*3.5. X-Ray Crystallographic Analysis of Compounds* **3** *and* **6**

All crystallographic data were collected on an Agilent Xcalibur Eos Gemini CCD plate diffractometer, using graphite monochromatized Cu/Kα radiation (λ= 1.54178 Å) [25]. The data were corrected for absorption by using the program SADABS [26]. The structures were solved by direct methods with the SHELXTL software package [27]. All nonhydrogen atoms were refined anisotropically. The H atoms were located by geometrical calculations, and their positions and thermal parameters were fixed during the structure refinement. The structure was refined by full-matrix least-squares techniques [28].

*Crystal data for compound* **3***:* C12H22O4, F.W. = 230.30, Orthorhombic space group P2(1)2(1)2(1), unit cell dimensions *a* = 5.4655(4) Å, *b* = 5.5812(6) Å, *c* = 41.275(3) Å, *V* = 1259.06(19) Å3, α =β =γ = 90◦, *Z* = 4, *d*calcd = 1.215 mg/m3, crystal dimensions 0.40 <sup>×</sup> 0.28 <sup>×</sup> 0.10 mm3, <sup>μ</sup> = 0.734 mm–1, *F*(000) = 504. The 2385 measurements yielded 1827 independent reflections after equivalent data were averaged, and Lorentz and polarization corrections were applied. The final refinement gave *R*<sup>1</sup> = 0.0487 and w*R*<sup>2</sup> = 0.0970 (*I* > 2σ(*I*)). The Flack parameter was 0.0 (5) in the final refinement for all 1827 reflections with 147 Friedel pairs.

*Crystal data for compound* **6***:* C12H20O4, F.W. = 228.13, Orthorhombic space group P2(1)2(1)2(1), unit cell dimensions *a* = 5.5217(5) Å, *b* = 7.6778(7) Å, *c* = 28.947(2) Å, *V* = 1227.17(19) Å3, α =β =γ = 90◦, *Z* = 6, *d*calcd = 1.236 mg/m3, crystal dimensions 0.35 <sup>×</sup> 0.24 <sup>×</sup> 0.16 mm3, <sup>μ</sup> = 0.752 mm–1, *F*(000) = 496. The 5282 measurements yielded 2081 independent reflections after equivalent data were averaged, and Lorentz and polarization corrections were applied. The final refinement gave *R*<sup>1</sup> = 0.0727 and w*R*<sup>2</sup> = 0.1620 (*I* > 2σ(*I*)). The Flack parameter was 0.5 (7) in the final refinement for all 2081 reflections with 150 Friedel pairs.

#### *3.6. Acetylation of Compounds* **3** *and* **4**

To 5 μmol samples of compound **3** or **4** in glass-stoppered flask were added 400 μL dichloromethane, then excess amount of triethylamine was added. Drip 20 μmol of acetylchloride slowly into the flask in ice bath and keeping the reaction for 12 h. Then stop the reaction by adding 20 μL of water into the flask. The progress of the reaction was monitored by TLC analysis. The resulting reaction mixture was extracted with dichloromethane (2 × 400 μL), dried with Na2SO4, and concentrated in vacuo to obtain the product.

#### *3.7. Antimicrobial Assay*

Antimicrobial evaluation against two human pathogens (*Escherichia coli* EMBLC-1, *Staphylococcus aureus* EMBLC-2) and ten aquatic pathogens (*Aeromonas hydrophilia* QDIO-1, *Edwardsiella ictarda* QDIO-9, *E. tarda* QDIO-2, *Micrococcus luteus* QDIO-3, *Pseudomonas aeruginosa* QDIO-4, *Vibrio alginolyticus* QDIO-5, *V*. *anguillarum* QDIO-6, *V*. *harveyi* QDIO-7, *V*. *parahaemolyticus* QDIO-8, and *V*. *vulnificus* QDIO-10), as well as 15 plant-pathogenic fungi (*Alternaria solani* QDAU-1, *Bipolaris sorokiniana* QDAU-5, *Ceratobasidium cornigerum* QDAU-6, *Colletotrichum glecosporioides* QDAU-2, *Coniothyrium diplodiella* QDAU-7, *Fusarium graminearum* QDAU-4, *F. oxysporum* f. sp. *cucumerinum* QDAU-8, *F*. *oxysporum* f. sp. *momodicae* QDAU-9, *F*. *oxysporum* f. sp. *radicis lycopersici* QDAU-10, *F*. *solani* QDAU-11, *Glomerella cingulate* QDAU-12, *Helminthosporium maydis* QDAU-15, *Penicillium digitatum* QDAU-14, *Physalospora piricola* Nose QDAU-15, and *Valsa mali* QDAU-16), was carried out by the 96-well microtiter plates assay [29]. The pathogens were obtained from the Institute of Oceanology, Chinese Academy of Sciences. Chloramphenicol and amphotericin were used as positive controls for bacteria and fungi, respectively. All of the tested compounds and controls were dissolved in DMSO.
