legal expenses of approximately $174,000 and the write-off of certain patent costs and an increase in accounting fees and other consulting fees of approximately $26,000.
Selling, General and Administrative Expenses:
Selling, general and administrative expenses were approximately $7,724,000 for the three months ended June 30, 2023, as compared to approximately $8,439,000 for the three months ending June 30, 2022, a decrease of $715,000. This decrease was due to a decrease in non-cash stock compensation expense of approximately $191,000, a decrease in travel and entertainment expenses of approximately $99,000, a decrease in public relations costs of approximately $96,000, a decrease in advertising costs of approximately $82,000, a decrease in royalty expense of approximately $73,000, a decrease in commercial insurance of approximately $56,000, a decrease in salaries, commissions and related costs of approximately $43,000, and a decrease in other general and administrative expenses of approximately $75,000.
Gain (Loss) on Foreign Currency Transactions:
For the three months ended June 30, 2023, the gain on foreign currency transactions was approximately $415,000 as compared to a loss of approximately $2,523,000 for the three months ended June 30, 2022. The 2023 gain was directly related to the increase in the spot exchange rate of the Euro to the U.S. dollar at June 30, 2023 as compared to March 31, 2023. The spot exchange rate of the Euro to the U.S. dollar was $1.091 per Euro at June 30, 2023, as compared to $1.086 per Euro at March 31, 2023. The 2022 loss was directly related to the decrease in the spot exchange rate of the Euro at June 30, 2022 as compared to March 31, 2022. The spot exchange rate of the Euro to the U.S. dollar was $1.05 per Euro as of June 30, 2022, as compared to $1.11 per Euro as of March 31, 2022.
Comparison for the six months ended June 30, 2023 and 2022:
Revenues:
Revenue from product sales was approximately $15,982,000 for the six months ended June 30, 2023, as compared to approximately $15,255,000 for the six months ended June 30, 2022, an increase of approximately $727,000, or 5%. Distributor sales increased by approximately $597,000, or 10%. Overall direct sales increased by approximately $130,000, or 1%. The change in the exchange rate of the Euro to U.S. dollar did not have a significant impact on product sales during the six months ended June 30, 2023.
Grant income was approximately $2,888,000 for the six months ended June 30, 2023 as compared to approximately $1,932,000 for the six months ended June 30, 2022, an increase of approximately $956,000 or 49%. During the six months ended June 30, 2022, our research and development employees were either deployed to work-from-home status or reassigned to assist in activities related to increasing the production of CytoSorb. In 2023, research and development employees were assigned exclusively to grant and other research and development activities.
Total revenues were approximately $18,870,000 for the six months ended June 30, 2023, as compared to total revenues of approximately $17,187,000 for the six months ended June 30, 2022, an increase of approximately $1,683,000, or 10%.
Cost of Revenues:
For the six months ended June 30, 2023 and 2022, cost of revenue was approximately $7,396,000 and $5,828,000, respectively, an increase of approximately $1,568,000. Product cost of revenue was approximately $4,624,000 and $4,008,000, respectively, for the six months ended June 30, 2023 and 2022, an increase of approximately $616,000 and grant cost of revenue increased by approximately $952,000. These increases were due primarily to an increases in both product sales and grant revenue. Product gross margins were approximately 71% for the six months ended June 30, 2023 and approximately 74% for the six months ended June 30, 2022. The reduction in product gross margin is due primarily to start-up costs associated with our new manufacturing facility in Princeton, New Jersey during the six months ended June 30, 2023.
Research and Development Expenses:
For the six months ended June 30, 2023, research and development expenses were approximately $7,883,000 as compared to research and development expenses of approximately $8,427,000 for the six months ended June 30, 2022, a decrease of approximately $544,000.