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Diphenethylpiperidine alkaloids with tracheal smooth muscle relaxation activity from Hippobroma longiflora (L.) G. Don
- Chan, Zi-Yang, Govindaraju, Kayatri, Krishnan, Premanand, Low, Yun-Yee, Chong, Kam-Weng, Yong, Kien-Thai, Ting, Kang-Nee, Lim, Kuan-Hon
- Phytochemistry letters 2019 v.30 pp. 93-98
- Hippobroma longiflora, X-ray diffraction, alkaloids, carbachol, chemical constituents of plants, copper, rats, smooth muscle
- Phytochemical investigations on the whole plant of Hippobroma longiflora (L.) G. Don have resulted in the isolation and elucidation of three new diphenethylpiperidine alkaloids, hippofoline A (1), hippofoline B (2), and (−)-cis-2′,2′′-diphenyllobelidiol N-oxide (5), alongside two known alkaloids, (−)-lobeline (3) and (−)-cis-2′,2′′-diphenyllobelidiol (4). The absolute configurations of alkaloids 1 and 2 were deduced based on experimental and calculated ECD data as well as biogenetic consideration, while the absolute configurations of alkaloids 3 and 4 in their free base form were confirmed by Cu Kα radiation X-ray diffraction analyses. Alkaloids 2–4 were shown to induce concentration-dependent relaxation effects on rat isolated tracheal rings that were pre-contracted with carbachol.