Chem. Pharm. Bull. 54(10) 1370—1379 (2006)

herb of the family Labiatae, which is distributed in Nepal, India, Pakistan, and Afghanistan. In Nepal, the plant is called Gumpati or Gumma and its whole herb is a crude drug which is known as Dronapuspi and has been used as diaphretic, anti-inflammatory, edema, and obstinate urinary troubles including diabetes for diseases due to the aggravator of pitta (the force governing heat, temperature, and all chemical reactions) in the Ayurvedic system of medicine. In Pakistan, it is registered useful in the treatment of cough, cold, and gastric complaints for warm and dry in second order in the Unic system of medicine. Regarding the chemical constituents of this drug, only two sterols, b-sitosterol and its glucoside have been reported. In the course of our studies on Nepalese crude drugs, we have investigated the chemical constituents of Dronapuspi. A hot MeOH extract of the material was defated with nhexane, and partitioned between 1-butanol and water. Repeated chromatographic separation of the 1-butanol-soluble fraction led to the isolation of nineteen compounds (1—19), including five new ones, labdane-, norlabdane-, and abietanetype diterpenes named leucasdins A (1), B (2), and C (3), respectively, and two protostane-type triterpenes named leucastrins A (4) and B (5), together with a known triterpene (6), five sterols (7—11), and eight flavones (12—19), as described in the experimental section. This paper deals with identification of their structures. The structures of the known compounds (6—19) were identified as oleanolic acid (6), 7-oxositosterol (7), 7-oxostigmasterol (8), 7a-hydroxysitosterol (9), 7a-hydroxystigmasterol (10), stigmasterol (11), 5-hydroxy-7,4 dimethoxyflavone (12), pillion (13), gonzalitosin I (14), tricin (15), cosmosin (16), apigenin 7-O-b-D-(6O-p-coumaroyl)glucopyranoside (17), anisofolin A (18), and luteolin 4 -O-b-D-glucuronopyranoside (19), respectively, by direct comparison with authentic samples or of the respective spectral and chemical data with those described in the literatures. Leucasdin A (1) was obtained as colorless needles, mp 167—168 °C (dec.), [a]D 33.4°, and showed IR absorption bands assignable to esters (1740, 1724, 1248, 1240 cm ). The molecular formula was deduced to be C25H38O8 from the high resolution (HR)-MS and C-NMR spectral data. Twenty-five carbon signals were observed in the C-NMR spectrum, and their multiplicities were determined based on the distortionless enhancement by polarization transfer (DEPT) spectrum. The presence of a formyl and two acetyl groups were deduced from the Hand C-NMR spectra which showed characteristic signals at d 8.11, 2.24, and 2.03, and d 160.8, 171.2, and 170.5 (Tables 1, 2), respectively. The C-NMR spectrum showed the remaining signals due to four methyls (d 27.5, 19.7, 17.5, 16.9), seven methylenes (d 65.7, 36.9, 36.5, 34.7, 30.3, 29.2, 23.6), five sp-hybridized methines (d 96.7, 80.2, 70.4, 48.1, 31.3), and four quaternary sp-carbons (d 92.9, 89.3, 42.3, 38.4) as shown in Table 2. From these data and the index of hydrogen deficiency given by the molecular formula of 1, 1 was suggested to be a tetracyclic diterpenoid. The H–H-shift correlation spectroscopy (COSY) analysis for the functional groups thus established led to seventeen partial structures which were supported by the H–C longrange COSY spectrum. The connection of these partial structures was determined by the H–C long-range COSY correlations. Based on this evidence, the planar structure of 1 was elucidated. The relative stereochemistry of the decaline moiety of 1 was determined as follows. H-3 and H-6 were deduced as being axial and equatorial from the valu of JH-3,H2-2 (11, 5 Hz) and JH-5,H-6,H2-7 (3, 3, 3 Hz), respectively. In the difference nuclear Overhauser effect (DIFNOE) spectrum, irradiation of H3-18 enhanced the intensities of the H-3, H-5, H-6 and H319 signals, whereas irradiation of H3-20 enhanced those of the H-8, H3-19, H-2b (d 1.65, brqd, J 12, 4 Hz), H-1b (d 1.35, ddd, J 12, 4, 4 Hz), and the formylmethin proton signal as shown in Fig. 1. The above data suggested that both of the Aand B-ring existed in chair conformation with C-10 methyl and C-6 formyloxy groups in an axial arrangement and a C-3 acetoxy group in equatorial one, and the decaline 1370 Vol. 54, No. 10 Chem. Pharm. Bull. 54(10) 1370—1379 (2006)