Novel mechanisms for the synthesis of important secondary metabolites in Ginkgo biloba seed revealed by multi-omics data

Advances in the biosynthesis of naturally occurring benzylisoquinoline alkaloids

Benzylisoquinoline alkaloids (BIAs) are a prominent class of plant metabolites with significant pharmaceutical and industrial significance that have garnered substantial attention from researchers worldwide. BIAs exhibit several pharmacological activities and have been used extensively. Examples include analgesics such as morphine, tetrahydropalmatine, antimicrobials such as berberine, and antineoplastic agents including cepharanthine. Most BIAs are derived and isolated from medicinal plants; however, these plants are predominantly wild resources that are scarce. Their high environmental impact, slow growth rate, scarcity of resources, and expensive direct extraction costs pose a significant challenge. Certain BIAs are present in trace amounts in medicinal plants; moreover, they have complex chemical structures and unstable properties. Designing chemical synthesis routes and processes is challenging. Thus, a major obstacle in developing and utilizing these natural products in the pharmaceutical industry lies in their low abundance in nature. Consequently, the limited supply of these molecules fails to meet high research and market demands. In recent years, biosynthesis approaches have emerged as a novel and efficient method to obtain BIAs. In this review, recent progress in the field of enzymes related to the elucidation of biosynthetic pathways and the biosynthesis of BIAs are discussed, and future perspectives for designing viable strategies for their targeted manipulation are presented.

The Pharmacology and Toxicology of Ginkgolic Acids: Secondary Metabolites from Ginkgo biloba

Ginkgolic acids (GAs) are distinctive secondary metabolites of Ginkgo biloba (G. biloba) primarily found in its leaves and seeds, with the highest concentration located in the exotesta. GAs are classified as long-chain phenolic compounds, and exhibit structural similarities to lignoceric acid. Their structural diversity arises from variations in the length of side chains and their number of double bonds, resulting in six distinct forms within G. biloba extracts (GBE). Of these, GA (C15:1) is the most prevalent. As inhibitors of SUMOylation, GAs demonstrate significant antitumor activity, and can exert antineoplastic effects through multiple pathways, which positions them as potentially promising therapeutic agents for cancer treatment. Additionally, GAs exhibit notable anti-inflammatory, antibacterial, and antiviral properties, highlighting their multifaceted medicinal potential. Although the pharmacological properties of GAs have been extensively investigated, the associated risks of liver and kidney damage must not be overlooked. GAs can induce significant hepatic damage by promoting cellular apoptosis, oxidative stress, and the disruption of various metabolic processes. Furthermore, a limited number of studies have indicated that GAs may exhibit nephrotoxicity, as well as adverse effects on the skin and nervous system. Due to their recognized toxicity, the concentration of GAs is typically regulated to within 5[Formula: see text]ppm in the standardized G. biloba leaf extract EGb 761. Currently, there is no definitive evidence supporting the mutagenic toxicity of GAs. This review primarily synthesizes recent advancements in understanding the pharmacological and toxicological effects of GAs, along with their underlying mechanisms. It is anticipated that this review will stimulate scholarly discourse and elicit valuable insights.

Ginkgo biloba L. exocarp petroleum ether extract inhibits methicillin-resistant Staphylococcus aureus by modulating ion transport, virulence, and biofilm formation in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

As reported in the Ancient Chinese Medicinal Books, Ginkgo biloba L. fruit has been used as a traditional Chinese medicine for the treatment asthma and cough or as a disinfectant. Our previous study demonstrated that G. biloba exocarp extract (GBEE), an extract of a traditional Chinese herb, inhibits the formation of methicillin-resistant Staphylococcus aureus (MRSA) biofilms. However, GBEE is a crude extract that contains many components, and the underlying mechanisms of purified GBEE fractions extracted with solvents of different polarities are unknown.

AIM OF THE STUDY

This study aimed to investigate the different components in GBEE fractions extracted with solvents of different polarities and their antibacterial effects and mechanisms against MRSA and Staphylococcus haemolyticus biofilms both in vitro and in vivo.

METHODS

The components in different fractions were detected by high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). Microbroth dilution assays and time growth curves were used to determine the antibacterial effects of the fractions on 15 clinical bacterial isolates. Crystal violet staining, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to identify the fractions that affected bacterial biofilm formation. The potential MRSA targets of the GBEE fraction obtained with petroleum ether (PE), denoted GBEE-PE, were screened by transcriptome sequencing, and the gene expression profile was verified by quantitative polymerase chain reaction (qPCR).

RESULTS

HPLC-HRMS analysis revealed that the four GBEE fractions (extracted with petroleum ether, ethyl acetate, n-butanol, and water) contained different ginkgo components, and the antibacterial effects decreased as the polarity of the extraction solvent increased. The antibacterial activity of GBEE-PE was greater than that of the GBEE fraction extracted with ethyl acetate (EA). GBEE-PE improved H. illucens survival and reduced MRSA colonization in model mouse organs. Crystal violet staining and SEM and TEM analyses revealed that GBEE-PE inhibited MRSA and S. haemolyticus biofilm formation. Transcriptional analysis revealed that GBEE-PE inhibits MRSA biofilms by altering ion transport, cell wall metabolism and virulence-related gene expression. In addition, the LO2 cell viability and H. illucens toxicity assay data showed that GBEE-PE at 20 mg/kg was nontoxic.

CONCLUSION

The GBEE fractions contained different components, and their antibacterial effects decreased with increases in the polarity of the extraction solvent. GBEE-PE limited MRSA growth and biofilm formation by affecting ion transport, cell wall synthesis, and virulence-related pathways. This research provides a more detailed overview of the mechanism by which GBEE-PE inhibits MRSA both in vitro and in vivo and suggests that GBEE-PE is a new prospective antimicrobial with the potential to be used in MRSA therapeutics in the future.