Butea monosperma (LAM.) TAUB. (Fabaceae), known in Thai as Tong-kwoaw, is a medium sized deciduous tree of up to 50 feet high with stunning flower clusters, very conspicuous when in flower, and the trunk is usually crooked and twisted with irregular branches and rough, grey bark. The flowers are bright orange red, large and in rigid racemes. 1)This plant species has been found to display a wide variety of biological activities. The stem bark is used in indigenous medicine for the treatment of dyspepsia, diarrhea, dysentery, diabetes, ulcers, sore throat and snake bites.2) The flower extract showed antidiabetic effect in rats.3) The plant leaves exhibited antiinflammatory effect 4) and exerted effect on stress, anxiety and cognition in rats.5) Anti-diarrhoeal activity of the ethanolic extract of the stem bark 6) and anticonvulsive activity of the petroleum ether extract of the flowers 7) of this plant species in experimental animals have been reported. The plant extracts exhibited other biological activities including aphrodisiac activity in male rats, 8) anthelmintic activity, 9,10) and dermal wound healing in rats. 11) Isolation of (Ϫ)-medicarpin with antifungal activity from this part of the plant has also been reported. 12) From the flowers of this plant species the flavonoids butin (1), butein (2), butrin (3), isobutrin, palasitrin, coreopsin, isocoreopsin, sulphuresin, monospermoside (4), isomonospermoside (5) and 7,3Ј,4Ј-trihydroxyflavone (6) have been isolated. [13][14][15] Antihepatotoxic activity of the flower extract 16) and of compound 3 and isobutrin 17) has been observed. Compound 1 which was isolated from the seeds of this plant species showed estrogenic and postcoital anti-conceptive activity in rats.18) A lectin was also isolated from the seeds and was found to agglutinate human erythrocytes. The activity was inhibited by N-acetyl galactosamine and did not require a divalent ion.19) The euphane triterpenoid 3a-hydroxyeuph-25-ene and the alcohol 2,14-dihydroxy-11,12-dimethyl-8-oxo-octadec-11-enylcyclohexane have been isolated from the stem.20) The imide palasimide has been isolated from the pods of this plant species.21) Stigmasterol, stigmasterol-3-O-b-D-glucopyranoside and nonacosanoic acid were also among those isolated compounds. 15,20) As part of an ongoing project on bioactive compounds from Thai medicinal plants for the treatments of tropical diseases, the plant species was investigated and it was found that the EtOAc and MeOH extracts exhibited antimycobacterial activity. The present report deals with the One new dihydrochalcone, dihydromonospermoside (7), was isolated from the flowers of Butea monosperma together with three known chalcones, butein (2), monospermoside (4) and isoliquiritigenin (8), one flavone, 7,3 ,4 -trihydroxyflavone (6), four flavanones, (؊)-butin (1a), (؊)-butrin (3a), (؉)-isomonospermoside (5b) and (؊)-liquiritigenin (9a), and three isoflavones, formononetin (10), afrormosin (11) and formononetin-7-O-b b-D-glucopyranoside (12). The structure of the new compound was e...

Background Holarrhena antidysenterica has been employed as an ethnobotanical plant for the treatment of dysentery, diarrhoea, fever, and bacterial infections. Biological activities of the principle compound, conessine including anti-diarrhoea and anti-plasmodial effects were documented. Our previous study reported potency of Holarrhena antidysenterica extract and conessine as resistance modifying agents against extensively drug-resistant Acinetobacter baumannii. This study aimed to investigate (i) whether conessine, a steroidal alkaloid compound, could act as a resistance modifying agent against multidrug-resistant Pseudomonas aeruginosa, and (ii) whether MexAB-OprM efflux pump involved in the mechanism.MethodsConessine combined with various antibiotics were determined for synergistic activity against P. aeruginosa PAO1 strain K767 (wild-type), K1455 (MexAB-OprM overexpressed), and K1523 (MexB deletion). H33342 accumulation assay was used to evaluate efflux pump inhibition while NPN uptake assay was assessed membrane permeabilization.ResultsConessine significantly reduced MICs of all antibiotics by at least 8-fold in MexAB-OprM overexpressed strain. The levels were comparable to those obtained in wild-type strain for cefotaxime, levofloxacin, and tetracycline. With erythromycin, novobiocin, and rifampicin, MICs were 4- to 8-fold less than MICs of the wild-type strain. Loss of MexAB-OprM due to deletion of mexB affected susceptibility to almost all antibiotics, except novobiocin. Synergistic activities between other antibiotics (except novobiocin) and conessine observed in MexB deletion strain suggested that conessine might inhibit other efflux systems present in P. aeruginosa. Inhibition of H33342 efflux in the tested strains clearly demonstrated that conessine inhibited MexAB-OprM pump. In contrast, the mode of action as a membrane permeabilizer was not observed after treatment with conessine as evidenced by no accumulation of 1-N-phenylnaphthylamine.ConclusionsThe results suggested that conessine could be applied as a novel efflux pump inhibitor to restore antibiotic activity by inhibiting efflux pump systems in P. aeruginosa. The findings speculated that conessine may also have a potential to be active against homologous resistance–nodulation–division (RND) family in other Gram-negative pathogens.

Other bioactive products U 1300 Bioactive Flavonoids of the Flowers of Butea monosperma. -[isolation, structure determination and antimycobacterial activity of dihydromonospermoside (I), known chalcones, one flavone, flavanones, and isoflavones]. -(CHOKCHAISIRI, R.; SUAISOM, C.; SRIPHOTA, S.; CHINDADUANG, A.; CHUPRAJOB, T.; SUKSAMRARN*, A.; Chem.