Kyoung Hwa Jang

Hydroxy‐α‐sanshool activates TRPV1 and TRPA1 in sensory neurons

Sanshools are major active ingredients of Zanthoxylum piperitum and are used as food additives in East Asia. Sanshools cause irritant, tingling and sometimes paresthetic sensations on the tongue. However, the molecular mechanism underlying the pungent or tingling sensation induced by sanshools is not known. Because many transient receptor potential (TRP) channels are responsible for the sensations induced by various spices and food additives, we expressed 17 TRP channels in human embryonic kidney (HEK) cells and investigated their activation by hydroxy‐α‐sanshool (HαSS) or hydroxy‐β‐sanshool (HβSS) isolated from Zanthoxylum piperitum. It was found that HαSS, but not HβSS, depolarized sensory neurons with concomitant firing of action potentials and evoked inward currents. Among 17 TRP channels expressed in HEK cells, HαSS caused Ca2+ influx in cells transfected with TRPV1 or TRPA1, and evoked robust inward currents in cells transfected with TRPV1 or TRPA1. In primary cultured sensory neurons, HαSS induced inward currents and Ca2+ influx in a capsazepine‐dependent manner. Moreover, HαSS‐induced currents and Ca2+ influx were greatly diminished in TRPV1–/– mice. HαSS evoked licking behavior when injected into a single hind paw of wild‐type mice, but this was much reduced in TRPV1‐deficient mice. These results indicate that TRPV1 and TRPA1 are molecular targets of HαSS in sensory neurons. We conclude that the activations of TRPV1 and TRPA1 by HαSS explain its unique pungent, tingling sensation.

Meroditerpenoids from the Brown Alga Sargassum siliquastrum

Eleven new meroditerpenoids (7-11, 14-17, 19, 20) and nine known compounds (1-6, 12, 13, 18) were isolated from the brown alga Sargassum siliquastrum. Combined chemical and spectroscopic analyses revealed a common tetraprenyl hydroquinone structure; these compounds belonged to the nahocol, isonahocol, and sargahydroquinoic acid classes. The dihydroquinone moiety of 20 was unique and unprecedented in a brown alga. Stereochemical assignments were made for several of the known compounds based on their chemical reactivity. These compounds exhibited moderate to significant radical-scavenging activity as well as weak inhibitory activities against sortase A and isocitrate lyase.

Haliclonin A, a New Macrocyclic Diamide from the Sponge Haliclona sp.

Haliclonin A (1), a macrocyclic diamide of a novel skeletal class, was isolated from the marine sponge Haliclona sp. collected from Korean waters. The structure of this compound was determined using a combination of spectroscopic and chemical analyses. The new compound exhibited moderate cytotoxicity and antibacterial activity against diverse microbial strains.

Acremostrictin, a Highly Oxygenated Metabolite from the Marine Fungus Acremonium strictum

The novel natural product acremostrictin was isolated from the culture broth of Acremonium strictum, a marine fungus collected from a Choristida sponge off the coast of Korea. Structurally, acremostrictin is a tricyclic lactone of an unprecedented skeletal class based on combined spectroscopic and X-ray crystallographic analyses. The new compound exhibited weak antibacterial and moderate antioxidant activities.

Monoglycerides from the brown alga Sargassum sagamianum: Isolation, synthesis, and biological activity.

Polyunsaturated fatty acid-derived monoglycerides were characterized from the marine brown alga Sargassum sagamianum, collected from Jeju Island, Korea. A new compound of this structural class was isolated and determined to be 1-octadecatetraenoyl glycerol, by combined spectroscopic methods. Based on the structures and bioactivity of these compounds, a series of monoglycerides were synthesized using glycerol and various fatty acids. Several compounds exhibited moderate to significant inhibition of phospholipase A(2) and cyclooxygenase-2.

Sesterterpenoids from the Sponge Sarcotragus sp.

Nineteen new sesterterpenoids and eight known compounds were isolated from the sponge Sarcotragus sp. collected from Soheuksan Island, Korea. The structures of these compounds were determined to be linear sesterterpenoids containing furan or related oxygenated functionalities on the basis of combined chemical and spectroscopic analyses. In addition, the configurations of several previously undetermined compounds were assigned. Several compounds exhibited moderate to major antibacterial activity (compounds 1- 3, 17, 18) and cytotoxicity ( 3, 11, 12) against the K562 cell line and inhibitory activity against isocitrate lyase ( 6, 13).

New polyunsaturated fatty acid amides isolated from the seeds of Zanthoxylum piperitum

Five linear fatty acid amides (1–5) of the sandshool class, including two new compounds, were isolated from Zanthoxylum piperitum seeds. Based on combined spectral analyses, the structures of new compounds 4 and 5 were determined to be 2′,3′-dihydroxy-α-sanshool and 2′,3′-dihydroxy-β-sanshool, respectively. These compounds exhibited weak cytotoxicity in the A-549 (human lung cancer) cell line.

Polyoxygenated diterpenes from the sponge Phorbas sp.

Ten new polyoxygenated diterpenes (7-16) along with six known gagunin compounds (1-6) were isolated from the sponge Phorbas sp. collected in the Korean Sea. On the basis of a combination of NMR and mass spectroscopic analyses, the molecular structures of these diterpenes, designated as gagunins H-Q, were determined to be penta- or hexa-oxygenated diterpenes of the 10,13-bis-epi-homoverrucosane class. A new diterpene acid (17) of a bisabolane-related skeletal class was also isolated and structurally defined by the spectroscopic analyses. These compounds exhibited moderate to significant cytotoxicity against the K-562 cell line as well as weak inhibitory activity against isocitrate lyase (ICL).

Sesquiterpenes from the leaves of Laurus nobilis L.

Ten sesquiterpenes, together with 12 known compounds were isolated from leaves of Laurus nobilis L. Based on spectroscopic analyses, the 10 compounds were determined to be eudesmane lactones and their corresponding methyl esters. Most of these compounds exhibited moderate-to-significant cytotoxicity towards K562 leukemia cells. One compound had a higher cytotoxicity than doxorubicin, while other compounds had moderate to no activity.

Cyclic Bis-1,3-dialkylpyridiniums from the sponge Haliclona sp.

Eight novel cyclic bis-1,3-dialkylpyridiniums, as well as two known compounds from the cyclostellettamine class, were isolated from the sponge Haliclona sp. from Korea. Structures of these novel compounds were determined using combined NMR and FAB-MS/MS analyses. Several of these compounds exhibited moderate cytotoxic and antibacterial activities against A549 cell-line and Gram-positive strains, respectively. The structure-activity relationships of cyclostellettamines are discussed based on their bioactivities.