Comparison of antimalarial activity of the alkaloidal fraction of Hydrangea macrophylla var. Otaksa leaves with the hot-water extract in ICR mice infected with Plasmodium yoelii 17 XL

Dichroa febrifuga Lour.: A review of its botany, traditional use, phytochemistry, pharmacological activities, toxicology, and progress in reducing toxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Dichroa febrifuga Lour., a toxic but extensively used traditional Chinese medicine with a remarkable effect, is commonly called "Changshan" in China. It has been used to treat malaria and many other parasitic diseases.

AIM OF THE REVIEW

The study aims to provide a current overview of the progress in the research on traditional use, phytochemistry, pharmacological activities, toxicology, and methods of toxicity reduction of D. febrifuga. Additionally, further research directions and development prospects for the plant were put forward.

MATERIALS AND METHODS

The article uses "Dichroa febrifuga Lour." "D. febrifuga" as the keyword and all relevant information on D. febrifuga was collected from electronic searches (Elsevier, PubMed, ACS, CNKI, Google Scholar, and Baidu Scholar), doctoral and master's dissertations and classic books about Chinese herbs.

RESULTS

30 chemical compounds, including alkaloids, terpenoids, flavonoids and other kinds, were isolated and identified from D. febrifuga. Modern pharmacological studies have shown that these components have a variety of pharmacological activities, including anti-malarial activities, anti-inflammatory activities, anti-tumor activities, anti-parasitic activities and anti-oomycete activities. Meanwhile, alkaloids, as the material basis of its efficacy, are also the source of its toxicity. It can cause multiple organ damage, including liver, kidney and heart, and cause adverse reactions such as nausea and vomiting, abdominal pain and diarrhea. In the current study, the toxicity can be reduced by modifying the structure of the compound, processing and changing the dosage forms.

CONCLUSIONS

There are few studies on the chemical constituents of D. febrifuga, so the components and their structure characterization contained in it can become the focus of future research. In view of the toxicity of D. febrifuga, there are many methods to reduce it, but the safety and rationality of these methods need further study.

Synthesis, antimalarial, antileishmanial evaluation, and molecular docking study of some 3-aryl-2-styryl substituted-4(3H)-quinazolinone derivatives

Quinazolinones are a diverse group of nitrogen-containing heterocyclic compounds with promising antimalarial and antileishmanial activities. Herein, some 3-aryl-2-styryl substituted-4(3H)-quinazolinones were synthesized via cyclization, condensation, and hydrolysis reactions. ¹H NMR, FTIR and elemental microanalysis was used to verify the structures of the synthesized compounds. The in vivo antimalarial and in vitro antileishmanial activities of the target compounds were investigated using mice infected with Plasmodium berghi ANKA and Leishmania donovani strain, respectively. Among the test compounds, 8 and 10 showed better antimalarial activities with percent suppression of 70.01 and 74.18, respectively. In addition, (E)-2-(4-nitrostyryl)-3-phenylquinazolin-4(3H)-one (6) showed promising antileishmanial activity (IC₅₀ = 0.0212 µg/mL). It is two and 150 times more active than the standard drugs amphotericin B deoxycholate (IC₅₀ = 0.0460 µg/mL) and miltefosine (IC ₅₀ = 3.1911 µg/mL), respectively. Its superior in vitro antileishmanial activity was supported by a molecular docking study conducted in the active site of Lm-PTR1. Overall, the synthesized 3-aryl-2-styryl substituted-4(3H)-quinazolinones showed promising antileishmanial and antimalarial activities and are desirable scaffolds for the synthesis of different antileishmanial and antimalarial agents.

Hepatoprotective Role of Hydrangea macrophylla against Sodium Arsenite-Induced Mitochondrial-Dependent Oxidative Stress via the Inhibition of MAPK/Caspase-3 Pathways

Sodium arsenite (NaAsO₂) has been recognized as a worldwide health concern. Hydrangea macrophylla (HM) is used as traditional Chinese medicine possessing antioxidant activities. The study was performed to investigate the therapeutic role and underlying molecular mechanism of HM on NaAsO₂-induced toxicity in human liver cancer (HepG2) cells and liver in mice. The hepatoprotective role of HM in HepG2 cells was assessed by using 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (MTT), reactive oxygen species (ROS), and lactate dehydrogenase (LDH) assays. Histopathology, lipid peroxidation, serum biochemistry, quantitative real-time polymerase chain reaction (qPCR) and Western blot analyses were performed to determine the protective role of HM against NaAsO₂ intoxication in liver tissue. In this study, we found that co-treatment with HM significantly attenuated the NaAsO₂-induced cell viability loss, intracellular ROS, and LDH release in HepG2 cells in a dose-dependent manner. Hepatic histopathology, lipid peroxidation, and the serum biochemical parameters alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were notably improved by HM. HM effectively downregulated the both gene and protein expression level of the mitogen-activated protein kinase (MAPK) cascade. Moreover, HM well-regulated the Bcl-2-associated X protein (Bax)/B-cell lymphoma-2 (Bcl-2) ratio, remarkably suppressed the release of cytochrome c, and blocked the expression of the post-apoptotic transcription factor caspase-3. Therefore, our study provides new insights into the hepatoprotective role of HM through its reduction in apoptosis, which likely involves in the modulation of MAPK/caspase-3 signaling pathways.

In vivo antimalarial evaluation of some 2,3-disubstituted-4(3H)-quinazolinone derivatives

BACKGROUND

Malaria is a neglected tropical parasitic disease affecting billons of people around the globe. Though the number of cases and deaths associated with malaria are decreasing in recent years, it is the most deadly disease in the world. This study aimed at investigating the in vivo antimalarial activities of some 2,3-disubstituted-4(3H)-quinazolinone derivatives.

RESULTS

The in vivo antimalarial activities of the test compounds (6-9 and 11-13) were investigated using the 4-day suppressive standard test in mice infected with chloroquine-sensitive Plasmodium berghei ANKA strain. The tested compounds showed significant antimalarial activities with mean percentage suppression of 43.71-72.86 % which is significantly higher than the negative control group (p < 0.05). Compounds 12 and 13 displayed better antimalarial activities from the group with mean percentage suppression of 67.60 and 72.86 % respectively.

CONCLUSION

The tested compounds showed significant in vivo antimalarial activities in mice infected with P. berghi ANKA strain. Thus, 3-aryl-2-(substitutedstyryl)-4(3H)-quinazolinones represent a possible scaffold for the development of antimalarial agents.

Plasmodium berghei: efficacy of 5-fluoroorotate in combination with commonly used antimalarial drugs in a mouse model

Resistance to antimalarial antifolates necessitates a search for new antimetabolites targeting other enzymes of the folate metabolic pathway. In this study, 5-fluoroorotate (FOA), reported to be an inhibitor of thymidylate synthase, was assayed against Plasmodium berghei NK 65 in mice, with(out) an oral uridine supplement. FOA (2.5 and 5.0 mg/kg bw.) was tested alone, or in a double and triple combination with a fixed oral dose of 1.25 and 2.5 mg/kg of pyrimethamine (PYR); 1.0 and 2.0 mg/kg of dapsone (DAP); 1.0 and 2.0 mg/kg of artesunate (ART). FOA achieved high suppression which ranged from 95.7% to aparasitaemic, activity that was dose-dependent. At the highest dosages used, FOA-PYR and FOA-DAP-ART combinations were synergistic with 100% cure rate, while FOA-PYR-ART was antagonistic. Drugs in a synergistic combination may exert less resistance selection pressure, thus FOA-PYR and FOA-DAP-ART warrant further evaluation with an ultimate object of possible clinical use against drug-resistant malaria.

Plasmodium berghei: lack of antimalarial activity of an analogue of folate precursor, 2,4-diamino-6-hydroxymethylpteridine in a mouse model

It was earlier hypothesized that the malarial parasite may convert precursors of folate analogues to synthesize de novo inhibitors toxic to itself, but not to the mammalian cell. It was suggested that one such analogue, 2,4-diamino-6-hydroxymethylpteridine (DAP) may be converted to aminopterin (AMP), a known dihydrofolate reductase inhibitor. In the present study, we evaluated the ability of DAP to inhibit proliferation of Plasmodium berghei NK65 in mice, with(out) folinic acid rescue. Cumulative dosages of DAP ranging from 0.1 to 20mg/kg bw. administered either orally or intraperitoneally showed no suppression of parasite growth, or gave mild activities that were not statistically significant (P>0.05). Our findings do not seem to support the hypothesis of selective de novo metabolism of DAP to AMP by the malarial parasite.

Antimalarial activity of methanolic extracts from plants used in Kenyan ethnomedicine and their interactions with chloroquine (CQ) against a CQ-tolerant rodent parasite, in mice

Methanolic extracts from 15 medicinal plants representing 11 families, used traditionally for malaria treatment in Kenya were screened for their in vivo antimalarial activity in mice against a chloroquine (CQ)-tolerant Plasmodium berghei NK65, either alone or in combination with CQ. The plant parts used ranged from leaves (L), stem bark (SB), root bark (RB), seeds (S) and whole plant (W). When used alone, extracts from seven plants, Clerodendrum myricoides (RB), Ficus sur (L/SB/RB), Maytenus acuminata (L/RB), Rhamnus prinoides (L/RB), Rhamnus staddo (RB), Toddalia asiatica (RB) and Vernonia lasiopus (RB) had statistically significant parasitaemia suppressions of 31.7-59.3%. In combination with CQ, methanolic extracts of Albizia gummifera (SB), Ficus sur (RB), Rhamnus prinoides and Rhamnus staddo (L/RB), Caesalpinia volkensii (L), Maytenus senegalensis (L/RB), Withania somnifera (RB), Ekebergia capensis (L/SB), Toddalia asiatica (L/RB) and Vernonia lasiopus (L/SB/RB) gave statistically significant and improved suppressions which ranged from 45.5 to 85.1%. The fact that these activities were up to five-fold higher than that of extract alone may suggest synergistic interactions. Remarkable parasitaemia suppression by the extracts, either alone or in combination with CQ mostly resulted into longer mouse survival relative to the controls, in some cases by a further 2 weeks. Plants, which showed significant antimalarial activity including Vernonia lasiopus, Toddalia asiatica, Ficus sur, Rhamnus prinoides and Rhamnus staddo warrant further evaluation in the search for novel antimalarial agents against drug-resistant malaria.

Combination effects of chloroquine with the febrifugine and isofebrifugine mixture against a blood-induced infection with chloroquine-resistant Plasmodium berghei NK65 in ICR mice

The combination effects of chloroquine with a mixture of febrifugine and isofebrifugine were evaluated against a blood-induced infection with chloroquine-resistant P. berghei NK65 in ICR mice. Mice in the untreated control showed a progressively increasing parasitemia leading to mouse death. A two-day dosage of 20 mg base/kg of chloroquine alone showed little effect against P. berghei NK65 infection, and all mice died from day 13 to 14 with an increasing parasitemia. A four-day dosage of 1 mg/kg of the febrifugine and isofebrifugine mixture alone showed a little antimalarial activity, but all mice died from day 19 to 27 with an increasing parasitemia. On the other hand, mice treated with chloroquine plus alkaloids survived during the experiment. All mice treated with chloroquine alone or the alkaloid mixture alone showed low parasitemia levels during a drug administration and following a few days, but then malaria parasites increased in the bloodstream of the treated mice until death. On the other hand, malaria parasites in the mice given chloroquine plus alkaloids decreased on day 6 and then were not detected by a microscopic examination during observation period.