Bioassay-Guided Isolation of <i>cis</i>-Clerodane Diterpenoids and Monoglycerides from the Leaves of <i>Solidago gigantea</i> and Their Antimicrobial Activities
A previously undescribed <i>cis</i>-clerodane diterpenoid, diangelate solidagoic acid J (<b>1</b>), along with two known <i>cis</i>-clerodane diterpenoids, solidagoic acid C (<b>2</b>) and solidagoic acid D (<b>3</b>), as well as two known...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
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| Series: | Plants |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2223-7747/14/14/2152 |
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| Summary: | A previously undescribed <i>cis</i>-clerodane diterpenoid, diangelate solidagoic acid J (<b>1</b>), along with two known <i>cis</i>-clerodane diterpenoids, solidagoic acid C (<b>2</b>) and solidagoic acid D (<b>3</b>), as well as two known unsaturated monoacylglycerols, 1-linoleoyl glycerol (<b>4</b>) and 1-α-linolenoyl glycerol (<b>5</b>), were isolated and characterized from the <i>n</i>-hexane leaf extract of <i>Solidago gigantea</i> (giant goldenrod). Compounds <b>2</b>–<b>5</b> were identified first in this species, and compounds <b>4</b> and <b>5</b> are reported here for the first time in the <i>Solidago</i> genus. The bioassay-guided isolation procedure included thin-layer chromatography (TLC) coupled with a <i>Bacillus subtilis</i> antibacterial assay, preparative flash column chromatography, and TLC–mass spectrometry (MS). Their structures were elucidated via extensive spectroscopic and spectrometric techniques such as one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and high-resolution tandem mass spectrometry (HRMS/MS). The antimicrobial activities of the isolated compounds were evaluated by a microdilution assay. All compounds exhibited weak to moderate antibacterial activity against the Gram-positive plant pathogen <i>Clavibacter michiganensis</i>, with MIC values ranging from 17 to 133 µg/mL, with compound <b>5</b> being the most potent. Only compound <b>1</b> was active against <i>Curtobacterium flaccumfaciens</i> pv. <i>flaccumfaciens</i>, while compound <b>3</b> demonstrated a weak antibacterial effect against <i>B. subtilis</i> and <i>Rhodococcus fascians</i>. Additionally, the growth of <i>B. subtilis</i> and <i>R. fascians</i> was moderately inhibited by compounds <b>1</b> and <b>5</b>, respectively. None of the tested compounds showed antibacterial activity against Gram-negative <i>Pseudomonas syringae</i> pv. <i>tomato</i> and <i>Xanthomonas arboricola</i> pv. <i>pruni</i>. No bactericidal activity was observed against the tested microorganisms. Compounds <b>2</b> and <b>3</b> displayed weak antifungal activity against the crop pathogens <i>Bipolaris sorokiniana</i> and <i>Fusarium graminearum</i>. Our results demonstrate the efficacy of bioassay-guided strategies in facilitating the discovery of novel bioactive compounds. |
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| ISSN: | 2223-7747 |