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1,3-diaxial interaction between 3H-20 and the 6β-hydroxy group results in a paramagnetic shift of the methyl resonance, supporting this assignment. 3 2 4 1 19 18 5 HO 20 H ax O 10 OH 6 12 16 17 11 H 9 15 13 7 H 14 8 O O OCCH 3 Figure 16: Chair conformation of compound I showing the relationship between H- 5, H-6 and H-7 There have been two reports of compound I being isolated previously (Mehrotra et al., 1989; Rasikari, 2007). The NMR data compares well with literature (Rasikari, 2007), however the C-4 and C-10 resonances are switched around, but we have assigned C-4 based on an HMBC correlation with H-6 and are confident in our assignment. With regard to the stereochemistry of the molecule, in Rasikari (2007) it is important to point out that the stereochemistry in the name of the compound does not correspond with the structure. We think that the compound was incorrectly named as 7α-acetoxy instead of 7β-acetoxy as a coupling constant of 3.5 Hz is used as a basis for this assignment. Mehrotra et al. (1989) is also used as a comparison in the identification in Rasikari et al. (2007). However, Mehrotra et al. (1989) observed a JH-6, H-7 of 3.5 Hz, close enough to that observed by Rasikari (2007) of JH-6, H-7 of 2.0 Hz, and concluded a 6β-axial, 7β- equatorial configuration. The structure of the molecule in Rasikari (2007) is however correctly depicted as the 6β-ax, 7β-eq form. While the 1 H NMR data also compares well to that in Mehrotra et al. (1989), the carbon resonances of C-6, 13, 15-17, 19 and 20 all differ by 1-3 ppm and the carbon resonance of C-18 is very different (33.68 as opposed to 21.00 in the literature). The carbonyl 107
esonance at δC 185.76 of C-14 is also different to that of 179.00 and that of the acetyl carbon at δC 169.61 is 3ppm higher than the acetyl carbon at 166.00. The C-2 carbon resonance in compound I is also 5ppm lower than that cited in Mehrotra et al. (1989). Although Hensch et al. (1975) report the 7α-axial acetoxy isomer, the coupling constant JH-6, H-7 is reported to be 2.0 Hz and we think that this is the 7β-equatorial acetoxy isomer. The NMR data is therefore used for comparison. The NMR data for compound I compares well with that in Hensch et al. (1975). Compound II is a yellow compound soluble in dichloromethane and methanol with a melting point of 125 °C and an optical rotation of [α] 20 D -47° (c 0.0063g/100ml, CHCl3). The GC-MS did not show a molecular ion peak at m/z 348 but the LC-MS showed a peak at m/z 347 in the negative ion mode which supports the molecular formula of C20H28O5 with a molecular mass of 348 amu. The UV spectrum showed a maximum absorbance at a wavelength of 192nm (log ε = 2.73). The 1 H and 13 C NMR data for compound II is similar to that of compound I, with a few notable differences. The H-7 resonance moved upfield from δH 5.64 to δH 4.54. The methyl acetyl resonance at δH 2.02 was also absent and a new one-proton resonance appeared as a broad singlet at δH 3.00. Another broad singlet could now be distinguished at δH 1.70. In the 13 C NMR spectrum of compound II, the acetyl carbonyl resonance was absent as well as the acetyl methyl resonance. Furthermore, the carbonyl stretching band in the IR spectrum was also absent. All these changes were consistent with the acetyl group at C-7 being replaced by a hydroxyl group. The broad singlet resonance at δH 3.00 was attributed to the hydroxyl group proton at C-7 because of a COSY correlation to H-7. This proton resonance did not correlate to any of the carbon resonances in the HSQC spectrum. The resonance at δH 1.70 also did not correlate to any of the carbon resonances and was attributed to the hydroxyl group at C-6. This resonance could have also been present in compound I, but could not be 108
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UNIVERSITY OF KWAZULU-NATAL FACULTY
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Preface The experimental work descr
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Acknowledgements First and foremost
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GC-MS - gas chromatography-mass spe
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Table 19: NMR data of compound III
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Spectrum 1d: Expanded DEPT spectrum
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Compound V, stigmasterol 217 Spectr
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2 19 1 4 18 O 20 5 Structures of co
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3.4 Results and Discussion of the c
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compounds are also classified as tr
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1 H CO2H 19 20 CHO 18 10 5 H 12 14
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may be referred to as a norabietane
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In the mevalonic acid pathway, the
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N thiamine diphosphate (TPP) O OH N
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in the kauranes. From the kauranes,
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References Abad, A., Agullo, C., Cu
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The flower colour varies among the
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Clade 1 unplaced groups Group A: Pl
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different medical conditions and in
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Plectranthus species Skin condition
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Plectranthus species Heart, circula
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Use of the minimum inhibitory conce
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Plectranthus species Coleus kiliman
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Plectranthus species Extraction med
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Plectranthus species Coleus kiliman
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Methanol, ethanol and water seem to
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Plectranthus species P. amboinicus
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Plectranthus species P. amboinicus
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variation is observed within ring B
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Compound Name Synonym 39 40 41 42 4
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compounds (Table 6b). Depending on
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Table 6c: Royleanone-type abietanes
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R 1 R2CH2 19 O H 3CCO 19 O H 6 12 O
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Compound Name Synonym 81 82 83 84 8
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Compound Name Synonym 104 105 106 1
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R 1 19 3 3 1 18 1 18 20 20 O H O H
Page 73 and 74: educed furan ring. The linear side
Page 75 and 76: Compound Name Synonym HCO O 128 129
Page 77 and 78: Thirty-six compounds (131-167) havi
Page 79 and 80: Compound Name Synonym 147 148 HO HO
Page 81 and 82: In compounds 149-165 (Table 9b), an
Page 83 and 84: Compound Name Synonym 163 164 165 R
Page 85 and 86: Table 9c: Coleon-type abietanes wit
Page 87 and 88: 1 18 3 20 4 O 5 19 R 1 R2 11 9 10 A
Page 89 and 90: The majority of the abietanes isola
Page 91 and 92: Plectranthus species Plant part Com
Page 93 and 94: The leaves seem to be the most freq
Page 95 and 96: Table 14 contains six abietanes iso
Page 97 and 98: References Abdel-Mogib, M., Albar,
Page 99 and 100: Cos, P., Hermans, N., de Bryne, T.,
Page 101 and 102: Hulme, M. (1954) Wild flowers of Na
Page 103 and 104: Lingling, X., Jie, L., Weijia, L. a
Page 105 and 106: Oliveira, P.M., Alves, R.B., Ferrei
Page 107 and 108: Ruedi, P. and Eugster, C. H. (1977)
Page 109 and 110: Ulubelen, A., Birman, H., Oksuz, S.
Page 111 and 112: Chapter 3 Extractives from Plectran
Page 113 and 114: 4 20 10 O H 19 18 6 7 OH OH C 13 R
Page 115 and 116: a few cases (specifically stated in
Page 117 and 118: The leaves (184.63g) were air-dried
Page 119 and 120: The ethyl acetate extract (0.98g) w
Page 121 and 122: 3.4.1 Structural elucidation of Com
Page 123: esonance showed HMBC correlations t
Page 127 and 128: Position Moiety Compound I 3 CH2 5
Page 129 and 130: Table 18: 13 C NMR data for compoun
Page 131 and 132: The equatorial methyl group at C-4,
Page 133 and 134: The proton NMR data for compound II
Page 135 and 136: Position 6 7 Compound III (400MHz)
Page 137 and 138: 3.4.3 Structure elucidation of Comp
Page 139 and 140: showed HMBC correlations to another
Page 141 and 142: H HO 3 OH H 2 4 24 eq 1 23 5 ax Hax
Page 143 and 144: HO HO Position 2 23 4 10 24 25 26 9
Page 145 and 146: Position Compound IV 4.1 4.2 4.3 b
Page 147 and 148: multiplet at δH 1.91 (H-21) and a
Page 149 and 150: 1 H Position Compound VI Burns et a
Page 151 and 152: Ultraviolet spectrum (λ max): 192n
Page 153 and 154: References Ansell, S.M. (1989) The
Page 155 and 156: Laing, M.D., Drewes, S.E. and Gurla
Page 157 and 158: van Vuuren, S. (2007) The antimicro
Page 159 and 160: Since the 7α-isomers of compounds
Page 161 and 162: eing incubated for 24 hours at 37°
Page 163 and 164: This indicated that the dihydroxy c
Page 165 and 166: acetic acid and air drying the plat
Page 167 and 168: whereas GI50 values for the renal a
Page 169 and 170: Table 28: Growth inhibition values
Page 171 and 172: Gaspar-Marques, C., Duarte, M.A., S
Page 173 and 174: Chapter 5 Conclusion The aim of thi
Page 175 and 176:
References Abdel-Mogib, M., Albar,
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Table of Contents Page Compound I,
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Compound II, 6β,7β-dihydroxyroyle
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Compound IV, euscaphic acid HO HO 2
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HO Compound VI, lupeol 3 24 25 26 2
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HO 218
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HO 220
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222
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