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The emergence of multi-resistant strains of bacteria reinforces the need to discover new antibacterial agents that are able to combat resistant microorganisms. Medicinal plants are a valuable natural source of bioactive substances against various infectious diseases. Melastoma malabathricum L. is an important herb that is traditionally used to treat several ailments associated with microbial infection diseases such as wounds, diarrhea, dysentery, and toothache. This study investigated extracts of M. malabathricum L. for antibacterial properties against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA). Disc diffusion and TLC-contact bioautography techniques were employed to examine antibacterial properties of n-hexane, ethyl acetate, and ethanol extracts with observations of diameter inhibition zones and Rf values. Investigation of active compounds in TLC-bioautography used several reagents including citroboric, cerium (IV) sulfate and 2,2-diphenyl-1-picrylhydrazyl (DPPH), continued by identification of chromatogram profiles through densitometry analysis. The three extracts showed good inhibition against bacterial strains with diameter inhibition zones in the range of 8.0 – 14.0 mm with a number of active spots on TLC-contact bioautography for each extract. This plant may serve as useful source of antibacterial agents for resistant microorganisms and further investigation is needed of its bioactive pure compounds as well as their particular therapeutic potentials and applications.

Tuna skin, a byproduct of the fish processing industry, is used as an alternative collagen source to replace bovine and porcine products. This study aimed to extract collagen from tuna skin with acetic acid, and investigated the antioxidant activity. Collagen extraction was carried out through a pretreatment process, defatted with butyl alcohol, and soaking in acetic acid to extract the Acid Soluble Collagen (ASC). The effect of concentration of sodium hydroxide and soaking time on the non-collagenous protein removed were measured, and evaluated. The yield and antioxidant activity of each sample were evaluated and the best result was determined by ANOVA. The highest yield of collagen was 3.18% based on dry weight reached at the treatment with sodium hydroxide 0.2 M and acetic acid 1 M. The different treatments did not result in any significant differences in the spectrum of amide A, B, I, II and III which are the characteristics spectra of collagen. Based on the electrophoretic pattern, tuna skin collagen has two  chains (1 and 2), and one β chain. Therefore, it is classified as type I collagen. The main amino acids were glycine and proline. In addition, the strongest antioxidant activity was found in the sample treated with sodium hydroxide 0.05 M and acetic acid 1 M treatment with IC50 value of 0.45 mg/mL. This study is the first to report on antioxidant activity from fish collagen (not hydrolysate or peptide products).

Melastoma malabathricum is an Indo-Pacific herb that has been used traditionally to treat numerous ailments such as wounds, dysentery, diarrhea, toothache, and diabetes. The objective of this study was to evaluate the variability of the metabolic profiles of M. malabathricum across its geographic distribution. By employing thin layer chromatography (TLC), specimens collected from six terrestrial and archipelago regions of Indonesia were analyzed by densitometry for metabolomic fingerprinting analysis combined with chemometric tools: principal component analysis (PCA) and hierarchical cluster analysis (HCA). Two PCAs were identified as PC1 and PC2 with 41.90% and 20.36%, respectively. Our results indicate the importance of considering geographic distribution during field-collection efforts since they demonstrate regional metabolic variation in secondary metabolites of M. malabathricum, as illustrated by TLC and their biological activities.

Mangkokan is one of traditional medicinal plants that has many benefits in restoring health, such as preventing hair loss, treating wounds, antibacterial agent, improving blood circulation and as an antioxidant agent. This study aimed to examine the activity of the ethanol extract of the mangkokan leaf (Polyscias scutellarium (Burm.f.) Fosberg) against Escherichia coli and Staphylococcus aureus. The extraction process was carried out by gradual maceration through three solvents including n-hexane, ethyl acetate, and ethanol. The antibacterial activity test was carried out by agar diffusion method by calculating diameter of the inhibition zone from ethanol extract of mangkokan leaf with four variation concentrations: 20%, 40%, 60%, and 80%. The antibacterial activity of the ethanolic extract of the mangkokan leaf against Escherichia coli resulted in the average diameter od the inhibition zone at the following concentrations: 20% (5,9 mm), 40% (5,2 mm), 60% (5,9 mm), dan 80% (7,03 mm. While antibacterial test against Staphylococcus aures resulted in the average diameter of the inhibition zone at the following concentrations: 20% (9,66 mm), 40% (10,71 mm), 60% (11,27 mm), 80% (12,42 mm).