Structural determination of three new germacrane-type sesquiterpene alcohols from curdione by microbial transformation

Metabolism and distribution of two major constituents of 'Xing-Nao-Jing Injection'-germacrone and curdione in rats

Germacrone and curdione are germacrane-type sesquiterpenoids that are widely distributed and have extensive pharmacological activities; they are the main constituents of 'Xing-Nao-Jing Injection' (XNJ). Studies on the metabolic features of germacrane-type sesquiterpenoids are limited. In this study, the metabolites of germacrone and curdione were characterized by UHPLC-Q-Exactive Oribitrap mass spectrometry after they were orally administered to rats. In total, 60 and 76 metabolites were found and preliminarily identified in rats administered germacrone and curdione, respectively, among which at least 123 potential new compounds were included. New metabolic reactions of germacrane-type sesquiterpenoids were identified, which included oxidation (+4 O and +5 O), ethylation, methyl-sulfinylation, vitamin C conjugation, and cysteine conjugation reactions. Among the 136 metabolites (including 113 oxidation metabolites, two glucuronidation, two methylation, nine methyl-sulfinylation, three ethylation, six cysteine conjugation, and one Vitamin C conjugation metabolites), 32 metabolites were detected in nine organs, and the stomach, intestine, liver, kidneys, and small intestine were the main organs for the distribution of these metabolites. All 136 metabolites were detected in urine and 64 of them were found in feces. The results of this study not only contribute to research on in vivo processes related to germacrane-type sesquiterpenoids but also provide a strong foundation for a better understanding of in vivo processes and the effective forms of germacrone, curdione, and XNJ.

Curcumae Rhizoma: A botanical drug against infectious diseases

Curcumae Rhizoma is the dry rhizome coming from Curcuma longa L. which grow widely in tropical south and southwest Asia. It has been used to treat conditions such as dermatoses, infections, stress, and depression. Moreover, in China, Curcumae Rhizoma and its active constituents have been made into different pharmaceutical preparations. Growing evidence suggests that these preparations can exert antioxidant, anti-inflammatory, and anti-cancer effects, which may play crucial roles in the treatment of various diseases, including cancer, infectious-, autoimmune-, neurological-, and cardiovascular diseases, as well as diabetes. The anti-infective effect of Curcumae Rhizoma has become a popular field of research around the world, including for the treatment of COVID-19, influenza virus, hepatitis B virus, human immunodeficiency virus, and human papilloma virus, among others. In this paper, the basic characteristics of Curcumae Rhizoma and its active constituents are briefly introduced, and we also give an overview on their applications and mechanisms in infectious diseases.

Pharmacokinetics and bioavailability of curdione in mice by UPLC-MS/MS

A UPLC-MS/MS method was developed to determinate curdione in the mouse blood, and the pharmacokinetics of curdione in mice after intravenous (5 mg kg−1) and oral (20 mg kg−1) administration were studied. The HSS T3 column was used for separation, and column temperature was set at 40 °C. Multiple reaction monitoring (MRM) mode were used for determination of curdione. Blood samples were taken from the caudal vein of Institute of Cancer Research (ICR) mice after administration of curdione. It showed a good linear relationship in the range of 1–500 ng mL−1 (r > 0.998); the intra-day precision was <13%, the inter-day precision was <15%, and the accuracy was 90%–105%, the recovery was >77%, and the matrix effect was 97%–107%. The half-life was relatively short, and the bioavailability was 6.5%. The developed method was suitable for the pharmacokinetics of curdione in mice.

Biotransformation of sesquiterpenoids: a recent insight

Sesquiterpenoids have been identified as natural compounds showing remarkable biological activities found in medicinal plants. There is great interest in developing methods to obtain sesquiterpenoids derivatives and biotransformation is one of the alternative methods for structural modification of complex sesquiterpenes structures. Biotransformation is a great drug design tool offering high selectivity and green method. The present review describes a comprehensive summary of biotransformation products of sesquiterpenoids and its structural modification utilizing a variety of biocatalysts including microorganisms, plant tissue culture and enzymes. This review covers recent literatures from 2007 until 2020 and highlights the experimental conditions for each biotransformation process.

Biotransformation of Curcumenol by Mucor polymorphosporus

Biocatalysis of curcumenol (1) was performed by Mucor polymorphosporus AS 3.3443. Six metabolites including five new compounds were obtained, and their structures were elucidated as 10β-hydroxy-9,10-dihydrocurcumenol (2), 2β-hydroxycurcumenol (3), 15-hydroxycurcumenol (4), 12-hydroxycurcumenol (5), 1-hydroxy-4αH-guai-1,6,9-triene-2,8-dione (6), and 5-hydroxycarbonyl-1-oxo-3,7-dimethylindane (7) by spectroscopic analysis. M. polymorphosporus catalyzed unusual degradation and rearrangement reactions to generate a ring-contracted metabolite (7) of curcumenol (1). Curcumenol (1) and metabolites 4-7 exhibited inhibitory activities against lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages, with 7 exhibiting more potent activity than curcumenol.

Natural sesquiterpenoids

This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. 423 references are cited.

Comparative analysis on microbial and rat metabolism of ginsenoside Rb1 by high-performance liquid chromatography coupled with tandem mass spectrometry

Ginsenoside Rb1 is an active protopanaxadiol saponin from Panax species. In order to compare the similarities and differences of microbial and mammalian metabolisms of ginsenoside Rb1, the microbial transformation by Acremonium strictum and metabolism in rats were comparatively studied. Microbial transformation of ginsenoside Rb1 by Acremonium strictum AS 3.2058 resulted in the formation of eight metabolites. Ten metabolites (M1-M10) were detected from the in vivo study in rats and eight of them were identified as the same compounds as those obtained from microbial metabolism by liquid chromatography-tandem mass spectrometry analysis and comparison with reference standards obtained from microbial metabolism. Their structures were identified as ginsenoside Rd, gypenoside XVII, 20(S)-ginsenoside Rg3, 20(R)-ginsenoside Rg3, ginsenoside F2, compound K, 12beta-hydroxydammar-3-one-20(S)-O-beta-d-glucopyranoside, and 25-hydroxyl-(E)-20(22)-ene-ginsenoside Rg3, respectively. The structures of the additional two metabolites were tentatively characterized as 20(22),24-diene-ginsenoside Rg3 and 25-hydroxyginsenoside Rd by HPLC-MS/MS analysis. M7-M10 are the first four reported metabolites in vivo. The time course of rat metabolism of ginsenoside Rb1 was also investigated.

Microbial transformation of alantolactone by Mucor polymorphosporus

Two new transformed sesquiterpenes of alantolactone by Mucor polymorphosporus were obtained. They were characterized as 3beta-hydroxy-11betaH-eudesm-5-en-8beta,12-olide (2) and 3beta,11alpha-dihydroxy-eudesm-5-en-8beta,12-olide (3), on the basis of spectral methods including 2D NMR. And product 3 was an unusual hydroxylation derivative of alantolactone at C-11.

Structural determination of two new sesquiterpenes biotransformed from germacrone by Mucor alternata

Eight transformed sesquiterpenes of germacrone by Mucor alternata were obtained. Their structures were characterized on the basis of spectral methods including 2D NMR. Among them, (1S, 4S, 5S, 10R)-isozedoarondiol (2) and (1R, 4S, 5S, 10R)-diepoxy-12-hydroxygermacrone (3) are new compounds.