Andi Setiawan

AGOSTEROL A, A NOVEL POLYHYDROXYLATED STEROL ACETATE REVERSING MULTIDRUG RESISTANCE FROM A MARINE SPONGE OF SPONGIA SP.

Abstract Agosterol A (1) has been isolated from a marine sponge of Spongia sp. and the absolute stereo-structure elucidated. Agosterol A (1) is a novel polyhydroxylated sterol acetate, which completely reverses multidrug resistance in human carcinoma cells caused by overexpression of two kinds of membrane glycoprotein.

REVERSAL OF MULTIDRUG RESISTANCE IN HUMAN CARCINOMA CELL LINE BY AGOSTEROLS, MARINE SPONGEAN STEROLS

Abstract We have isolated agosterol A ( 1 ) from a marine sponge of Spongia sp. as a reversing substance to multidrug resistance (MDR) in human carcinoma cell lines, KB-C2 and KB-CV60, overexpressing P-glycoprotein and MRP, respectively. Further investigation led us to isolate analogous sterols, agosterols B ( 2 ), C ( 5 ), A 4 ( 7 ), D 2 ( 10 ), A 5 ( 13 ) and C 6 ( 14 ) from the same sponge and determine their structures. From the structure-activity relationship study, each of the 3,4,6-acetoxyl groups and 11,22-hydroxyl groups was elucidated to be crucial for reversing MDR in tumor cells.

Hypoxia‐Selective Growth Inhibition of Cancer Cells by Furospinosulin‐1, a Furanosesterterpene Isolated from an Indonesian Marine Sponge

It is generally accepted that cancer cells, which have adapted to the hypoxic environments in tumor tissues, aggravate cancer pathology by promoting tumor growth, angiogenesis, metastasis, and drug resistance. Therefore, compounds that selectively inhibit the growth of tumor cells in hypoxic environments are expected to provide new leads for promising anticancer drugs. Furospinosulin‐1, a marine‐sponge‐derived furanosesterterpene, exhibited selective antiproliferative activity against DU145 human prostate cancer cells under hypoxic conditions in concentrations ranging from 1 to 100 μM. Furospinosulin‐1 also demonstrated antitumor activity at 10–50 mg kg−1 oral administration in a mouse model inoculated with sarcoma S180 cells. Mechanistic analysis revealed that furospinosulin‐1 suppresses transcription of the insulin‐like growth factor‐2 gene (IGF‐2), which is selectively induced under hypoxic conditions through prevention of the binding of nuclear proteins to the Sp1 consensus sequence in the IGF‐2 promoter region.

Stylissamide X, a new proline-rich cyclic octapeptide as an inhibitor of cell migration, from an Indonesian marine sponge of Stylissa sp.

A new proline-rich cyclic octapeptide named stylissamide X (1) was isolated from an Indonesian marine sponge of Stylissa sp. as an inhibitor of cell migration from the guidance of wound-healing assay. The chemical structure of stylissamide X (1) was determined on the basis of spectroscopic analysis, and stereostructure of the amino acids were deduced by Marfeys method. Compound 1 showed inhibitory activity against migration of HeLa cells in the ranges of 0.1-10 μM concentration through both wound-healing assay and chemotaxicell chamber assay, while the cell viability was maintained more than 75% up to 10 μM concentration of 1.

DedA Protein Relates to Action-Mechanism of Halicyclamine A, a Marine Spongean Macrocyclic Alkaloid, as an Anti-dormant Mycobacterial Substance

A macrocyclic alkaloid, halicyclamine A, was re-discovered from an Indonesian marine sponge of Haliclona sp. 05A08 as an anti-dormant mycobacterial substance. To clarify action-mechanism of halicyclamine A, halicyclamine A-resistant strains were screened from the transformants of Mycobacterium smegmatis with the genomic DNA library of M. bovis BCG, which were constructed in the multi-copy shuttle cosmid pYUB145. Sequencing analysis of the cosmids isolated from the halicyclamine A-resistant transformants revealed that the responsible gene was involved in the genome region between 2920.549 kb and 2933.210 kb. Further experiments using the transformants over-expressing individual gene contained in the responsible region were executed, and the transformant, which over-expressed BCG2664 gene assigned as dedA gene, was found to become halicyclamine A-resistant. This evidence strongly suggested that DedA protein correlates with the action-mechanism of halicyclamine A as an anti-dormant mycobacterial substance.

Dysideamine, a new sesquiterpene aminoquinone, protects hippocampal neuronal cells against iodoacetic acid-induced cell death

In the course of our search for neuroprotective agents, dysideamine (1), a new sesquiterpene aminoquinone, was isolated along with bolinaquinone (2) from Indonesian marine sponge of Dysidea sp. Compounds 1 and 2 showed neuroprotective effect against iodoacetic acid (IAA)-induced cell death at 10 microM concentration in mouse HT22 hippocampal neuronal cells. Dysideamine (1) inhibited production of reactive oxygen species (ROS) by IAA treatment, whereas it exhibited no effect on depletion of intracellular ATP of the IAA-treated HT22 cells. Moreover, 1 induced neurite outgrowth against mouse neuroblastoma Neuro 2A cells with increase of acetylcholinesterase (AChE) activity, which is a marker of neuronal differentiation.

Marine spongian sesquiterpene phenols, dictyoceratin-C and smenospondiol, display hypoxia-selective growth inhibition against cancer cells.

In the course of our search for hypoxia-selective growth inhibitors against cancer cells, a sesquiterpene phenol, dictyoceratin-C (1), was isolated from the Indonesian marine sponge of Dactylospongia elegans under the guidance of the constructed bioassay. Dictyoceratin-C (1) inhibited proliferation of human prostate cancer DU145 cells selectively under hypoxic condition in a dose-dependent manner at the concentrations ranging from 1.0 to 10 μM. The subsequent structure-activity relationship study using nine sesquiterpene phenol/quinones (2-10), which were isolated from marine sponge, was executed. We found that smenospondiol (2) also exhibited the similar hypoxia-selective growth inhibitory activity against DU145 cells, and the para-hydroxybenzoyl ester moiety would be important for hypoxia-selective growth inhibitory activity of 1. In addition, the mechanistic analysis of dictyoceratin-C (1) revealed that the 10 μM of 1 inhibited accumulation of Hypoxia-Inducible Factor-1α under hypoxic condition.

Identification of the target protein of agelasine D, a marine sponge diterpene alkaloid, as an anti-dormant mycobacterial substance.

One of the major reasons for the wide epidemicity of tuberculosis and for the necessity for extensive chemotherapeutic regimens is that the causative agent, Mycobacterium tuberculosis, has an ability to become dormant. Therefore, new lead compounds that are anti‐bacterial against M. tuberculosis in both active and dormant states are urgently needed. Marine sponge diterpene alkaloids, agelasines B, C, and D, from an Indonesian marine sponge of the genus Agelas were rediscovered as anti‐dormant‐mycobacterial substances. Based on the concept that the transformants over‐expressing targets of antimicrobial substances confer drug resistance, strains resistant to agelasine D were screened from Mycobacterium smegmatis transformed with a genomic DNA library of Mycobacterium bovis BCG. Sequence analysis of the cosmids isolated from resistant transformants revealed that the responsible gene was located in the genome region between 3475.051 and 3502.901 kb. Further analysis of the transformants over‐expressing the individual gene contained in this region indicated that BCG3185c (possibly a dioxygenase) might be a target of the molecule. Moreover, agelasine D was found to bind directly to recombinant BCG3185c protein (KD 2.42 μm), based on surface plasmon resonance (SPR). This evidence strongly suggests that the BCG3185c protein is the major target of agelasine D, and that the latter is the anti‐mycobacterial substance against dormant bacilli.

Anti-dormant mycobacterial activity and target molecule of melophlins, tetramic acid derivatives isolated from a marine sponge of Melophlus sp.

Tuberculosis (TB), caused by Mycobacterium tuberculosis infection, is a major world health problem that is responsible for the deaths of 1.5 million people each year. In addition, the requirement for long-term therapy to cure TB complicates treatment of the disease. One of the major reasons for the extended chemotherapeutic regimens and wide epidemicity of TB is that M. tuberculosis has the ability to persist in a dormant state. We therefore established a new screening system to search for substances with activity against dormant mycobacteria using M. smegmatis and M. bovis BCG cultivated in medium containing propionate as sole carbon source to induce dormancy. Subsequently, melophlins A (1), G (2), H (3), and I (4), tetramic acid derivatives, were re-discovered from the Indonesian marine sponge of Melophlus sp. as anti-dormant mycobacterial substances. Moreover, target analysis of melophlin A indicated that it targeted the BCG1083 protein of putative exopolyphosphatase and the BCG1321c protein of diadenosine 5′,5‴-P1,P4-tetraphosphate phosphorylase.

N-Methylniphatyne A, a New 3-Alkylpyridine Alkaloid as an Inhibitor of the Cancer Cells Adapted to Nutrient Starvation, from an Indonesian Marine Sponge of Xestospongia sp.

In the course of searching for selective growth inhibitors of the cancer cells adapted to nutrient starvation, a new 3-alkylpyridine alkaloid named N-methylniphatyne A (1) was isolated from an Indonesian marine sponge of Xestospongia sp. The chemical structure of 1 was determined on the basis of the spectroscopic analysis and comparison with the synthesized 1 and its analogues. Compound 1 showed the cytotoxic activity against PANC-1 cells under the condition of glucose starvation with IC50 value of 16 µM, whereas no growth-inhibition was observed up to 100 µM under the general culture conditions.