Amir Husni

Tyrosinase inhibition by water and ethanol extracts of a far eastern sea cucumber, Stichopus japonicus.

BACKGROUND Tyrosinase plays a key role in hyperpigmentaion and enzymatic browning. The present study was aimed at investigating the inhibitory effects of water and 70% aqueous ethanol extracts of Stichopus japonicus, a sea cucumber long consumed as a tonic food and traditional medicine, on the diphenolase activity of tyrosinase. RESULTS In the tyrosinase inhibition study, high-performance liquid chromatography completely separated L-3,4-dihydroxyphenylalanine and dopachrome from other compounds present in the extracts, and provided more reliable results than the commonly used spectrophotometry. The ethanol extract (IC(50)=0.49-0.61 mg mL(-1)) showed higher inhibitory activity than the water extract (IC(50)=1.80-1.99 mg mL(-1)). Enzyme inhibition by the extracts was reversible and of mixed type. For both extracts, the dissociation constants for binding to free enzyme were significantly smaller than those for binding to enzyme-substrate complex. Ethyl-α-D-glucopyranoside (IC(50)=0.19 mg mL(-1)), isolated for the first time from sea cucumber, and adenosine (IC(50)=0.13 mg mL(-1)), were identified as key tyrosinase inhibitors. CONCLUSION The sea cucumber extracts were demonstrated to possess considerable inhibitory potency against the diphenolase activity of tyrosinase, suggesting that the sea cucumber may be a good source of safe and effective tyrosinase inhibitors.

Cultivation and Conservation of Indonesian Native Fish (Rasbora lateristriata) Through Fish Farmer Group Empowerment in Yogyakarta

Wader pari (Rasbora lateristriata) is one of the Indonesian endemic fish, which is very popular, especially for culinary delicacy. As consequence, the fish is currently undergoing massive exploitation in the wild, due to high market demand. The lack of public awareness of the importance of conservation is one of the reasons that until recently there is no cultivation and conservation program for wader pari fish, which should be encouraged for maintaining the availability of wader fish in nature. We initiated the implementation of integrated fish cultivation and conservation program since 2015, with Handayani and Mandiri Sejahtera fish farmer group, of Kulon Progo and Sleman regency, respectively. The implementation programs consisted of five stages as follows: (1) introduction of the fish conservation concept as initial step, (2) farmer training programs for fish biology, (3) reproduction techniques and cultivation technology, (4) fish cultivation implementation for fry production, and (5) evaluation program. Overall results showed that we succeed to cultivate wader pari at the cultivation pond.

Anti-stress activity of Sargassum polycystum extracts using a cold restraint stress model

Anti-stress effects of polyphenol extracts of Sargassum polycystum were evaluated. Polyphenol extracts of S. polycystum and diazepam were compared for anti-stress activities using a cold restraint animal stress model. S. polycystum extracts were administered orally at dosages of 150 and 450 mg/kg. Diazepam, an anti-stress agent, was used as a standard drug at 0.18 mg/kg p.o. Both dosages of S. polycystum extracts showed good anti-stress effects. Due to cold restraint stress there was an imbalance in levels of biochemical parameters, including glucose, triglycerides, cholesterol, alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate amino transferase (AST), which were near normalized following adminstration of S. polycystum extracts. Polyphenol extracts of S. polycystum at oral dosages of 150 and 450 mg/kg exerted anti-stress effects.

Ketahanan Bakteri Psikotrofik dari Produk Perikanan Segar terhadap Bakteriosin

Fresh fishery products are highly perishable and susceptible to spoilage caused by rapid growth and activity of bacteria. Psychotropic bacteria are the major microorganisms responsible for spoilage when these products stored in ice or under refrigeration. The purposes of this study were to isolate psychrotrophic bacteria from fresh fishery products and to evaluate its resistance to bacteriocins. Fresh fishery products (kembung fish, shrimp, shellfish) samples were obtained from Demangan and Kranggan traditional market. Colony count methods were used to enumerate bacteria, whereas isolation and identification of bacteria was performed by the identification method of Lahallec and Colin (1995). The identification conducted were covering Gram staining and cell morphological examintaion (cell form), motilitym presence or absence of an oxidise, mode of glucose utilization, and capacity for glucose or lactose fermentation, H2S production, and gas production. The resistance assyas by bacteriocin were carried out using agar diffusion method. Seventeen isolates were found abd they were classified as Pseudomonas, Xanthomonas, and Flavobacterium/ Cytophaga. The results show that psychrotropic bacteria resistance to supernatant of lactic acid bacteria and nisin.

Aplikasi Campuran Alginat dari Sargassum crassifolium dan Gum sebagai Pengental Textile Printing

Penelitian aplikasi campuran alginat dari Sargassum crassifolium dan gum untuk meningkatkan viskositas alginat sebagai pengental pada textile printing telah dilakukan. Viskositas campuran alginat dengan guar gum, gum arab, dan locust bean gum diamati pada penyimpanan selama 8 jam. Produk terbaik diujikan sebagai pengental pada textile printing. Campuran alginat dengan guar gum pada perbandingan 90:10 dan 80:20 meningkatkan viskositas dan stabilitas alginat selama penyimpanan. Campuran alginat dengan gum arab dan locust bean gum akan menurunkan viskositas alginat sehingga tidak sesuai untuk aplikasi textile printing. Aplikasi campuran alginat dengan guar gum 90:10 dan 80:20 sebagai pengental pada tekstil printing menghasilkan produk akhir yang setara dengan pengental komersial manutex.

KARAKTERISTIK SURIMI DARI CAMPURAN DAGING MANYUNG DAN CUCUT

Manyung ( Arius spp.) and shark ( Carcharhinus sp.) are the most of low value fishes in Yogya. In order to increase the value, the fishes were processed into surimi. In this research, fishes were mixed in different ratio of manyung and shark, namely 90%:10%, 70%:30%, 50%:50%, 30%:70%, and 10%:90%. The water content, protein content, lipid content, sensory properties and gel strength were determined. The result showed that surimi from manyung and shark in ratio of 90%:10% produced the highest folding test value (AA) and the highest score of sensory properties.

KEMAMPUAN PEMBENTUKAN GEL SURIMI MANYUNG (Arius spp.) PADA BERBAGAI KONDISI PEMANASAN DAN PENCUCIAN

Manyung is one of low value fish in Yogyakarta. In order to increase the value, manyung was processed into surimi. In this research, manyung was processed into surimi with different heating temperatures (40, 45, 50, 55, 60, and 70 o C) and washing time frequency (0, 1, 2, 3, 4, and 5 times) to investigate the gel properties of manyung surimi. Gel strength of manyung surimi increased as washing time treatment increased from 0 to 5 times. Statistical analysis showed that the 4 washing time and 5 washing time have similar gel strength and sensory characteristics. Manyung surimi with 5 washing time and pre-incubation at 60 o C followed by cooking at 90 o C produced the highest gel strength.