Further Bisabolenes and Dammarane Triterpenes of Commiphora kua Resin

Abstract

The plant species Commiphora kua (Burseraceae) is known for an oleoresin exudate which is an important article of commerce. 1) The plant is also used in herbal medicine as a remedy for snakebite, gonorrhoea, stomach disorders, and livestock related diseases. 2) Previous phytochemical studies on the plant resin afforded cycloartane triterpenes, 3) bisabolenes, and furanosesquiterpenoids based on a germacrane skeleton, 4) dammarane triterpenes, and octanordammaranes. 5) In continuing with our study, we now report the isolation and structural elucidation of bisabolene; 6-hydroxy-2-methyl-5-(5Ј-hydroxy-1Ј(R),5Ј-dimethylhex-3Ј-enyl)-phenol (1) along with two novel dammarane triterpenes; 3b,16b,20(S),25-tetrahydroxydammar-23-ene (3) and its acetate derivative, 3b-acetoxy-16b,20(S),25-trihydroxydammar-23-ene (4). Also being reported from the plant are known compounds characterised as 2-methyl-5-(4Ј(S)-hydroxy-1Ј(R),5Ј-dimethylhex-5Ј-enyl)-phenol (2), 6) 2-methoxyfuranodienone and 2-acetoxyfuranodienone, 7) b-amyrin and its acetate derivative, 8) 3b,16b,20(R)-trihydroxydammar-24-ene (5) and its acetate, 3b-acetoxy-16b,20(R)-dihydroxydammar-24-ene (6). 9) Their structures have been established based on extensive spectroscopic (UV, IR, 1 H-and 13 C-NMR and MS) and chemical studies.Compound 2 inhibited the growth of the plant pathogenic fungus Cladosporium cucumerinum on thin layer chromatography plates. Results and DiscussionCompound 1 displayed a molecular ion peak at m/z 250 in the mass spectrum, corresponding to C 15 H 22 O 3 . In its 1 H-NMR spectrum the main features of a tetra-substituted benzene ring were evident: two low field protons appearing as doublets at d H 6.90 and 6.70, a benzenoid methyl singlet (d H 2.23), a benzylic proton (d H 2.60), and two benzenoid hydroxyls (d H 7.20, D 2 O exchangeable) were present. The two dimensional total correlation spectroscopy (2D TOCSY) experiments 10,11) together with 1 H-1 H correlation spectroscopy (COSY) correlations were used to identify the spin system for the two protons, thus locating them at positions C-3 and C-4, respectively, a fact further corroborated by nuclear Overhauser effect spectroscopy (NOESY) cross peaks (Fig. 1). The structure of the 5Ј-hydroxy-1Ј(R),5Ј-dimethylhex-3Ј-enyl side chain at C-5 was confirmed by 1 H-and 13 C-NMR, 1 H-detected heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond connectivity (HMBC) experiments. 12) Also characteristic of the 1 H-NMR spectrum were the presence of a hydroxy isopropyl moiety at d H 1.30 and a twoproton multiplet at d H 5.56. The latter resolved in benzene-d 6 indicating the presence of a trans double bond. 6) The 13 C-NMR data (Table 1) ascertained these molecular features and peaks at d C 72.6 (C-5Ј), 124.7 (C-3Ј), and 138.2 (C-4Ј) were in accordance with the foregoing evidence. Furthermore, the two carbons at d C 124.7 and 138.2 represented an internal double bond and were linked to protons at d H 5.50 and 5.46, respectively. The HMBC correlations (Fig. 1) confirmed the double bon...

Further flavonol and iridoid glycosides from Ajuga remota aerial parts

“…The terminal rhamnosyl units were linked to the two primary glucose units through 1 ! 6 bonds as evidenced by downfield shifts of approximately þ 6.0 ppm at d 68.8 and d 67.4, respectively[14], a fact further corroborated by HMBC correlations of the rhamnosyls H-1 to the various glucosyls C-6. Thus, compound 6 was myricetin 3-O-rutinoside-4 0 -O-rutinoside.…”

Antioxidant, antimicrobial and cytotoxic activities of selected medicinal plants from Yemen

“…Antifungal activities against plant pathogenic fungi could be shown (Dekebo et al, 2002;Manguro et al, 2003). Whether similar compounds are responsible for the observed antimicrobial and cytotoxic activities of the extracts of the leaves remains unclear.…”

The genus Commiphora: A review of its traditional uses, phytochemistry and pharmacology

“…S3). Dammarane triterpenoids constitute the biggest group of Commiphora triterpenoids, and more than twenty-one dammarane triterpenoids have been found in the resins of four Commiphora species, including C. kua (Dekebo et al, 2002b;Manguro et al, 2003a), C. dalzieli (Waterman and Ampofo, 1985), C. confuse (Dekebo et al, 2002b;Manguro et al, 2003b) and C. myrrha (Shen et al, 2009). Polypodane triterpenoids from this genus are only discovered in the species of C. mukul (Kimura et al, 2001;Matsuda et al, 2004a,b).…”