ABSTRACT
Multidrug resistance (MDR) is a major obstacle to successful chemotherapy for cancer; thus, novel MDR reversers are urgently needed. In the present study, we assessed whether two synthetic derivatives of 23-hydroxybetulinic acid, 3,23-O-diacetyl-17-1,4'-bipiperidinyl betulinic amide (DABB) and 3,23-O-dihydroxy-17-1,4'-bipiperidinyl betulinic amide (DHBB), could reverse MDR induced by ATP-binding cassette (ABC) transporters. Using the MTT assay, we found that DABB and DHBB could enhance the cytotoxicities of ABCB1 substrates doxorubicin, vincristine, and paclitaxel in ABCB1-overexpressing HepG2/ADM and MCF-7/ADR cells, whereas that of a non-ABCB1 substrate cisplatin was unaffected. The ABCB1 substrate accumulation and efflux assay showed that DABB and DHBB not only enhanced the retention of doxorubicin and rhodamine123 but also inhibited the efflux of rhodamine123. Further mechanistic studies by reverse transcription PCR, western blot, and ABCB1 ATPase activity assay indicated that DABB and DHBB suppressed ABCB1 ATPase activity, but did not alter mRNA or protein expression of ABCB1. ABCB1 siRNA pretreatment attenuated the reversal effect of DABB and DHBB, indicating that their reversal effects were partially dependent on ABCB1. Docking analysis also implied that DABB and DHBB bind directly to ABCB1 at a site partly overlapped with that of verapamil. Taken together, our findings suggest that two bipiperidinyl derivatives of 23-hydroxybetulinic acid reverse ABCB1-mediated MDR through modulation of ABCB1 ATPase activity, thereby inhibiting its efflux function in both HepG2/ADM and MCF-7/ADR cells. These findings may contribute toward the development of novel MDR reversers using DABB and DHBB as adjuvant anticancer chemotherapy.
Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Drug Resistance, Neoplasm/drug effects , Piperidines/pharmacology , Triterpenes/chemistry , Triterpenes/pharmacology , ATP Binding Cassette Transporter, Subfamily B , ATP Binding Cassette Transporter, Subfamily B, Member 1/chemistry , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Cell Line, Tumor , Cytochrome P-450 CYP3A , Cytochrome P-450 CYP3A Inhibitors , Doxorubicin/pharmacology , Drug Resistance, Multiple/drug effects , Drug Screening Assays, Antitumor/methods , Hep G2 Cells/drug effects , Humans , MCF-7 Cells , Molecular Docking Simulation , Paclitaxel/pharmacology , Piperidines/chemistry , Rhodamine 123/pharmacokinetics , Verapamil/metabolism , Verapamil/pharmacology , Vincristine/pharmacologyABSTRACT
Repeated column chromatography of the EtOAc-soluble fraction of the aerial parts of Dodonaea viscosa led to the isolation of two new modified clerodanes, methyl dodovisate A (1) and methyl dodovisate B (2), two new prenylated flavonoids, 5,7,4'-trihydroxy-3',5'-di(3-methylbut-2-enyl)-3,6-dimethoxyflavone (10) and 5,7,4'-trihydroxy-3'-(4-hydroxy-3-methylbutyl)-5'-(3-methylbut-2-enyl)-3,6-dimethoxyflavone (11), together with eight known compounds, dodonic acid (3), hautriwaic acid (4), hautriwaic lactone (5), (+)-hardwickiic acid (6), 5alpha-hydroxy-1,2-dehydro-5,10-dihydroprintzianic acid methyl ester (7), strictic acid (8), dodonolide (9), and aliarin (12). The structures of the new compounds were elucidated by spectroscopic data analysis. Compounds 1-9 and 11 were evaluated on larvicidal activity against the fourth-instar larvae of Aedes albopictus and Culex pipens quinquefasciatus.
Subject(s)
Diterpenes, Clerodane/isolation & purification , Drugs, Chinese Herbal/isolation & purification , Flavonoids/isolation & purification , Sapindaceae/chemistry , Aedes/drug effects , Animals , Culex/drug effects , Diterpenes, Clerodane/chemistry , Diterpenes, Clerodane/pharmacology , Drugs, Chinese Herbal/chemistry , Drugs, Chinese Herbal/pharmacology , Flavonoids/chemistry , Flavonoids/pharmacology , Larva/drug effects , Molecular Structure , Nuclear Magnetic Resonance, BiomolecularABSTRACT
The repellent activity of steam-distilled essential oil from Zanthoxlum beecheyamum var. alatum fresh leaves against Culex pipens quinquefasciatus was evaluated according to the "Laboratory Efficacy Criterions of Public Health Insecticides for Pesticide Registration-Repellent (GB/T 17322. 10-1998)" with some modifications in test procedure, the fumigating insecticidal activity of the essential oil to Cx. pipens quinquefasciatus adults was assessed by the "Efficacy Test Methods of Public Health Insecticides for Pesticide Registration-Method of Laboratory Efficacy Test for Electric Mat (GB 13917.5-1992)", and the larvicidal and pupicidal activities of the essential oil against Cx. pipens quinquefasciatus were investigated by immersion method in laboratory. Besides, the chemical components of the essential oil were analyzed and determined by gas chromatography-mass spectrometry. At the dosage of 1.5 mg x cm(-2), the essential oil provided 100% protection against laboratory-reared female blood-starved individuals of Cx. pipens quinquefasciatus for (6.54 +/- 0.17) h. The 24 h LC50 value of the essential oil for Cx. pipens quinquefasciatus adults was 6.895 microg x cm(-3) when the fumigating dosage was 11.850 microg x cm(-3), and the KT50 value of the essential oil for the adults was 6.46 min. The 24 h LC50 value of the essential oil for IV instar larvae was 119.020 microg x ml(-1). Seventeen compounds in the essential oil were identified, accounting for 97.4% of the total. This essential oil exhibited high repellent activity and remarkable toxicity against Cx. pipens quinquefasciatus.
