Prabir Kumar Chaudhuri

A new triterpenoid, 2α,24–diacetoxy–3β–hydroxyolean–12–en–28–oic acid (1), was characterised from the rhizomes of Nelumbo nucifera Gaertn by spectroscopic and chemical methods along with four known compounds, hyptatic acid-A (2α,3β,24–trihydroxyolean–12–en–28–oic acid) (2), maslinic acid (2α,3β–dihydroxyoleane–12–ene–28–oic acid), betulin and lupeol.

Andrographolide (1) on asymmetric reduction with nickel boride in situ led to the identification of a product as 12,13 R-dihydroandrographolide (3) in de (>96%). The structure and stereochemistry of compound 3 were established by NMR study and confirmed by X-ray crystallographic analysis. β-Substituent of γ-butyrolactone in andrographolide exerted diastereomeric selectivity in reduction. Neoandrographolide (2) under similar condition yielded 5.

A new ursane triterpenoid ester, urs-12-en-3β-O-9E,12E-octadecadienoate, was identified from the rhizomes of Nelumbo nucifera by spectral and chemical analyses along with the isolation of seven known compounds: palmitic acid, linoleic acid, 9E,12E,15E-octadecatrienoic acid, α-amyrin, β-sitosterol, betulinic acid, and β-sitosterol-3-O-glucoside.