Dammarenediol II

Dammarenediol-II Prevents VEGF-Mediated Microvascular Permeability in Diabetic Mice.[Pubmed:26400610]

Phytother Res. 2015 Dec;29(12):1910-6.

Diabetic retinopathy is a major diabetic complication predominantly caused by vascular endothelial growth factor (VEGF)-induced vascular permeability in the retina; however, treatments targeting glycemic control have not been successful. Here, we investigated the protective effect of dammarenediol-II, a precursor of triterpenoid saponin biosynthesis, on VEGF-induced vascular leakage using human umbilical vein endothelial cells (HUVECs) and diabetic mice. We overproduced the compound in transgenic tobacco expressing Panax ginseng dammarenediol-II synthase gene and purified using column chromatography. Analysis of the purified compound using a gas chromatography-mass spectrometry system revealed identical retention time and fragmentation pattern to those of authentic standard dammarenediol-II. Dammarenediol-II inhibited VEGF-induced intracellular reactive oxygen species generation, but it had no effect on the levels of intracellular Ca(2+) in HUVECs. We also found that dammarenediol-II inhibited VEGF-induced stress fiber formation and vascular endothelial-cadherin disruption, both of which play critical roles in modulating endothelial permeability. Notably, microvascular leakage in the retina of diabetic mice was successfully inhibited by intravitreal dammarenediol-II injection. Our results suggest that the natural drug dammarenediol-II may have the ability to prevent diabetic microvascular complications, including diabetic retinopathy.

3-epi-Dammarenediol II 1.075 hydrate: a dammarane triterpene from the bark of Aglaia eximia.[Pubmed:23284420]

Acta Crystallogr Sect E Struct Rep Online. 2012 Nov 1;68(Pt 11):o3089-90.

The title dammarane tritepene, 3alpha,20(S)-dihy-droxy-dammar-24-ene, which crystallized out in a hydrated form, C(30)H(52)O(2).1.075H(2)O, was isolated from the Aglaia eximia bark. The three cyclo-hexane rings adopt chair conformations. The cyclo-pentane has an envelope conformation with the quaternary C at position 14 as the flap atom with the maximum deviation of 0.288 (2) A. The methyl-heptene side chain is disordered over two positions with 0.505 (1):0.495 (1) site occupancies and is axially attached with an (+)-syn-clinal conformation. The hydroxyl group at position 3 of dammarane is in a different conformation to the corresponding hydroxyl in Dammarenediol II. In the crystal, the dammarane and water mol-ecules are linked by O(Dammarane)-Hcdots, three dots, centeredO(water) and O(water)-Hcdots, three dots, centeredO(Dammarane) hydrogen bonds into a three-dimensional network.

Production of dammarane-type sapogenins in rice by expressing the dammarenediol-II synthase gene from Panax ginseng C.A. Mey.[Pubmed:26398795]

Plant Sci. 2015 Oct;239:106-14.

Ginsenosides are the main active ingredients in Chinese medicinal ginseng; 2,3-oxidosqualene is a precursor metabolite to ginsenosides that is present in rice. Because rice lacks a key rate-limiting enzyme (dammarenediol-II synthase, DS), rice cannot synthesize dammarane-type ginsenosides. In this study, the ginseng (Panax ginseng CA Mey.) DS gene (GenBank: AB265170.1) was transformed into rice using agrobacterium, and 64 rice transgenic plants were produced. The Transfer-DNA (T-DNA) insertion sites in homozygous lines of the T2 generation were determined by using high-efficiency thermal asymmetric interlaced PCR (hiTAIL-PCR) and differed in all tested lines. One to two copies of the T-DNA were present in each transformant, and real-time PCR and Western blotting showed that the transformed DS gene could be transcribed and highly expressed. High performance liquid chromatography (HPLC) analysis showed that the dammarane-type sapogenin 20(S)-protopanaxadiol (PPD) content was 0.35-0.59 mg/g dw and the dammarane-type sapogenin 20(S)-protopanaxatriol (PPT) content was 0.23-0.43 mg/g dw in the transgenic rice. LC/MS analysis confirmed production of PPD and PPT. These results indicate that a new "ginseng rice" germplasm containing dammarane-type sapogenins has been successfully developed by transforming the ginseng DS gene into rice.

Dammarenediol-II production confers TMV tolerance in transgenic tobacco expressing Panax ginseng dammarenediol-II synthase.[Pubmed:22102695]

Plant Cell Physiol. 2012 Jan;53(1):173-82.

Panax ginseng is one of the famous medicinal plants. Ginsenosides, a class of tetracyclic triterpene saponins, are mainly responsible for its pharmacological activity. Most ginsenosides are composed of dammarenediol-II aglycone with various sugar moieties. Dammarenediol-II synthase is the first enzyme in the biosynthesis of ginsenosides. Here, we report that transgenic tobacco expressing the P. ginseng dammarenediol-II synthase gene (PgDDS) produced dammarenediol-II, and conferred resistance to Tobacco mosaic virus (TMV). Upon infection with TMV, lesions developed more rapidly in transgenic tobacco plants, and their size was smaller than those of wild-type plants. Transgenic tobacco plants showed a low level of both the viral titer and mRNA accumulation of TMV coat protein (CP) compared with the wild type. The production of dammarenediol-II in transgenic tobacco stimulated the expression of tobacco pathogenesis-related genes (PR1 and PR2) under both virus-untreated and -treated conditions. When the leaves of wild-type plants were inoculated with a mixture of TMV and dammarenediol-II, the leaves exhibited a reduced viral concentration and TMV-CP expression than those receiving TMV treatment alone. When the leaves of P. ginseng were infected with TMV, transcription of PgDDS was significantly increased. Transgenic P. ginseng plants harboring a beta-glucuronidase (GUS) gene driven by the PgDDS promoter were constructed. The GUS expression was activated when the transgenic ginseng plants were treated with TMV. These results indicate that the medicinally important dammarenediol-II can be ectopically produced in tobacco, and the production of dammarenediol-II in tobacco plants allows them to adopt a viral defense system.