There is a growing interest in the exploitation of agricultural byproducts. This study explored the potential beneficial health effects from the main biowaste, tea seed pomace of Camellia oleifera Abel (Theaceae), produced when tea seed is processed. Eighteen compounds were isolated from the 70% EtOH extract of the seed cake of C. oleifera. Their structures were determined by ESI-MS, H- and C-NMR together with literature data. All fractions and compounds were evaluated for the antioxidant and melanogenesis inhibitory activities. As the result, AcOEt fraction has the best in vitro antioxidant and antimelanogenesis activities, compounds 7 - 12 and 15 showed remarkable antioxidant activity, compounds 4, 6, 8, and 15 - 17 exhibited superior inhibitory activities against melanogenesis. Furthermore, tyrosinase inhibitory activity assay suggested that compound 8 could suppress melanogenesis by inhibiting the expression of tyrosinase.
Main observation and conclusion
The new racemic and dimeric indole alkaloids with the characteristic cyclopenta[b]indole backbone, (+)‐ and (–)‐spondomine (1a/1b), were isolated from a cultured sponge Tedania anhelans. A semi‐synthesis was employed to obtain 1a/1b and the other four stereoisomers 1c—1f. Their structures were determined by spectroscopic analysis, single‐crystal X‐ray, and quantum chemical calculations. Six stereoisomers differ in bioactivity according to their absolute configurations. Especially, (+)‐spondomine (1a) displayed cytotoxicity against the K562 cell line and exhibited stronger Wnt and HIF1 dual signaling inhibitory activity at 5 μmol/L than the positive control, which offers an exciting starting point for further investigations. All stereoisomers significantly promoted angiogenesis and showed moderate anti‐inflammation in zebrafish. A quantum chemical calculation and deuteration experiment were applied to unveil the reaction mechanism which guides the synthesis of the target compounds.
Five new furanobutenolide-derived C 19 -norcembranoid diterpenes, sinudenoids A−E (1−5, respectively), were isolated from the soft coral Sinularia densa. Sinudenoid A (1) possesses an uncommon 5/5/11-fused tricyclic ring system. Sinudenoids B−D (2−4, respectively) share the same tetracyclic 5/5/6/6 ring system but represent two kinds of new skeletons. Sinudenoid E ( 5) is the second compound with the rare 8/8 bicyclic carbon core. A plausible biosynthesis pathway for compounds 1−6 is proposed. Compound 5 exhibits strong antiinflammatory activity in the zebrafish model.
Five new cembranes, named sarcoeleganolides C–G (1–5), along with three known analogs (6–8) were isolated from soft coral Sarcophyton elegans collected from the Yagong Island, South China Sea. Their structures and absolute configurations were determined by extensive spectroscopic analysis, QM-NMR, and TDDFT-ECD calculations. In addition, compound 3 exhibited better anti-inflammation activity compared to the indomethacin as a positive control in zebrafish at 20 μM.
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