Dimeric Acylphloroglucinol Derivatives with New Skeletons from Leptospermum scoparium

Abstract

Leptosparones A–F (1–6), six new dimeric acylphloroglucinol derivatives with unprecedented skeletons, were isolated from Leptospermum scoparium. Compounds 1–3 and 5–6 are phenylpropanoyl‐phloroglucinol dimers, while 4 is a phenylpropanoylphloroglucinol‐isovalerylphloroglucinol hybrid. Structurally, these compounds represent the first examples of dimeric phloroglucinols with unprecedented C(7′)−C(8) linkage between the phloroglucinol core and the acyl side chain. Their structures were elucidated by comprehensive analyses of spectroscopic data, single crystal X‐ray diffraction and chemical calculations. In addition, all compounds showed inhibitory effects against α‐glucosidase with IC50 values ranging from 39.5 to 186.8 μM.

Five New Phenylpropanoyl Phloroglucinol Derivatives from Leptospermum scoparium

“…The IR spectrum of 5 displayed the characteristic absorptions for benzene ring (1608 and 1465 cm −1 ), and the UV spectrum showed absorption maxima at 256, 291, and 327 nm. The 1 H and 13 C‐NMR data of 5 showed very similar signals to those of leptosparone D, [15] the mainly difference was that the isovaleryl moiety located at C(1′) was replaced by a 2‐methyl butyryl group in 5 , which was evidenced by the spin system (from H‐10′ to H‐11′) observed in the 1 H‐ 1 H COSY spectrum and HMBC between H‐9′/H‐11′ and C‐7′. The absolute configuration of 5 was defined as 8′ R by comparing the experimental and calculated ECD spectra ( Figure 4).…”

“…The IR spectrum displayed the presence of carbonyl (1738 cm À 1 ) and benzene ring (1607 and 1445 cm À 1 ). The 1D NMR data of 4 highly resembled with those of leptosparone C, [15] with the slight difference of C(5) caused by the absence of the methoxy unit and the presence of a hydroxy group located at C (6) [δ H 11.99 (1H, s)] in 4. The above deduction was supported by the HMBCs between OH-6 and C(1)/C(5)/C (6).…”

“…[14] Our previously study on L. scoparium had discovered several bioactive phloroglucinol derivatives. [8,15] During our ongoing investigation of phloroglucinol constituents from the title plant, five phenylpropanoyl phloroglucinol derivatives, leptosperols CÀ G (1 -5) (Figure 1), were isolated from the leaves of L. scoparium. Structurally, compounds 1 -3 are phenylpropanoyl phloroglucinol-sesquiterpene adducts with new carbon skeletons.…”

“…Leptospermum scoparium (Myrtaceae), well‐known as the source plant of Manuka honey, is an ever green shrub native to New Zealand and has been used as a Maori medical plant for the treatment of colds, dysentery, and urinary [14] . Our previously study on L. scoparium had discovered several bioactive phloroglucinol derivatives [8,15] . During our ongoing investigation of phloroglucinol constituents from the title plant, five phenylpropanoyl phloroglucinol derivatives, leptosperols C−G ( 1 – 5 ) ( Figure 1), were isolated from the leaves of L. scoparium .…”

Identification of Potential Antiviral Hops Compounds against Chikungunya Virus

“…Meanwhile, phloroglucinols could couple with terpenes, triketones, or other phloroglucinols to build more complex natural products, which exhibit multiple biological activities. Structures with unprecedented skeletons, such as phenylpropanoyl–phloroglucinol dimers, were isolated from Leptospermum scoparium (Myrtaceae), well known as the source of manuka honey, an evergreen shrub distributed widely in New Zealand [ 26 ]. By having similar structure, we are making the hypothesis that dimers could be formed after interaction between β - and α -acids from hops.…”