enmein and oridonin

Topics: Antineoplastic Agents; Apoptosis; Biological Products; Cell Line, Tumor; Cell Proliferation; Cyclin B1; Diterpenes; Diterpenes, Kaurane; Esters; Humans; Reactive Oxygen Species; Spironolactone; Structure-Activity Relationship

The terrestrial plants, Isodon japonicus (Burm. f.) H. Hara and Isodon trichocarpus (Maxim.) Kudô (Labiatae), are native to Japan. Different parts of these plants have been used as a traditional bitter stomachic, under the name Isodon herb (Enmei-so). Ent-kaurane diterpenoids are the major constituents of Isodon herb that contribute to the herb's medicinal properties. However, large variability with respect to the composition of these diterpenoids limits the suitability of Isodon herb as a pharmaceutical ingredient. Thus, an investigation of the factors that affect its chemical composition is required. In this study, the DNA-barcoding method, using internal transcribed spacer sequences of nuclear ribosomal DNA, was applied to cultivated and commercial samples of Isodon herb. Further, each such sample was separated into leaves, stems, and flowers and analyzed for diterpenoid content by HPLC. Moreover, the diterpenoid content in coarsely cut and powdered samples was evaluated. Results confirmed that the source species of these samples was I. japonicus or I. trichocarpus. The three major diterpenoids in Isodon herb were enmein, oridonin, and ponicidin. The diterpenoid content was affected by milling process. Moreover, the diterpenoid content was greatly affected by the ratio between leaves and stems in each sample. Thus, to accurately quantify the diterpenoids in Isodon herb, the use specific conditions such as drying using mild temperature conditions and avoiding milling of the samples might be necessary. This may help in regulating variations in the herb's composition, in turn, providing better quality and a safe herbal product for pharmaceutical use.

Topics: Chromatography, High Pressure Liquid; Diterpenes; Diterpenes, Kaurane; Drug Evaluation, Preclinical; Flowers; Humans; Isodon; Plant Extracts; Plant Leaves; Plant Stems; Solvents; Tandem Mass Spectrometry; Temperature

A series of enmein-type derivatives were synthesized and assayed for their antimycobacterial effects. The structures of the synthesized compounds were established by (1)H NMR, (13)C NMR and mass spectral analysis. All the compounds were screened for their antimycobacterial properties against Mycobacterium phlei, Mycobacterium smegmatis and Mycobacterium marinum. Compounds 2, 6g and 6i were found to exhibit potent antimycobacterial activity against M. phlei at a concentration of 0.5 μg/mL, which was comparable to that of positive drug streptomycin. Furthermore, five compounds were tested against Mycobacterium tuberculosis H₃₇Rv based on the promising preliminary screening results. Among them, compound 10 showed potent activity with IC₅₀ value of 17.1 μg/mL against M. tuberculosis H₃₇Rv strain. Thus, compound 10 could emerge as a promising lead for further research work.

Topics: Antitubercular Agents; Diterpenes; Diterpenes, Kaurane; Microbial Sensitivity Tests; Molecular Structure; Mycobacterium

A series of enmein-type diterpenoid analogs (11-20) derived from natural kaurene-type diterpenoid oridonin were synthesized and biologically evaluated. All target compounds showed improved anti-proliferative activities against four human cancer cell lines compared with natural oridonin and parent compound 10. Some compounds were more potent than positive control Taxol. Furthermore, mechanistic investigation showed that the representative compound 17 affected cell cycle and induced apoptosis at low micro-molar level in human hepatoma Bel-7402 cells, via an oxidative stress triggered mitochondria-related caspase-dependent pathway.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Line, Tumor; Diterpenes; Diterpenes, Kaurane; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Molecular Conformation; Structure-Activity Relationship

Starting from commercial available natural product oridonin (1), a practical synthesis of ent-6,7-seco-oridonin derivatives (2, 3, 5, and 9) was accomplished and their biological activities were evaluated. The conversion of spirolactone-type diterpenoid to enmein-type was first completed. The results demonstrated that all synthesized ent-6,7-seco-oridonin derivatives could markedly inhibit the proliferation of cancer cells. Compared with Taxol, the most cytotoxic compound 5 has similar potency in A549 cell and slightly less cytotoxicity in Bel-7402 cell. Compound 5 was also more potent than parent compound oridonin in mice with MGC-803 gastric cancer in vivo. Then a series of novel 14-O-derivatives of 5 were further designed and synthesized, which showed better activity than 5 and similar activity as Taxol in vitro. The structure-activity relationships of oridonin derivatives were also discussed in the present investigations.

Topics: Animals; Antineoplastic Agents; Chemistry Techniques, Synthetic; Diterpenes; Diterpenes, Kaurane; Female; Humans; K562 Cells; Mice; Spironolactone; Structure-Activity Relationship; Xenograft Model Antitumor Assays

Isodonis Herba is used as a Japanese dietary supplement and folk medicine. The extract of the herb (Isodonis extract) is also used as a food additive whose major compound is enmein (1). Here we compared internal transcribed spacer sequences of nuclear ribosomal DNA from Isodonis Herba available on the Japanese and Chinese crude drug markets, and found that the former derived from Isodon japonicus and Isodon trichocarpus, while the latter derived from distinct species such as Isodon eriocalyx. The liquid chromatography/mass spectrometry profiles of Isodonis Herba were classified into four chemotypes (A to D) according to the ratio of the major constituents. Types B and C contained 1 and oridonin (2) as major components, respectively. An intermediate (or mixed) form of types B and C in various ratios was designed type A. Type D contained eriocalyxin B (3) as its major component. Japanese herba were types A-C, while Chinese herba were types C and D. The commercial Isodonis extract products tested were classified as type D, suggesting that they originated from Chinese Herba. Understanding the relationship between extract constituents and DNA profiles is important for the official specification of dietary supplements and food additives of plant origin.

Topics: Chromatography, Liquid; Diterpenes; Diterpenes, Kaurane; DNA, Ribosomal Spacer; Food Additives; Isodon; Mass Spectrometry; Molecular Structure; Phenotype; Plant Extracts; Plants, Medicinal

Rabdosia trichocarpa is used in a popular home-made remedy for gastric and stomachic complaints in Japan. A diterpene, trichorabdal A from R. trichocarpa, showed a very strong in vitro antibacterial activity against Helicobacter pylori. With regard to the antibacterial activity of the extract and constituents of R. trichocarpa against H. pylori, the effect of traditional use of this plant for the treatment of gastritis is probably due to the suppression of H. pylori since the extract of R. trichocarpa particularly inhibits the growth of H. pylori. It could be a promising native herb treatment for patients with gastric complaints including gastric ulcer caused by H. pylori.

Topics: Anti-Bacterial Agents; Diterpenes; Diterpenes, Kaurane; Drugs, Chinese Herbal; Helicobacter pylori; Microbial Sensitivity Tests; Penicillin G; Plant Extracts