Antiviral constituents against respiratory viruses from Mikania micrantha

Mikania micrantha Kunth: An Ethnopharmacological Treasure Trove of Therapeutic Potential

Mikania micrantha is utilized as a therapeutic for the treatment of various human ailments including insect bites, rashes and itches of skin, chicken pox, healing of sores and wounds, colds and fever, nausea, jaundice, rheumatism, and respiratory ailments. This study aimed at summarizing the traditional uses, phytochemical profile, and biological activities of M. micrantha based on obtainable information screened from different databases. An up-to-date search was performed on M. micrantha in PubMed, Science Direct, clinicaltrials.gov, and Google Scholar databases with specific keywords. No language restrictions were imposed. Published articles, theses, seminar/conference papers, abstracts, and books on ethnobotany, phytochemistry and pharmacological evidence were considered. Based on the inclusion criteria, this study includes 53 published records from the above-mentioned databases. The results suggest that fresh leaves and whole plant are frequently used in folk medicine. The plant contains more than 150 different phytochemicals under the following groups: essential oils, phenolics and flavonoids, terpenes, terpene lactones, glycosides, and sulfated flavonoids. It contains carbohydrates and micronutrients including vitamins and major and trace minerals. M. micrantha possesses antioxidant, anti-inflammatory, anti-microbial, anti-dermatophytic, anti-protozoal, anthelmintic, cytotoxic, anxiolytic, anti-diabetic, lipid-lowering and antidiabetic, spasmolytic, memory-enhancing, wound-healing, anti-aging, and thrombolytic activities. No clinical studies have been reported to date. M. micrantha might be one of the potential sources of phytotherapeutic compounds against diverse ailments in humans. Studies are required to confirm its safety profile in experimental animals prior to initiating clinical trials. Moreover, adequate investigation is also crucial to clarify exact mechanism of action for each biological effect.

Therapeutic Potential of Bioactive Compounds from Edible Mushrooms to Attenuate SARS-CoV-2 Infection and Some Complications of Coronavirus Disease (COVID-19)

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a highly infectious positive RNA virus, has spread from its epicenter to other countries with increased mortality and morbidity. Its expansion has hampered humankind's social, economic, and health realms to a large extent. Globally, investigations are underway to understand the complex pathophysiology of coronavirus disease (COVID-19) induced by SARS-CoV-2. Though numerous therapeutic strategies have been introduced to combat COVID-19, none are fully proven or comprehensive, as several key issues and challenges remain unresolved. At present, natural products have gained significant momentum in treating metabolic disorders. Mushrooms have often proved to be the precursor of various therapeutic molecules or drug prototypes. The plentiful bioactive macromolecules in edible mushrooms, like polysaccharides, proteins, and other secondary metabolites (such as flavonoids, polyphenols, etc.), have been used to treat multiple diseases, including viral infections, by traditional healers and the medical fraternity. Some edible mushrooms with a high proportion of therapeutic molecules are known as medicinal mushrooms. In this review, an attempt has been made to highlight the exploration of bioactive molecules in mushrooms to combat the various pathophysiological complications of COVID-19. This review presents an in-depth and critical analysis of the current therapies against COVID-19 versus the potential of natural anti-infective, antiviral, anti-inflammatory, and antithrombotic products derived from a wide range of easily sourced mushrooms and their bioactive molecules.

Isolation and identification of the endophytic fungus J2-3 and its disease-preventive and growth-promoting effects on cucumber

There are many problems that result from the use of a large number of chemical pesticides to control plant diseases, including pathogenic bacteria resistance, environmental contamination, and human health effects. Recently, endophytic fungi have become a significant source of bioactive fungicide products and an invaluable resource for excavating microbial pesticides. In this study, endophytic fungi with biocontrol potential were isolated and screened from Mikania micrantha leaves, stems, and roots. Fifty endophytic fungi were isolated and their antagonistic activity was studied in vitro using the confrontation culture method. The J2-3 strains from stems exhibit broad-spectrum and high activity. The strain's biological characteristics were determined by various culture conditions, and it was identified as Fusarium proliferatum by both morphological and ITS sequence analysis. Biological characteristics of the J2-3 strain were also tested. The optimum temperature for mycelium growth and sporulation was 25 °C and 30 °C, respectively. For mycelium growth, starch was the optimum carbon source, and peptone was the optimum nitrogen source for sucrose, mycelium growth, and sporulation. Mycelium growth was killed by a temperature of 60 °C, and sporulation was killed by a temperature of 55 °C. The light aided mycelium growth, and the light alternated between light and dark cycles for sporulation. Further, pot experiments were conducted to determine the antagonistic and viable effects of highly antagonistic strains on cucumber. The spore suspension's final control efficacy on cucumber wilt disease was up to 62.79% and it also promoted cucumber growth significantly. The results show that the entophytic fungus J2-3 from M. micrantha can protect cucumbers from wilt disease and promote growth.

Germacrane Sesquiterpene Dilactones from Mikania micrantha and Their Antibacterial and Cytotoxic Activity

Four new germacrane sesquiterpene dilactones, 2β-hydroxyl-11β,13-dihydrodeoxymikanolide (1), 3β-hydroxyl-11β,13-dihydrodeoxymikanolide (2), 1α,3β-dihydroxy-4,9-germacradiene-12,8:15,6-diolide (3), and (11β,13-dihydrodeoxymikanolide-13-yl)-adenine (4), together with five known ones (5-9) were isolated from the aerial parts of Mikania micrantha. Their structures were elucidated on the basis of extensive spectroscopic analysis. Compound 4 is featured with an adenine moiety in the molecule, which is the first nitrogen-containing sesquiterpenoid so far isolated from this plant species. These compounds were evaluated for their in vitro antibacterial activity against four Gram-(+) bacteria of Staphyloccocus aureus (SA), methicillin-resistant Staphylococcus aureus (MRSA), Bacillus cereus (BC) and Curtobacterium. flaccumfaciens (CF), and three Gram-(-) bacteria of Escherichia coli (EC), Salmonella. typhimurium (SA), and Pseudomonas Solanacearum (PS). Compounds 4 and 7-9 were found to show strong in vitro antibacterial activity toward all the tested bacteria with the MIC values ranging from 1.56 to 12.5 µg/mL. Notably, compounds 4 and 9 showed significant antibacterial activity against the drug-resistant bacterium of MRSA with MIC value 6.25 µg/mL, which was close to reference compound vancomycin (MIC 3.125 µg/mL). Compounds 4 and 7-9 were further revealed to show in vitro cytotoxic activity toward human tumor A549, HepG2, MCF-7, and HeLa cell lines, with IC₅₀ values ranging from 8.97 to 27.39 μM. No antibacterial and cytotoxic activity were displayed for the other compounds. The present research provided new data to support that M. micrantha is rich in structurally diverse bioactive compounds worthy of further development for pharmaceutical applications and for crop protection in agricultural fields.

Discovery of natural-derived Mpro inhibitors as therapeutic candidates for COVID-19: Structure-based pharmacophore screening combined with QSAR analysis

The main protease (M^pro ) is an essential enzyme for the life cycle of SARS-CoV-2 and a validated target for treatment of COVID-19 infection. Structure-based pharmacophore modeling combined with QSAR calculations were employed to identify new chemical scaffolds of M^pro inhibitors from natural products repository. Hundreds of pharmacophore models were manually built from their corresponding X-ray crystallographic structures. A pharmacophore model that was validated by receiver operating characteristic (ROC) curve analysis and selected using the statistically optimum QSAR equation was implemented as a 3D-search tool to mine AnalytiCon Discovery database of natural products. Captured hits that showed the highest predicted inhibitory activities were bioassayed. Three active M^pro inhibitors (pseurotin A, lactupicrin, and alpinetin) were successfully identified with IC₅₀ values in low micromolar range.

Alpinetin: a Dietary Flavonoid with Diverse Anticancer Effects

Cancer is  a global burden and mechanistically complex disease with a plethora of genetic, physiological, metabolic, and environmental alterations. The development of dietary nutraceuticals into cancer chemotherapeutics has emerged as a new paradigm in cancer treatment. Alpinetin (ALPI) is a novel flavonoid component of multiple edible and medicinal plants and possesses a wide range of biological and pharmacological activities including antibacterial, anti-hemostatic, anti-oxidative, anti-hepatotoxic, stomachic, immunosuppressive, and anti-inflammatory. Recently, ALPI has been reported as a bioactive dietary nutraceutical with promising anticancer activity in various human cancers through multiple mechanisms. The purpose of this review is to compile the data on natural sources of ALPI, and its anticancer activity including cellular targets and anticancer mechanism in various human cancers. Moreover, this review will set the stage for further design and conduct pre-clinical and clinical trials to develop ALPI into a lead structure for oncological therapy.

Alpinetin: A Review of Its Pharmacology and Pharmacokinetics

Flavonoids isolated from medicinal herbs have been utilized as valuable health-care agents due to their virous biological applications. Alpinetin is a natural flavonoid that emerges in many widely used medicinal plants, and has been frequently applied in Chinese patent drugs. Accumulated evidence has demonstrated that alpinetin possesses a broad range of pharmacological activities such as antitumor, antiinflammation, hepatoprotective, cardiovascular protective, lung protective, antibacterial, antiviral, neuroprotective, and other properties through regulating multiple signaling pathways with low systemic toxicity. However, pharmacokinetic studies have documented that alpinetin may have poor oral bioavailability correlated to its extensive glucuronidation. Currently, the reported pharmacological properties and pharmacokinetics profiles of alpinetin are rare to be scientifically reviewed. In this article, we aimed to highlight the mechanisms of action of alpinetin in various diseases to strongly support its curative potentials for prospective clinical applications. We also summarized the pharmacokinetics properties and proposed some viable strategies to convey an appreciable reference for future advances of alpinetin in drug development.

Sesquiterpenoids from Artemisia vestita

Eleven previously undescribed sesquiterpenoids, arvestolides D-J, arvestonates A-C, and arvestonol were isolated from the aerial parts of Artemisia vestita W. Their structures were elucidated by extensive analysis of HRMS, UV, IR, and NMR spectroscopic data, and the absolute configurations were determined by single crystal X-ray diffraction, empirical rules, and comparison of calculated and experimental ECD data. Arvestolides H and I showed inhibitory effects on nitric oxide production in BV-2 cells induced by lipopolysaccharide with IC₅₀ values of 43.2 and 39.9 μM, respectively.

Antiviral Activity of the Sesquiterpene Lactones from Centipeda minima against Influenza a Virus in vitro

During the course of searching for antiviral agents from Chinese medicinal herbs, we found that the supercritical fluid extract (SFE) of Centipeda minima possessed good in vitro antiviral activity against influenza virus A/Puerto Rico/8/34 H1N1 (PR8). Bioassay-guided isolation and identification led to the isolation from this extract of seven pseudoguaianolides (1-7). These, as well as nine other sesquiterpene lactones (8-16) previously isolated from this herb were all tested for their anti-PR8 activity using both the cytopathogenic effect (CPE) reduction and cell counting kit 8 (CCK8) assays. As a result, eight pseudoguaianolides (1-8) possessing an α,β-unsaturated cyclopentenone moiety showed antiviral activity against PR8 to different extents. Of the active compounds, brevilin A (4) exhibited the strongest anti-PR8 activity, with an IC50 value much lower than that of the positive control ribavirin. Mechanistic study revealed that brevilin A affected the intracellular replication of PR8 via downregulating the expression of viral M2 protein. All these results suggest the potential application of the pseudoguaianolides containing an α,β-unsaturated cyclopentenone moiety (e.g. brevilin A) in the treatment of influenza virus infection.

Assessment of sesquiterpene lactones isolated from Mikania plants species for their potential efficacy against Trypanosoma cruzi and Leishmania sp

Four sesquiterpene lactones, mikanolide, deoxymikanolide, dihydromikanolide and scandenolide, were isolated by a bioassay-guided fractionation of Mikania variifolia and Mikania micrantha dichloromethane extracts. Mikanolide and deoxymikanolide were the major compounds in both extracts (2.2% and 0.4% for Mikania variifolia and 21.0% and 6.4% for Mikania micrantha respectively, calculated on extract dry weight). Mikanolide, deoxymikanolide and dihydromikanolide were active against Trypanosoma cruzi epimastigotes (50% inhibitory concentrations of 0.7, 0.08 and 2.5 μg/mL, for each compound respectively). These sesquiterpene lactones were also active against the bloodstream trypomastigotes (50% inhibitory concentrations for each compound were 2.1, 1.5 and 0.3 μg/mL, respectively) and against amastigotes (50% inhibitory concentrations for each compound were 4.5, 6.3 and 8.5 μg/mL, respectively). By contrast, scandenolide was not active on Trypanosoma cruzi. Besides, mikanolide and deoxymikanolide were also active on Leishmania braziliensis promastigotes (50% inhibitory concentrations of 5.1 and 11.5 μg/mL, respectively). The four sesquiterpene lactones were tested for their cytotoxicity on THP 1 cells. Deoxymikanolide presented the highest selectivity index for trypomastigotes (SI = 54) and amastigotes (SI = 12.5). In an in vivo model of Trypanosoma cruzi infection, deoxymikanolide was able to decrease the parasitemia and the weight loss associated to the acute phase of the parasite infection. More importantly, while 100% of control mice died by day 22 after receiving a lethal T. cruzi infection, 70% of deoxymikanolide-treated mice survived. We also observed that this compound increased TNF-α and IL-12 production by macrophages, which could contribute to control T. cruzi infection.

Phenolics from Mikania micrantha and Their Antioxidant Activity

A phytochemical study on the aerial parts of Mikania micrantha led to the isolation of two new phenolic compounds, benzyl 5-O-β-d-glucopyranosyl-2,5-dihydroxybenzoate (1) and (7S,8R)-threo-dihydroxydehydrodiconiferyl alcohol 9-acetate (2), together with twelve known compounds, benzyl 2-O-β-d-glucopyranosyl-2,6-dihydroxybenzoate (3), 4-allyl-2,6-dimethoxyphenol glucoside (4), (+)-isolariciresinol (5), icariol A₂ (6), 9,10-dihydroxythymol (7), 8,9,10-trihydroxythymol (8), caffeic acid (9), p-coumaric acid (10), ethyl protocatechuate (11), procatechuic aldehyde (12), 4-hydroxybenzoic acid (13), and hydroquinone (14). Their structures were elucidated on the basis of extensive spectroscopic analysis. Except 8 and 9, all the other compounds were isolated from this plant species for the first time. The antioxidant activity of those isolated compounds were evaluated using three different assays. Compounds 1, 2, 3, 9, 10, 13, and 14 demonstrated significant 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) free radical cation scavenging activity ranging from SC50 0.31 to 4.86 µM, which were more potent than l-ascorbic acid (SC50 = 10.48 µM). Compounds 5, 9, 11, and 12 exhibited more potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (SC50 = 16.24-21.67 µM) than l-ascorbic acid (39.48 µM). Moreover, the ferric reducing antioxidant power (FRAP) of compounds 2, 5, 9, and 11 were discovered to be also comparable to or even more potent than l-ascorbic acid.

Phenolic constituents from the roots of Mikania micrantha and their allelopathic effects

Four new thymol derivatives, 8,10-dihydroxy-9-benzoyloxythymol (1), 9-isobutyryloxy-10-hydroxythymol (2), 7,8,9,10-tetrahydroxythymol (3), and 7,8,10-trihydroxy-9-E-feruloyloxythymol (4), were isolated from the fresh roots of Mikania micrantha , along with 8,9,10-trihydroxythymol (5), 8,10-dihydroxy-9-acetoxythymol (6), 8,10-dihydroxy-9-isobutyryloxythymol (7), 8,10-dihydroxy-9-(2-methylbutyryloxy)thymol (8), 8,9-dehydro-10-hydroxythymol (9), 8-methoxy-9-hydroxythymol (10), ethyl caffeate (11), ethyl ferulate (12), 3,5-di-O-caffeoylquinic acid (13), and mikanin (14). Their structures were determined by spectroscopic methods. The known thymol derivatives (5-10) were obtained from the genus Mikania for the first time. Allelopathic effects of these compounds on Arabidopsis thaliana seeds were evaluated by a filter paper assay. After the treatment at 0.1 mM for 4 days, the seed germination rate with compound 8 was 48% and the inhibitory rates of shoot growth with compounds 1, 2, 7-10, and 12 were over 40%. The IC50 values of compounds 1 and 8 on shoot growth were 342.5 and 625 μM, respectively.

In vitro evaluation of antiprotozoal and antiviral activities of extracts from Argentinean Mikania species

The aim of this study was to investigate the antiprotozoal and antiviral activities of four Argentinean Mikania species. The organic and aqueous extracts of Mikania micrantha, M. parodii, M. periplocifolia, and M. cordifolia were tested on Trypanosoma cruzi epimastigotes, Leishmania braziliensis promastigotes, and dengue virus type 2. The organic extract of M. micrantha was the most active against T. cruzi and L. braziliensis exhibiting a growth inhibition of 77.6 ± 4.5% and 84.9 ± 6.1%, respectively, at a concentration of 10 μg/ml. The bioguided fractionation of M. micrantha organic extract led to the identification of two active fractions. The chromatographic profile and infrared analysis of these fractions revealed the presence of sesquiterpene lactones. None of the tested extracts were active against dengue virus type 2.