Chemical Constituents from Leaves of Camellia nitidissima and Their Potential Cytotoxicity on SGC7901 Cells

Objective To isolate and identify the bioactive phytochemicals from the leaves of Camellia nitidissima. Methods The chemical constituents were isolated and purified by repeated silica gel, Sephadex LH-20, MCI gel columns, recrystallization, and semi-preparative HPLC techniques. The chemicl structures of these compounds were identified on the basis of spectral data including NMR and MS. Then quorum sensing inhibition （QSI） activities of these compounds were tested using Chromobacterium violaceum CV026 as the bioindicator strain. The antitumor activities of these compounds were measured using SGC7901 as cell proliferation and cytotoxicity. Results cx-Spinasteryl-I^-D-glucopyranoside （1）, stigmasta-7,22-diene-3-O-[c^-L-arabinopyranosyl （1 -2）]-β-D-galactopyranoside （2）, kaempferol 3-O-[2-O-（trans-p-coumaroyl）-3-O-α -D-glucopyranosyl]-α-D-glucopyranoside （3）, aromadendrin （4）, catechin （5）, phlorizin 4＇-O-β-D-glucopyranoside （6）, （3R,6R,7Lg-3-hydroxy-4,7-megastigmadien- 9-one （7）, dodecanoic acid （8）, 3α-acetoxy-20-1upanol （9）, and 3β,6α- trihydroxyolean- 7-one （1 0） were successively isolated from the leaves of C. nitidissima. Unfortunately, these compounds had no QSI activity. Based on Cell Counting Kit-8 （CCK-8） assay, compound 10 showed the best anti-tumor activity or all compounds （ICs0 = 91.7 μg/mL）. Conclusion Apart from compounds 4 and 5, other eight compounds are reported in this plant for the first time. All compounds show no QSI activity, compound 10 shows potential cytotoxic activity on SGC7901 cells in vitro.

Quorum sensing inhibition of hordenine analogs on Pseudomonas aeruginosa and Serratia marcescens

Quorum sensing(QS)plays an essential role in virulence factor production,biofilm formation,and antimicrobial resistance.As a potent QS inhibitor,hordenine can inhibit both QS and biofilm formation in Pseudomonas aeruginosa and Serratia marcescens.In this work,we tested the QS inhibitory potential of 27 hordenine analogs against QS and biofilm formation in P.aeruginosa and S.marcescens.Among the tested analogs,seven(12,28,27,26,2,23,and 7)exhibited strong QS inhibitory activity against P.aeruginosa,five of which(12,28,27,26,and 2)showed better inhibitory activity than hordenine.In addition,seven analogs(28,12,23,7,26,2,and 27)exhibited better biofilm inhibition against P.aeruginosa than hordenine.Four analogs(7,28,2,and 12)showed QS inhibitory activity against S.marcescens,two of which(7 and 28)demonstrated better inhibitory activity than hordenine.Furthermore,analog 7 showed similar biofilm inhibition against S.marcescens as hordenine.Structure-activity relationship(SAR)analysis indicated that the inhibitory activities of the analogs were related to four factors,i.e.,carbon chain length,presence or absence of anα,β-C=C bond,amino group with/without lipophilic group,such as methyl group,and hydroxyl group in benzene ring.