Antioxidant properties of clove bud have been widely studied due to its potential use in the pharmaceuticals field. One of the chemical bioactive compounds that show antioxidant activity is flavonoid. Our study revealed that the flavonoid content of ethanol-derived extract of clove bud was approximately 93.245 mg QE/100 gram. Less is known regarding the mode of actions of antioxidant from clove bud in cellular systems. In this study, we used model organism yeast Saccharomyces cerevisiae to study the action of antioxidant activity in cellular systems. We found that ethanol-derived clove bud extract (100 ppm) enhanced cells viability following H2O2-induced oxidative stress. Interestingly, clove bud extract increased yeast-antioxidative stress tolerance phenotype in a dose-independent manner. Suggesting, prooxidant activity of clove bud extract. Mitochondria have been known to involve in oxidative stress tolerance mechanisms primarily via mitochondrial adaptive ROS-signaling. Our data revealed that yeast mitochondrial membrane potential was unchanged following 100 ppm extract treatment yet significantly increased in higher extract treatment. Our study indicated that 100 ppm extract-supplementation in yeast culture resulted in a higher survival rate of yeast after 15-days of incubation, compared to that without extract treatments. We suggest that clove bud extract (100 ppm) could enhance oxidative stress tolerance phenotype in yeast S. cerevisiae, which then attributed on life span extension through its ROS scavenging activity. Further study must be conducted to confirm the underlying mechanisms of clove bud extract both physiologically and genetically.

Ketersediaan sumber pakan yang rendah menjadi salah satu permasalahan yang dihadapi petani madu lebah A. dorsata di Kampar, Riau. Aktivitas lebah terdiri dari spatial learning atau pengenalan lingkungan, foraging atau mencari sumber pakan dan aktivitas migrasi. Penelitian bertujuan  menganalisis aktivitas terbang lebah dan mengidentifikasi keanekaragaman polen yang ada di dalam madu. Pengamatan aktivitas terbang dilakukan dengan menghitung aktivitas keluar sarang, masuk sarang tanpa polen dan masuk sarang dengan polen selama 3 hari dengan 3 interval waktu. Polen didapatkan dari madu asal Kampar, Riau. Aktivitas lebah A. dorsata keluar sarang, masuk ke sarang tanpa polen dan masuk ke sarang dengan polen selama 3 hari paling tinggi berada pada pukul 11-12, yang merupakan bukan waktu terbang untuk mencari nektar dan polen pada umumnya. Aktivitas terbang meningkat seiring dengan meningkatnya suhu dan intensitas cahaya. Sebanyak 13 spesies tumbuhan yang menjadi sumber pakan A. dorsata terdiri atas habitus pohon, perdu, semak dan herba. Jumlah persentase polen paling banyak yang menjadi sumber pakan A. dorsata merupakan habitus pohon yaitu Pentace sp. (64%), Eucalyptus alba (22.9%) dan Elaeis guineensis (4%).

A total of 6 fungi isolates of growing at pH 9 and 2 isolates on pH 10 with amylolytic indexes 0f 0.07-1.42 have been isolated from cassava starch liquid waste. Two isolates having the highest amylolytic index were identified as Aspergillus sydowii K10 (1.42) and Aspergillus versicolor L30 (1.4). Both A. sydowii K10 and A. versicolor L30 were described as alcalotolerant for being able to grow with range pH 5-10. The optimal -amylases production of A. sydowii K10 and A. versicolor L30 was obtained after 4 and 3 days of incubation at 300C. The optimum of -amylase activity from A. sydowii K10 was at 400C and 700C, and pH 6; while those from A. versicolor L30 was at 500C and pH 6 respectively. Both A. sydowii K10 and A. versicolor L30 could produce glucoamylase. The optimum of glucoamylase activity from A. sydowii K10 was at 400C and pH 5, while those from A. versicolor L30 was at 500C and pH 5 respectively.

Abstract. Abubakar H, Astuti RI, Listyowati S, Batubara I, Wahyudi AT. 2022. An orange pigment from the marine bacterium Paracoccus haeundaensis SAB E11 as a prospective source of natural antioxidants. Biodiversitas 23: 4730-4737. Bacterial pigment extracts are the source of many natural antioxidant substances. The present study aimed to assess the antioxidant activity of an orange pigment derived from a marine bacterium, identified as Paracoccus haeundaensis SAB E11, analyzed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis(ethylbenzothiazoline-6-sulfonic acid) (ABTS). Methanol-pigmented crude extract of P. haeundaensis SAB E11 exhibited the best DPPH scavenging activity with an IC50 value of 54.7 mg/mL, while the n-hexane crude pigment extract of the bacterium reduced ABTS optimally with an IC50 value of 24.46 mg/mL. The analysis of antioxidant compounds in P. haeundaensis SAB E11 was identified by combining liquid chromatography with tandem mass spectrometry (LCMS/MS). The five antioxidant compounds from methanol and n-hexane crude pigment extract of P. haeundaensis SAB E11 have been detected. Polyphenols were found to be the major compound, such as 3,5,3’,4’-tetrahydroxystilbene, scopoletin, and liquiritigenin. The other compounds were dihydroactinidiolide (terpenes) and ricinoleic acid (a fatty acid compound). The orange-colored extract of marine bacterium P. haeundaensis SAB E11 could be promising pharmacological capabilities as an antioxidant.