Assessing the Roles of Molecular Markers of Antimalarial Drug Resistance and the Host Pharmacogenetics in Drug-Resistant Malaria

A comprehensive review of antimalarial medicinal plants used by Tanzanians

CONTEXT

Tanzania has rich medicinal plant (MP) resources, and most rural inhabitants rely on traditional healing practices for their primary healthcare needs. However, available research evidence on antimalarial MPs is highly fragmented in the country.

OBJECTIVE

This systematic review compiles ethnomedicinal research evidence on MPs used by Tanzanians as antimalarials.

MATERIALS AND METHODS

A systematic web search was conducted using various electronic databases and grey materials to gather relevant information on antimalarial MPs utilized by Tanzanians. The review was per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The data were collected from 25 articles, and MS Excel software was used to analyse relevant ethnobotanical information using descriptive statistics.

RESULTS

A total of 227 MPs belonging to 67 botanical families and 180 genera were identified. Fabaceae (15.9%) is the most frequently utilized family. The ethnobotanical recipes analysis indicated leaves (40%) and trees (44%) are the preferred MPs part and life form, respectively. Decoctions (67%) are the dominant preparation method of remedies. Of the recorded MPs, 25.9% have been scientifically investigated for antimalarial activities with positive results. However, 74.1% of MPs have no scientific records on antimalarial activities, but they could be potential sources of remedies.

CONCLUSIONS

The study discloses a wealth of antimalarial MPs possessed by Tanzanians and suggests a need for research to authenticate the healing potential of antimalarial compounds from the unstudied MPs. Additionally, it indicates that some of the presented MPs are potential sources for developing safe, effective and affordable antimalarial drugs.

Assessment of antimalarial activity of crude extract of Chan-Ta-Lee-La and Pra-Sa-Chan-Dang formulations and their plant ingredients for new drug candidates of malaria treatment: In vitro and in vivo experiments

The emergence and spread of antimalarial drug resistance have become a significant problem worldwide. The search for natural products to develop novel antimalarial drugs is challenging. Therefore, this study aimed to assess the antimalarial and toxicological effects of Chan-Ta-Lee-La (CTLL) and Pra-Sa-Chan-Dang (PSCD) formulations and their plant ingredients. The crude extracts of CTLL and PSCD formulations and their plant ingredients were evaluated for in vitro antimalarial activity using Plasmodium lactate dehydrogenase enzyme and toxicity to Vero and HepG2 cells using the tetrazolium salt method. An extract from the CTLL and PSCD formulations exhibiting the highest selectivity index value was selected for further investigation using Peter's 4-day suppressive test, curative test, prophylactic test, and acute oral toxicity in mice. The phytochemical constituents were characterized using gas chromatography-mass spectrometry (GC-MS). Results showed that ethanolic extracts of CTLL and PSCD formulations possessed high antimalarial activity (half maximal inhibitory concentration = 4.88, and 4.19 g/mL, respectively) with low cytotoxicity. Ethanolic extracts of the CTLL and PSCD formulations demonstrated a significant dose-dependent decrease in parasitemia in mice. The ethanolic CTLL extract showed the greatest suppressive effect after 4 days of suppressive (89.80%) and curative (35.94%) testing at a dose of 600 mg/kg. Moreover, ethanolic PSCD extract showed the highest suppressive effect in the prophylactic test (65.82%) at a dose of 600 mg/kg. There was no acute toxicity in mice treated with ethanolic CTLL and PSCD extracts at 2,000 mg/kg bodyweight. GC-MS analysis revealed that the most abundant compounds in the ethanolic CTLL extract were linderol, isoborneol, eudesmol, linoleic acid, and oleic acid, whereas ethyl 4-methoxycinnamate was the most commonly found compound in the ethanolic PSCD extract, followed by 3-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-4H-chromen-4-one, flamenol, oleic acid amide, linoleic acid, and oleic acid. In conclusions, ethanolic CTLL and PSCD extracts exhibited high antimalarial efficacy in vitro. The ethanolic CTLL extract at a dose of 600 mg/kg exhibited the highest antimalarial activity in the 4-day suppressive and curative tests, whereas the ethanolic PSCD extract at a dose of 600 mg/kg showed the highest antimalarial activity in the prophylactic test.

Baseline and recurrent exposure to the standard dose of artemisinin-based combination therapies (ACTs) induces oxidative stress and liver damage in mice (BALB/c)

Background

In malaria-endemic countries, repeated intake of artemisinin-based combination therapies (ACTs) is rampant and driven by drug resistance, improper usage, and easy accessibility. Stress effects and potential liver toxicity due to the frequent therapeutic use of ACTs have not been extensively studied. Here, we investigated the effects of repeated treatment with standard doses of the commonly used ACTs artemether/lumefantrine (A/L) and artesunate-amodiaquine (A/A) on oxidative stress and liver function markers in male mice (BALB/c).

Methods

Forty Five mice were divided into three groups: control, A/L, and A/A. The drugs were administered three days in a row per week, and the regimen was repeated every two weeks for a total of six cycles. The levels of oxidative stress and liver function markers were measured in both plasma and liver tissue after initial (baseline) and repeated exposures for the second, third, and sixth cycles.

Results

Exposure to A/L or A/A caused a significant (p < 0.001) increase in plasma malondialdehyde (MDA) levels after the first and repeated exposure periods. However, Hepatic MDA levels increased significantly (p < 0.01) only after the sixth exposure to A/A. Following either single or repeated exposure to A/L or A/A, plasma and liver glutathione peroxidase (GPx) and catalase (CAT) activities, plasma aspartate and alanine transaminase, alkaline phosphatase activity, and bilirubin levels increased, whereas total plasma protein levels decreased significantly (p < 0.001). Varying degrees of hepatocyte degeneration and blood vessel congestion were observed in liver tissues after a single or repeated treatment period.

Conclusion

Irrespective of single or repeated exposure to therapeutic doses of A/L or A/A, plasma oxidative stress and liver damage were observed. However, long-term repeated A/A exposure can led to hepatic stress. Compensatory processes involving GPx and CAT activities may help reduce the observed stress.

Medicinal plants used for treatment of malaria by indigenous communities of Tororo District, Eastern Uganda

BACKGROUND

Malaria remains the leading cause of death in sub-Saharan Africa. Although recent developments such as malaria vaccine trials inspire optimism, the search for novel antimalarial drugs is urgently needed to control the mounting resistance of Plasmodium species to the available therapies. The present study was conducted to document ethnobotanical knowledge on the plants used to treat symptoms of malaria in Tororo district, a malaria-endemic region of Eastern Uganda.

METHODS

An ethnobotanical study was carried out between February 2020 and September 2020 in 12 randomly selected villages of Tororo district. In total, 151 respondents (21 herbalists and 130 non-herbalists) were selected using multistage random sampling method. Their awareness of malaria, treatment-seeking behaviour and herbal treatment practices were obtained using semi-structured questionnaires and focus group discussions. Data were analysed using descriptive statistics, paired comparison, preference ranking and informant consensus factor.

RESULTS

A total of 45 plant species belonging to 26 families and 44 genera were used in the preparation of herbal medicines for management of malaria and its symptoms. The most frequently mentioned plant species were Vernonia amygdalina, Chamaecrista nigricans, Aloe nobilis, Warburgia ugandensis, Abrus precatorius, Kedrostis foetidissima, Senna occidentalis, Azadirachta indica and Mangifera indica. Leaves (67.3%) were the most used plant part while maceration (56%) was the major method of herbal remedy preparation. Oral route was the predominant mode of administration with inconsistencies in the posology prescribed.

CONCLUSION

This study showed that the identified medicinal plants in Tororo district, Uganda, are potential sources of new antimalarial drugs. This provides a basis for investigating the antimalarial efficacy, phytochemistry and toxicity of the unstudied species with high percentage use values to validate their use in the management of malaria.