Antifungal activity of protein hydrolysates from Thai Phatthalung Sangyod rice (Oryza sativa L.) seeds

Research (Published online: 13-05-2023)

14. Antifungal activity of protein hydrolysates from Thai Phatthalung Sangyod rice (Oryza sativa L.) seeds

Juthatip Jeenkeawpieam, Prawit Rodjan, Sittiruk Roytrakul, Kritsada Pruksaphon, Watcharapong Mitsuwan, Noppharat Tanthanathipchai, Chaiwat Boonkaewwan, Irma Tedja, and Monsicha Pongpom

Veterinary World, 16(5): 1018-1028

Juthatip Jeenkeawpieam: Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat 80160, Thailand; One Health Research Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand.

Prawit Rodjan: School of Agricultural Technology and Food Industry, Walailak University, Nakhon Si Thammarat, 80160, Thailand.

Sittiruk Roytrakul: Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, Pathum Thani 12120, Thailand.

Kritsada Pruksaphon: Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.

Watcharapong Mitsuwan: Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat 80160, Thailand; One Health Research Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand.

Noppharat Tanthanathipchai: Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat 80160, Thailand.

Chaiwat Boonkaewwan: Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat 80160, Thailand; One Health Research Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand.

Irma Tedja: Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia.

Monsicha Pongpom: Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.

doi: 10.14202/vetworld.2023.1018-1028

Article history: Received: 24-12-2022, Accepted: 10-04-2023, Published online: 13-05-2023

Corresponding authors: Monsicha Pongpom

E-mail: monsicha.p@cmu.ac.th

Citation: Jeenkeawpieam J, Rodjan P, Roytrakul S, Pruksaphon K, Mitsuwan W, Tanthanathipchai N, Boonkaewwan C, Tedja I, and Pongpom M (2023) Antifungal activity of protein hydrolysates from Thai Phatthalung Sangyod rice (Oryza sativa L.) seeds, Veterinary World, 16(5): 1018-1028.

Abstract

Background and Aim: Fungal zoonoses are an economic and public health concern because they can cause various degrees of morbidity and mortality in animals and humans. To combat this issue, alternative natural antifungals, such as products derived from rice protein hydrolysates or rice antifungal protein/peptide are being considered because they are highly bioactive and exhibit various functional properties. Thailand is a leading rice producer and exporter. Among the various cultivated rice varieties, Sangyod rice (Oryza sativa L.) is exclusively indigenous to Thailand’s Phatthalung province; it has a Thai geographical indication tag. Here, we investigated whether the Phatthalung Sangyod rice seeds have bioactive antifungal peptides.

Materials and Methods: Antifungal activity in four Sangyod rice seed extracts (SYPs) – namely, (1) the crude lysate, SYP1; (2) the heat-treated lysate, SYP2; (3) the heat- and pepsin digested lysate, SYP3; and (4) the heat- and proteinase K-digested lysate, SYP4 – was analyzed. Protein concentrations in these SYPs were determined using the Bradford assay. The total phenolic compound content was determined using the modified Folin–Ciocalteu method in a 96-well microplate. Then, the SYP protein pattern was determined using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Subsequently, using the agar well diffusion method, the antifungal properties of these SYPs were tested against ten medically important pathogenic fungi. The minimal inhibitory concentration (MIC) and minimal fungicidal concentration values were determined for the active SYPs – SYP2-4. Finally, the clinical safety of SYP4 was determined using a hemolytic assay (using canine red blood cells [RBCs]).

Results: The crude lysate SYP1 did not show antifungal activity against any of the ten tested pathogenic fungi. Surprisingly, hydrolysates SYP2, SYP3, and SYP4 displayed antifungal properties against the ten tested pathogenic fungi. Thus, heat and enzymatic hydrolysis seem to transform the bioactivity of the crude protein extract – SYP1. Further, SYP4 shows the most effective antifungal activity. It completely inhibited Cryptococcus neoformans, Talaromyces marneffei yeast phase, Trichophyton mentagrophytes, and Trichophyton rubrum. A partial inhibitory action on Candida albicans and Microsporum gypseum was possessed while showing the least activity to C. neoformans. SYP4 was nontoxic to canine RBCs. Hemolysis of canine RBCs was undetectable at 1 × MIC and 2 × MIC concentrations; therefore, it can be safely used in further applications.

Conclusion: These results indicate that heat and proteinase K hydrolyzed SYP is a very potent antifungal preparation against animal and human fungal pathogens and it can be used in future pharmaceuticals and functional foods.

Keywords: antifungal peptide, Oryza sativa L., Phatthalung Sangyod rice, protein hydrolysate, Thai rice seed, zoonoses.