Four new depsidones, mollicellins O–R (compounds 1–4), along with three known compounds 5–7, were isolated from cultures of the fungus Chaetomium sp. Eef-10, an endophyte isolated from Eucalyptus exserta. The structures of the new compounds were elucidated by analysis of the 1D and 2D NMR and HR-ESI-MS spectra. The known compounds were identified by comparison of their spectral data with published values. Compounds 1–7 were evaluated for antibacterial activities against Staphylococcus aureus (sensitive and resistant strains), Escherichia coli, Agrobacterium tumefaciens, Salmonella typhimurium, Pseudomonas lachrymans, Ralstonia solanacearum, Xanthomonas vesicatoria and cytotoxic activities against two human cancer cell lines (HepG2 and Hela). Mollicellin H (6) displayed best antibacterial activity, with IC₅₀ values of 5.14 µg/mL against S. aureus ATCC29213 and 6.21 µg/mL against S. aureus N50, MRSA, respectively. Mollicellin O (1) and mollicellin I (7) also exhibited antibacterial activities against S. aureus ATCC29213 and S. aureus N50. Mollicellin G (5) was active against both two human cancer cell lines, with IC₅₀ values of 19.64 and 13.97 µg/mL while compounds 6 and 7 only showed cytotoxic activity against one cell line. In addition, mollicellin O (1) showed antioxidant activity based on DPPH radical scavenging, with an IC₅₀ value of 71.92 µg/mL.

Sandalwood (Santalum album L.), as one of the most valuable trees in the world, is known for its expensive essential oil from heartwood that can be used in perfumery and pharmaceuticals. Because of its high value, sandalwood has been increasingly planted in southern China over the last two decades. Since 2012, a severe wilt disease has been discovered on sandalwood in several commercial plantations in Dongguan, Guangdong province. Typical symptoms included leaf browning and wilting, withered and died branches, and discolored vascular tissues at the bases of dead or dying branches and stems. Under suitable conditions (with 30-35˚C air temperature and 65-95% relative humidity), the disease incidence could increase rapidly to 60% in a plantation. Twelve fungal isolates were isolated from the internal stem bases of five diseased sandalwood trees, and consistently identified as Neofusicoccum parvum according to their morphological characteristics (Crous et al. 2006). Cultures of single-conidial isolate grew at an average rate of 7.9 mm per day on PDA at 28 ˚C in the dark. Colonies on PDA were white at the early stage, and turned gray to black after 5 days. Pycnidia were produced on 2% water agar embedded with sterilized pine needles (Pinusmassoniana) at 28 ˚C under near UV light for 25 days. Conidia were hyaline, one-celled, smooth, fusiform to ellipsoidal, with an average length (L) of 16.3μm (from 11.0 to 21.2μm), an average width (W) of 5.7μm (from 4.4 to 7.2μm), and a L/W ratio of 2.86 (n = 50). Sequences of the internal transcribed spacer (ITS) regions amplified with primers ITS1F/ITS4 (Gardes and Bruns, 1993; White et al., 1990) from two randomly selected isolates were deposited in GenBank (KP701781 and KP701782). Both of the sequences were 99% identical to those of N. parvum (GenBankJQ411396.1 and GU066716.1) by a BLAST query. The two isolates were also used for artificial inoculation of one-year-old potted healthy S. album plants. Briefly, the plants were scratched at the bases of the stems with a fine scalpel to generate some wedge-shaped wounds (1cm in length), and seven-day-old hyphae grown on PDA (1cm in diameter) were placed on the wounds. The control stems were inoculated with sterile PDA of the same sizes. All inoculations were sealed with wet cotton wool and wrapped with sealing film for 48h to prevent drying. Plants were placed into an incubator with 14-h photoperiod and 90% relative humidity at 30℃. Each treatment was carried out with ten plants. Symptoms developed on the N. parvum isolate inoculated plants after about 30 days were similar to those observed on naturally infected plants, with dark vascular tissues and an average lesion length of 11.3±0.9 mm; while the control plants remained completely healthy. In addition, N. parvum was successfully re-isolated from the artificially inoculated plants. N. parvum has been reported to cause dieback and canker in a wide range of fruit crops, including Juglans sinensis (Cheon et al. 2013) and Vitis heyneana (Wu et al. 2014). To our knowledge, this is the first report of N. parvum causing wilt and stem rot on S. album.

Archidendron clypearia (Jack) Benth. (common name: Monkey-pod) is a perennial arbor tree belonging to the family Fabaceae. It is used to produce a traditional medicine to treat a variety of heat to...