Skrining Fitokimia dan Uji Aktivitas Antibakteri Fraksi Etil Asetat dan n-Heksana dari Daun Mangga Kasturi (Mangifera casturi Kosterm.)

Kasturi mango (Mangifera casturi Kosterm.) is a typical mango of South Kalimantan. Kasturi mango leaves are reported to have antioxidant activity and are potential for treating various diseases, including diseases related to antibacterial. This study examines the antibacterial activity of ethyl acetate fraction and the n-hexane fraction of mango musk leaves on bacteria that cause acne. Experimental research started with plant determination, making extracts and fractions, phytochemical screening, and antibacterial testing against Staphylococcus aureus and Propionibacterium acnes using the disk diffusion method. The study results found that the ethyl acetate and n-hexane fractions had weak antibacterial activity against S. aureus and P. acnes bacteria, which cause acne

Brevinin-2GHk, a Peptide Derived from the Skin of Fejervarya limnocharis, Inhibits Zika Virus Infection by Disrupting Viral Integrity

Several years have passed since the Zika virus (ZIKV) pandemic reoccurred in 2015–2016. However, there is still a lack of proved protective vaccines or effective drugs against ZIKV. The peptide brevinin-2GHk (BR2GK), pertaining to the brevinin-2 family of antimicrobial peptides, has been reported to exhibit only weak antibacterial activity, and its antiviral effects have not been investigated. Thus, we analyzed the effect of BR2GK on ZIKV infection. BR2GK showed significant inhibitory activity in the early and middle stages of ZIKV infection, with negligible cytotoxicity. Furthermore, BR2GK was suggested to bind with ZIKV E protein and disrupt the integrity of the envelope, thus directly inactivating ZIKV. In addition, BR2GK can also penetrate the cell membrane, which may contribute to inhibition of the middle stage of ZIKV infection. BR2GK blocked ZIKV E protein expression with an IC50 of 3.408 ± 0.738 μΜ. In summary, BR2GK was found to be a multi-functional candidate and a potential lead compound for further development of anti-ZIKV drugs.

Understanding the Mechanism of Action of NAI-112, a Lanthipeptide with Potent Antinociceptive Activity

NAI-112, a glycosylated, labionine-containing lanthipeptide with weak antibacterial activity, has demonstrated analgesic activity in relevant mouse models of nociceptive and neuropathic pain. However, the mechanism(s) through which NAI-112 exerts its analgesic and antibacterial activities is not known. In this study, we analyzed changes in the spinal cord lipidome resulting from treatment with NAI-112 of naive and in-pain mice. Notably, NAI-112 led to an increase in phosphatidic acid levels in both no-pain and pain models and to a decrease in lysophosphatidic acid levels in the pain model only. We also showed that NAI-112 can form complexes with dipalmitoyl-phosphatidic acid and that Staphylococcus aureus can become resistant to NAI-112 through serial passages at sub-inhibitory concentrations of the compound. The resulting resistant mutants were phenotypically and genotypically related to vancomycin-insensitive S. aureus strains, suggesting that NAI-112 binds to the peptidoglycan intermediate lipid II. Altogether, our results suggest that NAI-112 binds to phosphate-containing lipids and blocks pain sensation by decreasing levels of lysophosphatidic acid in the TRPV1 pathway.

Cytotoxic and antimicrobial activities of phytoconstituents of the stem bark extract of Psychotria djumaensis

Phytochemical investigation of the stem bark extract of Psychotria djumaensis led to the isolation of ten known pentacyclic triterpenoids among which one lupane-, three oleanane-, and six ursane-types. The structures of the isolated compounds were established by means of spectroscopic methods and by comparison with previously reported data. The isolated compounds were tested against five strains of bacteria, and the cytotoxicity against the human cervix carcinoma KB-3-1 cell was evaluated. The isolates exhibited weak antibacterial activity against the five strains. The cytotoxic activity exhibited by 3β,19α-dihydroxyurs-12-en-28-oic acid (5) (IC50 5.9 µM) was about three times more significant than that of the reference [(+) griseofulvin, IC50 17-21 µM].

Bioactivities of plant extracts collected in Halmahera, Indonesia: A bioprospection study of underexplored plant species

The discovery of new antibiotics to overcome the growing resistance problem as well as the discovery of new natural, safe antioxidants to combat oxidative stress are still urgently needed. Medicinal plants are known to produce potential therapeutic substances which are more biologically selective than synthetic compounds. Therefore, we explored the bioactivities of 35 ethanolic extracts from 24 underexplored plant species collected in Halmahera, to find potential sources for antibacterial and antioxidant agents. Dried plant parts were extracted using ethanol 96%. Thin layer chromatography-direct-bioautography (TLC-DB) and minimum inhibitory concentration (MIC) determination were used to evaluate the antibacterial effect. Antioxidant activity was determined against DPPH using TLC-DB and microdilution assay. Total phenolic content (TPC) was determined using Folin-Ciocalteu’s method. The ethanolic extracts exhibited moderate to weak antibacterial activity against Escherichia coli and Staphylococcus aureus. However, the leaf extract of Elaeocarpus dolichostylus, Elaeocarpus multiflorus, and Psychotria celebica as well as the stem bark extract of Elaeocarpus dolichostylus, Cinnamomum sintoc, and Garcinia latissima displayed very strong antioxidant activities against DPPH with AAI values between 4.60 to 13.42. A strong correlation between TPC and antioxidant activity with r = 0.8712 was observed. Despite the moderate to weak antibacterial activity, eight underexplored plant species exhibit strong antioxidant activities. A high correlation between TPC and antioxidant activity indicating a prominent role of phenolic compounds in the plants’ antioxidant properties. These findings indicate that collected plants from Halmahera are potential to be studied and developed further as the potential sources for novel antioxidants.

Bioactive Polyketide and Diketopiperazine Derivatives from the Mangrove-Sediment-Derived Fungus Aspergillus sp. SCSIO41407

Ten polyketide derivatives (1–10), including a new natural product named (E)-2,4-dihydroxy-3-methyl-6-(2-oxopent-3-en-1-yl) benzaldehyde (1), and five known diketopiperazines (11–15), were isolated from the mangrove-sediment-derived fungus Aspergillus sp. SCSIO41407. The structures of 1–15 were determined via NMR and MS spectroscopic analysis. In a variety of bioactivity screening, 3 showed weak cytotoxicity against the A549 cell line, and 2 exhibited weak antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Compounds 3, 5, and 6 showed inhibition against acetylcholinesterase (AChE) with IC50 values of 23.9, 39.9, and 18.6 μM. Compounds 11, 12, and 14 exhibited obvious inhibitory activities of lipopolysaccharide (LPS)-induced nuclear factor-κB (NF-κB) with IC50 values of 19.2, 20.9, and 8.7 μM, and they also suppressed RANKL-induced osteoclast differentiation in bone marrow macrophages cells (BMMCs), with the concentration of 5 μM. In silico molecular docking with AChE and NF-κB p65 protein were also performed to understand the inhibitory activities, and 1, 11–14 showed obvious protein/ligand-binding effects to the NF-κB p65 protein.

New Alkaloids From a Hawaiian Fungal Strain Aspergillus felis FM324

Two new alkaloids tryptoquivaline Y (1) and pseurotin I (2), together with eight known compounds (3–10), were purified from a fungal strain Aspergillus felis FM324, which was isolated from a Hawaiian beach soil sample. The absolute configuration and physicochemical data of tryptoquivaline Z (3) were reported for the first time here in this paper. Compound 1 is an uncommon tryptoquivaline analog containing a 3-O-isobutanoyl group. The structures of the new compounds 1–2 and known compound 3 were elucidated through HRESIMS, NMR spectroscopy and ECD analysis. All the compounds were evaluated for their antiproliferative, antibacterial and NF-κB inhibitory activities. Compound 4 showed weak antibacterial activity against Staphylococcus aureus, methicillin resistant Staphylococcus aureus and Bacillus subtilis with the same MIC value of 59.2 µM. Compounds 3 and 2 inhibited NF-κB with IC50 values of 26.7 and 30.9 μM, respectively.

Herbicidal activity of fluoroquinolone derivatives

Development of herbicides with novel modes of action are crucial for weed control and to hinder herbicide resistance. An attractive novel herbicidal target is plant DNA gyrase, which has been demonstrated to be effectively inhibited by the known antimicrobial ciprofloxacin. Despite this good herbicidal activity ciprofloxacin is not suitable as a herbicide due to its antimicrobial activity, therefore, a diverse library of analogues was analysed to gain insight into the aspects required for herbicidal activity. This analysis revealed significant structural modifications were tolerated and that the fluoride at C-6 and a cyclic amino group at C-7 were not crucial for herbicidal activity. The analysis also revealed that these modifications also affected the antibacterial activity with one compound demonstrating good herbicidal activity and weak antibacterial activity, against both Gram-positive and Gram-negative bacteria.

Characterization of 2 linear peptides without disulfide bridges from the venom of the spider Lycosa poonaensis (Lycosidae)

ABSTRACT Spider venom is a complex mixture of bioactive components, in which peptides play an important role by showing neurotoxicity or cytotoxicity. Disulfide-rich peptides are major components in the venom, but linear peptides without disulfide bridges are also present and often show antimicrobial activity. In this study, we analyzed the venom of the spider Lycosa poonaensis (Lycosidae) to find novel antimicrobial peptides using mass spectrometry. The result revealed that 120 out of 401 detected components were nondisulfide-bridged peptides. From them, the sequence of 2 peptides (lyp2370 and lyp1987) were determined by MS/MS analysis. The biological activity test revealed that lyp2370 has only weak antibacterial activity. On the other hand, lyp1987, which is identical to M-lycotoxin-Ls3b from the Lycosa singoriensi venom, showed significant antibacterial activity. The weak activity of lyp2370 was found to be due to the presence of a Glu residue on the hydrophilic face of its amphipathic α-helical structure.

Screening of Methanolic Extract for Antimicrobial Activity of Hyphaene thebaica L. Fruit Pulp from Sudanese Folklore

Aim: To evaluate the antimicrobial potential of the methanolic extract of the fruit pulp of Hyphaene thebaica (Doum), a famous natural product in Sudan. Methods: Agar-well diffusion test and minimum inhibition diffusion test (MIC). Results: The investigation revealed that the extract showed no antifungal effect against Aspergillus niger ATCC 6275 and Candida albicans ATCC 10231. While it exhibited remarkable antibacterial activity against Staphylococcus aureus ATCC BAA 1026 and Pseudomonas aeruginosa ATCC 10145. Whereas, weak antibacterial activity was recorded with Bacillus cereus ATCC 10876 and Escherichia coli ATCC 1637. Conclusion: The fruit pulp of Hyphaene thebaica (Doum) has good antibacterial activity against some Gram-positive and Gram-negative bacteria. Accordingly, the consumption of this fruit would exert several beneficial effects by virtue of its antibacterial activity, and further studies using different bacterial strains and clinical pathogens are recommended.