Flavonoids and other Non-alkaloidal Constituents of Genus Erythrina: Phytochemical Review

Bioinformatics Study of Flavonoids From Genus Erythrina As Ace2 inhibitor Candidates For Covid-19 Treatment

Purpose

This study aimed to screen potential drug candidates from the flavonoids of the genus Erythrina for the Corona Virus Disease 2019 (COVID-19) treatment.

Patients and Methods

A comprehensive screening was conducted on the structures of 473 flavonoids derived from the genus Erythrina, focusing on their potential toxicity and pharmacokinetic profiles. Subsequently, flavonoids that were non-toxic and possessed favorable pharmacokinetic properties underwent further analysis to explore their interactions with the angiotensin-converting enzyme 2 (ACE2) receptor, employing molecular docking and molecular dynamics simulations.

Results

Among 473 flavonoids, 104 were predicted to be safe from being mutagenic, hepatotoxic, and inhibitors of the human ether-a-go-go-related gene (hERG). Among these 104 flavonoids, 18 compounds were predicted not to be substrates of P-glycoprotein (P-gp). Among these 18 flavonoids, gangetinin (471) and erybraedin D (310) exhibit low binding affinities and root mean square deviation (RMSD) values, indicating stable binding to the ACE2 receptor. The physicochemical attributes of compounds 310 and 471 suggest that they possess drug-like properties.

Conclusion

Gangetinin (471) and erybraedin D (310) may serve as promising candidates for COVID-19 treatment due to their potential to inhibit the ACE2-RBD interaction. This warrants further investigation into their inhibitory effects on ACE2-RBD binding through in vitro experiments.

Virtual Screening and ADMET Prediction to Uncover the Potency of Flavonoids from Genus Erythrina as Antibacterial Agent through Inhibition of Bacterial ATPase DNA Gyrase B

The emergence of antimicrobial resistance due to the widespread and inappropriate use of antibiotics has now become the global health challenge. Flavonoids have long been reported to be a potent antimicrobial agent against a wide range of pathogenic microorganisms in vitro. Therefore, new antibiotics development based on flavonoid structures could be a potential strategy to fight against antibiotic-resistant infections. This research aims to screen the potency of flavonoids of the genus Erythrina as an inhibitor of bacterial ATPase DNA gyrase B. From the 378 flavonoids being screened, 49 flavonoids show potential as an inhibitor of ATPase DNA gyrase B due to their lower binding affinity compared to the inhibitor and ATP. Further screening for their toxicity, we identified 6 flavonoids from these 49 flavonoids, which are predicted to have low toxicity. Among these flavonoids, erystagallin B (334) is predicted to have the best pharmacokinetic properties, and therefore, could be further developed as new antibacterial agent.

Success stories of natural product-derived compounds from plants as multidrug resistance modulators in microorganisms

Microorganisms evolve resistance to antibiotics as a function of evolution. Antibiotics have accelerated bacterial resistance through mutations and acquired resistance through a combination of factors. In some cases, multiple antibiotic-resistant determinants are encoded in these genes, immediately making the recipient organism a "superbug". Current antimicrobials are no longer effective against infections caused by pathogens that have developed antimicrobial resistance (AMR), and the problem has become a crisis. Microorganisms that acquire resistance to chemotherapy (multidrug resistance) are a major obstacle for successful treatments. Pharmaceutical industries should be highly interested in natural product-derived compounds, as they offer new sources of chemical entities for the development of new drugs. Phytochemical research and recent experimental advances are discussed in this review in relation to the antimicrobial efficacy of selected natural product-derived compounds as well as details of synergistic mechanisms and structures. The present review recognizesand amplifies the importance of compounds with natural origins, which can be used to create safer and more effective antimicrobial drugs by combating microorganisms that are resistant to multiple types of drugs.

An overview of techniques and strategies for isolation of flavonoids from the genus Erythrina

Plants in the genus Erythrina is a potential source of chemical constituents, one of which is flavonoids, which have diverse bioactivities. To date, literature on the flavonoids from the genus Erythrina has only highlighted the phytochemical aspects, so this review article will discuss isolation techniques and strategies for the first time. More than 420 flavonoids have been reported in the Erythrina genus, which are grouped into 17 categories. These flavonoid compounds were obtained through isolation techniques and strategies using polar, semi-polar, and non-polar solvents. Various chromatographic techniques have been developed to isolate flavonoids using column flash chromatography, quick column chromatography, centrifugally accelerated thin-layer chromatography, radial chromatography, medium-pressure column chromatography, semi-preparative high-performance liquid chromatography, and preparative high-performance liquid chromatography. Chromatographic processes for isolating flavonoids can be optimized using multivariate statistical applications such as response surface methodology with central composite design, Box-Behnken design, Doehlert design, and mixture design.

Wedelolactone: A molecule of interests

BACKGROUND

The search for bioactive molecules from medicinal plants of the family Asteraceae has been one of the targets in various phytochemical and pharmacological investigations for many years. According to these studies, wedelolactone, a coumestan of the secondary metabolite type, is a key compound found in several Eclipta and Wedelia herbal plants. To date, numerous experimental studies with intention of highlighting its role in drug development programs were carried out, but an extensive review is not sufficient.

OBJECTIVE

The current review aims to fill the gaps in extensive knowledge about phytochemistry, synthesis, pharmacology, and pharmacokinetics of coumestan wedelolactone.

MATERIALS AND METHODS

The databases Google Scholar, Scopus, PubMed, Web of Science, Science Direct, Medline, and CNKI were used to compile the list of references. In order to find references, "wedelolactone" was considered separately or in combination with "phytochemistry", "synthesis", "pharmacology", and "pharmacokinetics." Since the 1950s, >100 publications have been collected and reviewed.

RESULTS

Wedelolactone is likely to be a characteristic metabolite of two genera Eclipta and Wedelia, the family Asteraceae, while it could be synthetically derived from mono-phenol derivatives, through Sonogashira and cross-coupling reactions. Numerous biomedical investigations on wedelolactone revealed that its pharmacological values included anticancer, antiinflammatory, antidiabetic, antiobesity, antimyotoxicity, antibacterial, antioxidant, antivirus, anti-aging, cardiovascular, serine protease inhibition, especially its protective health benefits to living organs such as liver, kidney, lung, neuron, eye, bone, and tooth. The combination of wedelolactone and potential agents is a preferential approach to improve its biomedical values. Pharmacokinetic study exhibited that wedelolactone was metabolized in rat plasma due to hydrolysis, open-ring lactone, methylation, demethylation, and glucuronidation.

CONCLUSIONS

Wedelolactone is a promising agent with the great pharmacological values. Molecular mechanisms of the actions of this compound at both in vitro and in vivo levels are now available. However, reports highlighting biosynthesis and structure-activity relationship are still not adequate. Moreover, chemo-preventive records utilizing nano-technological approaches to improve its bioavailability are needed since the solubility in the living body environment is still limited.

Flavanones from Erythrina crista-galli Twigs and Their Antioxidant Properties Determined through In Silico and In Vitro Studies

Flavonoids are a secondary metabolite group with various bioactivities, such as antioxidants. They are rich in the genus Erythrina, such as Erythrina crista-galli. This research aims to isolate and characterize flavonoids from the twigs of E. crista-galli and determine their antioxidant properties through in silico and in vitro assays. The ethyl acetate extract of E. crista-galli twigs were separated by column chromatography and characterized using spectroscopic methods. Density functional theory (DFT) calculations were performed on the isolated flavonoids and the reference compounds (ascorbic acid and quercetin) to obtain global descriptive parameters and a donor–acceptor map (DAM). We successfully isolated lupinifolin (1) and citflavanone (2) for the first time from E. crista-galli, along with lonchocarpol A (3), which has been discovered previously. The DAM suggests that these flavanones are good antiradicals with effective electron donors. However, they tend to be electron acceptors in methanol. The frontier molecular orbital analysis implies that lupinifolin (1) is a better antiradical than the other flavanones. The DPPH assays show that lupinifolin (1) has the highest antioxidant (antiradical) activity, with an IC50 value of 128.64 ppm. The in silico studies showed similar trends to the in vitro assays using the DPPH method.

Ethnobotany, phytochemistry, pharmacology, and conservation of the genus Calanthe R. Br. (Orchidaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The Genus Calanthe (family Orchidaceae) consists of more than 207 species distributed in both tropical and subtropical regions. In traditional medicine, Calanthe species provide remedies against various conditions such as arthritis, rheumatism, traumatic injuries, snake-bites, abdominal discomfort, nose bleeding, common colds, ulcers, chronic coughs, and others. Some species are also used as aphrodisiacs, tonics, and as pain relievers on joints and toothaches.

AIM OF THE REVIEW

This review provides comprehensive information on the herbal uses, chemical components, pharmacological activities, and conservation of Calanthe, which might be useful in the future development of potent herbal medicines and facilitate the enactment of better conservation strategies.

MATERIALS AND METHODS

Relevant information was obtained from online databases including SCI-Finder, Google Scholar, Web of Science, Science Direct, PubMed, Springer, IOP Science, and other web sources such as PubChem, The Plant List, and World Flora Online. Books, Ph.D. and MSc dissertations were used for unpublished literature. Information from Chinese literature was obtained from the CNKI database.

RESULTS

In total, 19 species of the genus Calanthe have been reported to be used in traditional medicine in different countries of Asia. A total of 265 chemical compounds from different chemical classes including, alkaloids, terpenoids, phenolic compounds and phenolic derivatives, phenanthrenes, and others, have been identified from Calanthe species. Calanquinone A isolated from C. arisanensis has been reported to exhibit antitumor activity against six malignant cell lines. Other bioactive compounds from Calanthe with pharmacological activity include phenanthrenes, phenanthrenequinones, 6'-O-β-D-apiofuranosylindican, 4H-Pyran-4one, 2, 3-dihydro-3,5 dihydroxy-6-methyl, and calanthoside. These compounds exhibit valuable biological properties such as hair restoration, anticancer activity, anti-inflammatory and antiarthritic activity, antidiabetic and hepatoprotective potency, antiplatelet aggregation action, and antibacterial and antifungal activities. Some Calanthe species, including C. ecallosa and C. yuana, are endangered in the IUCN red list. The high risk of extinction is attributed to illegal trade and unsustainable harvesting and utilization.

CONCLUSIONS

This review summarizes the herbal uses, chemical components, biological activity, and conservation of Calanthe. The pharmacological studies on this genus are limited; thus, extensive research on the toxicology, pharmaceutical standardization, and mechanism of action of the isolated bioactive compounds are needed. Since some species of Calanthe are listed as endangered, stringent guidelines on trade, collection, and sustainable utilization of medicinal orchids should be set up to facilitate the conservation of these species.

Genus Tupistra: A Comprehensive Review of Phytochemistry and Pharmacological Activity

In the current paper, secondary metabolites separated from Tupistra plants have been reviewed. Approximately 200 phytochemicals, classified in various chemical classes of bioactive compounds, have been compiled, along with their sources and references. The most striking feature is that the most frequently isolated compounds have been spirostanol sapogenins, and spirostanol and furostanol saponins, most of which are new in nature. The application of both Tupistra plant extracts and isolated compounds in biological assays is also one of the crucial aims in pharmacological discoveries. Tupistra constituents have demonstrated valuable properties in the field of pharmacology, such as antioxidative, antimicrobial, antidiabetic, and antihepatic activities, but their cytotoxic and anti-inflammatory actions can be considered as the more remarkable. In vivo cancer-related activities of the tested Tupistra samples were mostly based on apoptosis. Further phytochemical investigations, together with extensive assessments of the biological profiles and mechanism of action studies of the components of Tupistra species are to be expected.

Biologically Active Constituents from Plants of the Genus Xanthium

Herbaceous annual plants of the genus Xanthium are widely distributed throughout the world and have been employed medicinally for millennia. This contribution aims to provide a systematic overview of the diverse structural classes of Xanthium secondary metabolites, as well as their pharmacological potential. On searching in various reference databases with a combination of three keywords "Xanthium", "Phytochemistry", and "Pharmacology", relevant publications have been obtained subsequently. From the 1950s to the present, phytochemical investigations have focused mainly on 15 Xanthium species, from which 300 compounds have been isolated and structurally resolved, primarily using NMR spectroscopic methodology. Xanthium constituents represent several secondary metabolite types, including simple phenols, sulfur and nitrogen-containing compounds, lignans, sterols, flavonoids, quinones, coumarins, and fatty acids, with terpenoids being the most common of these. Among the 174 terpenoids characterized, xanthanolide sesquiterpenoids are abundant, and most of the compounds isolated containing sulfur were found to be new in Nature. The ethnomedical uses of Xanthium crude extracts are supported by the in vitro and in vivo effects of their constituents, such as cytotoxicity, antioxidant, antibacterial, antifungal, antidiabetes, and hepatoprotective activities. Toxicological results suggest that Xanthium plant extracts are generally safe for use. In the future, additional phytochemical investigations, along with further assessments of the biological profiles and mechanism of action studies of the components of Xanthium species, are to be expected.

Biologically Active Constituents from Plants of the Genus Desmos

The combination of traditional knowledge of medicinal plants with scientific rationale has yielded positive results in recent years. Bioactive compounds isolated from herbaceous plants have long been used as drugs that benefit human health, as well as providing useful compounds for drug development lead compound optimization. This chapter aims to provide a systematic overview of the structural types of Desmos secondary metabolites, along with their biological potential. Various chromatographic and spectroscopic methods have been utilized for isolating, purifying, and elucidating the structures of compounds from Desmos species. From 1982 to the present time, more than 200 metabolites have been isolated from members of this genus. Desmos spp. constituents include terpenoids, phytosterols, polyoxygenated cyclohexanes and cyclohexenes, oxepinones, fatty acids, with flavonoids, alkaloids, and miscellaneous phenols being the predominant compounds. The essential oils of Desmos species have also been investigated. Both crude plant extracts and isolated compounds from this genus have been evaluated for their biological activities. Desmos constituents have been found to exhibit cytotoxic, antimicrobial, antioxidative, anti-inflammatory, and aromatase and NFAT transcriptive inhibition effects.