Aristolactame and aporphine alkaloid from the ethyl acetate extract of stems Melodorum fruticosum L.

Melodorum fruticosum (Annonaceae), a shrub with fragrant yellow flowers, distributed in South East Asia, more specifically indigenous to Thailand, Laos, Cambodia, and Vietnam. In Vietnam, M. fruticosum has been used as folk medicine remedies for the treatment of digestive diseases, abdominal dyspepsia in women after giving birth. This plant has been used as a tonic, a mild cardiac stimulant, antipyretics and as a hematinic to resolve dizziness by Thai people. The essential oil of M. fruticosum flowers is used in aromatherapy and as traditional medicines in Thailand. Its flowers and barks have been reported to have antifungal, antioxidant, and cytotoxic activities. Phytochemical investigation on the fractions EA.3 and EA.4 from the ethyl acetate extract of stem of M. fruticosum led to the isolation of five alkaloids including aristolactame AII (1), goniopedalin (2), piperolactame C (3), 10-amino-3,6-dihydroxy-2,4-dimethoxyphenanthrene-1-carboxylic acid (4) and noraristolodione (5). Their chemical structures were elucidated by 1D and 2D–NMR, ESI-MS as well as compared with data in the literatures. All these compounds were isolated for the first time from the M. fruticosum collected at Di Linh district, Lam Dong province, Vietnam. All isolated were evaluated for their cytotoxicity against KB, Hep-G2, and MCF-7 cell lines. Among them, compound (2) showed weak cytotoxicity against the tested cell lines.