancer agents in this plant.

Anti-inflammatory activity of Buchholzia coriacea Engl. (Capparaceae) leaf extract: evaluation of components of the inflammatory response involved.

BACKGROUND: Earlier studies in our laboratory demonstrated the anti-inflammatory activity of Buchholzia coriacea Engl. (Capparaceae) leaf extract, a herbal remedy used to treat disorders of inflammation. This study was undertaken to evaluate its anti-inflammatory mechanism(s). METHODS: The effects of methanol leaf extract of B. coriacea (200 and 400 mg/kg) on vascular permeability and leukocyte migration were studied in rodents, while activity on complement system and membrane stabilization were evaluated in vitro. RESULTS: The extract (200 and 400 mg/kg) inhibited acetic acid-induced increase in vascular permeability in a non-dose-related manner and significantly (p < 0.05) reduced the total and differential leukocyte counts, respectively, in a dose-related manner. It also significantly (p < 0.05) inhibited complement-induced hemolysis of sheep red blood cells (40-72%) and moderately inhibited heat- (6%) and hypotonic solution-(24%) induced hemolysis in vitro in a non-dose-related manner. CONCLUSIONS: Results demonstrated that the anti-inflammatory activity of B. coriacea leaf extract is mediated through inhibition of increase in vascular permeability, leukocyte migration and complement system, and enhanced membrane stabilization.