Isolation and Characterization of Antibacterial Carotane Sesquiterpenes from Artemisia argyi Associated Endophytic Trichoderma virens QA-8

Carotane sesquiterpenes from Peperomia pellucida and their anti-infective activities

Owing to the challenges of antimicrobial resistance, investigations of new antibiotics from medicinal plants are continuously being conducted. Peperomia pellucida is a pantropical plant used in traditional medicine for the treatment of various disorders. From the ethanol extract of a whole P. pellucida plant, one previously undescribed carotane sesquiterpene (pellucarotine), one known carotane sesquiterpene (daucol), and one phenylpropanoid (dillapiol) were isolated and structurally elucidated. Their structures were determined based on 1D and 2D NMR, HR-ESI-Mass, experimental, and computational electronic circular dichroism spectroscopic data and compared with those reported in the literature. Antimicrobial assay results showed that pellucarotine had an anti-infective effect on Candida albicans with an MIC of 512 µg/mL.

Phytochemistry, Pharmacology and Mode of Action of the Anti-Bacterial Artemisia Plants

Over 70,000 people die of bacterial infections worldwide annually. Antibiotics have been liberally used to treat these diseases and, consequently, antibiotic resistance and drug ineffectiveness has been generated. In this environment, new anti-bacterial compounds are being urgently sought. Around 500 Artemisia species have been identified worldwide. Most species of this genus are aromatic and have multiple functions. Research into the Artemisia plants has expanded rapidly in recent years. Herein, we aim to update and summarize recent information about the phytochemistry, pharmacology and toxicology of the Artemisia plants. A literature search of articles published between 2003 to 2022 in PubMed, Google Scholar, Web of Science databases, and KNApSAcK metabolomics databases revealed that 20 Artemisia species and 75 compounds have been documented to possess anti-bacterial functions and multiple modes of action. We focus and discuss the progress in understanding the chemistry (structure and plant species source), anti-bacterial activities, and possible mechanisms of these phytochemicals. Mechanistic studies show that terpenoids, flavonoids, coumarins and others (miscellaneous group) were able to destroy cell walls and membranes in bacteria and interfere with DNA, proteins, enzymes and so on in bacteria. An overview of new anti-bacterial strategies using plant compounds and extracts is also provided.

Antimicrobial activity in Asterceae: The selected genera characterization and against multidrug resistance bacteria

Plants from the Asteraceae family are widely used as ethno medicines to treatment parasitic, malaria, hematemesis, pruritus, pyretic, anthelmintic, wound healing. The aim of this review is to provide an overview of Asteraceae plants antimicrobial activity. The most relevant results from the published studies are summarized and discussed. The species in genus of Artemisia, Echinacea, Centaurea, Baccharis, and Calendula showed antimicrobial activity. Most of these species are usually used as ethno medicines to treat infection, inflammation, and parasitics. The effective part or component for antimicrobial was essential oil and crude extract, and essential oil attracted more attention. It was also reported that nanoparticles coated with crude extract were effective against multidrug resistant bacteria. For multidrug resistant bacteria study, the species in Armtemisia were the most investigated, and Staphylococcus aureus and Escherichia coli were the most studied multidrug resistant strains. The antimicrobial activity was evaluated mainly based on the results of minimum inhibitory concentration (MIC). Few reports have been reported on minimum bactericide concentration (MBC) and its antibacterial mechanisms. According to the reported study results, some plants in Asteraceae have the potential to be developed as bacteriostatic agents and against multidrug resistant bacteria. However, most studies are still in vitro, further clinical and applied studies are needed.

Endophytic Fungi Isolated from Ageratina adenophora Exhibits Potential Antimicrobial Activity against Multidrug-Resistant Staphylococcus aureus

Multidrug-resistant bacteria such as Staphylococcus aureus (MRSA) cause infections that are difficult to treat globally, even with current available antibiotics. Therefore, there is an urgent need to search for novel antibiotics to tackle this problem. Endophytes are a potential source of novel bioactive compounds; however, the harnessing of novel pharmacological compounds from endophytes is infinite. Therefore, this study was designed to identify endophytic fungi (from Ageratina adenophora) with antibacterial activity against multidrug-resistant bacteria. Using fungal morphology and ITS-rDNA, endophytic fungi with antibacterial activities were isolated from A. adenophora. The results of the ITS rDNA sequence analysis showed that a total of 124 morphotype strains were identified. In addition, Species richness (S, 52), Margalef index (D^/, 7.3337), Shannon-Wiener index (H^/,3.6745), and Simpson's diversity index (D, 0.9304) showed that A. adenophora have abundant endophytic fungi resources. Furthermore, the results of the agar well diffusion showed that the Penicillium sclerotigenum, Diaporthe kochmanii, and Pestalotiopsis trachycarpicola endophytic fungi's ethyl acetate extracts showed moderate antibacterial and bactericidal activities, against methicillin-resistant Staphylococcus aureus (MRSA) SMU3194, with a MIC of 0.5-1 mg/mL and a MBC of 1-2 mg/mL. In summary, A. adenophora contains endophytic fungi resources that can be pharmacologically utilized, especially as antibacterial drugs.

Virenscarotins A-M, thirteen undescribed carotane sesquiterpenes from the fungus Trichoderma virens

A document investigation on the fungus Trichoderma virens led to the isolation of thirteen undescribed carotane sesquiterpenes and homologous. All structures were elucidated on the basis of NMR and HRESIMS data, and their absolute configurations were assigned by ECD calculation. Especially, virenscarotins A and B were first ramifications forged by aldol condensation of 4-hydroxy-3-isopentenyl-benzaldehyde with two hydroxyl groups in ring A of traditional carotane sesquiterpenes. Ring rearrangement/expansion and oxidative cleavage of normal carotane sesquiterpenes lead to the six-membered ring A of compound virenscarotin C and the ring A cleavage of compound virenscarotin D. All compounds were evaluated for cytotoxic, anti-inflammatory, and seed germination inhibitory activities.

Trichoderma species from plant and soil: An excellent resource for biosynthesis of terpenoids with versatile bioactivities

BACKGROUND

Trichoderma species are rich source of bioactive secondary metabolites. In the past decades, a series of secondary metabolites were reported from different Trichoderma fungi, among which terpenoids possessing versatile structural diversities and extensive pharmacological activities are one of the particularly important categories.

AIM OF REVIEW

The review aims to summarize the terpenoids isolated from Trichoderma species regarding their structural diversities, biological activities, and promising biosynthetic potentials.

KEY SCIENTIFIC CONCEPTS OF REVIEW

So far, a total of 253 terpenoids, including 202 sesquiterpenes, 48 diterpenes, 2 monoterpenes and 1 meroterpenoid, were isolated and identified from Trichoderma species between 1948 and 2022. Pharmacological investigations of Trichoderma terpenoids mainly focused on their antibacterial activities, antifungal activities, inhibitory activities on marine plankton species and cytotoxic activities, indicating that Trichoderma species are important microbial agents for drug discovery and environmentally friendly agrochemicals development. Intriguing chemistry and enzymology involved in the biosynthesis of Trichoderma terpenoids were also presented to facilitate further precise genome mining-guided novel structure discovery. Taken together, the abundance of novel skeletons, bioactivities and biosynthetic potentials presents new opportunities for drug and agrochemicals discovery, genome mining and enzymology exploration from Trichoderma species. The work will provide references for the profound study of terpenoids derived from Trichoderma, and facilitate further studies on Trichoderma species in the areas of chemistry, medicine, agriculture and microbiology.

Antibacterial and Antifungal Sesquiterpenoids: Chemistry, Resource, and Activity

Infectious diseases caused by bacteria and fungi are threatening human health all over the world. It is an increasingly serious problem that the efficacies of some antibacterial and antifungal agents have been weakened by the drug resistance of some bacteria and fungi, which makes a great need for new antibiotics. Sesquiterpenoids, with abundant structural skeleton types and a wide range of bioactivities, are considered as good candidates to be antibacterial and antifungal agents. In the past decades, many sesquiterpenoids were isolated from plants and fungi that exhibited good antibacterial and antifungal activities. In this review, the names, source, structures, antibacterial and antifungal degrees, and mechanisms of sesquiterpenoids with antibacterial and antifungal activity from 2012 to 2022 are summarized, and the structure-activity relationship of these sesquiterpenoids against bacteria and fungi is also discussed.

Antimicrobial Potential of Endophytic Fungi From Artemisia argyi and Bioactive Metabolites From Diaporthe sp. AC1

Endophytic fungi of medicinal plants are important sources of active natural products. In this study, 26 fungi were isolated from Artemisia argyi, which were belonging to eight genera, namely, Alternaria, Fusarium, Chaetomium, Phoma, Diaporthe, Trichoderma, Gibberella, and Colletotrichum. The antimicrobial activities of all fungal extracts were tested by using the cup-plate method against Staphylococcus aureus, Salmonella enteritidis, and Fusarium graminearum. The results demonstrated that 25 extracts (96%) exhibited inhibitory activity against at least one of the tested pathogenic microorganisms. The strain Diaporthe sp. AC1, which showed good antimicrobial activity and high yield of crude extract from fermentation, was selected for the study of secondary metabolites. The crude extract of strain AC1 was purified by silica gel column chromatography, Sephadex LH-20 gel column chromatography, and HPLC, and finally, a new compound phomopsolide G (1), together with three known phomopsolides (2–4) and four other known compounds (5–8), was obtained. The structures of the compounds were elucidated by NMR and/or HR-MS spectroscopy. Microdilution method and MTT colorimetry were used to determine the bioactivity of the compounds. The study demonstrated that the new compound 1 had moderate antifungal activity against F. graminearum, Fusarium moniliforme, and Botrytis cinerea and weak antibacterial activity against Staphylococcus aureus. Compound 1 also showed weak cytotoxicity against HepG2, A549, and MDA-MB-231, with IC50 values of 89.91, 107.65, and 53.97 μM. Additionally, other compounds also exhibited antimicrobial and/or cytotoxic activities. The findings provided the basis for searching drug and agricultural lead compounds from A. argyi-associated fungi resources.

Endophytic Fungi: An Effective Alternative Source of Plant-Derived Bioactive Compounds for Pharmacological Studies

Plant-associated fungi (endophytic fungi) are a biodiversity-rich group of microorganisms that are normally found asymptomatically within plant tissues or in the intercellular spaces. Endophytic fungi promote the growth of host plants by directly producing secondary metabolites, which enhances the plant's resistance to biotic and abiotic stresses. Additionally, they are capable of biosynthesizing medically important "phytochemicals" that were initially thought to be produced only by the host plant. In this review, we summarized some compounds from endophyte fungi with novel structures and diverse biological activities published between 2011 and 2021, with a focus on the origin of endophytic fungi, the structural and biological activity of the compounds they produce, and special attention paid to the exploration of pharmacological activities and mechanisms of action of certain compounds. This review revealed that endophytic fungi had high potential to be harnessed as an alternative source of secondary metabolites for pharmacological studies.

Fungal Endophytes: A Potential Source of Antibacterial Compounds

Antibiotic resistance is becoming a burning issue due to the frequent use of antibiotics for curing common bacterial infections, indicating that we are running out of effective antibiotics. This has been more obvious during recent corona pandemics. Similarly, enhancement of antimicrobial resistance (AMR) is strengthening the pathogenicity and virulence of infectious microbes. Endophytes have shown expression of various new many bioactive compounds with significant biological activities. Specifically, in endophytic fungi, bioactive metabolites with unique skeletons have been identified which could be helpful in the prevention of increasing antimicrobial resistance. The major classes of metabolites reported include anthraquinone, sesquiterpenoid, chromone, xanthone, phenols, quinones, quinolone, piperazine, coumarins and cyclic peptides. In the present review, we reported 451 bioactive metabolites isolated from various groups of endophytic fungi from January 2015 to April 2021 along with their antibacterial profiling, chemical structures and mode of action. In addition, we also discussed various methods including epigenetic modifications, co-culture, and OSMAC to induce silent gene clusters for the production of noble bioactive compounds in endophytic fungi.

Sesquiterpenoids and a steroid from the algicolous Trichoderma brevicompactum

Six new sesquiterpenoids including three bisabolane derivatives, trichobisabolins O₁, O₂, and P (1-3), two nerolidol derivatives, trichonerolins A and B (4 and 5), one acorane, trichoacorin A (6), along with one new steroid, isoergokonin B (7), were isolated from the culture of Trichoderma brevicompactum A-DL-9-2 obtained from the inner tissue of the red alga Chondria tenuissima. Their structures and relative configurations were assigned by interpretation of 1D/2D NMR and MS data. As acyclic sesquiterpenoids, compounds 4 and 5 were discovered from Trichoderma for the first time. Compounds 1-7 were evaluated for the inhibition of some marine-derived organisms, in which, 3 and 4/5 exhibited potent inhibition against Amphidinium carterae and Chattonella marina with IC₅₀ of 1.8 μg/mL and 1.2 μg/mL, respectively. In addition, compound 7 could inhibit the growth of Pseudoalteromonas citrea with an MIC value of 64 μg/mL.