Oligopeptides from Aster tataricus

Natural Products That Contain Higher Homologated Amino Acids

This review focuses on discussing natural products (NPs) that contain higher homologated amino acids (homoAAs) in the structure as well as the proposed and characterized biosynthesis of these non-proteinogenic amino acids. Homologation of amino acids includes the insertion of a methylene group into its side chain. It is not a very common modification found in NP biosynthesis as approximately 450 homoAA-containing NPs have been isolated from four bacterial phyla (Cyanobacteria, Actinomycetota, Myxococcota, and Pseudomonadota), two fungal phyla (Ascomycota and Basidiomycota), and one animal phylum (Porifera), except for a few examples. Amino acids that are found to be homologated and incorporated in the NP structures include the following ten amino acids: alanine, arginine, cysteine, isoleucine, glutamic acid, leucine, phenylalanine, proline, serine, and tyrosine, where isoleucine, leucine, phenylalanine, and tyrosine share the comparable enzymatic pathway. Other amino acids have their individual homologation pathway (arginine, proline, and glutamic acid for bacteria), likely utilize the primary metabolic pathway (alanine and glutamic acid for fungi), or have not been reported (cysteine and serine). Despite its possible high potential in the drug discovery field, the biosynthesis of homologated amino acids has a large room to explore for future combinatorial biosynthesis and metabolic engineering purpose.

Radix Asteris: Traditional Usage, Phytochemistry and Pharmacology of An Important Traditional Chinese Medicine

Radix Asteris (RA), also known as ‘Zi Wan’, is the dried root and rhizome of Aster tataricus L. f., which has been used to treat cough and asthma in many countries such as China, Japan, Korea and Vietnam. This article summarizes the available information on RA in ancient Chinese medicine books and modern research literature: its botanical properties, traditional uses, chemical composition, pharmacological activity, toxicity and quality control. Studies have shown that RA extracts contain terpenes, triterpenoid saponins, organic acids, peptides and flavonoids, and have various pharmacological activities such as anti-inflammatory, anti-tumor, anti-oxidation, and anti-depression. RA is considered to be a promising medicinal plant based on its traditional use, chemical constituents and pharmacological activities. However, there are few studies on its toxicity and the consistency of its components, which indicates the need for further in-depth studies on the toxicity and quality control of RA and its extracts.

Antitumor astins originate from the fungal endophyte Cyanodermella asteris living within the medicinal plant Aster tataricus

Medicinal plants are a prolific source of natural products with remarkable chemical and biological properties, many of which have considerable remedial benefits. Numerous medicinal plants are suffering from wildcrafting, and thus biotechnological production processes of their natural products are urgently needed. The plant Aster tataricus is widely used in traditional Chinese medicine and contains unique active ingredients named astins. These are macrocyclic peptides showing promising antitumor activities and usually containing the highly unusual moiety 3,4-dichloroproline. The biosynthetic origins of astins are unknown despite being studied for decades. Here we show that astins are produced by the recently discovered fungal endophyte Cyanodermella asteris We were able to produce astins in reasonable and reproducible amounts using axenic cultures of the endophyte. We identified the biosynthetic gene cluster responsible for astin biosynthesis in the genome of C. asteris and propose a production pathway that is based on a nonribosomal peptide synthetase. Striking differences in the production profiles of endophyte and host plant imply a symbiotic cross-species biosynthesis pathway for astin C derivatives, in which plant enzymes or plant signals are required to trigger the synthesis of plant-exclusive variants such as astin A. Our findings lay the foundation for the sustainable biotechnological production of astins independent from aster plants.

Composition of essential oil and allelopathic activity of aromatic water of Aster lanceolatus Willd: (Asteraceae)

The essential oil obtained from flowers of Aster lanceolatus was submitted the CG-MS and presented as result thirteen substances with largest concentration; among them, the caryophyllene oxide with the larger one. The aromatic water obtained during the extraction process of this essential oil was forwarded to allelopathic test, and demonstrated to be capable to inhibit the germination and growth of Lactuca sativa.

Phenolic and triterpenoid glycosides from Aster batangensis

A new phenolic glycoside, asterbatanoside A [p-hydroxyacetophenone-4-O-beta-D-xylopyranosyl-(1-->6)-beta-D- glucopyranoside], and two new triterpenoid saponins, asterbatanoside B [2 alpha,3 beta,23-trihydroxyolean-12-en-28-oic acid-28-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside] and asterbatanoside C [3-O-beta-D-glucopyranosyl-2 beta,3 beta,23-trihydroxyolean- 12-en-28-oic acid-28-O-beta-D-glucopyranoside] were isolated from the roots of Aster batangensis. Their structures were determined by spectroscopic methods and chemical evidence. The total synthesis of asterbatanoside A is also reported.

New pentapeptides from Aster tataricus

Three pentapeptides have been isolated from the roots of Aster tataricus and their structures elucidated on the basis of spectroscopic analysis as well as chemical and enzymatic methods.