Rhodoterpenoids A‒C, Three New Rearranged Triterpenoids from Rhododendron latoucheae by HPLC‒MS‒SPE‒NMR

Abstract

Rhodoterpenoids A‒C (1‒3), three new rearranged triterpenoids, together with one new biogenetically related compound, rhodoterpenoid D (4), were isolated and efficiently elucidated from Rhododendron latoucheae by high-performance liquid chromatography−mass spectrometry−solid-phase extraction−nuclear magnetic resonance (HPLC‒MS‒SPE‒NMR). Compounds 1 and 2 possess an unprecedented skeleton with a 5/7/6/6/6-fused pentacyclic ring system, while compound 3 contains a unique 6/7/6/6/6-fused pentacyclic carbon backbone. Their structures were determined by extensive spectroscopic methods and electronic circular dichroism (ECD) analyses. Plausible biogenetic pathways for 1‒4 were proposed. Compounds 1 and 4 showed potential activity against herpes simplex virus 1 (HSV-1) with IC50 values of 8.62 and 6.87 μM, respectively.

Anti-viral triterpenes: a review

“…A series of reactions such as dehydrogenation, oxidative ring-opening, and cyclization are reported to construct an unprecedented 5/7/6/6/6 fused pentacyclic ring system ( 146–147 ) (Fig. 9 ) which is unique in this class and a plausible biogenetic pathway is reported in detail earlier (Liu et al 2017 ). Apart from these, sulfur-containing triterpenoid saponin ( 169 ) reported from Ilex asprella suggests interesting phylogenetic modification by the involvement of imperative enzymes, which needs exploration to understand the possible diversification of triterpenoids.…”

“…Among the rhodoterpenoids A ( 146 ), B ( 147 ), C, and D ( 148 ), isolated from Rhododendron latoucheae by Liu and co-worker, 146 and 148 were reported as excellent anti-HSV-1 triterpenes with IC 50 values of 8.62 and 6.87 μM (Table 1 ) and SI of 2.2 and 7.0, respectively in comparison with the acyclovir (IC 50 0.41 µM; SI > 100) (Liu et al 2017 ). The 146 and 147 were reported to possess an unprecedented 5/7/6/6/6-fused pentacyclic ring system.…”

“…It was further detailed by the authors that the methylene at C-16 in 146 is extremely essential for the anti-HSV-1 activity. Its replacement with the keto group resulted in the loss of activity ( 147 ) (Liu et al 2017 ). …”

Recent Advances in Grayanane Diterpenes: Isolation, Structural Diversity, and Bioactivities from Ericaceae Family (2018–2024)

“…In terms of technological advancements, the development of more sophisticated analytical techniques will play a crucial role in future research [44][45][46]. Technological advances such as mass spectrometry, NMR spectroscopy, and X-ray crystallography could lead to more detailed and accurate structural elucidation of these compounds.…”

Minor Nortriterpenoids from the Twigs and Leaves of Rhododendron latoucheae

“…Rhododendron latoucheae Franch (Ericaceae) is used in traditional folk medicine for relieving cough, reducing sputum, and removing blood stasis . It has been reported that triterpenoids are also active against these conditions. , Previously, we reported the rapid isolation of four rare triterpenoids from R. latoucheae through this hyphenated NMR method . However, the biologically active components of this plant have been poorly studied.…”