Pergamon Tetrahedmn Letters 40 (i 999) 4239-4242 TETRAHEDRON LETTERS Staminol A, a Novel Diterpene from Orthosiphon stamineus Pavios Stampoulis,* Yasuhiro Tezuka,* Arjun H. Banskota," Kim Qui Tran, b Ikuo Saiki* and Shigetoshi K_adota *" °Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, 2630-SugitanL Toyama 930-0194, Japatt bNational University Hochiminh City, Hochiminh, Vietnam. Received I March 1999; revised 23 March 1999; accepted 26 March 1999 Abstract: From the aerial part of a Vietnamese medicinal plant, Orthosiphon stamineus BENTH. (Lamiaceae),staminolA (1), a diterpenewith a novel carbon framework,was isolatedtogether with four new isopimarane-typediterpenes, orthosiphols F--I (2---5). Their structures were elucidated by the spectroscopic analyses. © 1999 ElsevierScienceLtd. All rights reserved. Keywords:naturalproducts;terpenesand terpenoids; NMR Orthosiphon stamineus BENTH. (Lamiaceae) is a medicinal plant grown in Southeast Asia and is currently cultivated in Indonesia. The plant has been used in treating urinary lithiasis, edema, eruptive fever, influenza, rheumatism, hepatitis, jaundice and biliary lithiasisJ '2 In our continued studies on Vietnamese medicinal plants, a the MeOH extract of the aerial part of this plant was found to exhibit cytotoxic activity against a highly liver-metastatic colon 26-L5 carcinoma cells. 4 Thus we fractionated the MeOH extract into hexane-sohible, CHCl3-soluble, AcOEt-soluble, BuOH-soluble and H20-soluble fractions. Among these fractions, the CHCl3-soluble fraction showed the strongest activity against colon 26-L5 cells. Separation by silica gel column chromatography followed by preparative "ILC procedures afforded five new diterpenes, named staminol A (1) and orthosiphols FmI (2--5). Here we would like to communicate the structure elucidation of them by the spectroscopic analyses. 15 -~ 16 Ph COO,,, ~,~2p 17 PhCOQ. 20"~111~'~"OH CI'I,-J300,,,. ~ O CH3COO"" '" OCHa 19 18 1 R~, PhCOQ "f~..,, ~ PhCOQ~,~ c, o • OH OH 2 R1 = COCH3, R2=H, R3= COPh § 3 RI=COCH3, R2= R3= H 4 R1 = R2= COCH3, R3= COPh 6 R1 = H, R 2" = COCH3, R3= COPh Starninol A (1) 5 was obtained as colorless amorphous solid and showed [Of]D 25 -24.3 ° (c = 0.5 I, CHCIa). Its molecular formula was determined by high-resolution FAB-MS measurement to be C4oI-I4~O~3 (m/z 734). The IR spectrum of 1 showed absorptions of hydroxy (3550, 3430, 3300 cm-~), ester carbonyl (1725 crn-~) and phenyl (1600, 1450 cm -t) groups. The IH-NMR spectrum of 1 (Table 1) revealed signals due to four tertiary methyl, a vinyl, five oxygen-substituted methine and three aliphatic methine groups together with signals of two benzoyl and three acetyl groups. Moreover, its ]3C-NMR spectrum (Table 1) indicated the presence of a ketone and five ester carbonyl groups and four (two oxygen-substituted and two oxygen-non-substituted) quaternary carbons. Analyses of these signals by the IH-]H and ~H-~3C COSY experiments led to the partial structures depicted in Fig. 1. * Authorto whomcorrespondingshouldbe addressed. Fax: +81-764-34-5059.E-maihkadota@ms.toyama-mpu.ac.jp. 0040-4039/99/5 - see front matter © 1999 Elsevier Science Ltd. All rights reserved. PII: S0040-4039(99)00685-1