Antimicrobial Activity of Some Pentacyclic Triterpenes and Their Synthesized 3-O-Lipophilic Chains

Abstract

The pentacyclic triterpenes of ursane and oleanane skeletons found to accumulate in a number of terrestrial plants in free or glycosidic form.1) Some of these metabolites such as amyrins and ursolic acid have been reported as the bioactive constituents from a number of plants used in traditional and folk medicine.2,3) Amyrins were found to exhibit interesting pharmacological activities such as anti-inflammatory, 4,5) antiproteolytic, 6) antifungal 7) etc. whereas, ursolic acid was found to exhibit significant activities such as hepatoprotective, anti-inflammatory, antiviral and anti-tumor etc.8) Ursolic acid was identified as one of the active components in rosemary (Rosmarinus officinalis) to inhibit the growth of some of the food associated bacteria and yeast. 9) Ursolic acid and its 3-keto and 11-keto derivatives have been shown to inhibit the growth of Staphylococcus aureus.10) It was also reported that ursolic acid decreases the cytopatholic effects in vitro cells exposed to Herpes simplex virus.11) Interestingly a-amyrin palmitate isolated from Santalum album found to exhibit insect (Atteva fabriciella, Eligama norcissu, Eupterote geminata) growth inhibiting and chemosterilant activities.12) The low acute toxicity and structure activity studies of these skeletons suggest that defined substituents on the lipophilic 5-ring backbone can increase selectivity and potency of a desired action 13) and are identified as the potent natural lead compounds for drug development.In connection with our chemical screening on Diospyros melanoxylon leaves, we have isolated large quantities of amyrins (0.94%) as an inseparable mixture of a-and b-and ursolic acid (0.56%), which prompted us to screen for antimicrobial activity along with their synthesized lipophilic fatty acid ester chains. The common functionality in these compounds is the hydroxyl at C 3 . In case of ursolic acid it has got an additional carboxylic acid functionality at C 17 . It was reported in literature that the acid moiety at C 17 and ester functionality at C 3 are highly essential for enhanced pharmacological activities of pentacyclic triterpenes. 14,15) In view of these observations, the C 3 -OH can be exploited to synthesize highly lipophilic ester chains. Interestingly some of the higher fatty acid esters (C 16 , C 18 ) of pentacyclic triterpenes have been reported from natural sources. 12) Lipophilicity is an important parameter in the development of antimicrobial agents. It increases with increase of the carbon chain. Molecules with carbon chains above C-10 are fairly lipophilic and good candidates for pharmacological evaluation. Further the partition coefficient (log P), which is well known as an index of lipophilicity, is an important physicochemical parameter in the development of antibacterial agent because it is known to be closely related to the permeation through a lipid coat of bacteria.16) In view of the above, we have now prepared the highly lipophilic 3-O-fatty acid ester chains (C 12 -C 18 ) of amyrins and ursolic acid and screened for ...

Triterpenes From Ceriops Decandra (Griff.) W. Theob.

“…The NMR spectra of 1 are in accordance with data reported in the literature for 3β-E-coumaroylbetulinic acid (1) [17]; 2 for lupeol fatty acid esters [18], 3 for betulonic acid [19], 4 for betulin [20], 5 for betulinic acid [21], 6 for lupeol [16], 7 for lupenone [22], 8 for 3β-E-feruloyllupeol [2], 9 for 3β-Zferuloyllupeol [2], and 10 for chlorophyll a [23].…”

Antibacterial activity of oleanolic and ursolic acids and their derivatives

“…UA extracted from Diopsyros melanoxylon (Ebenaceae) and its liophylic 3-O fatty acids ester chains (C 12 -C 18 ) were evaluated for antimicrobial activity against Pseudomonas syringae, Bacillus sphaericus, Bacillus subtilis, E. coli and Salmonella typhi and moderate activity was reported [56] (Table 1). Also Chattopadhyay and coworkers found that n-butanol extracts of Alstonia macrophylla (Apocyanaceae) [57] and Mallotus pelatus (Euphorbiaceae) [58], enriched in UA and used in South Asian traditional medicine, showed moderate antibacterial activity against…”

Extended longevity ofDrosophila melanogasterby water and ethanol extracts ofStachys lavandulifolia

“…Both oleonolic acid and ursolic acid, which are rather similar because of the closeness of their chemical structures, have many important pharmacological effects. The literature includes numerous data on anti-inflammatory (Safayhi & Sailer, 1997), antitumor (Ovesna et al, 2004), anti-HIV (Kashiwada et al, 1998), antimicrobial (Mallavadhani et al, 2004. ), antifungal (Rocha et al, 2004), hypoglycemic (Perez et al, 1998) and antihyperlipidemic (Ma, 1982) properties.…”