Potential anti-inflammatory diterpenes from Premna obtusifolia

In Vitro Antiprotozoal Activity of Abietane Diterpenoids Isolated from Plectranthus barbatus Andr.

“…The rest of HMBC correlations were closely similar to those of Compound ( 4 ). The orientation for hydroxyl group at C6 was confirmed to be α by comparing 13 C-NMR chemical shift for C5, C6 and C7 with those reported for 6α,11,12,-trihydroxy-7β,20-epoxy-8,11,13-abietatriene, recently isolated from Premna obtusifolia (Verbenaceae) [11]. It is worth noting that similar structural compounds have been isolated from Coleus eskirolii and Salvia aspera [12,13] and identified as esquirolin D and 6-epi-demethylesquirolin D. However in esquirolin D, the hydroxyl group at position 6 was β-orientated rather than α as in Compound ( 5 ) and in 6-epi-demethylesquirolin D.…”

Diterpenoids from the stems of Tripterygium hypoglaucum (Celastraceae) and cytotoxic evaluation

“…The aforementioned spectroscopic analysis suggested that 2 was an isopimarane or ent-isopimarane diterpenoid (Sun and Li, 2012). The negative optical rotation value of 2, which was opposite with ent-8(14),15-sandaracopimaradiene,2a,18-diol, ent-8(14),15-sandaracopimaradiene,2b,18-diol (Camacho et al, 2001) and most ent-isopimarane diterpenoids (Su et al, 2002;Nagashima et al, 2003), and similar with 11R-isopimara-8(14),15-diene-11,18-diol and its analogs (Wu et al, 2013a,b;Salae et al, 2012;Zhang et al, 2011;Di et al, 2013;Kenmoku et al, 2004;Kimpe and Schamp, 1982), suggested the isopimarane skeleton of 2.…”

A Novel Diterpene Skeleton: Identification of a Highly Aromatic, Cytotoxic and Antioxidant 5‐Methyl‐10‐demethyl‐abietane‐type Diterpene fromPremna serratifolia

“…In the biosynthesis of C‐5 methyl diterpenes, such as the formation of clerodane skeleton of Premna species from their geranylgeranyl pyrophosphate precursor, one of the C‐4 methyl groups migrates to C‐5 whilst the C‐10 methyl moves to C‐9 position (Habtemariam et al , , ). In compound 1 , however, the gem‐dimethyl C‐4 group is intact as with Premna labdanes, abietanes, icetexanes and pimaranes (Habtemariam et al , , ; Salae et al , ; Suresh, et al , ; Yadav et al , ) whilst the C‐10 methyl moves to the unexpected biogenetically unique position of C‐5 to form a novel diterpene skeleton. This unique biosynthesis pathway that allowed the migration of the C‐20 methyl group from C‐10 position made it possible for the extended aromatisation in 1 through the three rings of the diterpene skeleton.…”

“…A number of diterpenes of biological significance belonging to the abietane (Salae et al , ), labdane and clerodane (Chin et al , ; Habtemariam et al , , , ; Habtemariam, , ), icetexane (Ayinampudi et al , ; Hymavathi et al , ; Suresh et al , ), kaurene (Padla et al , ) and pimarane, rosane and other structural classes (Rayanil et al , ; Salae et al , ) have been isolated from the genus Premna . Although their biological activity is yet to be demonstrated, the identification of three novel diterpenoids from the methanolic extract of root bark (RB) of P. serratifolia has also been documented in recent years (Yadav et al , ).…”