Bioactive Limonoid Constituents of Munronia henryi

Abstract

Fourteen new limonoids, munronins A-N (1-14), and eight known limonoids (15-22) were isolated from the whole plants of Munronia henryi. The structures of the new compounds were elucidated by 2D NMR spectroscopy and mass spectrometry, and the structure of 8 was confirmed by single-crystal X-ray diffraction analysis. Compound 1 represents the first limonoid found with a novel 7-oxabicyclo[2.2.1]heptane moiety produced by incorporating C-11 and C-14 via an oxygen atom. All compounds were evaluated for their anti-tobacco mosaic virus (TMV) activity and in vitro cytotoxicity against the human cancer HL-60, SMMC-7721, A-549, MCF-7, and SW-480 cell lines. Among them, compounds 2, 8, 9, 10, 11, 12, 18, and 20 showed significant anti-TMV activity, with IC50 values in the range 19.6-44.4 μg/mL. Compounds 1 and 18 exhibited cytotoxic effects for all five cancer cell lines, with IC50 values between 0.4 and 4.8 μM.

Diverse Ring‐seco Limonoids from Munronia unifoliolata and Their Biological Activities

“…The 1 H NMR spectrum (Table 1) exhibited a β ‐substituted furan ring group ( δ H 7.32, 7.18, 6.20, each 1H, br s), six tertiary methyl groups ( δ H 0.77, 1.17, 1.59, 1.62, 1.87, 2.14, each 3H, s), a methoxy group ( δ H 3.66, 3H, s), and a terminal double bond group ( δ H 5.06, 5.03, each 1H, s), which strongly suggested that 1 was a peieurianin‐type limonoid. The 13 C NMR (Table 1) and HSQC data (Figure S5.1.3) of 1 were very similar to those of munronoid A ( 23 ), [ 18 ] a rings A, B‐ seco limonoid with the conjugated Δ 8,30 and Δ 14,15 double bonds. The planar structure of 1 was established by detailed 2D NMR analysis (Figure 2A), in which the methoxy group was located at C‐3 ( δ C 170.7) instead of C‐7 ( δ C 175.0) by the HMBC correlations of H 3 ‐1′ ( δ H 3.66) and H‐1 ( δ H 5.62) to C‐3.…”

“…[ 11 ] At present, there are only a few reports on the research of M. unifoliolata , but a large number of limonoids with significant anti‐inflammatory, antimicrobial, and anti‐TMV biological activities have been isolated from its genus. [ 12‐19 ] In order to understand the main and active ingredients of M. unifoliolata , the systematic extraction and separation of dichloromethane extract, the main anti‐inflammatory active portion of the whole plants (IC 50 = 17.9 ± 4.6 μmol/L), were carried out in our current research. This resulted in isolation of twenty‐two new limonoids ( 1 — 22 ), including rings A, B‐ seco , ring A‐ seco , and ring‐intact types.…”

Natural product sciences: an integrative approach to the innovations of plant natural products

“…However, those with alkynyls usually show potent bioactivity. This may be critical to the anti-TMV and SAR activation activity of munronin O because munronin O is the most potent one among this series of munronins A-V (Yan et al, 2015). It was suggested that the epoxy group is indispensable to the bioactivity of munronin O as well, which was supported by the observation that munronoid O, an epoxy limonoid among munronoids A-O, showed stronger anti-TMV activity than the positive control ningnanmycin (Ge et al, 2012a;Ge et al, 2012b).…”

Natural Products Research in China From 2015 to 2016

“…Munronins B ( 406 ) and H–L ( 407 - 411 ) showed anti-TMV activities with IC 50 values ranging from 19.6 to 44.4 μg/mL (ningnanmycin, 44.6μg/mL). Munronin A ( 412 ) exhibited cytotoxic effects on HL-60 and SW480 cells with IC 50 values of 0.44 and 0.86 μM, respectively (Yan et al, 2015b ). Seven novel daphnane diterpenoids, stelleralides D–J, were obtained from the roots of Stellera chamaejasme (Baotou, Inner Mongolia, China).…”