[Synthesis and antituberculosis activity of the derivatives of glycoside steviolbioside from the plant Stevia rebaudiana and diterpenoid isosteviol containing hydrazone, hydrazide and pyridinoyl moieties]

Synthesis and Study of the Structure-Activity Relationship of Antiproliferative N-Substituted Isosteviol-Based 1,3-Aminoalcohols

Starting from isosteviol, a series of diterpenoid 1,3-aminoalcohol derivatives were prepared via stereoselective transformations. The acid-catalysed hydrolysis and rearrangement of natural stevioside produced isosteviol, which was transformed into the key intermediate methyl ester. In the next step, an 1,3-aminoalcohol library was prepared by the reductive amination of the intermediate 3-hydroxyaldehyde obtained from isosteviol in a two-step synthesis. To study the effect of the carboxylate ester function at position 4, the free carboxylic acid, benzyl ester and acryloyl ester analogues were prepared as elongated derivatives in comparison with our earlier results in this field. The antiproliferative activity of compounds against human tumour cell lines (A2780, HeLa, MCF-7 and MDA-MB-231) was investigated. In our preliminary study, the 1,3-aminoalcohol function with N-benzyl or (1H-imidazol-1-yl)-propyl substitution and benzyl ester moiety seemed essential for the reliable antiproliferative activity. The results obtained could be a good starting point to further functionalisation towards more efficient antiproliferative diterpenes.

Biological activity and structural modification of isosteviol over the past 15 years

Isosteviol is a tetracyclic diterpenoid obtained by hydrolysis of stevioside. Due to its unique molecular skeleton and extensive pharmacological activities, isosteviol has attracted more and more attention from researchers. This review summarized the structural modification, pharmacological activity and microbial transformation of isosteviol from 04/2008 to 10/2023. In addition, the research history, structural characterization, and pharmacokinetics of isosteviol were also briefly reviewed. This review aims to provide useful literature resources and inspirations for the exploration of diterpenoid drugs.

The Preparation of High Purity of Rebaudioside A and Stevioside and the Enrichment of Rebaudioside C by Subsequent Twice Crystallizations from Natural Stevia Resources

A comprehensive utilization of rebaudioside A (RA), stevioside (ST), and rebaudioside C (RC) from natural stevia resources was proposed. The influence of the solvent, solvent concentration, solid-liquid ratio, temperature, and time on the purity and recovery were investigated with response surface methodology. A 99% purity and 81% recovery of the RA were achieved by one crystallization of crude stevia under optimized conditions. Around a 95% purity and 80% recovery of the ST were easily achieved by the recrystallization of less value of mother liquor sugar (MLS) with a certain concentration of isopropyl alcohol–methanol aqueous solution. During the crystallization of the ST, the enriched RC in the liquid phase was more than three times higher than that in the crude stevia, which can provide cheaper RC raw material for the subsequent preparation of very expensive and high-purity RC.

The Introduction of Hydrazone, Hydrazide, or Azepane Moieties to the Triterpenoid Core Enhances an Activity Against M. tuberculosis

BACKGROUND

Triterpenoids exhibit a wide spectrum of antimicrobial activity.

OBJECTIVE

The objective of this study was to synthesize a series of nitrogen derivatives based on lupane, oleanane, and ursane triterpenoids with high antitubercular activity.

METHODS

Isonicotinoylhydrazones were prepared via the reaction of 3-oxotriterpenic acids or betulonic aldehyde with isoniazid (INH) in yields of 54-72%. N-Acylation of betulonic or azepanobetulinic acids led to lupane C28 hydrazides and dihydrazides. The derivatives were evaluated for their in vitro antimycobacterial activities against Mycobacterium tuberculosis (MTB) H37RV and single-drug resistance (SDR)-TB in the National Institute of Allergy and Infectious Diseases, USA. Molecular docking was performed to evaluate the possible binding modes of investigated compounds in the active site of Diterpene synthase (Rv3378c).

RESULTS

The obtained compounds are represented by C3 or C28 conjugates with hydrazine hydrate or INH. Some compounds demonstrated from high minimum inhibitory concentration (MIC ≤ 10 μg/mL) to excellent (MICs from 0.19 to 1.25 μg/mL) activity against MTB H37RV. Two lupane conjugates with INH were the leading compounds against MTB H37RV and some SDR-strains with MICs ranged from 0.19 to 1.70 μg/mL. Molecular docking of active compounds to diterpene synthase showed that these moieties accommodate the active site of the enzyme.

CONCLUSION

It was revealed that the conjugation of lupanes with INH at C3 is more effective than at C28 and the lupane skeleton is preferable among oleanane and ursane types. The replacement of native hexacarbocyclic A ring to seven-member azepane ring is favorably for inhibition of both MTB H37RV and SDR-strains. These data could possibly mean that the antitubercular activity against INH-resistant strains (INH-R) came from both triterpenoid and isoniazid parts of the hybrid molecules. Azepanobetulin showed the highest activity against both INH-R strains in comparison with other triterpenoids and INH. Thus, the introduction of hydrazone, hydrazide (dihydrazide), or azepane moieties into the triterpenoid core is a promising way for the development of new anti-tubercular agents.

A Review on Recent Trends in Green Synthesis of Gold Nanoparticles for Tuberculosis

Tuberculosis (TB) is a contagious disease that has affected mankind. The anti-TB treatment has been used from ancient times to control symptoms of this disease but these medications produced some serious side effects. Herbal products have been successfully used for the treatment of TB. Gold is the most biocompatible metal among all available for biomedical purposes so Gold nanoparticles (GNPs) have sought attention as an attractive biosynthesized drug to be studied in recent years for bioscience research. GNPs are used as better catalysts and due to unique small size, physical resemblance to physiological molecules, biocompatibility and non-cytotoxicity extensively used for various applications including drug and gene delivery. Greenly synthesized GNPs have much more potential in different fields because phytoconstituents used in GNP synthesis itself act as reducing and capping agents and produced more stabilized GNPs. This review is devoted to a discussion on GNPs synthesis with herbs for TB. The main focus is on the role of the natural plant bio-molecules involved in the bioreduction of metal salts during the GNPs synthesis with phytoconstituents used as antitubercular agents.

Bioactivity Profile of the Diterpene Isosteviol and its Derivatives

Steviosides, rebaudiosides and their analogues constitute a major class of naturally occurring biologically active diterpene compounds. The wide spectrum of pharmacological activity of this group of compounds has developed an interest among medicinal chemists to synthesize, purify, and analyze more selective and potent isosteviol derivatives. It has potential biological applications and improves the field of medicinal chemistry by designing novel drugs with the ability to cope against resistance developing diseases. The outstanding advancement in the design and synthesis of isosteviol and its derivative has proved its effectiveness and importance in the field of medicinal chemical research. The present review is an effort to integrate recently developed novel drugs syntheses from isosteviol and potentially active pharmacological importance of the isosteviol derivatives covering the recent advances.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

Isoniazid derivatives and their anti-tubercular activity

Tuberculosis (TB), which has been a scourge of humanity for thousands of years, is a worldwide pandemic disease caused mainly by Mycobacterium tuberculosis (MTB). The emergence of drug-resistant TB (DR-TB), multidrug-resistant TB (MDR-TB), extensively drug-resistant TB (XDR-TB) and totally drug-resistant TB (TDR-TB) increase the challenges to eliminate TB worldwide. Isoniazid (INH), a critical frontline anti-TB drug, is one of the most effective drugs used to treatment of TB infection for more than 60 years. Unfortunately, bacterial strains resistant to INH are becoming common which mainly due to the long-term widely use even abuse. Therefore, there is an urgent need to develop novel anti-TB agents. Numerous efforts have been undertaken to develop new anti-TB agents, but no new drug has been introduced for more than 5 decades. It has been suggested that the incorporation of lipophilic moieties into the framework of INH can increase permeation of the drug into bacterial cells, thereby enhancing the anti-TB. Therefore, INH derivatives with greater lipophilicity are emerging as one of the most potential anti-TB agents. Indeed, the INH derivative LL-3858 is in initial stages of phase II clinical trial for the treatment of TB and may be approved to treat TB in the near future. This review aims to summarize the recent advances made towards the discovery anti-TB agents holding INH as a nucleus including INH hybrids and INH hydrazide-hydrazone derivatives.

Unfolded and macrocyclic ammonium derivatives of diterpenoids steviol and isosteviol having choline moieties. Synthesis and inhibitory activities toward acetylcholine- and butyrylcholinesterases

Derivatives of isosteviol and steviol possessing choline moieties have been synthesized and assayed for AchE and BchE inhibitory activity.