Known antimicrobial peptides KT2 and RT2 as well as the novel RP9 derived from the leukocyte extract of the freshwater crocodile (Crocodylus siamensis) were used to evaluate the ability in killing human cervical cancer cells. RP9 in the extract was purified by a combination of anion exchange column and reversed-phase HPLC, and its sequence was analyzed by mass spectrometry. The novel peptide could inhibit Gram-negative Vibrio cholerae (clinical isolation) and Gram-positive Bacillus pumilus TISTR 905, and its MIC values were 61.2 µM. From scanning electron microscopy, the peptide was seen to affect bacterial surfaces directly. KT2 and RT2, which are designed antimicrobial peptides using the C. siamensis Leucrocin I template, as well as RP9 were chemically synthesized for investigation of anticancer activity. By Sulforhodamine B colorimetric assay, these antimicrobial peptides could inhibit both HeLa and CaSki cancer cell lines. The IC50 values of KT2 and RT2 for HeLa and CaSki cells showed 28.7-53.4 and 17.3-30.8 µM, while those of RP9 were 126.2 and 168.3 µM, respectively. Additionally, the best candidate peptides KT2 and RT2 were used to determine the apoptotic induction on cancer cells by human apoptosis array assay. As a result, KT2 and RT2 were observed to induce apoptotic cell death in HeLa cells. Therefore, these results indicate that KT2 and RT2 with antimicrobial activity have a highly potent ability to kill human cervical cancer cells.

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Antioxidant peptides were isolated from the leukocyte extract of the Siamese crocodile, Crocodylus siamensis. Crocodile leukocyte was extracted by a combination of methods including freeze-thawing, acetic acid extraction and homogenization. The peptides in the leukocyte extract were purified by anion exchange chromatography and reversed phase-high performance liquid chromatography. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay was used to evaluate the antioxidant activity of the elution peaks at each purification step. As a result, there were two purified peptides exhibiting strong antioxidant activity in reducing free radicals on DPPH molecules. The amino acid sequences of these peptides were determined by LC-MS/MS as TDVLGLPAK (912.5 Da) and DPNAALPAGPR (1,148.6 Da), and their IC₅₀ values were 153.4 and 95.7 μM, respectively. The results of this study therefore indicate that leukocyte extract of C. siamensis contains peptides with antioxidant activity which could be used as a novel antioxidant.

Leucrocin I is an antibacterial peptide isolated from crocodile (Crocodylus siamensis) white blood cell extracts. Based on Leucrocin I sequence, cationic peptide, NY15, was designed, synthesized and evaluated for antibacterial activity against Bacillus sphaericus TISTR 678, Bacillus megaterium (clinical isolate), Vibrio cholerae (clinical isolate), Salmonella typhi (clinical isolate), Salmonella typhi ATCC 5784 and Escherichia coli 0157:H7. The efficacy of the peptide made from all L-amino acids was also compared with all D-amino acids. The peptide made from all D-amino acids was more active than the corresponding L-enantiomer. In our detailed study, the interaction between peptides and the cell membrane of Vibrio cholerae as part of their killing mechanism was studied by fluorescence and electron microscopy. The results show that the membrane was the target of action of the peptides. Finally, the cytotoxicity assays revealed that both L-NY15 and D-NY15 peptides are non-toxic to mammalian cells at bacteriolytic concentrations.

Novel antioxidant and anti-inflammatory peptides were isolated from hydrolysates of Siamese crocodile (Crocodylus siamensis) hemoglobin. C. siamensis hemoglobin hydrolysates (CHHs) were obtained by pepsin digestion at different incubation times (2, 4, 6, and 8 H) at 37 °C and subjected to antioxidant and anti-inflammatory activity assessment. CHH obtained by 2-H hydrolysis (2H-CHH) showed the highest anti-inflammatory activity with respect to decreasing nitric oxide (NO) production, whereas the strongest antioxidant activity was found for 6-H hydrolysis (6H-CHH) against nitric oxide radicals. To evaluate the anti-inflammatory and antioxidant activity of individual peptide components, 2H-CHH and 6H-CHH were purified by semipreparative HPLC. Peptide fraction P57 isolated from 6H-CHH was found to exhibit the highest nitric oxide radical inhibition activity (32.0%). Moreover, purification of 2H-CHH yielded peptide fraction P16, which displayed a high efficacy in decreasing NO production of macrophage RAW 264.7 cells (83.2%) and significantly reduced proinflammatory cytokines and inflammatory mediators interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and prostaglandin-E2 (PGE ) production to about 2.0, 0.3, and 1.9 ng/mL, respectively. Using LTQ orbitrap XL mass spectrometry, active peptide sequences were identified as antioxidant KIYFPHF (KF7), anti-inflammatory SAFNPHEKQ (SQ9), and IIHNEKVQAHGKKVL (IL15). Additionally, CHHs simulated gastric and intestinal in vitro digestion positively contributed to antioxidant and anti-inflammatory activity. Taken collectively, the results of this work demonstrate that CHHs contain several peptides with anti-inflammatory and antioxidant properties, which may prove valuable as treatment or supplement against diseases associated with inflammation and oxidative stress.

Objectives Cutibacterium acnes is one of the common multifactorial causes that play an important role in the pathophysiology of acne vulgaris. We aimed to develop novel antimicrobial peptides for reduction of the hypercolonization. Methods Six cationic peptides were derived by de novo designation. The antimicrobial and cytotoxic activities of peptides were investigated. The peptide conformation was determined by circular dichroism spectrometry. The antimicrobial effects of peptides were evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and DNA-binding ability assay. Results Among designed peptides, WSKK11 and WSRR11 were effective antimicrobials against C. acnes at MICs of 128 and 64 mg/L, respectively. The MICs of WSKK11 against Staphylococcus epidermidis, Staphylococcus aureus and Candida albicans were 8, 8 and 32 mg/L, while those of WSRR11 were 64, 32 and 32 mg/L, respectively. WSKK11 and WSRR11 were less toxic to human erythrocytes (<2%) and not toxic to macrophages, keratinocytes and fibroblasts up to 512 mg/L. WSKK11 and WSRR11 mostly revealed the conformation of the undefined or random coil structures under mimicked environmental conditions. The peptides affected cell surfaces and cell membranes of C. acnes as well as possibly translocating through the cell membrane, observed by a combination of SEM and TEM, respectively. WSKK11 and WSRR11 had the ability to bind bacterial DNA. Conclusions The two novel antimicrobial peptides WSKK11 and WSRR11 are members of a new class of antimicrobial agents that could deal with acne problems. Therefore, the antimicrobial peptides may be promising novel active agents for dermatological, beauty and cosmeceutical applications.

The investigation into promising botanical materials for natural cosmetics is expanding due to environmental and health awareness. Here, we aimed to evaluate the phytochemical substances and the potential skin-related pharmacological activities of four Mucuna seeds, namely M. gigantea (Willd.) DC. (MGG), M. interrupta Gagnep. (MIT), M. monosperma Wight (MMM), and M. pruriens (L.) DC. (MPR), belonging to the Fabaceae family. In methodology, the Mucuna seeds were authenticated using morphological and molecular approaches. L-DOPA, phenolics, and flavonoid content, incorporated with HPLC and GC–MS fingerprinting analyses, were determined. Then, skin-related antimicrobial, antioxidant, and antiaging activities were determined. The results revealed that MPR showed the highest L-DOPA content (75.94 mg/100 mg extract), whereas MGG exhibited the highest phenolic and flavonoid content (56.73 ± 0.62 mg gallic/g extract and 1030.11 ± 3.97 mg quercetin/g extract, respectively). Only MMM and MPR could inhibit all of S. aureus, S. epidermidis, and C. albicans, but no sample could inhibit C. acnes. Furthermore, all samples demonstrated antioxidant activity. Interestingly, all Mucuna samples exhibited strong collagenase, elastase, and hyaluronidase inhibitory activities. We conclude that the ethanolic extracts of four Mucuna seeds are probably advantageous in the development of skincare cosmeceutical products.

Although many biological properties of Houttuynia cordata have been found, its anti-aging and anti-acne effects have not yet been investigated. This study was aimed to evaluate the in vitro anti-aging and anti-acne activities of H. cordata extracts and their cytotoxic activities and phytochemicals analyzed with liquid chromatography with tandem mass spectrometry (LC-MS/MS). Dried aerial parts of H. cordata were given different extractions. The aqueous and ethanolic extracts obtained were named HCA and HCE, respectively, and used to screen total phenolic and flavonoid contents. In vitro anti-aging, skin-related antimicrobial, scanning electron microscopy (SEM), in vitro cytotoxic, and LC-MS/MS analyses were performed. The total phenolic contents of the HCA and HCE were 5.11 ± 0.25 and 27.02 ± 1.07 mg gallic acid equivalent (GAE)/g dry extract while their total flavonoid contents were 104.94 ± 5.16 and 571.86 ± 2.86 mg quercetin equivalent (QE)/g dry extract, respectively. The HCA and HCE inhibited the activities of collagenase (28.33–46.00%), elastase (30.00–34.33%), and hyaluronidase (93.87–98.72%). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the HCA against Cutibacterium acnes DMST14916 were 5.77 and 5.77 mg/mL while those of the HCE were 2.47 and 2.47 mg/mL, respectively. Cell collapses of C. acnes after treatment with the extracts were observed with SEM. The HCE was not toxic to macrophages, keratinocytes, and fibroblasts up to 400 mg/mL. The HCA showed toxicity against macrophages at 62.5 mg/mL and both skin cells at 250 mg/mL. The main phytochemicals in the extracts were identified with LC-MS/MS. Phenolic compounds, flavonoids, and flavonoid derivatives in H. cordata extracts could be major phytochemicals to possess a broad spectrum of biological activities including antioxidant, antimicrobial, and anti-aging activities. The findings from this study showed that the HCE has potential anti-aging and anti-acne properties while having non-cytotoxic activities on the immune and skin cells. These results indicate that the extract is probably advantageous in the development of skincare cosmeceutics and beauty treatments.