Coenzyme A (CoA) is a well-known cofactor that plays an essential role in many metabolic reactions in all organisms. In Plasmodium falciparum, the most deadly among Plasmodium species that cause malaria, CoA and its biosynthetic pathway have been proven to be indispensable. The first and rate-limiting reaction in the CoA biosynthetic pathway is catalyzed by two putative pantothenate kinases (PfPanK1 and 2) in this parasite. Here we produced, purified, and biochemically characterized recombinant PfPanK1 for the first time. PfPanK1 showed activity using pantetheine besides pantothenate, as the primary substrate, indicating that CoA biosynthesis in the blood stage of P. falciparum can bypass pantothenate. We further developed a robust and reliable screening system to identify inhibitors using recombinant PfPanK1 and identified four PfPanK inhibitors from natural compounds.

Abstrak. Rahmawati Y, Sulandari S, Hartono S. 2015. Respons lima varietas padi terhadap infeksi virus penyebab penyakit kerdil rumput (Rice Grassy Stunt Virus). Pros Sem Nas Masy Biodiv Indon 1: 1123-1126. Rice Grassy Stunt Virus (RGSV) merupakan virus penyebab penyakit kerdil rumput padi yang merupakan anggota dari genus Tenuivirus. RGSV ditularkan secara persisten oleh wereng coklat. Serangan wereng coklat selain menyebabkan padi kering seperti bekas terbakar (hopperburn) juga berperan sebagai vektor penyakit kerdil yang disebabkan oleh virus. Saat ini di DI Yogyakarta dan Jawa Tengah dilaporkan terjadi outbreak wereng coklat dan penyakit kerdil rumput. Penyakit kerdil sangat sulit dikendalikan sehingga sangat merugikan karena dapat menyebabkan puso. Pengendalian menggunakan varietas masih terkendala karena selama ini belum ada varietas padi yang toleran terhadap RGSV. Pada umumnya semua varietas padi yang ditanam oleh petani hanya tahan terhadap vektor (wereng coklat) saja. Penelitian ini bertujuan untuk mengetahui respons beberapa varietas padi yang banyak ditanam petani terhadap infeksi virus penyebab penyakit kerdil. Parameter yang diamati meliputi masa inkubasi, variasi gejala, kejadian dan intensitas penyakit yang ditimbulkan. Penelitian ini dilaksanakan di Laboratorium Virologi Tumbuhan dan rumah kaca Jurusan Hama dan Penyakit Tumbuhan, Fakultas Pertanian, Universitas Gadjah Mada (UGM) Yogyakarta. Sumber inokulum diambil dari Desa Sumber Rahayu, Moyudan, Sleman, Yogyakarta. Wereng coklat yang digunakan sebagai vektor merupakan hasil rearing di laboratorium. Inokulasi virus dilakukan terhadap lima varietas padi meliputi: Membramo, Ciherang, Inpari 13, IR64, dan Situ Bagendit. Berdasarkan hasil penelitian diketahui setiap varietas memiliki respons yang berbeda terhadap penyakit kerdil padi. Insidensi penyakit yang ditimbulkan varietas Membramo (85,19%), Situ Bagendit dan Inpari 13 (92,59%), Ciherang (96,3%), dan IR64 (100%). Setiap varietas memiliki perbedaan masa inkubasi. Variasi gejala juga berbeda antar varieta,s antara lain berupa anakan tegak, daun kaku pucat atau menguning, serta terdapat bercak pada daun. Pada varietas Situ Bagendit tanaman tidak terlalu kerdil, tetapi pada Ciherang gejala yang ditimbulkan sangat parah, yaitu: tanaman menjadi sangat kerdil. Kata kunci: kerdil rumput, padi, RGSV, varietas, wereng coklat Abstract. Rahmawati Y, Sulandari S, Hartono S. 2015. Response of five rice varieties to viral infections by Rice Grassy Stunt Virus that causes rice grassy disease. Pros Sem Nas Masy Biodiv Indon 1: 1123-1126. Rice grassy stunt virus (RGSV), a member of the genusTenuivirus, is the virus that causes rice grassy disease in rice. RGSV is persistently transmitted by the brown planthopper (BPH). Besides attack, BPH also induces hopper burn disease by drying leaves and acts as vectors of stunt disease caused by a virus. The occurrence of an outbreak of BPH and grassy stunt disease has been reported in Yogyakarta and Central Java. Stunt disease is very difficult to control. Moreover, it is...

Iheyamide A (1) is an antitrypanosomal linear peptide isolated from a Dapis sp. marine cyanobacterium by our group in 2020, and based on structure−activity relationships of its natural analogues, the C-terminal pyrrolinone moiety has been identified as the phamacophore for its antiparasitic activity. Further, we isolated this pyrrolinone moiety by itself as a new natural product from the marine cyanobacterium and named it iheyanone (2). As expected, iheyanone (2) showed antitrypanosomal activity, but its potency was weaker than iheyamide A (1). To clarify more detailed structure−activity relationships, we completed a total synthesis of iheyamide A (1) along with iheyanone (2) and evaluated the antitrypanosomal activities of several synthetic intermediates. As a result, we found that the longer the peptide chain, the stronger the antitrypanosomal activity. As iheyamide A (1) showed selective toxicity against Trypanosoma brucei rhodesiense, these findings can provide design guidelines for antitrypanosomal drugs.

Hoshinoamide C (1), an antiparasitic lipopeptide, was isolated from the marine cyanobacterium Caldora penicillata. Its planar structure was elucidated by spectral analyses, mainly 2D NMR, and the absolute configurations of the α-amino acid moieties were determined by degradation reactions followed by chiral-phase HPLC analyses. To clarify the absolute configuration of an unusual amino acid moiety, we synthesized two possible diastereomers of hoshinoamide C and determined its absolute configuration based on a comparison of their spectroscopic data with those of the natural compound. Hoshinoamide C (1) did not exhibit any cytotoxicity against HeLa or HL60 cells at 10 μM, but inhibited the growth of the parasites responsible for malaria (IC50 0.96 μM) and African sleeping sickness (IC50 2.9 μM).

No abstract