Isolation of phytochemicals from Dolichandrone atrovirens followed by semisynthetic modification of ixoside via azomethine ylide cycloaddition; computational approach towards chemo-selection

Abstract

Aims of the study were the phytochemical investigation and chemical transformation of isolated compounds of medicinal plant listed in ‘Ayurveda’ like Dolichandrone atrovirens, endemic to Indian subcontinents. From chloroform extract of D. atrovirens four compounds; Ursolic acid (1), Maslinic acid (2), Lupeol (3), β-sitosterol (4) and from methanol extract five compounds; β-sitosterol-3-O-β-D-glucopyranoside (5), 10-O-trans-p-Methoxycinnamoylcatalpol (6), Kaempferol-3-O-β-D-glucopyranoside (7), 6-O-[6"(S)-hydroxy-2",6"dimethyl-2"(E)-7"-octadienoyl] catalpol (8) and Ixoside (9) were isolated. Ixoside was used for the semi-synthetic modification via azomethine ylide cycloaddition leading to novel spiro-oxindolo-pyrrolizidine adduct. The structures of novel adducts were elucidated by analysis of IR, MS and 1 D/2D NMR data. Furthermore, to confirm the chemo selection of only one double bond, we performed density functional theory (DFT) calculation, which confirms the chemo selectivity. In addition, in-silico ADME studies and atom-additive approach based on SASA was also examined for the molecules which suggest that they may be potential future candidates for drug discovery.

Graphical Abstract

Keywords:

• Dolichandrone atrovirens
• Iridoid glycoside
• ixoside
• Spiro-oxindole
• Dipolar cycloaddition
• semi-synthesis

Acknowledgements

M.S, BUH, SP thanks to DOP, Ministry of Chemical and Fertilizers, Govt. of India, for providing fellowship. We also thank R. Gajbhiye, NIPER-Kolkata for his assistance in acquiring HRMS spectra. We thank Dr Bilal Ahmad Mir, Assistant Professor, Department of Botany, University of Kashmir (Kargil Campus) for his help in plant authentication report.

Disclosure statement

The authors declare that they have no known competing financial interests.