title: Discovery of a marine-derived bis-indole alkaloid fascaplysin, as a new class of potent P-glycoprotein inducer and establishment of its structure-activity relationship.
abstract: The screening of IIIM natural products repository for P-gp modulatory activity in P-gp over-expressing human adenocarcinoma LS-180 cells led to the identification of 7 natural products viz. withaferin, podophyllotoxin, 3-demethylcolchicine, agnuside, reserpine, seseberecine and fascaplysin as P-gp inducers. Fascaplysin (6a), a marine-derived bis-indole alkaloid, was the most potent among all of them, showing induction of P-gp with EC50 value of 25 nM. P-gp induction is one of the recently targeted strategy to increase amyloid-β clearance from Alzheimer brains. Thus, we pursued a medicinal chemistry of fascaplysin to establish its structure-activity relationship for P-gp induction activity. Four series of analogs viz. substituted quaternary fascaplysin analogs, D-ring opened quaternary analogs, D-ring opened non-quaternary analogs, and β-carbolinium analogs were synthesized and screened for P-gp induction activity. Among the total of 48 analogs screened, only quaternary nitrogen containing analogs 6a-g and 10a, 10h-l displayed promising P-gp induction activity; whereas non-planar non-quaternary analogs 9a-m, 13a-n, 15a-h were devoid of this activity. The P-gp induction activity of best compounds was then confirmed by western-blot analysis, which indicated that fascaplysin (6a) along with 4,5-difluoro analog of fascaplysin 6f and D-ring opened analog 10j displayed 4-8 fold increase in P-gp expression in LS-180 cells at 1 μM. Additionally, compounds 6a and 6f also showed inhibition of acetylcholinestease (AChE), an enzyme responsible for neuronal loss in Alzheimer's disease. Thus, fascaplysin and its analogs showing promising P-gp induction along with AChE inhibition at 1 μM, with good safety window (LS-180: IC50 > 10 μM, hGF: 4 μM), clearly indicates their promise for development as an anti-Alzheimer agent.
authors.affiliation: Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India; Academy of Scientific & Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Sudhakar
authors.initials: S
authors.lastname: Manda
authors.affiliation: Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Sadhana
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Abubakar
authors.initials: A
authors.lastname: Wani
authors.affiliation: Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India; Academy of Scientific & Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Prashant
authors.initials: P
authors.lastname: Joshi
authors.affiliation: Academy of Scientific & Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India; Preformulation Laboratory, PKPD Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Kumar
authors.affiliation: Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Guru
authors.affiliation: Preformulation Laboratory, PKPD Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Sonali S
authors.initials: SS
authors.lastname: Bharate
authors.affiliation: Academy of Scientific & Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India; Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Shashi
authors.initials: S
authors.lastname: Bhushan
authors.affiliation: Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India; Academy of Scientific & Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: Ram A
authors.initials: RA
authors.lastname: Vishwakarma
authors.affiliation: Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India. Electronic address: ajaykmahajan@hotmail.com.
authors.forename: Ajay
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India; Academy of Scientific & Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India. Electronic address: sbharate@iiim.ac.in.
authors.forename: Sandip B
authors.initials: SB
authors.lastname: Bharate
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D001688:Biological Products / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line; D060326:Chemistry Techniques, Synthetic; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical / Q000379:methods; D006801:Humans; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D062105:Molecular Docking Simulation; D012995:Solubility; D013329:Structure-Activity Relationship; D000644:Quaternary Ammonium Compounds; D002243:Carbolines; D007212:Indolizines
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001688:Biological Products; D002800:Cholinesterase Inhibitors; D007211:Indoles; C069346:fascaplysine; D000644:Quaternary Ammonium Compounds; D002243:Carbolines; D007212:Indolizines
keywords: Acetylcholinesterase; Alzheimer's disease; Fascaplysin; P-glycoprotein induction; Quaternary analogs; β-carboline