A new mono-hydroxy acetylated sterol derivative: 12β-hydroxy-3β, 15α, 16β-triacetoxy-cholest-5-en-7-one (halymeniaol) (1), and cholesterol (2) were isolated from the marine red alga Halymenia floresii. The structure of the compound 1 (halymeniaol) was established from its spectral data, derived from HRMS/MS and 2D NMR. Compound 1 exhibited growth inhibitory activity against chloroquine-resistant Plasmodium falciparum 3D7 strain with an IC of 3.0 μM.

The structure of a new cysteine framework (-C-CC-C-C-C-) "M"-superfamily conotoxin, Mo3964, shows it to have a β-sandwich structure that is stabilized by inter-sheet cross disulfide bonds. Mo3964 decreases outward K(+) currents in rat dorsal root ganglion neurons and increases the reversal potential of the NaV1.2 channels. The structure of Mo3964 (PDB ID: 2MW7 ) is constructed from the disulfide connectivity pattern, i.e., 1-3, 2-5, and 4-6, that is hitherto undescribed for the "M"-superfamily conotoxins. The tertiary structural fold has not been described for any of the known conus peptides. NOE (549), dihedral angle (84), and hydrogen bond (28) restraints, obtained by measurement of (h3)JNC' scalar couplings, were used as input for structure calculation. The ensemble of structures showed a backbone root mean square deviation of 0.68 ± 0.18 Å, with 87% and 13% of the backbone dihedral (ϕ, ψ) angles lying in the most favored and additional allowed regions of the Ramachandran map. The conotoxin Mo3964 represents a new bioactive peptide fold that is stabilized by disulfide bonds and adds to the existing repertoire of scaffolds that can be used to design stable bioactive peptide molecules.

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Developing new antibiotics, it is becoming increasingly difcult, with greater time-consuming and more expensive to develop new antibiotics, especially because emerging strains are becoming increasingly resistant to existing antibiotics. Phytochemically, saponins are plant secondary metabolites with powerful therapeutic effects and there are several scientic evidences that plant saponins are potent pharmacological agents. In this study, Effect of Saponins derived from the leaves of Sapindus mukorossi on prevalent bacterial pathogens growth and efux-pump activity were tested on Pseudomonas aeruginosa and Staphylococcus aureus. An antibiotic standard ampicillin was comparable to the inhibitory effects of saponins at 1.80 mg/mL of concentration on bacterial growth. The saponins from Sapindus mukorossi had showed a MIC of 0.0036 mg/mL and an MBC of 0.96 mg/mL, making them the most effective against S. aureus and P. aeruginosa. It was proven that plant saponins had bacteriostatic effects on P. aeruginosa and S. aureus. Sapindus mukorossi saponins inhibited the drug efux pump susceptible in P. aeruginosa, which resulted in a 132% increase in Rhodamine-6G accumulations compared to the control. As a result, Leaf saponins from Sapindus mukorossi exhibited antibacterial activity as well as the ability to inhibit the compounds energy dependent transport across cell membranes, and these saponins can be used as potential principal composites for the development of herbal based anti-pathogenic bacterial agents and their adjunct composites

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