The minor ecdysteroids from Ajuga turkestanica

INTRODUCTION

Ajuga turkestanica is a plant used in traditional medicine for its high ecdysteroid content, including the presence of the particularly active turkesterone, which possess efficient anabolic activity.

OBJECTIVES

To isolate and identify minor ecdysteroids present in a semi-purified plant fraction containing ca. 70% turkesterone.

MATERIAL AND METHODS

Multi-step preparative HPLC (combining RP- and NP-HPLC systems) was used to purify the different components present in the turkesterone fraction. Isolated compounds were identified by high-resolution mass spectrometry and 2D-NMR.

RESULTS

Fourteen ecdysteroids (including turkesterone and 20-hydroxyecdysone) were isolated. Seven of these, all bearing an 11α-hydroxy group, were previously unreported.

CONCLUSION

Ajuga turkestanica ecdysteroids are characterised by the abundance of 11α-hydroxylated compounds and by the simultaneous presence of 24C, 27C, 28C and 29C ecdysteroids. It is expected that even more ecdysteroids are to be found in this plant since the starting material for this study lacked the less polar ecdysteroids. The simultaneous presence of 20-hydroxyecdysone and turkesterone (its 11α-hydroxy analogue) as the two major ecdysteroids suggests that every ecdysteroid is probably present in both 11α-hydroxy and 11-deoxy forms.

Identification and isolation of non-polar compounds from the chloroform extract of Scutellaria ramosissima

In the present study, chloroform extract obtained from aerial parts of Scutellaria ramosissima was phytochemically investigated. A non-polar fraction was obtained from the chloroform extract and the chemical composition of this fraction was identified by GC-MS. The major components of the non-polar fraction of S. ramosissima were determined as heneicosane (12.18%), palmitic acid (11.79%), acetovanillone (6.28%), 5,6-dihydroxy-7,8-dimethoxyflavone (31.87%), (9Z)-octadecenoic (oleic) acid (8.21%), stigmasterol (2.68%), β-sitosterol (2.65%) and 5,2'-dihydroxy-6,7,8,6'-tetramethoxyflavone (2.13%). In addition, 5,6-dihydroxy-7,8-dimethoxyflavone was isolated from the same fraction by PTLC.

Antimicrobial Action Mechanisms of Natural Compounds Isolated from Endophytic Microorganisms

Infectious diseases are a significant challenge to global healthcare, especially in the face of increasing antibiotic resistance. This urgent issue requires the continuous exploration and development of new antimicrobial drugs. In this regard, the secondary metabolites derived from endophytic microorganisms stand out as promising sources for finding antimicrobials. Endophytic microorganisms, residing within the internal tissues of plants, have demonstrated the capacity to produce diverse bioactive compounds with substantial pharmacological potential. Therefore, numerous new antimicrobial compounds have been isolated from endophytes, particularly from endophytic fungi and actinomycetes. However, only a limited number of these compounds have been subjected to comprehensive studies regarding their mechanisms of action against bacterial cells. Furthermore, the investigation of their effects on antibiotic-resistant bacteria and the identification of biosynthetic gene clusters responsible for synthesizing these secondary metabolites have been conducted for only a subset of these promising compounds. Through a comprehensive analysis of current research findings, this review describes the mechanisms of action of antimicrobial drugs and secondary metabolites isolated from endophytes, antibacterial activities of the natural compounds derived from endophytes against antibiotic-resistant bacteria, and biosynthetic gene clusters of endophytic fungi responsible for the synthesis of bioactive secondary metabolites.