Normaytancyprine (2), a new minor antileukemic maytansinoid, was isolated from Putterlickia verrucosa Szyseyl. (Celastraceae) during the isolation of maytansine 1, a potent antileukemic ansa macrolide originally isolated from Maytenus serrata (Celastraceae) with low yield (ca. 0.0001%). An ethanolic extract of 60 kg of the dried stem wood and stem bark of P. verrucosa was subjected to the isolation procedure developed for Maytenus buchananii, involving extensive column chromatography and preparative thin layer chromatography (ptlc) of maytansinoid-containing fractions, leading to the isolation of 6 mg (0.00001%) of 2 as pale tan microcrystals with a melting point of 143-145°C. The structure of 2 was elucidated by a chemical interconversion to normaysine, as well as by ¹H and ¹³C nuclear magnetic resonance (nmr) spectroscopy and mass spectrometry. The ultraviolet (UV) spectrum of 2 had absorption maxima at 232, 252, 280, and 289 nm, and the infrared (IR) spectrum had bands at 1750, 1710, and 1635 cm⁻¹, suggesting it was a maytanside ester. The mass spectrum was typical of a maytanside ester, with the highest observable ion at m/e 670 corresponding to M⁺-H₂O-HNCO and a pattern of ions at m/e 471, 456, and 436 indicative of the macrocyclic ring. Final structure elucidation was accomplished by comparison of its ¹³C nmr spectra with those of maytansine 1 and normaysine 4: 2 lacked the two quartets due to the (18)N-CH₃ and C(4')H₃ groups present in 1, instead having five new signals (three doublets at 20.3, 23.3, and 27.5 ppm and two quartets at 12.2 and 17.4 ppm) consistent with a 2,3-dimethylcyclopropanecarboxylic acid derivative as the N-acyl moiety of the C-3 amino acid ester. Normaytancyprine was thus found to contain an unusual dimethylcyclopropylcarboxyl moiety in its C-3 amino acid ester.