LAUSR

Abstract Three new alkaloids, hipporidine A ( 1 ), hipporidine B ( 2 ), and (−)-lobeline N -oxide ( 3 ), were discovered from the whole plant of Hippobroma longiflora together with five known compounds ( 4 – 8 ). Their 2,6-disubstituted piperidine structures were established based on the HRESIMS, NMR (COSY, HMBC, HSQC, NOESY), and UV spectroscopic data. Hipporidines A ( 1 ) and B ( 2 ) possess a rare 1,3-oxazinane moiety. Compound 3 is the N -oxide derivative of (−)-lobeline ( 6 ). Moreover, the absolute configuration of norlobeline ( 5 ) was established by single-crystal X-ray diffraction analysis. Three major secondary metabolites ( 6 – 8 ) were evaluated for their neuroprotective effect against paclitaxel-induced neurotoxicity. Consequently, pretreatment with compound 8 at a concentration of 1.0 µM displayed significant attenuation on paclitaxel-damaged neurite outgrowth of dorsal root ganglion neurons without interfering with the cytotoxicity of paclitaxel on cervical cancer SiHa cells.