Chem. Pharm. Bull. 53(12) 1577—1579 (2005)

Brazilian medicinal plant, we studied on chemical constituents in the aerial parts of Hyptis fasciculate BENTH. (Labiatae), which is a widespread perennial plant through the southern countries of South America. Its dried leaves and stems have been used for treatment of gout, expectorant, and fever. Although a few interesting cytotoxic a-pyrones and lignans have been found in some species of the genus Hyptis, there is no document regarding chemical study of this medicinal plant. During a chemical survey of constituents of H. fasciculate, we have encountered two new labdane diterpenoids 1 and 2 named 15b-methoxyfaciculatin and 15amethoxyfaciculatin, repectively, along with the previously known methoxynepetaefolin (3). In this paper, we report evidence leading to structures for new compounds 1 and 2. The methanol extract of the aerial parts of H. fasciculate was partitioned between ethyl acetate and water. The ethyl acetate soluble portion was purified by a combination of silica gel chromatography, centrifugal liquid–liquid partition chromatography, and preparative HPLC, which yielded two new diterpenes 1 and 2 along with methoxynepetafolin (3). The structure of compound 3 was elucidated as the previouly know methoxynepetaefolin by comparison of spectral data with those reported in the literatures and finally confirmed by our independent X-ray crystallographic analysis. 15b-Methoxyfaciculatin (1) had the molecular formula C23H32O8 determined by high-resolution (HR)-EI-MS at m/z 436.2072 [M] , indicating eight degrees of unsaturation. Its IR spectrum displayed absorptions due to the presence of two ester (1726, 1732 cm ) groups, which were supported by the observation of two ester carbonyls resonated at d 170.4 and 175.4 in the C-NMR spectrum. The Hand C-NMR (Table 1) spectral data of 1 showed the presence of one tertiary methyl [d 1.15 (3H, s); d 22.2], one acetyl [d 2.03; d 21.0, 170.4] and one methoxy [d 3.35; d 55.1] groups, and one acetal moiety [d 5.11 (1H, dd, J 5.6, 2.3 Hz); d 105.5] as well as of an exocyclic epoxide ring [d 2.36 (1H, d, J 3.8 Hz), 2.66 [1H, d, J 3.8 Hz; d 47.5 (C-17), 56.0 (C8)], which was supported by the HMQC and HMBC (H17/C-8) correlations. In addition to the above functional carbons, its C-NMR data (Table 1) contained nine methylenes including two oxymethylenes [d 74.0 (C-20), 75.6 (C-16)], one methine and one oxymethine [d 67.8 (C-6)], and four quaternary carbons, two of which were assigned as oxygenbearing carbons [d 86.4 (C-9), 90.0 (C-13)]. The routine analyses of H–H COSY and HMQC indicated the presence of four partial structures A—D (bold line), as shown in Fig. 2. Subsequently, HMBC experiment was carried out to assemble these structural fragments and results are summarized in Fig. 2. The sole tertiary methyl signal showed the HMBC correlations to C-3, C-4, C-5, and the C-19 ester carbonyl at d 175.4, whereas the H-20 signals [d 3.99 (dd, J 11.5, 1.5 Hz) and 5.07 (dd, J 11.5, 2.0 Hz)] correlated to C-1, CDecember 2005 Notes Chem. Pharm. Bull. 53(12) 1577—1579 (2005) 1577