Flavonoid Versus Artemisinin Anti-malarial Activity in Artemisia annua Whole-Leaf Extracts

The plant matrix of Artemisia annua L. for the treatment of malaria: Pharmacodynamic and pharmacokinetic studies

Artemisinin-based combination therapies (ACTs) constitute the principal strategy for combating malaria in contemporary times, and research into the multifaceted components of Artemisia annua L. (A. annua) has garnered widespread interest among scientists. The aim of this study was to prepare A. annua extracts (nACTs) and to explore whether nACTs have higher bioavailability and efficacy than artemisinin (ART) alone due to its multiple bioactive components. Initially, the in vivo antimalarial activity of nACTs was evaluated by two murine malaria models. The results revealed that the antimalarial effect of nACTs was about 10-fold higher than that of ART alone when administered at the same dosage of ART. Then, we analyzed the pharmacokinetic characteristics of nACTs in rat plasma. Remarkably, nACTs exhibited significantly enhanced oral bioavailability, longer half-life as well as extended mean retention time in rats. In addition, the impact of nACTs on P-glycoprotein (P-gp) was evaluated using the Caco-2 cell line. The results showed that both ART and nACTs reduced the efflux rate of the P-gp substrate rhodamine 123 (R123) and induced the expression of P-gp in Caco-2 cells over a range of concentrations. nACTs had certain components-deoxyartemisinin (DEART), artemisinic acid (AA), and dihydroartemisinic acid (DHAA)-that inhibited the efflux and translocation of P-gp and facilitated the reduction of ART efflux. In conclusion, A. annua extracts significantly improved the antimalarial efficacy and bioavailability compared with ART.

Aqueous extract of Enantia chlorantha Oliv. demonstrates antimalarial activity and improves redox imbalance and biochemical alterations in mice

BACKGROUND

Malaria is an infectious disease, which has continued to cause inconceivable loss of lives every year, almost unabatedly. Currently, it has become more difficult to treat the disease due to the emergence and spread of resistance to recommended antimalarial drugs. This situation necessitates an urgent search for antimalarial compounds with unique modes of action. Here, we investigate the antimalarial activity, antioxidant and anti-inflammatory capacity of Enantia chlorantha aqueous stem bark extract (EcASBE) in vivo.

METHODS

The extract was screened for selected phytoconstituents including alkaloids and flavonoids. We evaluated the antimalarial activity of EcASBE against Plasmodium berghei NK65 infection in mice, using curative, prophylactic, and suppressive antimalarial test models, respectively. In addition, the antioxidant and anti-inflammatory activities of the extract were assessed.

RESULTS

The EcASBE significantly (p < 0.05) inhibited parasitaemia dose-dependently, with the highest inhibition (80.4%) and prolonged survival (MST = 20) observed in the curative test. Our findings reveal significant (p < 0.05) improvement of serum ALT, AST, ALP, GGT, and levels of TNF-α, creatinine and urea following extract administration. Furthermore, the extract led to a significant (p < 0.05) rise in the levels of CAT, SOD, GPx, and GSH, with a concomitant reduction in NO and MDA levels.

CONCLUSION

The antimalarial, antioxidative, antiperoxidative, and inflammatory-inhibiting properties of the plant in infected mice demonstrate its great value for therapeutic intervention, and substantiate its use in traditional medicine for malaria treatment. Hence, further investigation to identify the repertoire of the active antimalarial components is warranted.

From Traditional Use to Modern Evidence: The Medicinal Chemistry of Antimalarials from Genus Artemisia

While the use of plants in traditional medicine dates back to 1500 B.C., modern advancements led to the development of innovative therapeutic techniques. On the other hand, in the field of anti-infective agents, lack of efficacy and the onset of resistance stimulate the search for novel agents. Genus Artemisia is one of the most diverse among perennial plants with a variety of species, properties, and chemical components. The genus is known for its therapeutic values and, in particular, for its role in the origin of antimalarial agents derived from artemisinin. In this review, we aim to provide an updated overview of the evolution of natural and nature-inspired compounds related to the genus Artemisia that have been proven, in vitro and in vivo, to possess antimalarial properties. An overview of the chemical composition and a description of the ethnopharmacological aspects will be presented, as well as an updated report on in vitro and in vivo evidence that allowed the translation of artemisinin and its derivatives from traditional chemistry into modern medicinal chemistry. The biological and structural properties will be discussed, also dedicating attention to the challenging tasks that still are open, such as the identification of optimal combination strategies, the routes of administration, and the full assessment of the mechanism of action.

Enhanced Antimalarial Activity of Extracts of Artemisia annua L. Achieved with Aqueous Solutions of Salicylate Salts and Ionic Liquids

Artemisinin, a drug used to treat malaria, can be chemically synthesized or extracted from Artemisia annua L. However, the extraction method for artemisinin from biomass needs to be more sustainable while maintaining or enhancing its bioactivity. This work investigates the use of aqueous solutions of salts and ionic liquids with hydrotropic properties as alternative solvents for artemisinin extraction from Artemisia annua L. Among the investigated solvents, aqueous solutions of cholinium salicylate and sodium salicylate were found to be the most promising. To optimize the extraction process, a response surface method was further applied, in which the extraction time, hydrotrope concentration, and temperature were optimized. The optimized conditions resulted in extraction yields of up to 6.50 and 6.44 mg·g-1, obtained with aqueous solutions of sodium salicylate and cholinium salicylate, respectively. The extracts obtained were tested for their antimalarial activity, showing a higher efficacy against the Plasmodium falciparum strain compared with pure (synthetic) artemisinin or extracts obtained with conventional organic solvents. Characterization of the extracts revealed the presence of artemisinin together with other compounds, such as artemitin, chrysosplenol D, arteannuin B, and arteannuin J. These compounds act synergistically with artemisinin and enhance the antimalarial activity of the obtained extracts. Given the growing concern about artemisinin resistance, the results here obtained pave the way for the development of sustainable and biobased antimalarial drugs.

The Effect of Bacillus Cereus on the Ion Homeostasis, Growth Parameters, and the Expression of Some Genes of Artemisinin Biosynthesis Pathway in Artemisia Absinthium Under Salinity Stress

Background

Soil salinity is a major problem in the world that affects the growth and yield of plants. Application of new and up-to-date techniques can help plants in dealing with salinity stress. One of the approaches for reducing environmental stress is the use of rhizosphere bacteria.

Objective

The aim of present study was to investigate the effect of the inoculation of Bacillus cereus on physiological and biochemical indicators and the expression of some key genes involved in the Artemisinin biosynthesis pathway in Artemisia absinthium under salinity stress.

Materials and Methods

The study was conducted using three different salinity levels (0, 75, 150 mM/NaCl) and two different bacterial treatments (i. e, without bacterial inoculation and co-inoculation with B. cereus isolates). The data from the experiments were analyzed using factorial analysis, and the resulting interaction effects were subsequently examined and discussed.

Results

The results showed that with increasing salinity, root and stem length, root and stem weight, root and stem dry weight, and potassium content were decreased, although the content of sodium was increased. Rhizosphere bacteria increased the contents of Artemisinin, potassium, calcium, magnesium, and iron and the expression of Amorpha-4,11-diene synthase and Cytochrome P450 monooxygenase1 genes as well as the growth indicators; although decreased the sodium content. The highest ADS expression was related to co-inoculation with B. cereus isolates E and B in 150 mM salinity. The highest CYP71AV1 expression was related to co-inoculation with B. cereus isolates E and B in 150 mM salinity.

Conclusion

These findings showed that the increase in growth indices under salinity stress was probably due to the improvement of nutrient absorption conditions as a result of ion homeostasis, sodium ion reduction and Artemisinin production conditions by rhizosphere B. cereus isolates E and B.

Honey as a Natural Nutraceutical: Its Combinational Therapeutic Strategies Applicable to Blood Infections-Septicemia, HIV, SARS-CoV-2, Malaria

Honey is a natural substance that has existed alongside humanity since the time of antiquity, acting then as a source of nutrition, as well as a source of medicinal aid for people. Ancient civilizations from multiple nations of the world, from ancient China to ancient Greece and Egypt, utilized the supposed healing properties of honey to treat lacerations and wounds, as well as for internal pathologies such as intestinal disease. At present, honey has entered the modern scientific research program in search of novel antibiotics. In recent research, honey has demonstrated its potential use for static and/or cidal effects on microbial strains which are becoming resistant to chemical antibiotics. Additionally, the use of honey as an agent of treatment for more severe infections, namely blood infections pertaining to septicemia, HIV, and SARS-CoV-2, as well as parasitic infections such as malaria, have also been investigated in recent years. In this article, the literature has been reviewed on some of the therapeutic properties of natural nutraceutical honey, where it has been observed to act as a potential ameliorating agent; reducing the severity of such conditions that may amplify a disease, as well as reducing the progression of the disease and its symptoms.

Multi-omics reveal key enzymes involved in the formation of phenylpropanoid glucosides in Artemisia annua

Although mainly known for producing artemisinin, Artemisia annua is enriched in phenylpropanoid glucosides (PGs) with significant bioactivities. However, the biosynthesis of A. annua PGs is insufficiently investigated. Different A. annua ecotypes from distinct growing environments accumulate varying amounts of metabolites, including artemisinin and PGs such as scopolin. UDP-glucose:phenylpropanoid glucosyltransferases (UGTs) transfers glucose from UDP-glucose in PG biosynthesis. Here, we found that the low-artemisinin ecotype GS produces a higher amount of scopolin, compared to the high-artemisinin ecotype HN. By combining transcriptome and proteome analyses, we selected 28 candidate AaUGTs from 177 annotated AaUGTs. Using AlphaFold structural prediction and molecular docking, we determined the binding affinities of 16 AaUGTs. Seven of the AaUGTs enzymatically glycosylated phenylpropanoids. AaUGT25 converted scopoletin to scopolin and esculetin to esculin. The lack of accumulation of esculin in the leaf and the high catalytic efficiency of AaUGT25 on esculetin suggest that esculetin is methylated to scopoletin, the precursor of scopolin. We also discovered that AaOMT1, a previously uncharacterized O-methyltransferase, converts esculetin to scopoletin, suggesting an alternative route for producing scopoletin, which contributes to the high-level accumulation of scopolin in A. annua leaves. AaUGT1 and AaUGT25 responded to induction of stress-related phytohormones, implying the involvement of PGs in stress responses.

Artemisinin as a therapeutic vs. its more complex Artemisia source material

Covering: up to 2017-2022Many small molecule drugs are first discovered in nature, commonly the result of long ethnopharmacological use by people, and then characterized and purified from their biological sources. Traditional medicines are often more sustainable, but issues related to source consistency and efficacy present challenges. Modern medicine has focused solely on purified molecules, but evidence is mounting to support some of the more traditional uses of medicinal biologics. When is a more traditional delivery of a therapeutic appropriate and warranted? What studies are required to establish validity of a traditional medicine approach? Artemisia annua and A. afra are two related but unique medicinal plant species with long histories of ethnopharmacological use. A. annua produces the sesquiterpene lactone antimalarial drug, artemisinin, while A. afra produces at most, trace amounts of the compound. Both species also have an increasing repertoire of modern scientific and pharmacological data that make them ideal candidates for a case study. Here accumulated recent data on A. annua and A. afra are reviewed as a basis for establishing a decision tree for querying their therapeutic use, as well as that of other medicinal plant species.

Future antimalarials from Artemisia? A rationale for natural product mining against drug-refractory Plasmodium stages

Covering: up to 2023Infusions of the plants Artemisia annua and A. afra are gaining broad popularity to prevent or treat malaria. There is an urgent need to address this controversial public health question by providing solid scientific evidence in relation to these uses. Infusions of either species were shown to inhibit the asexual blood stages, the liver stages including the hypnozoites, but also the sexual stages, the gametocytes, of Plasmodium parasites. Elimination of hypnozoites and sterilization of mature gametocytes remain pivotal elements of the radical cure of P. vivax, and the blockage of P. vivax and P. falciparum transmission, respectively. Drugs active against these stages are restricted to the 8-aminoquinolines primaquine and tafenoquine, a paucity worsened by their double dependence on the host genetic to elicit clinical activity without severe toxicity. Besides artemisinin, these Artemisia spp. contain many natural products effective against Plasmodium asexual blood stages, but their activity against hypnozoites and gametocytes was never investigated. In the context of important therapeutic issues, we provide a review addressing (i) the role of artemisinin in the bioactivity of these Artemisia infusions against specific parasite stages, i.e., alone or in association with other phytochemicals; (ii) the mechanisms of action and biological targets in Plasmodium of ca. 60 infusion-specific Artemisia phytochemicals, with an emphasis on drug-refractory parasite stages (i.e., hypnozoites and gametocytes). Our objective is to guide the strategic prospecting of antiplasmodial natural products from these Artemisia spp., paving the way toward novel antimalarial "hit" compounds either naturally occurring or Artemisia-inspired.

Artemisia annua water extract attenuates DNCB-induced atopic dermatitis by restraining Th2 cell mediated inflammatory responses in BALB/c mice

ETHNOPHARMACOLOGICAL RELEVANCE

Artemisia annua L. (A. annua) is a traditional Chinese medicine that has been used since ancient times to treat malaria, eczema, dermatomycosis, jaundice, and boils. Modern pharmacological studies show that it has immunosuppressive and anti-inflammatory effects. However, the mechanism of A. annua in the treatment of atopic dermatitis (AD) remains unclear.

AIM OF THE STUDY

This study was aimed to investigate the effect of A. annua water extract (AWE) on 2,4-dinitrochlorobenzene (DNCB)-induced AD mouse model and tried to explore its possible underlying mechanisms.

MATERIALS AND METHODS

AD was induced in BALB/c mice by the topical repeated application of DNCB. Oral drug intervention of AWE and dexamethasone (DEX, positive control) began from the 7th day and continued for 13 consecutive days. The clinical skin score, ear thickness and the weight of ear and spleen were assessed. The ear tissue were stained with toluidine blue and hematoxylin and eosin (H&E) to detect inflammatory cell infiltration. IgE, terleukin (IL)-4 and IL-13 levels in the serum and IgE level in splenocytes were quantified by enzyme-linked immunosorbent assay (ELISA). The mRNA expression levels of IL-4, IL-6, IL-13, IL-17, tumor necrosis factor (TNF)-α and thymic stromal lymphopoietin (TSLP) were measured by quantitative real time polymerase chain reaction. The phosphorylation levels of mitogen-activated protein kinases (MAPKs)-p38 and nuclear factor (NF)-κB in ear tissue were detected by Western blot.

RESULTS

Results demonstrated that AWE treatment significantly attenuated the AD-like symptoms in DNCB-induced BALB/c mice, including the skin dermatitis severity and ear edema. Further study disclosed that AWE treatment suppressed the expressions of IgE, IL-4, IL-6, IL-13, IL-17, TNF-α and TSLP at mRNA and protein levels. Moreover, AWE showed inhibitory effect on the phosphorylation of p38 MAPK and NFκB in ear tissues of AD mice.

CONCLUSIONS

Collectively, our results suggested that AWE suppressed DNCB-induced AD in mice probably by restraining Th2 type inflammatory response. These findings might pave the road for the potential clinical application of AWE for AD treatment.

Artemisia annua Growing Wild in Romania—A Metabolite Profile Approach to Target a Drug Delivery System Based on Magnetite Nanoparticles

The metabolites profile of a plant is greatly influenced by geographical factors and the ecological environment. Various studies focused on artemisinin and its derivates for their antiparasitic and antitumoral effects. However, after the isolation and purification stage, their pharmaceutical potential is limited due to their low bioavailability, permeability and lifetime. The antibacterial activity of essential oils has been another topic of interest for many studies on this plant. Nevertheless, only a few studies investigate other metabolites in Artemisia annua. Considering that secondary metabolites act synergistically in a plant, the existence of other metabolites with antitumor and high immunomodulating activity is even more important. Novel nano-carrier systems obtained by loading herbs into magnetic nanoparticles ensures the increase in the antitumor effect, but also, overcoming the barriers related to permeability, localization. This study reported the first complete metabolic profile from wild grown Romanian Artemisia annua. A total of 103 metabolites were identified under mass spectra (MS) positive mode from 13 secondary metabolite categories: amino acids, terpenoids, steroids, coumarins, flavonoids, organic acids, fatty acids, phenolic acids, carbohydrates, glycosides, aldehydes, hydrocarbons, etc. In addition, the biological activity of each class of metabolites was discussed. We further developed a simple and inexpensive nano-carrier system with the intention to capitalize on the beneficial properties of both components. Evaluation of the nano-carrier system’s morpho-structural and magnetic properties was performed.

New insights into the spread of resistance to artemisinin and its analogues

Plasmodium falciparum, the causative agent of malaria, has been developing resistance to several drugs worldwide for more than five decades. Initially, resistance was against drugs such as chloroquine, pyrimethamine, sulfadoxine, mefloquine and quinine. Research studies are now reporting parasites with resistance to the most effective and novel drug used against malaria infection worldwide, namely artemisinin. For this reason, the first-line treatment strategy of artemisinin-based combination therapy is becoming unsuccessful in areas where drug resistance is highly prevalent. The increase in artemisinin-resistant P. falciparum strains has threatened international efforts to eliminate malarial infections and to reduce the disease burden. Detection of several phenotypes that display artemisinin resistance, specification of basic genetic factors, the discovery of molecular pathways, and evaluation of its clinical outcome are possible by the current series of research on genomics and transcriptomic levels in Asia and Africa. In artemisinin resistance, slow parasite clearance among malaria-infected patients and enhanced in vitro survival of parasites occurs at the early ring stage. This resistance is due to single nucleotide polymorphisms within the Kelch 13 gene of the parasite and is related to significantly upregulated resistance signalling pathways; thus, the pro-oxidant action of artemisinins can be antagonised. New strategies are required to halt the spread of artemisinin-resistant malarial parasites.

In vitro reduction of Plasmodium falciparum gametocytes: Artemisia spp. tea infusions vs. artemisinin

ETHNOPHARMACOLOGICAL RELEVANCE

Artemisia annua has a long history of use in Southeast Asia where it was used to treat "fever", and A. afra has a similar history in southern Africa. Since their discovery, A. annua use, in particular, has expanded globally with millions of people using the plant in therapeutic tea infusions, mainly to treat malaria.

AIM OF THE STUDY

In this study, we used in vitro studies to query if and how A. annua and A. afra tea infusions being used across the globe affect asexual Plasmodium falciparum parasites, and their sexual gametocytes.

MATERIALS AND METHODS

P. falciparumstrain NF54 was grown in vitro, synchronized, and induced to form gametocytes using N-acetylglucosamine. Cultures during asexual, early, and late stage gametocytogenesis were treated with artemisinin, methylene blue, and A. annua and A. afra tea infusions (5 g DW/L) using cultivars that contained 0-283 μM artemisinin. Asexual parasitemia and gametocytemia were analyzed microscopically. Gametocyte morphology also was scored. Markers of early (PfGEXP5) and late stage (Pfs25) gametocyte gene expression also were measured using RT-qPCR.

RESULTS

Both A. annua and A. afra tea infusions reduced gametocytemia in vitro, and the effect was mainly artemisinin dependent. Expression levels of both marker genes were reduced and also occurred with the effect mainly attributed to artemisinin content of four tested Artemisia cultivars. Tea infusions of both species also inhibited asexual parasitemia and although mainly artemisinin dependent, there was a weak antiparasitic effect from artemisinin-deficient A. afra.

CONCLUSIONS

These results showed that A. annua and to a lesser extent, A. afra, inhibited parasitemia and gametocytemia in vitro.

In vitro analyses of Artemisia extracts on Plasmodium falciparum suggest a complex antimalarial effect

Dried-leaf Artemisia annua L. (DLA) antimalarial therapy was shown effective in prior animal and human studies, but little is known about its mechanism of action. Here IC50s and ring-stage assays (RSAs) were used to compare extracts of A. annua (DLAe) to artemisinin (ART) and its derivatives in their ability to inhibit and kill Plasmodium falciparum strains 3D7, MRA1252, MRA1240, Cam3.11 and Cam3.11rev in vitro. Strains were sorbitol and Percoll synchronized to enrich for ring-stage parasites that were treated with hot water, methanol and dichloromethane extracts of DLA, artemisinin, CoArtem™, and dihydroartemisinin. Extracts of A. afra SEN were also tested. There was a correlation between ART concentration and inhibition of parasite growth. Although at 6 hr drug incubation, the RSAs for Cam3.11rev showed DLA and ART were less effective than high dose CoArtem™, 8 and 24 hr incubations yielded equivalent antiparasitic results. For Cam3.11, drug incubation time had no effect. DLAe was more effective on resistant MRA-1240 than on the sensitive MRA-1252 strain. Because results were not as robust as observed in animal and human studies, a host interaction was suspected, so sera collected from adult and pediatric Kenyan malaria patients was used in RSA inhibition experiments and compared to sera from adults naïve to the disease. The sera from both age groups of malaria patients inhibited parasite growth ≥ 70% after treatment with DLAe and compared to malaria naïve subjects suggesting some host interaction with DLA. The discrepancy between these data and in-vivo reports suggested that DLA’s effects require an interaction with the host to unlock their potential as an antimalarial therapy. Although we showed there are serum-based host effects that can kill up to 95% of parasites in vitro, it remains unclear how or if they play a role in vivo. These results further our understanding of how DLAe works against the malaria parasite in vitro.

Phytochemistry and pharmacological activity of the genus artemisia

Artemisia and its allied species have been employed for conventional medicine in the Northern temperate regions of North America, Europe, and Asia for the treatments of digestive problems, morning sickness, irregular menstrual cycle, typhoid, epilepsy, renal problems, bronchitis malaria, etc. The multidisciplinary use of artemisia species has various other health benefits that are related to its traditional and modern pharmaceutical perspectives. The main objective of this review is to evaluate the traditional, modern, biological as well as pharmacological use of the essential oil and herbal extracts of Artemisia nilagirica, Artemisia parviflora, and other allied species of Artemisia. It also discusses the botanical circulation and its phytochemical constituents viz disaccharides, polysaccharides, glycosides, saponins, terpenoids, flavonoids, and carotenoids. The plants have different biological importance like antiparasitic, antimalarial, antihyperlipidemic, antiasthmatic, antiepileptic, antitubercular, antihypertensive, antidiabetic, anxiolytic, antiemetic, antidepressant, anticancer, hepatoprotective, gastroprotective, insecticidal, antiviral activities, and also against COVID-19. Toxicological studies showed that the plants at a low dose and short duration are non or low-toxic. In contrast, a high dose at 3 g/kg and for a longer duration can cause toxicity like rapid respiration, neurotoxicity, reproductive toxicity, etc. However, further in-depth studies are needed to determine the medicinal uses, clinical efficacy and safety are crucial next steps.

In-vitro analysis of free radical scavenging activities and suppression of LPS-induced ROS production in macrophage cells by Solanum sisymbriifolium extracts

The current study aims to evaluate the antioxidant, cytotoxicity activities and suppression of LPS-induced oxidative stress production and characterization of phytochemicals in Solanum sisymbriifolium leaf extracts. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity of the leaves of S. sisymbriifolium extracted with solvents of various polarities viz. water: ethanol, ratio 50: 50; ethyl acetate and dichloromethane, was assessed. The cytotoxicity of the extracts was determined using the [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] (MTT) assay on RAW 264.7 macrophage (Murine) cells and real-time cell analysis (RTCA) xCELLigence system was used for determining cell viability. Cell-based detection of reactive oxygen species (ROS) was investigated utilizing a 2',7'-Dichlorodihydrofluorescein diacetate (H₂DCF-DA) assay. The DPPH and ABTS scavenging activity results of extracts revealed a dose-dependent response with significantly lower activity in both DPPH and ABTS. The superoxide dismutase (SOD) enzyme activity was then evaluated and extracts displayed a high SOD enzyme activity with 90-50% activity. Cytotoxicity results revealed that S. sisymbriifolium extracts were not toxic to RAW 264.7 macrophage cells at the tested concentrations. All three extracts decreased the production of ROS in macrophage cells. Phytochemical analysis using Fourier-transform infrared spectroscopy (FTIR) indicated the presence of metabolite functional groups which may be responsible for the antioxidant activity. The current study indicates that S. sisymbriifolium contains phytochemicals that scavenge free radicals, with less toxicity, and suppresses the LPS-induced ROS production in RAW 264.7 macrophage cells.

Glandular trichomes: micro-organs with model status?

Glandular trichomes are epidermal outgrowths that are the site of biosynthesis and storage of large quantities of specialized metabolites. Besides their role in the protection of plants against biotic and abiotic stresses, they have attracted interest owing to the importance of the compounds they produce for human use; for example, as pharmaceuticals, flavor and fragrance ingredients, or pesticides. Here, we review what novel concepts investigations on glandular trichomes have brought to the field of specialized metabolism, particularly with respect to chemical and enzymatic diversity. Furthermore, the next challenges in the field are understanding the metabolic network underlying the high productivity of glandular trichomes and the transport and storage of metabolites. Another emerging area is the development of glandular trichomes. Studies in some model species, essentially tomato, tobacco, and Artemisia, are now providing the first molecular clues, but many open questions remain: How is the distribution and density of different trichome types on the leaf surface controlled? When is the decision for an epidermal cell to differentiate into one type of trichome or another taken? Recent advances in gene editing make it now possible to address these questions and promise exciting discoveries in the near future.

Medicinal plants used in the treatment of Malaria: A key emphasis to Artemisia, Cinchona, Cryptolepis, and Tabebuia genera

Malaria is one of the life-threatening parasitic diseases that is endemic in tropical areas. The increased prevalence of malaria due to drug resistance leads to a high incidence of mortality. Drug discovery based on natural products and secondary metabolites is considered as alternative approaches for antimalarial therapy. Herbal medicines have advantages over modern medicines, including fewer side effects, cost-effectiveness, and affordability encouraging the herbal-based drug discovery. Several naturally occurring, semisynthetic, and synthetic antimalarial medications are on the market. For example, chloroquine is a synthetic medication for antimalarial therapy derived from quinine. Moreover, artemisinin, and its derivative, artesunate with sesquiterpene lactone backbone, is an antimalarial agent originated from Artemisia annua L. A. annua traditionally has been used to detoxify blood and eliminate fever in China. Although the artemisinin-based combination therapy against malaria has shown exceptional responses, the limited medicinal options demand novel therapeutics. Furthermore, drug resistance is the cause in most cases, and new medications are proposed to overcome the resistance. In addition to conventional therapeutics, this review covers some important genera in this area, including Artemisia, Cinchona, Cryptolepis, and Tabebuia, whose antimalarial activities are finely verified.

It is not just artemisinin: Artemisia sp. for treating diseases including malaria and schistosomiasis

Artemisia sp., especially A. annua and A. afra, have been used for centuries to treat many ailments. While artemisinin is the main therapeutically active component, emerging evidence demonstrates that the other phytochemicals in this genus are also therapeutically active. Those compounds include flavonoids, other terpenes, coumarins, and phenolic acids. Artemisia sp. phytochemicals also improve bioavailability of artemisinin and synergistically improve artemisinin therapeutic efficacy, especially when delivered as dried leaf Artemisia as a tea infusion or as powdered dry leaves in a capsule or compressed into a tablet. Here results from in vitro, and in vivo animal and human studies are summarized and critically discussed for mainly malaria, but also other diseases susceptible to artemisinin and Artemisia sp. including schistosomiasis, leishmaniasis, and trypanosomiasis.