Novel galactonic acid-binding hexameric lectin from Hibiscus mutabilis seeds with antiproliferative and potent HIV-1 reverse transcriptase inhibitory activities.
A hexameric 150-kDa lectin was isolated from dried Hibiscus mutabilis seeds using a chromatographic protocol that involved ion exchange chromatography on SP-Sepharose, and gel filtration on Superdex 75 and Superdex 200. The lectin was not adsorbed on SP-Sepharose and was eluted from the Superdex 75 column in the void volume. It was eluted in the first peak from Superdex 200. It was strongly adsorbed on DEAE-cellulose and Q-Sepharose and could not be easily desorbed. The hemagglutinating activity of the lectin, which was stable at pH 4-7 and up to 50 degrees C, could be inhibited by 25 mM galactonic acid. This is the first report of a galactonic acid-binding lectin. It potently inhibited HIV-1 reverse transcriptase with an IC(50) of 0.2 microM. It exhibited weak antiproliferative activity towards both hepatoma HepG2 cells (40% inhibition) and breast cancer MCF-7 cells (50% inhibition) at 100 microM concentration of the lectin. It did not inhibit mycelial growth of a number of fungi tested.
Lam
Sze Kwan
SK
School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. lamszekwan@yahoo.com.hk
Ng
Tzi Bun
TB
D000595:Amino Acid Sequence; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D045744:Cell Line, Tumor; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors*; D006384:Hemagglutination / Q000187:drug effects; D056945:Hep G2 Cells; D031584:Hibiscus / Q000737:chemistry*; D006801:Humans; D020128:Inhibitory Concentration 50; D037121:Plant Lectins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D011485:Protein Binding; D055503:Protein Multimerization; D051381:Rats; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology; D012639:Seeds / Q000737:chemistry; D013400:Sugar Acids / Q000737:chemistry
D000972:Antineoplastic Agents, Phytogenic; D037121:Plant Lectins; D018894:Reverse Transcriptase Inhibitors; D013400:Sugar Acids; C012991:galactonic acid; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase