Investigation On The Secondary Metabolites Of Caesalpinia Pulcherrima And Rhododendron Capitatum Maxim And Their Biological Activities

The chemical constituents and their bioactivities of C.pulcherrima?Caesalpinia?and R.capitatum Maxim?Rhododendron?were studied.43 compounds were isolated by chromatographic methods?positive phase silica gel,reversed phase silica gel,Sephadex LH-20,MCI,HPLC?,and their structures including relative stereochemistry were elucidated on the basis of comprehensive spectral methods(¹H-NMR,¹³C-NMR,DEPT,COSY,HSQC,HMBC,NOESY,HRESIMS,IR,UV,ORD,ECD).Thirty-one compounds were isolated and identified from the stem of Ceasalpinia pulcherrima,among which sixteen new cassane diterpenes,caesalpulcherrin A-P?1-16?,one new natural product?17?,and fourteen known ones?18-31?.Most of these compounds displayed significant antifeedant activity against the generalist insect herbivore?Mythimna separate,Plutella xylostella?,compounds isovouacapenol C?19?and pulcherrin N?31?exhibited significant effects against M.separate with EC₅₀ values of 3.43?g/cm²and 4.20?g/cm²,respectively.Meanwhile,12-demethyl neocaesalpin F?29?and pulcherrimin C?30?exhibited antifeedant activity against P.xylostella with EC₅₀ values of 3.05?g/cm²and 4.00?g/cm².In addition,caesalpulcherrin B?2*?and caesalpulcherrin D?4*?performed significant NO production inhibition in LPS-induced BV-2 cells with an IC₅₀ value of 1.3?M and 0.3?M,which were better than the positive control quercetin of 2.4?M.It is worth mentioning that cassane diterpene was tested for the first time for its cytotoxic activity on U87 cell growth,neocaesalpin G?25?displayed the inhibitory activity with IC₅₀ value of10.7?M.Besides,compounds 6?-cinnamoyl-7?-hydroxy-vouacapen-5?-ol?28?and pulcherrimin C?30?showed the?-glucosidase inhibitory rate of 77.41%and 85.50%at 10?M.Twelve known?1-12?ones were isolated from the stem of Rhododendron capitatum Maxim.Compounds 3?-acetoxy-dammara-20,24-diene?1?and dendrapanoxide?2?displayed weak antifeedant activity against the M.separate with EC₅₀ values of 48.95?g/cm²and31.54?g/cm²,respectively.Meanwhile,8-methylnaringenin?11?showed the inhibitory activity on NO production in LPS-stimulated BV-2 cells with the rate of 74.2%at 10?M.