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Green Chem., 2009, 11, 1743 - 1745, DOI: 10.1039/b915093e

Efficient and highly regioselective acylation of andrographolide catalyzed by lipase in acetone

Zhi Gang Chen, Ren Xiang Tan and Lin Cao

Andrographolide, a diterpene lactone from Andrographis paniculata, has multiple pharmacological activities. And its acetylated derivatives showed improved antitumour activities. Herein, a total of ten lipases and four proteases were tested for regioselective acylation(s) of andrographolide by vinyl acetate in acetone. Although the enzyme activity was markedly source-dependent, the highest conversion with better initial reaction rate was achieved with immobilized Candida antarctica lipase B (Novozym 435), which displayed higher operational stability. The regioselective acylation at the 14-hydroxyl of the lactone was established by a combination of spectroscopic methods including 1H and 13C NMR, DEPT, ESI-MS and FTIR spectra of the transformed product. The present work accommodated a feasible enzymatic approach for preparing andrographolide monoester, which possesses obvious advantages over the multi-step chemical process in terms of excellent regioselectivity, simplicity, environmental friendliness and mild reaction conditions.

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