title: Preclinical evaluation of the supercritical extract of azadirachta indica (neem) leaves in vitro and in vivo on inhibition of prostate cancer tumor growth.
abstract: Azadirachta indica, commonly known as neem, has gained worldwide prominence because of its medical properties, namely antitumor, antiviral, anti-inflammatory, antihyperglycemic, antifungal, and antibacterial activities. Despite these promising results, gaps remain in our understanding of the molecular mechanism of action of neem compounds and their potential for use in clinical trials. We investigated supercritical extract of neem leaves (SENL) for the following: molecular targets in vitro, in vivo efficacy to inhibit tumor growth, and bioactive compounds that exert antitumor activity. Treatment of LNCaP-luc2 prostate cancer cells with SENL suppressed dihydrotestosterone-induced androgen receptor and prostate-specific antigen levels. SENL inhibited integrin β1, calreticulin, and focal adhesion kinase activation in LNCaP-luc2 and PC3 prostate cancer cells. Oral administration of SENL significantly reduced LNCaP-luc2 xenograft tumor growth in mice with the formation of hyalinized fibrous tumor tissue, reduction in the prostate-specific antigen, and increase in AKR1C2 levels. To identify the active anticancer compounds, we fractionated SENL by high-pressure liquid chromatography and evaluated 16 peaks for cytotoxic activity. Four of the 16 peaks exhibited significant cytotoxic activity against prostate cancer cells. Mass spectrometry of the isolated peaks suggested the compounds with cytotoxic activity were nimbandiol, nimbolide, 2',3'-dihydronimbolide, and 28-deoxonimbolide. Analysis of tumor tissue and plasma samples from mice treated with SENL indicated 28-deoxonimbolide and nimbolide as the bioactive compounds. Overall, our data revealed the bioactive compounds in SENL and suggested that the anticancer activity could be mediated through alteration in androgen receptor and calreticulin levels in prostate cancer.
authors.affiliation: Authors' Affiliations: Departments of Urology, Oncology, and Biochemistry and Molecular Biology; and Division of Anatomic Pathology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wu
authors.forename: Manish
authors.initials: M
authors.lastname: Kohli
authors.forename: H Robert
authors.initials: HR
authors.lastname: Bergen
authors.forename: John C
authors.initials: JC
authors.lastname: Cheville
authors.forename: R Jeffrey
authors.initials: RJ
authors.lastname: Karnes
authors.forename: Hong
authors.initials: H
authors.lastname: Cao
authors.forename: Charles Y F
authors.initials: CY
authors.lastname: Young
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Tindall
authors.forename: Mark A
authors.initials: MA
authors.lastname: McNiven
authors.forename: Krishna Vanaja
authors.initials: KV
authors.lastname: Donkena
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects; D031601:Azadirachta / Q000737:chemistry*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D022001:Focal Adhesions / Q000187:drug effects; D006801:Humans; D020128:Inhibitory Concentration 50; D008297:Male; D051379:Mice; D010936:Plant Extracts / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000633:toxicity; D018515:Plant Leaves / Q000737:chemistry*; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D011944:Receptors, Androgen / Q000378:metabolism; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D010936:Plant Extracts; D011944:Receptors, Androgen; D017430:Prostate-Specific Antigen