To analyze the chemical composition of the essential oils of Curcuma aeruginosa (C. aeruginosa), Curcuma mangga (C. mangga), and Zingiber cassumunar (Z. cassumunar), and study their antimicrobial activity. Essential oils obtained by steam distillation were analyzed by gas chromatography-mass spectrometry (GC-MS). The antimicrobial activity of the essential oils was evaluated against four bacteria: Bacillus cereus (B. cereus), Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa); and two fungi: Candida albicans (C. albicans) and Cyptococcus neoformans (C. neoformans), using disc-diffusion and broth microdilution methods. Cycloisolongifolene, 8,9-dehydro formyl (35.29%) and dihydrocostunolide (22.51%) were the major compounds in C. aeruginosa oil; whereas caryophyllene oxide (18.71%) and caryophyllene (12.69%) were the major compounds in C. mangga oil; and 2,6,9,9-tetramethyl-2,6,10-cycloundecatrien-1-one (60.77%) and α-caryophyllene (23.92%) were abundant in Z. cassumunar oil. The essential oils displayed varying degrees of antimicrobial activity against all tested microorganisms. C. mangga oil had the highest and most broad-spectrum activity by inhibiting all microorganisms tested, with C. neoformans being the most sensitive microorganism by having the lowest minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of 0.1 μL/mL. C. aeruginosa oil showed mild antimicrobial activity, whereas Z. cassumunar had very low or weak activity against the tested microorganisms. The preliminary results suggest promising antimicrobial properties of C. mangga and C. aeruginosa, which may be useful for food preservation, pharmaceutical treatment and natural therapies.

To investigate the antimicrobial property of mangrove plant Sonneratia alba (S. alba). The antimicrobial activity was evaluated using disc diffusion and microdilution methods against six microorganisms. Soxhlet apparatus was used for extraction with a series of solvents, n-hexane, ethyl acetate and methanol in sequence of increasing polarity. Methanol extract appeared to be the most effective extract while n-hexane extract showed no activity. The antimicrobial activities were observed against the gram positive bacteria Staphylococcus aureus (S. aureus) and Bacillus cereus (B. cereus), the gram negative Escherichia coli (E. coli) and the yeast Cryptococcus neoformans. Pseudomonas aeruginosa and Candida albicans appeared to be not sensitive to the concentrations tested since no inhibition zone was observed. E. coli (17.5 mm) appeared to be the most sensitive strain followed by S. aureus (12.5 mm) and B. cereus (12.5 mm). From this study, it can be concluded that S. alba exhibits antimicrobial activities against certain microorganisms.

Sea cucumbers are marine invertebrates of the phylum of Echinodermata that have been used in Asian traditional medicine since ancient times. This study was conducted to investigate the antioxidant and cytotoxic properties of aqueous and organic extracts from two sea cucumber species, Holothuria edulis Lesson (Holothuriidae) and Stichopus horrens Selenka (Stichopodidae). Antioxidant activities of the extracts were evaluated by DPPH· and β-carotene bleaching assays, while MTT and trypan blue exclusion assays were used to demonstrate the cytotoxic effects of the extracts against two human cancer cell lines, non-small cell lung cancer cells (A549) and esophageal cancer cells (TE1). The results showed that both aqueous and organic extracts of H. edulis were able to scavenge DPH radical (IC50 at 2.04 mg/ml and 8.73 mg/ml, respectively). Aqueous and organic extracts of S. horrens inhibited 79.62% and 46.66% of β-carotene oxidation by linoleate free radical. On the other hand, the organic extract of S. horrens exhibited the highest cytotoxic effects against A549 and TE1 cancer cells giving IC50 at 15.5 and 4.0 μg/ml, respectively. In conclusion, the present study revealed that H. edulis and S. horrens contain promising levels of antioxidant and cytotoxic natural products that might be used for cancer prevention and treatment.

To investigate the antimicrobial activities of n-hexane, ethyl acetate and methanol extracts of the leaves of Lumnitzera littorea (L. littorea) against six human pathogenic microbes. The antimicrobial activity was evaluated using disc diffusion and microdilution methods. The antimicrobial activities of the crude extracts were increased with increasing the concentration. It is clear that n-hexane extract was the most effective extract. Additionally, Gram positive Bacillus cereus (B. cereus) appear to be the most sensitive strain while Pseudomonas aeruginosa (P. aeruginosa) and the yeast strains (Candida albicans (C. albicans) and Cryptococcus neoformans (C. neoformans)) appear to be resistance to the tested concentrations since no inhibition zone was observed. The inhibition of microbial growth at concentration as low as 0.04 mg/mL indicated the potent antimicrobial activity of L. littorea extracts. The obtained results are considered sufficient for further study to isolate the compounds responsible for the activity and suggesting the possibility of finding potent antibacterial agents from L. littorea extracts.

Centaurea damascena a member of Asteraceae family was investigated for its aerial part essential oil composition and antibacterial activities. A total of 35 components were characterized with the presence of oxygenated terpenes that represents more than 86 % of the total essential oil components. The composition was dominated by 11.45 % fokienol, 8.8 % thymol, 8.21 % α-terpineol, 7.24 % chrysanthemic acid, 7.13 % terpinen-4-ol and 6.59 % borneol with a high degree of polymorphism in the occurrence of these compounds as compared with the different species of Centaurea. The antibacterial activity was assessed by using the disc diffusion methods and the minimum inhibition concentrations (MIC) using microdilution method. The essential oils from Centaurea damascena possessed antibacterial activity against eight out of ten tested microorganisms at 5 μg/mL. While same oil showed only inhibitory activity at 20 μg/mL against Klebsiella pneumoniae (BL) and Pseudomonas aeruginosa (BL). The MIC of essential oils of C. damascena ranged from 15-1000 μg/mL. A synergetic effect against E. coli and K. pneumoniae was observed when 5 μg/mL oils were used with some of the ineffective antibiotics such as gentamicin for E. coli and vancomycin, ampicilin and chloramphenicol for K. pneumoniae. The activity of the antibiotic cefixime was increased by 26 % against K. pneumoniae after combination with the oil suggesting using it as potential adjuvant in the antibiotic treatment of pneumonia caused by K. pneumoniae and other ailments caused by oil-susceptible bacteria.